Help! Voltage problems

Feraslan

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Oct 27, 2019
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Hello.
i have 350 watt 48 volt china ebike.
When I put my battery in the bike, the battery indicator shows on the screen and the engine starts. But after 5-10 minutes the voltage drops and the indicator goes down to zero. First I thought the battery was exhausted and I bought a new one. The same problem happened when I inserted the new battery.
Ps:There are 5 minutes between two pictures
 

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Nealh

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Aug 7, 2014
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It's a shame you went and bought a new battery as a simple check of the original with a multi meter would have shown the voltage to be good.

The issue is likely to be a controller fault and a faulty voltage regulater within, I had a similar problem with my now defunct Oxydrive kit. Two good batteries would initially work then the voltage would crash.
 
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Feraslan

Just Joined
Oct 27, 2019
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It's a shame you went and bought a new battery as a simple check of the original it with a multi meter would have shown the voltage to be good.

The issue is likely to be a controller fault and a faulty voltage regulater within, I had a similar problem with my now defunct Oxydrive kit. Two good batteries would initially work then the voltage would crash.

Thank you for answer .Is it possible to repair the controller?
 

Nealh

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Thank you for answer .Is it possible to repair the controller?
Probably if you are an electronics micro surgeon and know what components to replace, though likely more then one or two components might be damaged.
 
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vfr400

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Jun 12, 2011
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Buy one of those cheap wattmeters from EBay and put it between the controller and battery to see what's going on before you go any further. It will tell you if anything is draining the battery and by how much.
 
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Feraslan

Just Joined
Oct 27, 2019
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Buy one of those cheap wattmeters from EBay and put it between the controller and battery to see what's going on before you go any further. It will tell you if anything is draining the battery and by how much.
I have a multimeter, but I don't have that much technical knowledge.
 

vfr400

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The wattmeter justs fits in between those thick red and black wires. You'll need put some bullet connectors on it to match. For this test, crimping or wire twisting would be OK as a temporary measure if you can't solder.

There is a test you can do with your voltmeter that will give an indication of whether current is flowing. Set it to millivolts scale, slide in one probe under the insulation sleeve of the bullet connector so that it makes contact with the metal, then jag the other one through the red or black insulation of the same battery wire as far away as you can, say 10 cm. With the battery switched off or disconnected, you should see 0 MV. When you switch on or connect the battery you should still see close to 0mV. Something like 5mV would show that moderate current, say 5A, is flowing.
 
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