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- Опубліковано 7 лип 2024
- An existing design of a Li-ion battery pack for Roland V-Accordion was investigated. It does not use a battery management system (BMS), which is a bad idea. Charging process was measured, plotted and discussed. A proper design using BMS was discussed, built and tested.
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When I did my apprenticeship as a sparky in the 80s I used to do periods of battery maintenance. Talk 240V DC banks of lead acid batteries that would drive mostly at the time rotary inverters for black out and black starts for hydro Power stations. Vastly different technologies but same principles. Great video.
Great analysis - I learned a lot.
Perfect work
Nice to see You at work
Very instructive, learnt new things on Li Ion packs.. I still hope that you will perform on the accordion after final battery insertion.
Very very interesting! i think i will just stick with the pack directly from Roland. i've been using my FR8x since 2013 with the original pack. i treat it with respect and it still gives me over 7 hours of playing (external amp, no internal speakers used).
So we should stay with the NiMH batteries then?
Спасибо большое за инфо, 👍
I unfortunately purchased the Rainis pack and it quickly failed. After wasting my money I learned how to build a proper pack with BMS and purchased a good external Lithium-ion charger. I invested in a battery spot welder for this purpose. I am angry that I helped to fund Mr. Rainis's failed experiment.
Hello . I am interested if it is possible to connect the accordion roland fr8x to an external battery 20000-50000 mah 24 v. what connection cable do you need and what battery do you recommend for 24 volts? thank you.
@ 42:11 If it went that far it would be hard to put out even with a fire extinguisher.
So with the knockoff battery packs, "Buyer beware". Great session on current battery tech. Some FYI, for those really interested in battery tech abot Lith. I would reccomend the "DIY lithium batteries, How to build your own battery packs". This book is really good. The author is Micah Toll. Check it out.
Hi. How are you today? I hope that everything is fine and you are in good health. Can I use a battery with chip or it must be BMS? Thank you very much for your attention
Most BMS will float up the negative rail to keep the battery voltage OK, you probably don’t need to worry about trying to get the charge voltage lower, test the voltage at the cells when using the charger, you will see the negative of the pack isn’t the same as the negative output from the pack.
perhaps just a voltage drop on a mosfet and current shunt?
Very nice research!!!
the first attempt was to try to help reducing the weight as well as making batteries available for these accordions.
Yes the proper way of assembling a battery should have been involving BMS, No doubts!!!.
It has been an investment mainly from the production, which could not be adopted at this time and with the team that produced the batteries, it was impossible.
I would love to use BMS and some are actually will handle also charging method. but as said manufacturing becomes an issue.
The compromised solution is to charge the battery with a 29.6V for 7 cells LION. the available cheap Chinese are doing the work, but you have to tolerate longer charging time .. however you benefit with safe cutoff... which serves to assist long life span for the pack.
LION cell will most likely give up by the chemistry and will not get shorted.... (therefore one dead cell will disable the complete pack).
the thermal fuse is good enough for both thermal protection and shortage... the rate of 5A is for fast melting point.
The project has been initiated hopping that other people and manufacturer will followup and provide an alternative.... because of regulation of transportation batteries could not be shipped so, hopefully local technicians can produce these batteries .
To summarize :
1. BMS should have been employed in the battery pack.
2. Using Cheap 29.6V charger will be proper charging and the moderate current assist to maintain a high battery life span. For FR7x it is a no issue, for FR8x??? , avoiding internal charging?
3. there are many manufactures of Batteries, I tested few of them ... AWT seems to have a reliable spec, and more tolerating ...they also have 5000mah battery packs.
Good luck
Let me address the most important point in my view: you said "LION cell will most likely give up by the chemistry and will not get shorted.... (therefore one dead cell will disable the complete pack)". I am not sure what do you mean by "give up by the chemistry", but I think I understand the overall message. I agree that the most likely scenario is that a pack becomes "weak" or, in other words, its capacity drops to the point of being hardly usable, so the user just discards it. And quite likely that happens because of one weak cell. However, sometimes cells can go short or even go into a reversal. Look up "li-ion reversal". There are plenty of sources describing how this is possible. And thermal runaway is one possible outcome. Safety features are often designed to prevent rare, but expensive events. And BMS is one of them. Most probably you are going to be fine without grounding in all electrical outlets in you house. But people figured that sometimes shit happens, and you can get killed or your house can be destroyed. Just don't invite trouble. Especially when rather simple and effective measures exist.
Regarding the thermal fuse. It is a secondary point, but you seem to insist that they, in addition to their primary purpose, also provide over-current protection. I don't think so. They might happen to fail first in case of a short circuit, but they are not designed for that at all. Fuses have a rated current, at which they must blow within a particular time (there are slow and fast fuses). Thermal fuses must melt at a particular temperature, not necessarily caused by the current flowing through them. en.wikipedia.org/wiki/Thermal_cutoff
And what exactly do you mean by "AWT seems to have a reliable spec, and more tolerating"? Tolerating what? Do they say in the specs that their cells can handle overcharging? Or they don't catch fire? Or anything else of that sort?
Regarding Li-ion reversal. For instance, take a look at this paper: iopscience.iop.org/article/10.1149/1945-7111/aba00a
@@feedback-loop
Thermal fuse has 2 characteristic...
I agree that it is not a perfect solution, however, the original roland pack used it and i felt that it should be also a part of sny design.
