Battery lost capacity

[flecc]

Deep cycle discharging to empty is bad for batteries - no?

Repeatedly yes, but the specific instruction for these BMZ manufactured batteries is to run right to empty two or three times to establish the zero point for the built in potential capacity gauge to be accurate.

The OP has measured 40% capacity but without running to to empty at least once that may not be accurate.
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[nemesis]

I had the same battery as the OP a few years ago on the panasonic motor Kalkhoff,in two years of owning the bike two batteries had to be replaced because of the same problem as the OP.The panasonic motor was ultra reliable but the batteries not so and they were well looked after.

 

[J.B.]

bit if a newb question / comment but my understanding is the best way to build / rebuild capacity in a battery was to run it to 75% empty and recharge. Deep cycle discharging to empty is bad for batteries - no?

Good point anyone?
I think it might be about how long it's been left in deep discharge, anyone!?

 

[flecc]

Good point anyone?
I think it might be about how long it's been left in deep discharge, anyone!?

Any deep discharge stresses the cells, as does the peak charge of cells at the end of charge time. Usage of the central charge volume between 20% and 80% of charge is best for long life, but that's very difficult to arrange.

The most extreme example of this is in satellites using lithium batteries. They are much larger than really necessary and each day in the short dark phase only use one seventh of their content, that gently restored from the solar panels during the long light phase. The result is they last at least ten years with nearing 4000 charges. Of course having batteries seven times their current size on e-bikes isn't practical.

To some extent the bike and charger take care of this, the bike's low voltage cutoff is well short of full discharge and the battery's BMS full charge cutoff is short of the maximum possible.
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[J.B.]

Yesterday i set it at maximum assistance and went off with the trailer to fetch firewood. 10 miles done and the display was showing a fall from 10 bars to 5 with each drop happening gradually. This is an improvement simply because it seemed to be just going from 9 bars to 1 bar without me spotting anything in between. The displayed timed out while unloading the trailer when I switched on again it had dropped to 2. Did about a mile and half and it was down to zero bars. 4.8 miles later still going? I will ride it again tonight to get it to actually run out. So to date 16.3miles with the assistance set at max. Not as bad as I thought or better still its getting better. Can't be certain as I have yet to run it to cut out.

 

[J.B.]

Did about 2.5 miles before it conked out. So about 18.8 miles not horrendous but will see if it improves over time. Pressed the button for 5 seconds, only showed one light. Noted down the time I put it on charge. That may give me an idea of how much charge it takes.....assuming I spot it when it stops charging.

 

[J.B.]

These Kalkhoff-BMZ batteries supposely have a sleep mode, meaning the BMS shuts down after a couple of weeks, preventing further discharge. This doesn't seem to have worked for you.

I'd recommend you fully charge, then ride it to cut-off before fully charging again. Do that again if necessary. The ride doesn't have to be continuous, spread over a day or three is ok.

Have you tried a capacity check? To do that, hold down the test button for at least 5 seconds and the number of bars that appear indicate the potential capacity of the battery, each bar being 20% of the nominal capacity.

After the above ride to empty, try the capacity test again before and after charging.
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Did full discharge. Took about an hour and half to show a full recharge. Held button for 5 seconds only showed one red light?

 

[russ18uk]

No way did your battery recharge in 1.5 hours. That's only 126 Watt-hours of energy from a typical 42V 2A supply.

 

[J.B.]

No way did your battery recharge in 1.5 hours. That's only 126 Watt-hours of energy from a typical 42V 2A supply.

It shows 5 red lights and when I hold the button in it only shows one red light which according to the battery it now has zero capacity? ?

 

[flecc]

It shows 5 red lights and when I hold the button in it only shows one red light which according to the battery it now has zero capacity? ?

I suspect at least one cell might have failed or is failing. Failing cells can still maintain a high enough voltage to signal the 5 LED full charge, but collapse under load so not sustaining capacity.

Seems like it's time for a new battery.
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[J.B.]

I suspect at least one cell might have failed or is failing. Failing cells can still maintain a high enough voltage to signal the 5 LED full charge, but collapse under load so not sustaining capacity.

Seems like it's time for a new battery.
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Arhhhhhh
So any ideas on a replacement? Wouldn't mind another 17ah one but I really only need something for around 25miles. Pulling a trailer though.

 

[russ18uk]

I would recharge overnight and see what it is in the morning. If you have a 17Ah battery then <200Wh that you've put into the battery is only going to be around a 1/4 charge.

 

[Nealh]

1.5 hrs is not good for a 17a battery to charge, should be about 8 - 9 hrs using a 2a input.
You can use any 36v lion battery of any capacity, though ideally if you want 25 miles and towing go for the most capacity you can get. Probably the best option is to give Jimmy at BGA/Insat a call and have your current battery re=celled with GA or 30Q cells.

 

[J.B.]

The battery is switching off, as in the red lights have gone out. So I assume it is not charging anyway.
Is there a post on this bloke?
A bit of a pain as it is now that I need it. Does he take long to re-cell them?
Thanks for all your help

 

[J.B.]

Sorted searched BGA reworking thanks

 

[J.B.]

8miles today display showed 40% capacity left. Getting worse. Emailed 50cycles and kalkhoff Germany about a replacement battery. 50 cycles came back with, will pass it on to after sales. Kalkhoff Germany hasn't got back yet. Neither has BGA. Am thinking if I can't get a replacement from 50cycles or kalkhoff at a reasonable price will get a non original probably from eBay. As it appears from what the forum members are saying BGA are to busy for a quick re-cell. Will probably still send to them anyway. Anyone any knowledge of suppliers? This is the battery
https://www.ebay.co.uk/itm/Battery-13000mAh-13AH-for-E-Bike-Impulse-System-Kalkhoff-Raleigh/362321328130?redirect=mobile

 

[J.B.]

From 50cycles I asked if they could supply a replacement battery....

"HI There

I just tried calling but the number supplied seemed to be incorrect.

Unfortunately we are currently unable to supply replacement batteries as we no longer sell Kalkhoff bikes and are only dealing with them for warranty parts on bikes we have recently sold.

I have attached a link below to their dealer search facility on their website so you can use this to find your closest current Kalkhoff stockist who should be able to supply or order one in for you."

News to me. Thought they were main supplier of kalkoffs?

 

[J.B.]

BGA are sending a courier to fetch Tuesday said they would get mine done as quickly as possible.

 

[flecc]

News to me. Thought they were main supplier of kalkoffs?

They used to be, but once Kalkhoff set up a UK base they stopped handling them.
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[J.B.]

Went for a re-cell as he thinks that is the most likely outcome.