bike battery no green light

billyboya

Esteemed Pedelecer
Aug 10, 2016
1,137
90
73
uk
I have a 36 volt battery, and to be fully charged it has to say on multimeter 42 Volts which it does, well actuially its now at 42.1 volts but still green light on charger dont come on to say its done only has red light still and charging
 

guerney

Esteemed Pedelecer
Sep 7, 2021
11,531
3,277
Best wait for an expert before charging further.

My battery sometimes charges to 42.1V, because my charger sometimes measures 42.1V, instead of the usual 42V. Perhaps your battery is taking longer to charge or balance charge because of colder weather?
 

thelarkbox

Esteemed Pedelecer
Aug 23, 2023
1,252
385
oxon
has the battery been stood unused, or is it old? in either case it may require some post charge balancing of the cells and the low power circuits for balancing will not be super fast.

otherwise as long as your measurement was the battery voltage and not the charge voltage feel free to disconnect, especially if the battery is warmer than room temp to the touch.
but if 42.1v i suspect thats the charge voltage and not the battery voltage. disconnect the charger and measure the battery.
 

billyboya

Esteemed Pedelecer
Aug 10, 2016
1,137
90
73
uk
Hi all its sorted now as It was a faulty wire from charger to pin where it plugs into battery, I think its because when i fold up charger its obviously loosened a wire maybe, so will have to see if i can see inside the connector lead. btw my bike is used nearly every day, But I always let battery go down to say 35 Volts before i charge up again.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,981
8,565
61
West Sx RH
One doesn't have to regimentally let the battery SOC go down to 35v before charging, 38 - 39v is ok to charge battery to full again simply because the charge time is much shorter .
Charge depending on how you use the bike , always full charge before a longish ride where going down to 34/35v has benefits in range anxiety.
For local short riding trips / errands there is no need to deplete the battery all the time.
 

billyboya

Esteemed Pedelecer
Aug 10, 2016
1,137
90
73
uk
One doesn't have to regimentally let the battery SOC go down to 35v before charging, 38 - 39v is ok to charge battery to full again simply because the charge time is much shorter .
Charge depending on how you use the bike , always full charge before a longish ride where going down to 34/35v has benefits in range anxiety.
For local short riding trips / errands there is no need to deplete the battery all the time.
Oh ok as I was told to let battery go down to about 35 volts each time then recharge. so I will recharge when its down to 38 to 39. thanks for that Nealth :)
 

thelarkbox

Esteemed Pedelecer
Aug 23, 2023
1,252
385
oxon
What metric should we be on top of for basic battery care, Until reading the above my impression was to minimise the number of charge cycles so letting the battery deplete to circa 34-35v would be preferable to recharging at 38-9v??
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
7,005
3,241
Telford
What metric should we be on top of for basic battery care, Until reading the above my impression was to minimise the number of charge cycles so letting the battery deplete to circa 34-35v would be preferable to recharging at 38-9v??
The number of charge cycles has no bearing on anything. It's more the amount of usage that wears out the battery, and how hard the usage is. The only important things are to charge it to 100% most of the time, and never leave it in a fully discharged condition, and the thing that seems to kill batteries the most is to leave them for a long time unused, though not all batteries are affected by that.
 
  • Informative
Reactions: thelarkbox