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[Rogerdog23]

Hi, Replaced all three batteries on my kid’s motorcycle as they were totally dead. 36v system replaced with same 12v 12ah batteries. Went to charge and it said full charge rather immediately. My daughter rode it around and it immediately went from the full charge light on the indicator to “low” charge. It still goes pretty fast but not great. Rode it some more and recharged. Tried again and same thing after 2 minutes. Had my son ride it who weighs less and he got about 10 minutes before it went to “low” on the indicator. Meanwhile my daughter rode his Matching motorcycle with 3 year old batteries for 20 minutes before it finally went to “low” on the indicator. Checked chargers and they are both putting out 42v. Used spade connectors on old wiring harness to connect new batteries with f2 terminals. Tightened with needle nose to make sure they are on snug. All 3 battery fuses looked good. Tried testing both bikes voltage where the charger plugs in and didn’t get a reading on either bike (with power switch on). Any help is appreciated.

[TEV]

I would check the charger first.

[TEV]

(with power switch on). Any help is appreciated.

Try with the power switch in off position, maybe, like a safety feature, the circuit isn't completed when the power is on.

[Rogerdog23]

Checked the charger. Tried with power switch off and still no reading.

[TheRan]

Is the bike actually dying or is it just indicating that the battery is low? The state of charge indicator is likely very basic and essentially just a voltage meter, so it could be that the voltage is just dropping under load for some reason. If that is the case it should recover after a short period of not being used.

[Rogerdog23]

That’s a great question. My daughter says it slows down considerably but I’ll double check with a phone app and monitor speed with full charge vs running it for a bit. Will report back soon.

[Rogerdog23]

  Checked and it does indeed slow down when the low light comes on. It took about 5 minutes to come on this time but did come on and the bike slowed down. The bike with the old batteries and heavier rider is outperforming the new batteries and lighter rider. Ugh.