pears_91

I am now wondering,,, I am not entirely sure that I didn't replace 1 cell,, that may have been grouped with an existing pre charged cell.. So I connect a cell at 4.1v and one at 3.6v in parallel. I'm quite sure I didn't do this, because when I read them with volt meter all cell groups measure either 4.1 or 3.6 as a pair.. I think if I did replace just half of a pair it would measure 3.85v as a cell group.. But in the event that I did do that, am I right in thinking that the cells in parallel would not balance.. and upon charging, it would bring the group up to 4.1v.. one of the cells would be 3.85 the other would be 4.35v for example,, giving average 4.1v? As I say I'm quite sure I didn't do that just because the voltage of the pairs would have been different had I done that, but I just had a moment of slight worry.

Hi, to give update to the thread.., it has taken a while to arrive and for me to get around to it.. but I received the charger and charged up individually each set of cells. As saneagle suggested above, I did have to find a way to connect the charger and I chose to solder it to the lead strip on the battery pack. Around half of the cell groups needed charging until they reach fully charged, the other half were already full. So in summary , all of the cells that I replaced were nominal voltage 3.6v (as supplied) and at the time I did this all the other cells in the pack were fully charged 4.1v The charger has brought the all up to 4.1v by charging individually so now the pack is pretty well balanced.. according to my volt meter there's about 0.05v max different between the cell groups. So I will get much better range out of the battery now I hope .

The charger I have bought is Carson x-base 2.0 It does say it can do 1 cell, and covers the voltage range.

Hi To give a ending to the post After leaving 2 days it is not charging past the 39v I remove the battery from charge and in the meantime made a new battery pack that I am using until I fix the other one.. then I will have 2 packs to rotate. I have purchased a balance charger online for £24 to charge each cell group individually to 4.2v. There were cheaper options, such as using a light bulb or 5v charger which I have.. but both would need constant monitoring. I feel I can justify this because I am bone idle and will have flexibility such as to charge a car battery which I currently don't have either.. so I think it's a good multi functional tool to have.

No problem yes I will let you know I appreciate the help on here .

Thanks for the info.. I will leave it on charge .

Yes sorry, tricky probably not the right word. Maybe fiddily or time consuming. I have seen what seem reasonable balance chargers second hand for under £30.. but they seem to be for li-po battery not li-ion. And on Amazon there is multiple parallel charging boards.. less than £10 for some of them.

Hi [uSER=46203]@Ghost1951[/uSER] Thanks for confirming my understanding, and advice on how to fix.. it seems like a bit of a tricky one. I have also heard of some kind of charger that can perhaps perform balancing.. I might look into one of those as if my life carries on in this direction it might be a useful tool to have. I guess there quicker and more automated reliable way of doing it.. I think many of the cells I replaced may not have actually needed replacing in hind sight.. there was just a balancing problem all along. And the battery is not actually all that old..maybe 1 year but only 50-60 cycles. So I hope shouldn't be too much issue with cells being out of wack.

I have found an RC car charger that runs off USB. I'm quite happy because I guess this will fix a problem I have been having. My battery keeps cutting out. When it still appears to have charge. But I guess the BMS is cutting it out. Because some of the cells have reached the limit. Even though it shows still having charge. .

Ok I have discovered it needs to be balanced. I not need to find a way to do this I have seen a guy on YouTube using a light bulb.. to drain the cells that have higher charge. Any suggestions would be appreciated. I'm thinking I could get a 4.2v charger and just charge them all individually? If such charger exist. I guess it should.

Hi I wonder if anyone may help me here. I have recently replaced some cells in my e-bike battery. The cells are all the same. LG MJ1's I did buy them in separate batches .. they look identical. I made the battery pack and replaced the BMS which was broken. Now I have changed the battery just like I normally would, all of the new cells are only charging to 3.6V. compared to all of the original cells which charge to 4.15V. When the battery was new all cells would charge to approximately 4.2v. giving me the 42v fully charged battery pack. As it should be for 36v battery. Currently the whole pack charges to 39v. Then my charger light goes green. Asif all is fully charged. But the pack is made up of approx half new cells all 3.6v. and old cells 4.15. Sorry I don't think I explain in the most simple way but I hope someone can understand and maybe help me.

It's probably had around 40 charge cycles 18 months old. Unused for about 6 months at 1 point.

New cells

I have a bike with 36v battery. When it was new I'm sure it used to charge to 42v. But now it charges only to 36v. I made the battery pack myself, and will take apart and measure voltage over each cell etc.. I don't have any equipment for reviving battery cells or charging them other than my ebike charger.. so probably if I want to fix anything I guess I'll have to buy some equipment.. also I installed standard BMS not smart so I can't see any info on an app etc. Does anyone have any ideas as to what itay be.. and any advice best way to test and fix?

What I'm going to feel like pulling into work tomorrow morning for the first time on the brommy