Automotive

ebike battery help

  • Last Updated:
  • Jun 28th, 2018 10:36 pm
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga

ebike battery help

hopefully somebody can provide some guidance.

Ebike has 4 batteries wired in series. Each battery is 12v20ah = 960 watts (48v20ah).

I charged it, and the charger isn't showing the battery is charged...i tried the battery anyways, and the lights/signals work, but no power to start it.

I used my DC Voltage tester and tested the charger - it has slighly more than 50 voltages - which is good

I tested each battery (all connected up in series - i didn't disconnect)

battery 1 = about 12.5 v
battery 2 = about 12.5 v
battery 3 = about 9 v
battery 4 = about 10.5 v

does this mean battery 3 and 4 are toast? and battery 1 and 2 are still fine?
10 replies
Deal Addict
Feb 26, 2012
2234 posts
566 upvotes
MISSISSAUGA
That is what it looks like. I assume these are Lead Acid? Or Lithium Ion?

I would disconnect 3 & 4 and try charging individually and re measure voltage. If it's about the same then yes toast.

IF these are lithium ion and the BMS is located outside of the batteries DO NOT try charging individually and let us know!
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga
these batteries are REALLY heavy

6-dzm-20 - i think they are lead acid (i have 4 of them as mentioned above)

so in order for me to charge them with the ebike charger...i would actually have to disconnect battery 1 and 2....and only leave 3 and 4 connected in series then plug in the charger (like a computer power cable)
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga
well i wasn't planning on just disconnecting them...

i would have removed the 2 good ones from the series and then only had the 2 'bad' batteries connected in the series
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga
understood....this task hasn't been completed.

I wonder if I take them to CT - if they would charge for me
Deal Addict
Dec 27, 2007
4404 posts
1696 upvotes
Edmonton
So. Let's get this straight.
Your bike runs on 48v or 12v or 24v???(seems like its 48 if it's series, then why only have two hooked up?)

What is the voltage and amps of the charger. (Assuming it's charging 48v at ??? amps)

How long have you been charging them for?

Do you have a 12v charger and load tester?
(Then you can do it single piece by piece, and test them out by putting a load on it)

I am sure people can see where I am getting at.....
warming up the earth 1 gas fill-up at a time...
You only live once, get a v8
Member
Sep 7, 2007
339 posts
180 upvotes
Woodstock
You have four 12v batteries in series for a 48 volt system. Clearly 2 of them are not to par. If they are conventional lead-acid batteries, check the acid level and top up with distilled water if needed. First I would attempt to charge the 2 low ones individually with a 12 volt charger to see if they come up. If they do, then see how that works. If you can't get those 2 up, they need to be replaced with the same kind of battery.
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga
tmkf_patryk wrote: So. Let's get this straight.
Your bike runs on 48v or 12v or 24v???(seems like its 48 if it's series, then why only have two hooked up?)

What is the voltage and amps of the charger. (Assuming it's charging 48v at ??? amps)

How long have you been charging them for?

Do you have a 12v charger and load tester?
(Then you can do it single piece by piece, and test them out by putting a load on it)

I am sure people can see where I am getting at.....
yes I have four 12 v batteries in series = 48V, i dont have 2 hooked up...i was thinking i could hook up 2 to try and charge them based on advice from above

they are 12 v 20ah each.

When i checked DC voltage on the charger it showed about 50ish volts
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga
i do not have a 12 volt charger and these batteries are fully encased...I dont see any openings to add distilled water
Deal Addict
Dec 27, 2007
4404 posts
1696 upvotes
Edmonton
pardnme wrote: yes I have four 12 v batteries in series = 48V, i dont have 2 hooked up...i was thinking i could hook up 2 to try and charge them based on advice from above

they are 12 v 20ah each.

When i checked DC voltage on the charger it showed about 50ish volts
How much amps when your charging?
warming up the earth 1 gas fill-up at a time...
You only live once, get a v8
[OP]
Deal Addict
Feb 22, 2007
2033 posts
271 upvotes
Mississauga
I have no idea...nor do I know how to check that...

but the past few years, this charger/batteries have never been a problem

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