Glens carzy ebike
10 mW
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- Aug 3, 2019
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- 23
Why does my battery never charge to 83 volt any more only goes to 81 volts but one week ago it went to 83 volts?
72 volt battery only chargers to 81 volts not 83volts
- Thread starter Glens carzy ebike
- Start date
Check the output on the charger with a multimeter to see where it's at. If it's off, some chargers have adjustable pots inside which you can adjust to get it back to where it needs to be. It's possible that it got jostled out of calibration.
If the charger is outputting what it should, I'd be concerned about an issue with your battery pack, like a bad cell.
If the charger is outputting what it should, I'd be concerned about an issue with your battery pack, like a bad cell.
Glens carzy ebike
10 mW
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- Aug 3, 2019
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- 23
i have just done a test on my charger when i turn it up from 2 amps to 4 amps it starts to charge could it just be the charger ?
Sunder
10 MW
You probably need to provide more detail on the circumstances it stops charging at 81v.
E.g.
1. Your BMS will kill the charge early if one cell is over limit;
2. As your battery gets older, internal resistance goes up, so as the battery voltage gets close to the charger voltage, the rate of charge slows - if the battery is really unhealthy, possibly so low that the charger cuts off - but might resume if you turn up the charging rate, or disconnect/reconnect.
3. Could be something faulty in either the BMS or the charger.
Care to provide more details on how you know it's stopped at 81v, and what you've tried so far to get solve it?
E.g.
1. Your BMS will kill the charge early if one cell is over limit;
2. As your battery gets older, internal resistance goes up, so as the battery voltage gets close to the charger voltage, the rate of charge slows - if the battery is really unhealthy, possibly so low that the charger cuts off - but might resume if you turn up the charging rate, or disconnect/reconnect.
3. Could be something faulty in either the BMS or the charger.
Care to provide more details on how you know it's stopped at 81v, and what you've tried so far to get solve it?
Glens carzy ebike
10 mW
- Joined
- Aug 3, 2019
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- 23
i used different charger the battery now charge to 83 volts. i unplug the other charger started to smell like it was on fire
goatman
10 MW
why 83v and not 84v? a 20s battery should be balanced at 84 volts, 20x4.2v= 84v. 20x4.15=83volts. what is your bms specs for balancing? your bms isn't working properly at balancing or your charger isn't giving out the right voltage or the device youre using to measure the voltage isn't giving accurate readings. if I use a digital multi meter on my battery ill get an accurate reading but if I plug into bike the cycle analyst will be a slightly lower voltage reading. basically if youre trying to figure out whats going on with your bikes battery or charging system you need an accurate tool to measure the voltage. 83 volts is an odd number to balance a battery at. I know people will charge to 82v/4.1 to extend a batteries life and balance to 84v after 10 or 15 charges at 82v.
Yup, sounds like that charger is pooched.
83 vs 84 may result in a marginal increase in cycle life without giving up much range, so perhaps the bms was programmed that way intentionally. As long as they're balanced and within appropriate voltage range for the chemistry, I don't know if it's necessarily a bad thing that they never see 4.2v.
83 vs 84 may result in a marginal increase in cycle life without giving up much range, so perhaps the bms was programmed that way intentionally. As long as they're balanced and within appropriate voltage range for the chemistry, I don't know if it's necessarily a bad thing that they never see 4.2v.
MAXIMUM_AMPS
10 mW
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- Nov 13, 2019
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- 33
Do you even notice those 2 volts missing? I doubt I'd notice that small of a difference on my bike.
Other users are right, could be the BMS cut off charging to balance the cells. If any ONE (1) group of cells in series hits 4.225V, it SHOULD cut off the output, to bleed off that fully extra-charged group.
Other users are right, could be the BMS cut off charging to balance the cells. If any ONE (1) group of cells in series hits 4.225V, it SHOULD cut off the output, to bleed off that fully extra-charged group.
MAXIMUM_AMPS
10 mW
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- Nov 13, 2019
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That is ideal, but the vast majority of BMS boards are not like that.
The nicer ones with bluetooth programmability and monitoring like what EM3EV offers on their batteries is not the standard, that's an exception that puts them above the competition.
All BMS units need to cut off the charger input if any one cell group is above 4.2v, 3.7v for LiFePo4.
The nicer ones with bluetooth programmability and monitoring like what EM3EV offers on their batteries is not the standard, that's an exception that puts them above the competition.
All BMS units need to cut off the charger input if any one cell group is above 4.2v, 3.7v for LiFePo4.
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