Refurbishment of 3 old battery chargers, from flea market...
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- Опубліковано 25 вер 2016
- I got three old chargers from flea markets. One is very old (probably 1930's), one is from the 70's and there is one relatively new, probably late 80's.
All of them needed repairs, but the prices were $5, $5, and $1....
In this video I replace selenium rectifiers with diode bridge; cut apart transformer core and re-weld, and clean up a filthy charger that had corrosion problems.
FOLLOW-UP: New meter covers installed!
• Battery Charger Follow... - Авто та транспорт
We have found that plain epoxy glue works well as an insulator. Can simply be applied onto open terminals, and allowed to dry. The self-mixing 5-minute works well, but heat it up to make in fluid. then it runs into cracks and holes. Been using this for pond heaters for decades.
Another difference between selenium diodes and silicon (FWB) is the voltage drop across the diodes. Selenium is usually about 3 volts and silicon is about 0.7 so the output voltage with the silicon will be a little higher.
The reason the thermal fuse was buried in the windings is to sense the temperature of the windings in case something was to happen.
This is common in alot of devices to protect from fire due to transformer overheating. It is also done on motors for the same reason.
As it happens, I rebuilt my old 10 amp charger based entirely on your video. And it's working great. I had no idea what that old selenium diode arrangement was. But your testing proved that my "diode" is ok for now. All it was was a rotted cable. But, Now I have learned how to fix old (but good) battery chargers. Thanks a lot! Awesome vid, by the way.
Very glad you were able to correct your charger problems based on this video!
Good job brother! I’ve been waiting for someone that actually explains wtf we’re looking at and how to diagnose these little buggers. I have a stack of these in my shop to repair now. 😊
this is one of the best youtube uses i've ever seen!! Thanks for sharing your expertise.
I really appreciate this video. I’ve recently come to appreciate manual chargers, and still have a lot to learn about recognizing the different types of transformers and rectifiers inside them, but this helps a lot.
I'm glad the video helped you. There's a whole lot to be said about older, simpler equipment of all types. Needs to be kept going. Trust me.....
Believe, I’m right there with ya, especially since manual chargers have mysteriously disappeared from stores
Thanks for sharing your knowledge and craftsmanship. I have Schumacher that died unexpectedly recently. I do believe and support repair if possible, that which is broken.
Your video helps on many levels. Your electric knowledge is quite extensive, by the types of repairs you do. Thanks again.
One thing to be mindful of is that the selenium rectifier has a considerably higher forward voltage drop than does the silicon one. This means that the transformer output is higher to compensate, and the design would be such that it'll output rated current into a heavily discharged battery, and taper off as the charge level (and thus voltage) comes up. It'll work fine with the silicon unit, but you wouldn't want to leave it on too long as it will not taper off like it should. It will still output charging current, even when the battery voltage is well up.
Really enjoyed your video and was impressed with your thorough approach and understanding of the properties of electricity and battery charging. It's pleasing and informative to watch someone who has a hands-on technical grasp of what they're doing. You've obviously have had serious training in this arena. Thanks for taking the time to share.
Hi Jiffer. Thanks so much for the compliment! I do enjoy these sort of projects. :)
Thanks for showing us this. I have my Father's Woodward-Schumacher 4 amp charger from the 60's, Model WS84, still working, but a little crusty. It is very similar to your Schumacher 6 amp, but the cord does not have a grounded plug, so it must be from the late sixties. For more info on a 1 amp version of these search for "An Old Technician's Work Bench: One Amp Charger." He posts lots of details about it, such as a simplified schematic, info about selenium rectifiers, and shows a scope trace of the voltage from this half wave rectifier. His friend asked him about making his own charger, and there are tips on that too. Be sure to read the comments too.
I found this video after I lost track of the neutral on an old sears similar to the one featured . It helped me figure out what was going on and saved me $50 at harbour freight Thanks
Glad you were able to get it up and going!
I have my dad's old Sears 6V/12V charger. The cords were shot and I wanted to use the info from your video to rework it. I replaced the A/C power cord and put temporary jumpers in for the output. I got 12.1 volts and 6.0 volts with no load and a negative output from the diodes. When I hooked up to a 50W, 12V lamp the lamp works but the voltage drops to 9.4 volts. Time to rebuild.
