Is the battery bad or is it something else ?

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Vehicle is a four wheel electric scooter for people with disabilities. There are two 12V deep cycle batteries the size of an automotive battery, probably marine type.

Batteries are 3 to 4 years old. 24V charger does its job and when full, it stops charging and lights up a LED. When full, each battery reads 13.x Volts.

Once charged, the status bar on the scooter reads FULL. When riding, the scooter will suddenly stop and flash the status bar as if the battery was empty. If you turn it off then on, you once again see a full battery bar. You then begin riding and within two minutes the same symptom appears.

Is that the sign of bad batteries ? Deep cycles are pretty expensive, so I'd like to have other opinions before replacing them.
 
Seems the batteries are shot. Voltage drop from motor load causes the meter to flag empty and stops the scooter rolling to avoid over-discharging the batteries. When you switch it off and on again, the voltage test is back to normal because no load on the batteries.
 
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You need to read the battery voltage under load. Even running the motor with the drive wheels off the ground would be somewhat of a test.
 
Attach a separate voltmeter directly to the batteries and ride the scooter to watch what the voltage does. If it really sags down, could be the batteries failing. If voltage is normal at batteries but scooter still says dead batteries, look for loose, dirty, or corroded connections.

A voltage drop test along the main power wires while under load can help narrow down where the problem lies if there are no obviously bad connections.
 
Originally Posted By: Eddie
I agree with madRiver and think it may be a controller OR a sit-down safety switch. Ed


Yep....some safety feature. He says turning it off... then on... shows battery full. Some sort of short.
 
Did this happen all of a sudden? If it had been sitting a while, I'd be inclined to think that it's a sign that the batteries are going bad. Measuring the battery voltages, especially under load, would be a good start.
 
Sounds like bad batteries, especially at 3-4yrs old, but there could be another issue. Does the battery meter drop down to low under load? Most chairs don't have a seat safety switch. Otherwise, make sure the brake/clutch lever or levers (near the wheels) are fully seated nice and tight.

If you set the speed at max does it cut out sooner than at slow speed?

You can get the batteries tested at a battery store or medical supply store. Otherwise, a rudimentary 100 amp hand-held load tester should be sufficient to pinpoint a shot battery. The electronic conductance (cranking amp) testers used by most auto parts stores aren't good for testing deep cycle agm or gel batteries.
 
Thanks for the replies. When stores reopen I will get a 100A battery tester. I found one at a local store at decent price.

To my knowledge there are no safety switches as you can operate the scooter by walking beside it. I had to remove the seat and the hood under it to reach the batteries and I didn't have to unplug anything electrical other than the rear lights.

Are they AGM ? I have no idea. All stickers have been removed from them.

The problem started all of a sudden in late Fall. It's not used during winter so I left it in my heated garage and make sure to charge it every week until I figure out what is happening.

The problem happens whether you are riding full speed or lower.

One more thing I remember : with the status bar full, when you start riding it immediately loses a bar of charge. This bar is back when you "reboot" the scooter unless you've been really riding enough to get the battery to that level.
 
Originally Posted By: Superflan
Seems the batteries are shot. Voltage drop from motor load causes the meter to flag empty and stops the scooter rolling to avoid over-discharging the batteries. When you switch it off and on again, the voltage test is back to normal because no load on the batteries.


+1. If charged outdoors/in the cold the batteries may not be fully charged either.
 
I bought a load tester that puts a 100A charge on a battery.

While I do not know the battery's exact amperage capability since the stickers were removed, according to the tester the battery tests as just good enough for a 650-800 CCA. This test lasts 10 seconds as the test device gets pretty hot.
 
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