Good afternoon,
I have been a happy owner of a DIY e-bike since 2015.
My batteries are 12X 24v5000mah Turnigy and they are configured in 3sX4P (72v - 20 Ah ). Also Balance leads are connected accordingly.
They have always been balance charged with relatively low currents ( 5 to 10A) to 4.1V and never discharged below 3.6V seldom below 3.7. When I recharge them I put all 12 packs in parallel and recharge at 24V.
Now after 3 years I noticed that one of the cells was repeatedly going out of balance falling quite low compared to others.
So I took the packs apart and I noticed that 2 packs were puffed and several cells in these 2 packs had higher internal resistance compared to the other packs.
Now here's the questions that I would like to submit to the experts:
1- If in a group of packs ( 4 in my case ) one pack goes bad (again as in my case ) is it a possibility that the bad pack will deteriorate also the good ones? I ask you this because when also balance leads are paralleled there is little way for me to tell if one single pack is bad .Measuring from the balance lead of the group of four I will only be able to read the average voltage of the group of 4 but no of the single one. And this leads me to the next question
2- Ideally when using the bike the cells do not need to be in parallel but it would be much more beneficial to have them separate so that I could monitor each one of them and cut the power when the lowest one falls at a predeterminate voltage (like 3.6 x es.) Does anyone know if there is a way to monitor balance lead of each single pack ?. I was also thinking that inexpensive arduinos properly configured could be used to have this job done.
3 - What do you guys suggest to do with puffed lipos? Toss them? Probably I could reassemble them and use one of them for lighting system of the bike.
4- I recently bought some new LIPO packs same capacity different brand ( Multistar) with also different discharge rate ( 10c instead of 20c) . Do you think is ok to mix different packs? My idea would be to configure it 3sX7P to reach 72v 35Ah. What is the best strategy to put the battery packs toghether?
Cheers
Alberto.
I have been a happy owner of a DIY e-bike since 2015.
My batteries are 12X 24v5000mah Turnigy and they are configured in 3sX4P (72v - 20 Ah ). Also Balance leads are connected accordingly.
They have always been balance charged with relatively low currents ( 5 to 10A) to 4.1V and never discharged below 3.6V seldom below 3.7. When I recharge them I put all 12 packs in parallel and recharge at 24V.
Now after 3 years I noticed that one of the cells was repeatedly going out of balance falling quite low compared to others.
So I took the packs apart and I noticed that 2 packs were puffed and several cells in these 2 packs had higher internal resistance compared to the other packs.
Now here's the questions that I would like to submit to the experts:
1- If in a group of packs ( 4 in my case ) one pack goes bad (again as in my case ) is it a possibility that the bad pack will deteriorate also the good ones? I ask you this because when also balance leads are paralleled there is little way for me to tell if one single pack is bad .Measuring from the balance lead of the group of four I will only be able to read the average voltage of the group of 4 but no of the single one. And this leads me to the next question
2- Ideally when using the bike the cells do not need to be in parallel but it would be much more beneficial to have them separate so that I could monitor each one of them and cut the power when the lowest one falls at a predeterminate voltage (like 3.6 x es.) Does anyone know if there is a way to monitor balance lead of each single pack ?. I was also thinking that inexpensive arduinos properly configured could be used to have this job done.
3 - What do you guys suggest to do with puffed lipos? Toss them? Probably I could reassemble them and use one of them for lighting system of the bike.
4- I recently bought some new LIPO packs same capacity different brand ( Multistar) with also different discharge rate ( 10c instead of 20c) . Do you think is ok to mix different packs? My idea would be to configure it 3sX7P to reach 72v 35Ah. What is the best strategy to put the battery packs toghether?
Cheers
Alberto.