I mounted a 25A/400V bridge rectifier on a heatsink, mounted it on a side wall, and moved the diode wires to the ac terminals on the bridge, connected my positive output cable to the meter and the negative cable to the negative terminal on the rectifier bridge. I set the voltage selector switch to 12V and plugged it in. I got 12.4 volts. I then moved the voltage selector switch to the 6V setting and VOILA! I got 18.3V
What in the world??? Any ideas?
Solved!
Went through the unit last night trying different things. There is a metal cased fuse that is connected to a bracket on the inside of the charger. It is connected using one of the two power lugs on the fuse. I removed it from the bracket and everything went to normal. Re-installed on the bracket and voltage went back above 18V.
I dug out a pair of fiber washers and found a spot on the bottom where the fuse assembly would fit. I sat the fuse assembly on top of the washers which insulated the metal case from the chargers body and I then hot glued it down, Works perfectly and almost looks like it was meant to be.
Glad you got it solved! Sorry I was unable to reply before you got the problem fixed. :)
Bridges vs. Diodes: If your charger only has only two diodes, look up center tap configuration transformers for use with rectifiers. For the Schumacher 6 amp charger in this video, the center tap goes to the ammeter, then to the positive clamp to the positive post on the battery, and the "outer" taps go to the two diodes, then to the negative clamp.
Super Cool video, Thanks for posting. I have a really old Sears similar to one you have here on vid but I'm fairly sure it's older. I want to use it for Electrolysis now so I'll look into this thing after watching your vid....Thanks Again!
Nice explanation of the transformer fix.
Nicely done and great video! Another disadvantage to those gimmicky new 'smart' chargers is that they only charge a battery that's low. If it's completely dead they just cycle off and consider the battery "unchargable". Those old transformer type chargers don't care, they'll keep trying even if it boils the cells dry. So they can be used to bring back a dead battery, the new ones will not.
This video should be some help to me too, I have an old Western Auto charger that doesn't function, you've given me some ideas what to look for.
Thanks!
Very hypnotic listening to your voice, I grew up watching Mr. Rodgers and listening to you brought me back in time to then. I'm curious what you do for a living. Your unintimidated manor would make you a wonderful educator.
Thanks Barrett. I also enjoyed Mr. Rodgers as well!
For my work, I am a commissioning engineer for a major power generation equipment manufacturer. I go on site where out custom built generators are being installed. My job is to do the wiring and PLC software integration work.
I do enjoy teaching others about old technology, though!
I said the same thing, very old school and brilliant explanation
I was thinking the same thing. His demeanor, and accent, reminds me very much of the actor that played “J.F. Sebastian”, the engineer in the movie “Blade Runner.”
Those internal thermal fuses are a time bomb waiting to destroy your charger. It's put there deliberately so you'll come buy a new one and help fill the landfills, and keep good jobs with people making new ones that weren't really needed. Insanity.
This is very true! A simple automatic thermal circuit breaker would be the cat's meow. Or as a last resort, a thermal fuse mounted in an accessible place against the outside of the winding, where it could be replaced.
wait til your car's blower relay goes out, always the same old thermal fuse. the relay on my Acura is almost 30 bucks.
I have my dad's old charger that is like your $1:00 unit. Still works great.
The most thorough well made and executed video I've seen.
Excellent work good sir
Thank you!
I picked up the same Electromite 6 amp charger on CL for $5. The selenium rectifiers are weak and output is around 2 amps, just like in this video. Now I know exactly what to do to upgrade it back to 6 amp output.
Good that you kept the integrity of the function in a safe engineering process, great news thx for sharing. 🇬🇧
Gimmiky applies to modern motor cars too. So much you can easily do without.
Totally agree with this!
Interesting layman approach…. Troubling shooting 101!
Its gotta be a great feeling to be able to repair something that others have given up on...Good going..
The issue is knowing the difference between what's repairable and what's a lost cause.
I found a vintage sears one at recycling center that had its wires cut off. Rewired it and it works pretty good except gauge doesn't work, but it checks out with meter.
Excellent video! Thanks for posting! You are extremely knowledgeable and do a great job explaining things! Please keep posting!
Я всегда говорил и буду говорить, что трансформаторное зарядное устройство самое надежное!
Спасибо автору канала за то, что подарили этим работягам новую жизнь!
very detailed repair process, this video earned yourself another subscription, thanks for the effort that must go into these
where do you get the little button diodes. I have looked for them on ebay, amazon other sites not sure if what I find are right. Looks like I need to small ones with red circle around.
