Repairing an Ebike - start with the batteries

Since these are lead-acid packs, just take them to a battery store and have them load tested for free. Meanwhile, if you have a scooter or ebike in parts, maybe you need to get a digital multimeter.
 
For 4 SLA (sealed lead acid battery) in series, you could look for a 2 amp charger on ebay or amazon for 52 v LiIon batteries. Those should cut off at 52.8 v, which is 13.2 v per battery. That should be safe. You can usually see the cut off voltage in the blow-up of the sticker on the ad. You'll have to cut the connector off and install something else, usually.
I buy my DVM (digital voltmeter) from newark.com or parts-express.com . I've gotten accurate results from the tenma or PE products. OTOH the DVM from Harbor Freight at my volunteer job lied to us and caused us 2 afternoons of unnecessary work.
 
I have tested the batteries each with my voltmeter and they are 12.5 (The voltmeter is the YELLOW device in post #24), I thought that meant they were ok?
AC/DC, didn't think about that. Here is a pic of the ac tester (red and white) I was using to test the charger.
By the way, I'm in Canada and there isn't a Harbour Freight here (I wish)
 

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Since these are lead-acid packs, just take them to a battery store and have them load tested for free. Meanwhile, if you have a scooter or ebike in parts, maybe you need to get a digital multimeter.
Here is the voltmeter I'm using. When the bike is switched on with the key, it's says batteries are fully charged in the onboard display attached to the steering column
 

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By the way, I'm in Canada and there isn't a Harbour Freight here (I wish)
If I didn't make my point obvious enough, harbor freight sells garbage. Some things will last one or two uses, some things just ***** up the fastener you are trying to take off. They sell something that looks like steel, but isn't. Just like many of the bicycle vendors at the lower end of the market.
 
This is what an electric bike battery looks like on an electric bike. Bikes have pedals.
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Ok, have I been using the wrong terminology? Should I have been saying "escooter"? I am not sure what the above post is for...
Please see my post #23, #24 for my present issue and where I am at.
 
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Since these are lead-acid packs, just take them to a battery store and have them load tested for free.
A voltage test is not enough for a lead acid battery. You have to do it under a load to see how much the voltage drops. You could sit on the bike, attach your voltmeter, and try to watch the numbers. Hard to do.

Easier at the battery store. They put a resistive load on the battery and watch their tester.
 
I don't know if we have battery stores around here and those batteries are very heavy to lug around, especially four of them.
Maybe I am misunderstanding this, why is it hard to sit on the bike and test the batteries? Do you mean "drive" the bike and test the batteries? I could always prop up the back tire and let it spin if it requires that it is running/moving while testing, but I am a bit confused.
 
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I didn't read all your post. I assumed you had a bike that didn't run. Here in the USA, I can go to a Batterys Plus franchise down the street, where they will load test any kind of lead acid battery and even replace the battery in my Iphone. Nearby is an Advance Auto shop and also a Trak Auto that will load test car batteries. Scooter battery is no different. You must have Canadian Tire, etc, and also scooter shops. WIth lead acid packs, the time will come when you need a place you can trust to do an honest load test.

If the bike runs, and you got 12v, your light issues are due to flaky wiring, dirty switches, blown fuses, burnt out bulbs.

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The resistors listed in post 4 are a load test. I don't need a global warming car to drive to a batteriesplus store 4 miles from me across a busy dangerous Wall-Mart highway to do a load test. Surplussales or apexelectronic mail load test resistors right to my front porch. I bought the resistors to check repaired audio amplifiers. They are dual use.
Note I don't EVER ride a bike around Wall-Mart. People drive around there looking sideways for the best parking place. Death traps for bicyclists. Wall-Mart traffic was annoying when I drove a car. US 59 was destroyed between Texarkana & Houston by the installation of 5 Wall-Marts and their crazy traffic on all the bypasses. They are going to have to build parallel I69 for a twenty billion to avoid ***-**** Wall-Mart.
 
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Ok, good point on the finding a shop I can trust. I will go to my local Canadian Tire and see if they can do a load test, if not to a local scooter shop.
I have been doing research on the charger and created a rudimentary "Continuity Tester with an LED" to test the female and the male end cord of the charger.

TESTING CORDS NOT PLUGGED IN:
1) Male end to where it meets the circuit board of the charger - works, both prongs - LED Lights up.
2) Female end to where it meets the circuit board of the charger - works, both ends - LED Lights up.
3) Unlike an extension cord, I cannot test the entire MALE to FEMALE because of the components and circuitry in the charger - I am guessing it will not allow electrical current to flow through the entire board until it is plugged in or as you have said there is a load on it. So I cannot test the validity of the circuit board in the charger.

TESTING CHARGER PLUGGED IN AC :
Tested the charger for an hour plugged into the bike and wall outlet - charger did not get hot or even warm. Fan spins freely with my hand. I did have a thought about maybe the wires are loose on the bike plug LEADING to the batteries. I am going to check that next.

Also, is this a circuit breaker in the bike? I do not know what is does and it does flip, so unsure of which way it should be flipped.
Lights and wiring is next after getting the batteries checked and the charger working (or getting a new charger)
 

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Update - I phoned Canadian Tire and they said it wasn't busy so I brought all four batteries in. They took a look at them and said they don't have a device that can test these types of batteries.
The Scooter Store - I phoned them, but they are open open by appointment on Sunday and Monday. So I have to wait until Tuesday now. So far, 0-2.
Here are some pics of the batteries.
 

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Update :
Load test for batteries is now scheduled for Wednesday which is the first day they can get me in.
Using a continuity tester - ran from where the female end of the charger meets the circuit board all the way to the molex end of the charging socket - no resistance. Works
 

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I took the 4 batteries in today to get load tested at the ebike shop. 3 of the batteries were good, the last one the technician said was "ify" and would probably need to get replaced soon (I know I will have to replace all of them rather than just one). He said "then keep going until you need to replace them, no sense replacing them now".

The technician also asked me a few questions about that bike. I told him that the bike ran and throttled forward, but the lights didn't work. He then showed me a DC converter he had handy and said "that is the problem ,I bet".
 
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