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

Ok Thanks, I don't mind if it's silver or black and silver Let me know if I'm in luck.

Would you sell a rim by any chance?

Ok looks good, and yours is 28h? The one I bought was from BMS and is out of stock now but they only have advertised 36h. I wonder if it's been discontinued

Ahh on,, sorry yes I have 2 problems, The tyre tight fit and the spokes bent.. both not ideal and if I was starting again a 28hole motor would be better for a Brompton conversion... but on the other hand this q70 motor I am pleasantly surprised how good the finish and materials are, how powerful it feels and it does fit perfectly in the front forks. What motor did you use?

Hi whoosh,, I can't see me going down the threading onto 28h rim route, but from what I have seen online it is possible. route as the examples I can find wouldn't solve my problem anyway,, they use a crazy spoke pattern and they don't go into alternate holes on the rim,, so if they were angled they wouldn't be angled in the correct direction for this kind of spoke pattern anyway. So I would still get spokes bent and at even worse angles. There doesn't seem to be any 16inch 36h rim out there with angled spoke holes available in the UK.. some that look like they might be from AliExpress but they don't provide enough details for me to be sure. But I'll keep going as it is for now and update if I have any problems in the long term. I don't know if it's bedding in, or if my mind is adjusting but it doesn't look as bad to me now as it did when I first threaded them.. and if I do have any problems maybe there is a different spoke material that is more forgiving and will handle the bend,, such as titanium.

I've got standard marathon I've always had punctures from time to time even with marathon plus on my old bike. It's the downside of living in Sheffield the steal city.. scrap, screws, nails, nuts, bolts and glass all over the place.

I feel you with that,,, I took it off to change the inner tube today. I only just manage to do it with 3 metal tyre levers making the smallest steps around the wheel and pretty much hoping for the best I don't pop the inner tube in the process. I'm not looking forward to getting a puncture in the rain with this one. At least I can fold it up and get on the bus.

Yes that's the rim I bought, Out of interest what tyres do you use on it? I've got the marathons and they are very tight fit on this rim. I'll leave it all be for now and keep an eye on it.. but I can see me threading it onto the original Brompton 28h rim that I removed.. it doesn't have eyelets and the holes are slightly angled to each side.

I found a solution to ease my worries about battery.. a LIPO fire proof storage bag. for less than 10 quid and what we hear about fires and e bikes surely they should be essential?

Here are some pictures Needs cables tidying still,, but you can get an idea of the spoke pattern and bending.. they are like a gentle s shape bend. 2mm diameter spokes. I can't find a rim available online that has 36 holes with angled holes. Angled ones are available for Brompton with 28 holes and it sounds like a fancy spoke pattern with different length spokes will make that ok to thread 36 hole hub onto 28 hole rim. The battery pack I'm very happy with how compact it is.. I don't know how long the juice will last in reality yet.. but it's 36v 7ah. So in theory at 250 watt it should last 1 hour. The motor is very powerful on full throttle level 5 assistance, I don't see the need for anything more and can see why that's the legal limit for a bike to be honest.. feels like your going down hill when your going up hill with just a little peddling your flying. My partner had a go and it's quite funny to watch someone on a Brompton traveling up hill that fast.