Will a 8 amp 400V full wave bridge rectifier work? I have exactly the one you fixed with the internal fuse that caused so much trouble. Mine only needs diodes I think. I don't know how to wire the bridge into the charger.
Excellent information. Fixed my old Sears Battery Charger with no problem. Thanks David!
I have the exact same relic battery charger you have there it’s the one with the Mickey Mouse plastic cover over the meter bought brand new in 1970 and it works perfect still charging today and I mean today 👍🇺🇸⚡️
Thank you for sharing your time and vast knowledge you are so thorough .I have an old charger missing the guage on the front but when I put both leads on both wires for the guage I get 12.5 volts do I need a guage
Thanks so much for this very informative, and helpful video! I’ve definitely learned a few things from you in this video.
Hopefully you may have a couple minutes to answer a question here.. I have basically the same 10 Amp, dual rate, Schumacher charger as the last one you worked on in the video. But mine is an SE-40MA. The internal set up in mine only differs in that the circuit board is mounted horizontally (opposed to vertically), and the transformer is the same way. The one in your video has it mounted laying on its side.
My charger was working perfectly until the other day, when I accidentally touched the two battery clamps together with the unit plugged in with it set on Manual, and on the 12V setting. Which did cause a nasty little spark. After this happened, I could hear a slight humming coming from the unit. So I tested it with a multimeter, and the 12V circuit setting was only showing 1.04 V. Switched to the 6V setting, the hum goes away, and it shows 6.56V, which is normal.
Any advice on what your first thoughts are as to what may have gone south would be sincerely, and gratefully appreciated! Based on your video, I’m thinking it may be either the selector switch itself, or something on the board for the 12V side. Seems unlikely to me that it’s the winding fuse you pointed out, since the 6V side still works...
Anyway, thanks for any reply. Totally understand if you don’t. Liked and subbed anyway. Great video! 👍
Thank you for the comment. I don't know exactly how the voltage control board is made in these, but for it to work on the 6V setting but not on the 12V it would make me think that the rectifier and other major parts are working. There are two sections to the switch in this model. One changes the transformer tap, and the other changes the voltage control setpoint. You may indeed have a selector switch problem. I have had the clips touch on my charger as well, and it never damaged it.
Thanks so much for your reply! I’ve disassembled the switch, and it definitely has a bit of greenish white chalky corrosion all around the contact points on the board. The copper spring contact slides aren’t pretty either.
I’ll post back with the results. Regardless, I appreciate your time, and certainly don’t expect any further hand holding on this. If the switch isn’t the issue, I’ll keep going until I figure it out. I’m hell bent on fixing this thing now. 😂 Thanks again
@@MF-le7fp If I remember, the regulator board is made entirely of discrete components. If it is bad, it shouldn't be too hard to repair it.
Ok, so you were right. After taking out the switch, I cleaned it with electronic parts cleaner, then went over the copper slides, and the six contact points with a fine emery cloth. Hit it with compressed air to remove any fine dust left on it, and put it back in. 12V side now works, reading at 15.6V.
The one thing that isnt working now, is the analog amperage meter, which is pegged to the far left side of its housing. Possibly a bad shunt resistor? Which I thought was the tiny module you pointed out mounted to the center top of the back plate. But you didn’t refer to it as a shunt specifically.
Regardless, I have other ways of checking it’s output, so it’s not a big deal. Just glad it works now. Thanks again, man!
Very Good Job ! Excellent Job of Deciphering ! And Repairing and Explaining ! Thanks ! 👍
Thank you very much! Glad it helped!
I have a old Schumacher ,and old Sears,the sears was hooked up backwards ,once,how do I check it . and they both have been dropped. any suggestions . I wish I was as smart as you , so I could fix them,or least know if they working right. Thanks,I really like your video
Have you ever worked on a schumacher se-2151ma? i want to try and replace the rectifier with a diode bridge but there are 4 wires from the transformer and then a circuit board that is soldered to the rectifier...wasnt sure how i would go about replacing this. Any help is appreciated
So much more fun than a paint by number craft kit... THANKS
At 23:34 the way to safely insulate the connection I recommend Plasti Dip rubberized peelable coating.
Thanks For Sharing!
David, I have the 6 amp 6/12 volt Schumacher from the 70's in its original box. Made in USA. I also have the 10 amp Schumacher from 1999 made in Mexico also in pristine shape. Never thought much about these chargers as they always worked well. I used the 6 amp to charge my aircraft gell cell battery at my hanger. Interesting to see the internals.