To tell you the truth if a pack temprature goes up to 120 degrees, run away for life 🙂.
Yes.... a lot can be done to have exra protection and to have a better desgin .
However this is costly....
You are dealing with high power , high current source of power...
You do not have even the luxary to direct current with a diode like you suggested.
In your aim to protect the voltage , your circuit involves a diode in serious to charging or sourcing the accordion.
You should assume about 1a current flow, over 0.7V, it will deliver about 0.7w ... which is a very high power for a small diode... therefore heatsink should be involved...
The proper dedign should involve switching power only..
To conclude...
All you remarks are very valuable...
My assumption is that a good pack design is expensive and no commercial justification can support it.
My aim is to play long hours and i expect Roland or any design of the manufacture to support it safly.
Yes Good bms could assist most of my safty requirements and will assist long life span of the pack.
As for AWT..
I had many Q&A exchange with the engineers. Threir maufacturing , their consistancy of spec is very reliable...
Their tolerance is a bit better and testing with them togethrer, the cell modt likey will tolerate the 4.5v... (not more 🙂, and not recommended) .
They answer quickly, they assisted in finding good BMS TO SUPPORT THEIR SPEC.
I did a test with their supplied BMS.. i found it very good solution.
However, the lroject was a social project and the team that built the packs coukd not proroduce it... and also it made the battery very expensive.
You can also get from them cells with individual protection circuit .. which has no conflict with BMS on top.
Regarding the diode. I never proposed a regular diode with 0.7V drop. I explicitly said it is a schottky diode and marked it on the schematic accordingly. The voltage drop during discharge was about 0.3V, and the diode was barely warm.
Regarding AWT. Are you saying that their support engineers told you that it is fine to charge the cells to 4.5V? Really?
@@feedback-loop ..
Yes their engineer are very cooporative.
The never encouraged me to charge 4.5v a cell.
Their major concern has been the ability to hold the charge.
And most of the failures are cells quiting..become inactive galvanic.
I fid not try a shotky diode, yes it may less power sensative, stil the fr8x will attempt to drive up to 1.8A.. it is a high power also for 0.3v drop...for long time (I think so).
With all the part delivery delays I am surprised that you can crank out videos in a reasonable timeframe. Are you shooting several vids in parallel?
Sometimes, but this project took quite a while. Because of waiting for parts and a lot of experiments with charging-discharging, capacity measurements, arranging data collection and plots and so on.
FeedbackLoop Well, it was very interesting to see how you solve this puzzle. Thanks for putting so much time into it.
Hello, thanks for your videos. I've made a battery pack for a Roland FR7 I have bought with a lot of issues. I've repaired them but I have a great doubt about the battery pack schematic ! The Roland FR7 I have bought has not the original battery pack. Is it possible to have a schematic wiring from the ATX 4P plug to the batteries ? I have bought 2 BMS cards. 4s + 4s with 3 batteries on each BMS card I have 24 V. But, my battery pack has 2 wires, the positive and negative one. I dont know where to plug the NTC ! and I don't know where the positive and negative wires are on the ATX 4P plug ! (I have a great doubt). Thanks a lot...
@3:02
@@feedback-loop OK, thanks, I have not heard. It's the good position so !
@@musella974 I don't understand what you mean by 4s + 4s, and 2 BMS cards with 3 batteries on each. The li-ion pack must be 7S.
@@feedback-loop Yes, but here, in my little island and because of COVID, it's very difficult to order and receive correctly objects.. Also, I have not the Pedal board to charge the battery (I try to repair it. I have ordered some electronic parts but very difficult to receive them) so I have separate the 24 V into 2 x 12 V. It's more easy to charge 12 V. I have put a switch between the two 12V when I charge them. When it's charged, I switch it to 24V !
I have not understood where you put the sensor. I can't understand the word you're saying (I'm french !!!). My sensor has 2 wires. Thanks for your interest !
@@musella974 I would not recommend this 2 x 12 V configuration (8S). Max voltage is 8 * 4.2 = 33.6 V. We don't know if this is acceptable. You might destroy something in the accordion.
I wonder why the label says "designed and manufactured in LAOS PDR." Laos is a separate country, not somewhere in Israel.
It all stated with good intetion to help the VR accordion players.
I initiated the project aimming to "help".
LAOS is a small country in Asia, their income is very low, and some times there is a lake of source to maintain normal life.
I tried to help .. by getting some good people , trained them how to assemble the packs.
I invested in the parts, bought tools for them and never aimed to recover my investment🌹.
The group produced about 100 packs, some were good , some were "so so".
To make the long story shorter...
Few players were happy, few families in Laos got some extra joy and income ...🙂.
It was a social project.
Shipping batteries regulation killed the project...
Yes all the remarks in the research are very constractive... but building a complex pack was not possible with the team i had there🙂.
I dont understand why you lose your time with some idiots that use a thermal Fuse as Current limiting Fuse and wants to charge Li-Ion with 4.5V....
@Phil Braido Yes they are fine to use, if you want to put your house on fire.
The person who designed this battery pack dont know very much about electronic.
7X3.7V.................... IS NOT 24V
IS CCA 26V
THAT IS NOT OK FOR USE ROLAND ACCORDION------------!!!!
RISK FOR ROLAND ACCORDION
How did you reach that conclusion? Have you seen the measurements I showed?