ebike battery help

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Jun 28th, 2018 10:36 pm

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Jun 26th, 2018 9:38 am

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 26th, 2018 9:38 am

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

Jun 26th, 2018 9:50 am

Mr_Dogg: Deal Addict; Feb 26, 2012; 2234 posts; 566 upvotes; MISSISSAUGA

Jun 26th, 2018 9:50 am

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!

Jun 26th, 2018 10:04 am

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 26th, 2018 10:04 am

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)

Jun 26th, 2018 1:45 pm

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 26th, 2018 1:45 pm

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

Jun 27th, 2018 10:46 am

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 27th, 2018 10:46 am

understood....this task hasn't been completed.

I wonder if I take them to CT - if they would charge for me

Jun 27th, 2018 1:42 pm

tmkf_patryk: Deal Addict; Dec 27, 2007; 4404 posts; 1696 upvotes; Edmonton

Jun 27th, 2018 1:42 pm

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

Jun 27th, 2018 2:19 pm

oldyellr: Member; Sep 7, 2007; 339 posts; 180 upvotes; Woodstock

Jun 27th, 2018 2:19 pm

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.

Jun 28th, 2018 3:20 pm

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 28th, 2018 3:20 pm

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

Jun 28th, 2018 3:21 pm

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 28th, 2018 3:21 pm

i do not have a 12 volt charger and these batteries are fully encased...I dont see any openings to add distilled water

Jun 28th, 2018 3:37 pm

tmkf_patryk: Deal Addict; Dec 27, 2007; 4404 posts; 1696 upvotes; Edmonton

Jun 28th, 2018 3:37 pm

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

Jun 28th, 2018 10:36 pm

pardnme [OP]: Deal Addict; Feb 22, 2007; 2033 posts; 271 upvotes; Mississauga

Jun 28th, 2018 10:36 pm

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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