I have a relatively new Schumacher that I think got left on the start mode. What would you guess would be the point of failure? I'm hoping it's just the diodes...
Thanks, and nice work!
Great info, now I have to find some MIA (Made In America) chargers!
My grandpa had a Schumacher a lot like, if not the same as, the the gray one you have there. It was always plugged in, I found it still plugged in after I bought the place. Now I’m curious if it still works. I’ll have to go check it out, it’s still where he had it, just unplugged.
Do the two white wires go on the AC on the bridge rectifier and the black wire on the - on the bridge rectifier
Thanks
Well done. This is a good work
How do you use a bridge rect in place of the two? Where did you put the CT?
Great job on the repairs! I like how that bridge rectifier turned out mounted to the heat-sink! I happen to have a similar charger to the 1st one (6a Schumacher) however mine is 2amp with the same selenium rectifier in it and glass tube breaker. I'm thinking it's only half wave and wondering if I were to put the same bridge rectifier you used in the in the 10amp unit? Should I look for a lower amperage bridge rectifier or is it ok to use anything above 2? An interesting thing to note is that my rectifier is fed from the negative or common side and through the breaker to the negative lead. The 6 & 12 vac taps go through the selector switch then out to the positive lead.
Wow interesting. Yours is probably a lot older! If yours doesn't have a center-tap transformer you'll need to use all 4 terminals on the full-wave bridge to get the same voltage you're needing.
I would use a rectifier over 2 amps, so that it won't get too hot.
Really appreciate this video. I have an older schauer 12v charger that I believe the selenium rectifier went bad in. There are 2 wires into it and 1 wire out... all the bridge rectifiers I have seen on amazon have four prongs. Would a four prong one work?
hello very good video. A question I ask myself. That it is the value of the diode bridge that you put on the 1° charger. Thank you for your response
Hi Gege. That first charger was a relatively low current model. I used the rectifier I had on-hand which was a 20 amp 500V device. It is a full-wave rectifier, however only 3 terminals and two of the internal diodes are used. This allows push-pull operation.
Can you give us the part number of that rectifier you used to replace the old selenium one on the 6 amp charger? I have the same charger from my grandfather and i want to keep it going. Thanks
I wish someone around Columbus Mississippi could fix these chargers. I have 2 that need fixing
Very good information! I have an Ever Start brand charger that looks exactly like the last charger. I almost threw it out because it was not charging one of my batteries, but I recently discovered that it was one of those "smart" chargers that won't charge a battery that was under a certain voltage.
I checked it with a meter and it does put out a charge, so it does seem to still work.
I'm going to check it on a relatively old car battery that is still good to see if it will charge it.
I read online that you can put a good battery in parallel with a "dead" battery and fool a smart charger into charging them both until the "bad" one has enough voltage for the smart charger to charge it by itself.
@@duffman6675 Yup, I did that on a couple batteries and it worked. I think there is still something wrong with the charger though because when I go to charge a battery, it might show charged, but then I flip the amp switch back and forth a couple times and it will then show the battery needs charging. I'll keep it for a backup and get a charger that has a restore/fix mode.
Great video. You obviousely get as much enjoyment out of fixing things as I do.
Really great video, thankyou for recording it. I have a few older chargers but having a hard time trying to figure out how to test everything. especially the transformer cause im not sure sure how as in what wires and such
I had a very old 160cc Honda that had a selenium rectifier to supply DC for the battery, lights etc. I believe it had 6 maybe 8 plates. I believe this was about 1966. I saw some in use later so I am not sure when they changed to Germanium or solid state. Oh, when they went bad, they stank REAL BAD. And, the Sears is now much better than new, IMO!
on the first charger you fixed are you only using 3 of the 4 terminals of the new rectifier?
Yes, the rectifier has 4 diodes in it; but the charger only needs 2 of them for its circuit; so there is an unused terminal.
great video. solid explanations. thank you
First off very informative video. I also have a Electromite charger. However mine works on 6amp but does not work when switched to 12amp. Am I over thinking probability being it may just be a faulty switch? Look forward to your response.
Thanks,
Cory.
Hi Cory. I would say that the switch is probably the problem; or possibly there is a wire broken off the switch inside the housing.
