Cut-off voltage

[DouglasXK]

i have a BH Neo Cross. They're very nice bikes. At some time I'm going to re-cell the battery so have been trying to understand what I've got. This utube video might help anyone interested in these 36volt batteries.

On mine, when the battery voltage falls to around 34v, it shuts down. Why? I wonder.

Between 41 and 34 volts, the battery degrades at the rate of 8-10km per volt.

A logical explanation would be that the BMS is seeing 3.0v in one or more of the cells. I'm assuming the battery pack is 10S4P or 5P.

Can't see any other reason?

 

[Deleted member 4366]

That sounds about right. Some batteries go out of balance if you don't use them for a while, in which case you can open them up and balance them manually. Others go out of balance because cells leak, so can be repaired by replacing cells, but only do that on a newish battery. If it's had 250 charges or more, probably better to replace or recell it.

 

[nichodia]

That sounds about right. Some batteries go out of balance if you don't use them for a while, in which case you can open them up and balance them manually. Others go out of balance because cells leak, so can be repaired by replacing cells, but only do that on a newish battery. If it's had 250 charges or more, probably better to replace or recell it.

Sorry for jumping in here, but my battery has not been charged anywhere near that amount but unfortunately due to being left for 6 weeks has gone flat..no lights, charges for about an hour before the green light comes on.but still no lights on the battery before I buy a new one could it be that mine could be rebalanced..if so how (my son is very techy and mechanical minded).

Di

 

[Fordulike]

Sorry for jumping in here, but my battery has not been charged anywhere near that amount but unfortunately due to being left for 6 weeks has gone flat..no lights, charges for about an hour before the green light comes on.but still no lights on the battery before I buy a new one could it be that mine could be rebalanced..if so how (my son is very techy and mechanical minded).

Di

Before you start opening it up or buy a new battery, try leaving it on the charger for a day or two. The charger light will go green, but just leave it to see if it self balances.

 

[nichodia]

Before you start opening it up or buy a new battery, try leaving it on the charger for a day or two. The charger light will go green, but just leave it to see if it self balances.

Thank you I will try that.

 

[Deleted member 4366]

That long charging won't cure it, but it'll give you an idea whether the problem is balance. If it improves, then it can be improved further by balancing or leaving on the charger for a long time. If it doesn't improve, you have to open the battery to measure the cell voltages on the multi-pin connector.

 

[nichodia]

That long charging won't cure it, but it'll give you an idea whether the problem is balance. If it improves, then it can be improved further by balancing or leaving on the charger for a long time. If it doesn't improve, you have to open the battery to measure the cell voltages on the multi-pin connector.

I have absolutely no idea what that means d8veh..however I have left it on charge overnight and just before I went to bed last night I noticed the red charging light was on..it is green again this morning, so will leave it on charge and see what happens..it is all I can do at the moment. Thank you for your reply.

 

[Ultrafunkula]

You can try cycling the battery a few times to maybe improve the balance, fully charged to empty,straight on the charger again fully charge,repeat a few times see if there is improvement, if it's still really poor ,recycle bin time and get a new one, or get new one built into your shell.

 

[Deleted member 4366]

I have absolutely no idea what that means d8veh..however I have left it on charge overnight and just before I went to bed last night I noticed the red charging light was on..it is green again this morning, so will leave it on charge and see what happens..it is all I can do at the moment. Thank you for your reply.

You only have to read it sentence by sentence. It's English! Maybe start by reading post #2

 

[nichodia]

What I meant was I have no idea how to attempt to measure cell voltages..nor do I think I would be safe doing so (60 year old woman) but I will pass this on to my son who is more technical than me...thank you again for your advice and replies.

 

[Deleted member 4366]

What happened to "my son is very techy and mechanical minded"?

 

[Fordulike]

What happened to "my son is very techy and mechanical minded"?

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