Battery voltage

cyclenut1952

Esteemed Pedelecer
Nov 6, 2019
275
24
Leeds LS27
Hi. As a bit of a worrier, I keep reading that a fully charged battery is 42v my bikes are 4 months old, they both only charge to 40.6/.7. Is this normal. Thanks
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
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Winchester
It might be that the charger is set up for a slightly lower voltage. No all bad as that could (*) increase the life of your battery for a minimal drop in range per charge. If that's right then use of a different charger occasionally for full 42v might help to keep the cells balanced.

(*) I think there is quite a bit of contention on that point.
 

PC2017

Esteemed Pedelecer
Sep 19, 2017
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Scunthorpe
I would contact customer support and question that, check the under side of your charger and see if it states "output 42v" it could just be a faulty charger, are you using the same charger for both batteries?
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
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41.6v could well be within the error levels of your meter for 42v. You could also check the voltage on the charger; you'll probably see much the same figure but that won't say whether its the meter or the charger that is fractionally low.

I very much doubt there is any issue either way with that small difference.
 

Nealh

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Aug 7, 2014
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41.6/41.7 is fine and denotes a pretty well balanced battery, it might be that over several charges they both will eventually both balance out perfectly.
What does the meter say when you test the chargers voltage via the charge connector.
As mentioned 0.5v might be the error reading of the meter.
Also some BMS vary between 41.5v - 42v for the balance charge.
My Swizzbee's 24v LG BMS balances at 4.15v per cell group.
 

Woosh

Trade Member
May 19, 2012
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wooshbikes.co.uk
My apologies they both only charge to 41.6/.7. But never to 42v, sorry for misinformation.
42V is at the charging port. The electricity has to cross at least two FET junctions, one between the charging port and the cellpack, the second between the cellpack and the output port. You put in 42V and get 41.6V at the output.
 

cyclenut1952

Esteemed Pedelecer
Nov 6, 2019
275
24
Leeds LS27
Thanks . Your replies are very reassuring being a novice I mistakenly get things wrong as now.
This forum is invaluable to me and thanks to all who take the time to respond. Brian
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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West Sx RH
Hi Nealh. The voltage via charge connectors is 41.6/7
That is ok the anomaly of not reading 42v is likely the DVM % tolerance then, they can be out by easily 0.5v with the basic cheaper models most of us use.
If you have friends or know someone with a meter you can compare voltage readings, but is nothing to overly worry about.
 

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