Thanks! Ill install a new switch, and let you know how it turns out
It is a great feeling repairing somthing , really enjoyed watching this video while having my breakfast in the uk 👍
Hi I have an avacus ac/dc converter charger and its giving up more volt as it use to, 15.8 volts that which is usually 13 volts. I've check its internal parts and the transformer has a plastic wraped around it showing that its burned. I hope you have an idea to whats making it giving a lot of volts and amps, its making my batteries pour out acids. Please help thanks.
So what kind of work do you do? Intrested in how you can take time off when you want like that.
I've got a newer Schumacher battery charger, one of the few good brands left, it does a good job of bringing dead batteries back to life, it can also start an old LS V8 with relative ease, which is something cheaper chargers have a hell of a time doing, I find it good to store batteries off the ground in a relatively warm room when not in a vehicle that's going to be driven regularly, in the case of our old Escort wagon, we park it a 40-45 degree garage with a battery tender maintaining the battery so that come spring it wakes right up so I can re-repair the ever troublesome wiring on our 300K mile Grand Caravan
Can you do another telling how to hook up the bridge rectifiers? I couldn't follow the wiring for those. Thanks.
The old charger is from the later 60s to early 70s. It has a 3 prong cord that came into use in the late 60s.
you are the damn man.
THANKS FOR THE VID, GOT MINE APART BUT SO LOST
Thank you for this video, very timely that UA-cam recommended it to me today as I just brought an old charger home to use for electrolysis and it smoked. looking inside I found the smoke to be coming from a mysterious component which I now know (thanks to you) is a Diode Bridge Rectifier. I understand the Bridge Rectifier changes AC to DC normally with two AC wires in and Plus and Minus DC wires out. I'm confused about how your Bridge Rectifier can work with only 3 wires connected. Mine also only has 3 wires. I don't know which to connect assuming I can find a replacement BR Diode. Since 2 of the 3 wires on our Diods are the same color i assume both DC inputs are used, I don't know if the 3rd wire used is positive or negative. Is the Diode grounded on the mounting bolt?
Just a quick reply as I'm at work.
The diode bridge from your charger has only two diodes in it. It has two AC input terminals, and one + DC out. The 4-terminal diode bridges have 4 diodes. You simply don't connect one of the DC terminals. It will always have both AC terminals used. Then, either the + or the - of the DC will be used. The charger design will dictate which you use.
The two AC terminals go to the transformer winding, The DC out terminal goes to one of the battery clips. If it goes to the red positive clip, then connect it to the (+) terminal on the rectifier. If the wire goes to the black negative battery clip; hook it up to the (-) rectifier terminal. The key is, only use ONE of the DC terminals.
davida1hiwaaynet Perfect response thank you. I traced the single dc output from the diode through a thermal cut off, through the amp meter, and finally out to the black clamp. Checked twice because I was expecting it to lead to the red clamp for some reason. I believe I’ll be able to repair this charger once I find a diode. Thanks so much for the education.
Great that you're on the right track with it.
Look for industrial electronics shops in your area. Also, places like Fry's Electronics have diode bridges. Also if you can wait; online you can use Arrow, Mouser, or RadioShack. They all have diode bridges.
Question. The alligator clamps both came off loose. It’s an obvious question. But I need your professional opinion.
Now that they are loose. How do you know which one is positive and negative.
What I did Opens up the charger and trace the wire to the transformer assuming that the positive. And the other wire attacked to the chassis is the negative.
Mi neighbor used to charge a battery and said the wires got extremely hot. Any ideas? Thanks
Nice vid by the way. Thanks for sharing
Hey remember that when those diode s are being used in a push pull config, you only get half the voltage of the output transformer (center tap to one of the outer windings) but by bridging the two outer windings, you get double voltage.... be careful
Yes, there are some chargers with a full-wave bridge configuration for the highest voltage ranges, getting full secondary voltage; and using the center tap with push-pull for lower ranges.
Hey i have a old charger and it needs work. Where would I take it?? What would you charge
The glass bulb breaker; how do you reset that, after it has “worked?”
Most of the clear glass bulb breakers are auto-reset. If they don't reset after the system cools down, then it would need to be replaced.
Do you know if it's possible to modify Schumacher battery chargers to operate on 220 volts? (e.g.: do the input transformers have unused taps for 220 volts?) My friends brought a Schumacher SE-5121A and XCS15 to Bolivia, not realizing there would be only 220 volts instead of 110. Is there any possibility someone could modify either of these chargers in the field to work on 220 volts?
Hey; on these chargers in this video - the transformer didn't have any unused primary taps. They might have some models which are wound with a split primary which can be wired for 120 or 240; however I haven't seen that in battery chargers.
