Pink Nigel Dean

A slim chance, but if anyone lost a wheel, which I found this morning (Mon 25th May), I know where it is. Presumably it fell off a car because whoever lost it didn't ride home..

Thanks again, and yes, Jimmy will be fitting the Boston Power Swings....

I soldered two pins to a 5V phone charger, checked the polarity and connected to B-/B1. The voltage of the cell was 2.98V when I started, and after charging for 2.5 hours the voltage was 2.97. I checked the output of the phone charger at the pins before and after the session and confirmed that it was delivering 5V at the pins. This battery continues to defy logic.... Thank you for all your help, it really is appreciated, but I think this is now a job for re-celling. Maybe the inability of this battery to respond is down to the fact that it is 8 years old, and so just a little too far over the hill.

Well although the battery output and individual cell voltages declined significantly over the week the output of the battery charger remained exactly the same, suggesting that the meter was not the variable. Moreover, the new readings were obtained before changing the meter batteries, which didn't have any effect on voltage readings. If you think the pack is scrap and plan on replacing it, then no loss by raising cell voltage and charging outside away from the dwelling for safety reasons alone. If all goes well then can only assume an anomaly with meter reading or BMS at fault. If a cell group has an issue one or two may be different but all appear equal under the first voltage measuring practice. Fair point, nothing to lose as long as I avoid burning the house down. I'll do as you suggest and let you know what happens....

OK, but there is also the mystery of the voltage drop over this week. Individual cell groups measured 3.70 last week, but still wouldn't charge.

My meter doesn't have selectable voltage ranges, it scales automatically. Something doesn't add up though. As I understand it the two methods are essentially measuring the same thing but in different ways, and reading along the cells from B- should show a cumulative addition of the individual voltages measured between them, surely. I don't understand how the same meter measuring the same cells using the two methods produces results which don't correlate, and it's an important contradiction, because one set of results says charge the individual cells and it'll be OK, whilst the other says buy a new battery...Very odd

I repeated the B-/B1, B1/B2, B2/B3 measurements several times with the new batteries in the meter, and got very consistent results with all ten cell groups reading either 2.97 or 2.98. Measuring from B1 to B10 using B- as the neutral gave noticeably more erratic results, as above, with three consecutive cell groups showing 19.90v, then jumping by 10V to 29.9. Since I've now loaded the meter with brand new Duracells I don't understand why the two different methods of measurement are providing such conflicting results. How could this be?

These are the readings with new batteries in the meter. They were taken from the pins in the plug after first disconnecting the plug from the BMS. For each reading I held the probes in place until the meter gave a steady reading, and where the values differed from those I had obtained previously I took extra care to make sure I had a good contact. Using the method you first suggested, i.e. measuring across B-/B1, B1/B2, B2/B3 etc. all ten cells gave readings of 2.97 or 2.98. Measuring from B1 to B10 using B- as the neutral gave the following five sets of readings; B1 2.98 2.98 2.98 2.98 2.97 B2 7.00 7.00 6.98 6.99 6.69 B3 10.70 10.99 10.69 10.96 10.40 B4 14.42 13.98 14.41 14.67 14.11 B5 18.13 17.94 17.90 18.38 17.82 B6 19.90 19.90 19.90 19.90 19.90 B7 19.90 19.90 19.90 19.90 19.90 B8 19.90 19.90 19.90 19.90 19.90 B9 29.90 29.90 30.00 27.30 29.90 B10 29.90 33.50 33.60 30.0 29.90 I appreciate that the 10V jump from B8 to B9 is impossible, but that's what I got, which is why I took multiple readings. Looks like I need a new battery, but I still don't understand why the method of measuring across the pins in pairs gives near identical readings for all ten cells?

OK, I'll replace the meter battery and report back. Could a fault with the meter explain why the two methods of measurement gave such different results, which were consistent as I measured them several times?

