Schwinn s750 battery issue or something else? Need help with diagnosis.

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Socks
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Joined: 09/14/2016
Points: 14

Hi.

I am hoping someone could help me diagnose a problem with a used Schwinn s750 I just purchased off craigslist.

There seems to be an electrical issue with the scooter. Here's a little history. When I bought the scooter the seller told me that the scooter was fully charged and that he had charged it until the charger stopped blinking showing a solid green light on the charger. However, from what said it didn't seem like it was charged for the recommended 6-8 hours so I am not sure if this has anything to do with what I am experiencing.
The seller also mentioned that the batteries were changed in the previous year but I know they could still be the culprit. Lastly, he mentioned that the throttle was changed before.

The symptoms...

1. When I am running at full throttle, the scooter shuts down after 1-2 mins. The battery indicator lights go from green, yellow to red. The scooter then stalls. I would need to switch the scooter into the OFF position then to the ON position. The battery indicator light goes back to green but soon to yellow and red after running it a bit more then stalling again.

2. When I am running at a slower speed the scooter seems to last longer but still after using the scooter, the battery indicator would change from green to yellow to red then stall.

What could the issue be? Does it sound like the batteries are shot? The batteries do not seem to have any bulging or leakage. Or maybe something else like a controller? Any ideas?

Thanks

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Johnny J
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Joined: 07/08/2008
Points: 374
Re: Schwinn s750 battery issue or something else? Need help ...

The signs are quite clear that the batteries needs replacing.

LeftieBiker
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Joined: 07/09/2011
Points: 859
Re: Schwinn s750 battery issue or something else? Need help ...

SLA batteries are very easily damaged, especially by too-deep discharges, and by being left in a low state of charge for more than a few minutes before being recharged. The symptoms you describe sound like batteries that have either sulfated heavily from normal use and are no longer usable, or have developed a 'surface charge' and aren't fully charging. You can try discharging it to the first sign of red and then charging it for 6 hours, or for three or four hours after you get the green light. (Keep an eye on them in case they start to overheat.) This may work, but the odds are, at best, 50-50.

Socks
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Joined: 09/14/2016
Points: 14
Re: Schwinn s750 battery issue or something else? Need help ...

Johnny J wrote:

The signs are quite clear that the batteries needs replacing.

Thanks Johnny. I was hoping it would be something cheaper than another set of batteries.

LeftieBiker wrote:

SLA batteries are very easily damaged, especially by too-deep discharges, and by being left in a low state of charge for more than a few minutes before being recharged. The symptoms you describe sound like batteries that have either sulfated heavily from normal use and are no longer usable, or have developed a 'surface charge' and aren't fully charging. You can try discharging it to the first sign of red and then charging it for 6 hours, or for three or four hours after you get the green light. (Keep an eye on them in case they start to overheat.) This may work, but the odds are, at best, 50-50.

Thanks for the advice, leftiebiker. I will try to see if I can save this set of batteries before I purchase another set.

Thank you both for your help.

LeftieBiker
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Joined: 07/09/2011
Points: 859
Re: Schwinn s750 battery issue or something else? Need help ...

If you do have to replace the batteries, remember that not all SLAs are equal in performance. If a battery is cheap on Ebay, even if it seems to have a flashy label instead of a generic one, it probably performs like a cheap battery, too. I bought a pair of SLAs for an EZIP bicycle from Ebay last year, only to have them perform worse than the 3 year old OEM batteries they replaced...

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