Thank you for that quick response. I thought it was a long shot, but I wanted to ask in case there was a chance to help my friends.
Best Wishes! Elmer
You have solid knowledge and use your skills accurately.I was wondering where you might have salvaged the diodes from in the second battery charger? I'm wanting to convert from the button style diodes myself.
Excellent video. Very clear and informative. Thank you very much for doing this. DVD:)
Very good video! It was interesting and educational. I found this while looking for stuff to troubleshoot my golf cart charger. Believe it or not I found a couple things to look for. Thanks.
Thanks and glad it has helped you to troubleshoot your charger.
😈😀😇😈😁
Great video! I enjoy repairing and restoration of old stuff. I just finished a 1930s companion scroll saw, and a 1960s(?) Israeli made ac/DC low amp converter, which has a selenium rectifier. I would have never known what the heck that thing was! So thanks for the in depth and very helpful information and diagnostic methods.
I'm currently going back together with a Schumacher 6/2 model that looks like the 10 amp model you showcased last. Well, it's the same shape, but it's got a different volt meter and look to the faceplate. I came looking for a good shot of the switch and wires to and from the transformer. I cannot locate the pictures I had taken of everything, months ago. Ugh!! Per chance, do you happen to have a good clean shot of the switch and diode side of the transformer? I almost forgot, my charger isn't automatic, so it might be too different looking to help, but anything would potentially help. Thanks for anything you could do!
Hi John. Thanks for the comment! It sounds like you have a nice charger setup there. Unfortunately, I'm not at home to look at a charger and take any additional pictures.
Thanks, I was repairing mind, where do you find good cords, alligator clips, meter lights etc. Thanks again
Hey Will; when this video was made, we had a Radio Shack store for the clips, lights, etc. The radio shack closed, so now it's not as simple. The clips can be purchased from most any auto parts store, such as Advance or AutoZone. Most of them also have indicator lights and switches available. If the meters are faulty, they can be located online often.
The meter covers are available from PLP supply. Check www.plpbattery.com/ for these meter covers.
Hope this helps!
NAPA auto parts near me sells really nice copper clamps for batteries. About 3 or 4 inches long. They’re the best I can find. Forney brand is a second choice. They’re nearly OEM for my Century battery chargers
Will mac, i know this comment is a little (lot) late but theres always Fry's or even a battery world or place like that
I have battery chargers an they are not charging but if I touch the two cables I get a spark can they be fixed
Good work, nicely done.
Can you explain how you hooked the rectifier bridge up to the transformer I have the 10/2 amp sears I used 2 bigger rectifiers and put one of the ac output to each ac input positive an put a negative wire on the negative side of one of them and I got it to put out the output voltage of 10vdc at 2 amps and 12 dc at 10 amps but as soon as I hook it up to an amp meter or a batter the meter will go to 15 amps and it sounds really quite on 2 amps no load then it sounds really deep when you put a load on it an the transformer gets warm after a few seconds it was an automatic charger but I couldn't figure it out so I just removed the board
That was fun thanks for posting
I needed to see how you got the grommet back in the black on for the power cord. I have the same issue and cant get the grommet back in.
the selenium rectifier rectified half the ac wave, a bridge rectifier will recitify both halves of the ac wave,leading to a higher dc voltage and more bubbling of batter, overcharging. i did the same thing to an older selenium charger, i came back to find it had risen the battery to over 19v....simply just swap each of the selniums to single 10a diode in a heatsink, if charging a more dead battery 11v and lower you will exceed the 6a draw and push the transformer too hard, the peak is just that , for actual dead batterys, a battery near 12v unloaded is 50 percentcharged really
Actually, the selenium rectifier had two "diodes" working together. This worked as a push-pull rectifier along with the center-tapped transformer. The end result is a full wave rectified DC signal. The rectifier bridge is connected exactly the same way, with only two of its internal diodes in the circuit. It performs exactly the same as the selenium rectifier, other than being more efficient and therefore allowing a higher charging current.
None of these old chargers were ever intended to be automatic. There will be overcharging and bubbling of the battery if you leave them on the battery too long, selenium rectifier or diode would not matter.
how did you replace the selenium diodes with a full bridge rectifier? weren't the diodes set up in a different way?