Curioser and curioser.. I rechecked the output voltage of the battery, which was 37.2V last week, to find it has now dropped to 29.9V. I then rechecked the voltages of the original cells, which were previously all 3.70 or 3.71V, to find that they are now all between 2.97 and 3.01V. These seem quite significant decreases, but the battery has not been connected to anything in the interim. I then placed the black probe on B- and the red probe consecutively on B1 to B10, which I understand should produce increments of 4.2V in a healthy battery, and obtained the following voltages; B1 2.97V B2 6.97V B3 10.91V B4 13.95V B5 17.87V B6 19.60V B7 19.60V B8 29.60V B9 29.60V B10 33.30V These results suggest some very significant imbalances between cells, unless there is some reason why this is not a valid method of measurement? I then rechecked all the cells using the method Nealh recommended and found that they were still all between 2.97 and 3.01V, which suggests good balance. They can't both be right, so why are they producing different results, which I've now checked and confirmed several times?

Thanks Nealh, but is there anything else it could be now, apart from the BMS?

I know, I'd convinced myself that the cheap charger was going to save the day, but I need some idea of where the problem actually lies before I start investing in battery resurrection. Let's hope Nealh can help... I believe a BMS can be replaced, but with an 8 year old battery it might not be easy to find one.

My 2A charger arrived today, and I was hoping to be posting to say that all was well and the bike was charging again, but alas no. I checked the polarity and output of the new charger, plugged it in, and it sat there shining its annoying green light at me just like my original charger. Is there anything else it could be, other than the BMS, since the cells appear well-balanced? The fact that I measured a voltage at both the battery output lead and the battery charging port with the charger disconnected clearly shows that the cells are in contact with the charging port, so it can only be the BMS itself refusing to accept the charge can't it, or is there some other possibility?

Thanks Benjahmin - I also had a look to see if i could modify my cable run as you suggest, but it isn't long enough, and only just reaches the battery as it is.

It's much kinder to the wallet too, so this is welcome news thanks Nealh..

Thank you both for all your help so far, which is much appreciated, but I need to decide on the best way forward from here. Would you agree that the fault most probably lies with either the charger or the BMS, and that the result of the bulb test points a finger towards the charger? That being so it might be worth buying a new charger, since I've failed completely on borrowing one, but do I need an expensive 4A unit or would a much cheaper 2A charger do the job, albeit slower? Your opinions would be much appreciated.

You obviously have excellent taste. This one has lasted since 2012 albeit with a replacement LED display and controller. Thanks for the tip, but it isn't going out in the rain, in fact right now it isn't going anywhere.. The relay still clicks, as usual, but normally that precedes the yellow light and the fan, which aren't following now. This morning I wired the charger up to an incandescent bulb to simulate a load. It lit the bulb dimly, and entered a repeating cycle of relay click, bulb on, relay click, bulb off, but at no point did it turn on the yellow light or the fan. Presumably the issue could still be either the charger or the BMS, and another charger is probably the best way of working out which.

You were right, it was the bottom pot, but I turned it down to 41.7v and the charger still refuses to play.

Here you go, my pride and joy.... It's a classic 1990's Reynolds 531 road bike, which still fools most of the boy racers nowadays, which is why I'm so fond of it and so keen to get it back on the road. Thanks for the sensible pot turning advice, what voltage would you take it down to?

I still need to know which pot to adjust to what, but who is Nigel? Elaine

Yes, that's right, except that the yellow light and fan no longer kick in, but I've always used the same sequence you suggest.

I've posted on a couple of forums to see if I can find someone local with a charger I could borrow for a couple of minutes, but no luck so far, which is understandable since borrowing a charger is not yet on the approved list of reasons to leave home.. Would it be a fair conclusion that the problem most probably lies with either the charger or the BMS?

OK, but these measurements were not taken on a fully charged battery, indeed I had tried hard to run the battery down in case the level of charge was what was preventing it from accepting a charge.

It has a key, which turns it on and off and also unlocks it from the carrier so that it can be removed, but no other switch.

They were indeed fuzzy. Hopefully these are clearer, but I'm not sure if this is what you wanted to see, as there are no red or black wires in the vicinity of the pots, so please let me know if you needed to see something else? All ten voltage readings were either 3.70 or 3.71