Voltage check

[trevor.redman]

Could anyone tell me which terminals to check the voltage on a 705 Torque 575 battery please?
What reading should it be and what is acceptable?
Thanks Trevor

 

[Nealh]

If the terminal aren't marked +/- then usualy the outer terminal on each side , it matters not which probe goes in which port as all one will see if wrong is reverse polarity - sign show on the meter before the voltage reading. All one has to make sure is that the two probes don't tocuh each other causing shorting.
Voltage wise for 36v one wants to see 41.5v - 42v for a fully charged battery, less then 41.5v indicates an issue but will depend on how much lower the reading is.

 

[trevor.redman]

Thanks for reply. It’s reading 38.5 so is that not good?

 

[AGS]

It’s fine if it’s 70% charged. Not good if it’s 100% charged.

 

[trevor.redman]

Thanks . We’re in Portugal at the moment so will keep an eye on it. We don’t normally do much more than 20 miles so will make sure to put on charge after each ride
Thanks again Trevor

 

[Deleted member 16246]

Thanks for reply. It’s reading 38.5 so is that not good?

Is that after you take it off charge Trevor?

Could be that some cell groups are well out of balance. If so, what happens is that the BMS ceases charging any cells as soon as one group reaches 4.2v. This means the low cell groups never get properly charged, so the overall battery voltage is lower than it should be. On the road, the battery will shut down after a quite short range when the BMS detects that any group has reached the low voltage cut off point.

I had this problem, a while back after a long winter lay up, but in my case the charged voltage of the whole battery was higher than yours, and only one group was low - and it was really pretty far down. It is just possible that in your case, you have a couple or several groups that are low.

The solution I found was discovered after charging the battery to cut off, as normal, opening the battery case and using the multi meter to test and note the voltage of each parallel cell group. I had to solder tags onto the low group and individually charge that group with a 4.2v, lithium charger. This solved it, though that group does lose a wee bit of voltage vis a vis the others over time.

 

[Nealh]

It's quite simple read my post #2 , if it doesn't charge to 41.5v - 42v then it is faulty/has an issue.
If it is 38.5v becuas eit has been in use then likely no issue, one has to charge it up and then see ehat the voltage reads.
Voltage though doesn't always mean a battery may be good , battery age also has a part in the workings.