Hi Doctor. It is easier than it looks! The selenium rectifier was made up of two "diodes" with a common point (the metal plate the were mounted on). The full-wave bridge is a pair of TWO SETS of diodes, wired up just like the selenium rectifier. Since the charger doesn't need a full wave bridge, I only connected to the 3 points needed. One of the points on the full wave bridge is just not used.
Seems wasteful but in reality, these bridges are very inexpensive and it is cheaper and easier to just buy a full wave bridge and use half of it; than it is to try to find a half-bridge package.
Hope this explains it!
davida1hiwaaynet what about buying a pack of individual diodes
You could do this - but remember the diodes have to carry the current and will require a heat sink. A bridge rectifier package is just so convenient since it is already insulated from the heat sink.
there are some packages that can handle 50 amps each and would never get hot, tho in this case with the selenium rectifiers the terminals were perfect, but those that are soldered in, getting separate diodes would be the way to go
Hi David , I'm trying to do the same thing with an old 6/12 volt 6 amp battery charger . Mine has 3 wires off the output of the transformer (center tap ?) . I get 14 volts from either side to the center and 27 volts from the 2 outside leads . Each of the outside leads goes to one of the 2 old rectifiers and the center one goes to the output via the meter . I'm wondering if yours was the same and how you wired it through the bridge rectifier .
Thanks ,
Barry
Hi Barry. Yes each of these chargers has a transformer designed the same way as yours; with center tapped secondary.
It's very easy to wire. You will use only 3 terminals of the bridge rectifier. First of all, leave the center-tap of the transformer connected as it is, through the meter and out to the charging cable.
Connect the transformer secondary leads to the diode bridge. There are two terminals for the AC input, each marked (~). These two (~) terminals go to the secondary leads of the transformer.
This leaves the diode bridge (+) and (-) terminals. You will use ONE of them. The charger's original wire from the selenium rectifier backing plate will connect here. Look at the battery clip on the end of this wire which came from the rectifier backing plate. If the battery clip is the positive clip (the red one) then connect it to the (+) terminal of the new rectifier. If the battery clip which was going to the selenium rectifier backing plate is the black (negative) clip, then connect its wire to the new rectifier (-) terminal.
Hope this explains it!
Sincerely,
David
David ,
Thanks very much , I'll give that a try .
I appreciate you taking the time to reply .
Barry
Glad you found it helpful!
Hi David , Just to let you know , it works like a champ now . Thanks again , Barry
Barry, thank you for the follow-up. Very pleased you got your unit working again!
Old video I know, but I have an old AEC battery charger that looks similar to the black Schumacher 10 Amp charger in this video. It will not produce over 11.5 volts or so. If that is caused by the diodes, where can I find some replacement diodes for it? Thanks.
EDIT: Nevermind, I found some on Amazon.
Thanks for the comment! Glad you found your diodes. Before the downfall of Radio Shack, that was my local go-to place for things like this.
Great video. Do you repair battery chargers from other people? I have a old charger that does not work from the 60's (hate to toss it). Please let me know if you are interested.
I take it that was a no lol
I have two of those battery charges from the 1970's. they have been used thousands of time's, They have been absolutely abused. They still work perfect. There is good reason for it to be 6 and 2 amps. because lead acid battery should NEBER, EVER be charged any more than 1/10'th the amp hour rating of the battery. most car battery are around 50Ah. It should only be charged about 5 amps max. 6 is acceptable I guess in a hurry but two is better. the 2 amp setting is good for small batterys 20ah or higher. What reason all of the charger manufactuers are making 15 and 25 amp battery chargers these day is to full ignorant people who think a higher amp output is better. It is VERY bad for the battery and will ruin it.
Measuring the output voltage is easy, but how about measuring the output current if the built-in meter isn't accurate?
Hey, it's not too hard.
There are two types of current meters. One is really easy to use. It is a "clamp meter" known as Amprobe or Amp Clamp. These measure the magnetic field around the battery cable and calculate the amps flowing. They are best for high currents (10+ amps) and the ones which measure DC current are more expensive.
The best way to measure lower currents is to use a multimeter with a 10A scale. This requires you to disconnect one of the battery charger cables, and then connect the meter in series with the cable and battery. That way the current goes through the meter. Then you see the charge current!
So you didn't say what you hooked up the the bridge rectifier or I missed it so its 2 ac from the transformer and the 1 dc out ?
