12V Lead acid battery charging problems ...

My son's electric scooter's motor got pooched from harsh element riding, (Canadian winter -- go figure). In any event, I purchased a new
motor/controller/throttle assembly, and in testing before I install, I find that the batteries are too low to drive the motor, and the old charger is pooched as well. Hmmm ... someday I'm gonna have to have a talk with that boy!
The scooter uses 2 12V 10AH Lead acid (deep cycle?) batteries wired in parallel for 24v, so I obtained a 12V marine deep cycle recharger from a local hardware store which has a 10amp and a 2amp charge current, and some electronics to monitor battery in the process. My problem is that the manual for the charger indicates that you should specifically NOT charge 2 batteries in parallel (yes, I did RTFM such as it is). Doh!
I figure that before I just stupidly try it, and blow something up, I might run it past this group first, as my electronic skills are somewhat limited (to plug it in/turn it on kind of limited), to seek guidance. Do I really need to split the batteries before charging?
Any input for the noob??
Thanks in advance, Cheers, Rob.
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snipped-for-privacy@controlq.com wrote:

You mean serial? Serial gives you 24V.

If its serialially connected you will not be able to charge it.

Yes. You must split it. You 'can' put them in parallel to charge it - but straight forward parallel connection is dangerous. Ideally you have a big diode and high wattage resistor in series before connecting in parallel. But for all that trouble, best to split the batteries and charge them separately. Buy two chargers if necessary.

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A comment like that suggests that you should leave well alone and seek the assistance of a competent electrician.
There's a lot of dangerous energy available from the low source impedance of Plante batteries.
Seriously - seek help.

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Hi Rob,
Like e7 mentioned you must have them connected in series and not parallel to give you 24 Volts. There is no problem charging them connected together, keep in mind all bets are off if the batteries are of a different kind or condition. But if the batteries are always going to be used as a 24 Volt source then there is no problem. Problems occur when batteries in a different state of discharge or capacity are connected in series and charged. I work with life safety systems that uses 24 Volt battery backup supplies, and it both high and trickle charges the batteries as a single 24 Volt system. If you break it down even further, a 12 volt battery is actually six 2 Volt cells internally wired in series.
Hope this helps,
Alan Parekh
snipped-for-privacy@controlq.com wrote in message

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Alan,
Yes, of course I meant in series, but indicated parallel (twice yet -- I'm not typically that dense). From your reply, then I can quite happily charge the 24V system as wired, and yes, the batteries are in the same state of discharge (or should be).
Just in case, I'll be using the trickle charge mode (2amp), and monitor the handy indicator on the charger carefully ...
Thanks for the info!
Cheers, Rob
On Sat, 24 Jul 2004, AP wrote:

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