Did you figure this out? I'm currently working one
@@briholt100 yes I got mine working
Can you post how to check my charger. Its only putting out 8-10v if i just hook up too the leads. Im confused how to test
Hi Pat. The best way to test it is with a battery connected to the charger. The voltage should rise up to 13V or more while the charger is on. It's hard to measure the voltage without a battery attached, because of AC ripple voltage effects.
I have one that puts 12 volts out, but the amps are very low. your thoughts?
Very likely worn selenium rectifier.
some Á hole cut my power cord and the cord is solid black how do I know witch way to rewire a new power cord ??
If you can recess the meter, you could put a flat clear cover inside... see if you have room behind the meter to back it up a half inch or so. That's what I would do...
Hi Darryl. That is a good idea, but I have acquired new meter covers! Will be doing another video of the meter cover installs.
davida1hiwaaynet, thanks for your reply! No one ever does... I'm glad you found a new cover. Your video was very informative, and got me working on an cheap charger given to me that didn't work. It had two transistors mounted to a heat sink on a board with two LEDs. Only the transformer has power, so I decided to make a dumb charger out of it and ordered two 3A diodes to rectify the center-tap transformer. I also understand I should put a 2200mf capacitor across the DC output to smooth current. Oh, and add a 2A fuse to the line in. Does this sound about right to you? Thanks, in advance.
Hi Darryl. It sounds like you've got the right idea about the charger you're repairing. Just be sure that it doesn't overload its self after you remove the transistor setup. Sometimes they use that setup to regulate the charging current. Maybe not - just try it and see! If the current on the charger is much more than it was originally rated for, the transformer may burn out if used for long periods of time.
You really know you're stuff, quick question.... I have a Schauer Model B7612 which is a 6AMP , 6-volt and 12-volt charger....it's very old but always was very reliable. It didn't work when i attempted to charge the lawn-mower battery this last go with the bad lawn-mower battery, so I called Schauer tech support and he said it's just wore completely out (it's probably 25 year old). The AMP meter needle doesn't go up like it always did and then gradually go back down in amps as the battery charged, it just stays around the upper-middle (even when off). when i connect a volt/ohm meter to the charger Leads 6-volt mode shows about 8.2v and 12 volt mode shows about 14v , so i think the voltages look good (but this is not on a load)...but i also had a completely dead 12-volt lawn-mower battery i had the charger on so that could be why it seemed to not work....but the needle just might be broke and the unit might be fine. the needle is more than half way up (8-amp meter like most 6-amp chargers have on them) with the unit turned off! what's the best way to test this on a load, would i have to have two volt-ohm meters like you have? one on the voltage and one on the amp output during a load test (connected to a battery or a high wattage light like you were demonstrating)? sorry for such a long description, i'm not real good at explaining this situation.
if your ampere meter unit stays on the middle even when it's turn off then your ampere meter is broken. change that, buy with the one same slot dimension, if you can find with same slot dimension but bigger Amp rating (let's says it can read up to 20A) buy it. never go below your original rating but you can go with higher rating.
if you worry about your charger is broken down:
you can buy a cheap digital power meter, transformer without any load in output usually have very little power consumption (usually under 10% from full load capacity).
or the old trick is let it turn on for 30minutes without nothing to load on, if your transformer inside is very hot (you can't touch it, then it might be something wrong in your trafo (transformer).
Or just check the cable, usually the cable inside from transformer output is broken out / the cable sleeve melted so it touched bare metal ground or making it under load. if the cable inside is perfect, no open wire or something like that maybe your diode is broken out, your transformer probably outlived the diode or even your cable inside because difference temperature rating.
hope it is helpful
So the selenium rectifier is basically a primitive, 2-piece version of a 4-diode bridge rectifier?
THANK YOU.. 35:51 saved my day!! Mine is a schumacher 2/10/50 amp, using a rivet for an electrical connection failed on mine too! I bent the ear on the plate, drilled hole just like you did. its charging my battery! I'll buy you lunch!
.I have two of those chargers. One I bought new and the sears one I found in someone's end of the driveway garbage about 15 years ago. They all work and do have what appears to be the metal oxide (selenium) rectifiers. I have recently acquired an old 3 amp 6 volt and 12 volt charge which has no output and I plan to use a silicon bridge rectifier (using just 2 of the 4 diodes in it) to replace the failed selenium rectifier. I have to make tests as to what series power resistor I will need to make sure the batteries don't get overcharged due to the fact that selenium has a greater forward voltage drop across it than the silicon does. I need to simulate that voltage drop so the batteries don't overcharge and boil out or warp.