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using a lipo charger to charge a SLA?

Hey everyone !
I'm planning to use a lipo charger from my Ebike to charge some scooter SLA batteries.
I'm more of a li-po guy and haven't tried charging 3 SLA's in series before.

Original lipo was a 10s 8.8Ah 36V (nominal, maxed out at 42V) and had an on board BMS that took a stright 42V input from the charger.
the charger for it will deviver 42V @ 2amp and will let current flow until it hits 42V then automatically shuts off.
The scooter batteries are 3X 12V 20ah  (six cell I assume?)

by all-means, I should be able to wire the three batteries in series, (3 x 14.5V = 43.5V) then my charger should be a direct replacement right?
Still need to manually balance them occasionally but for daily use on a 2amp charge should be ok eh?

seandogue3 months ago

A simple current-limited DC power supply set to the right peak charging voltage for your battery pack will do the job perfectly. (presuming it will be charged after moderate depletion)

Standard SLAs generally like to see the current limit set around 2 amps but under dire circumstance it can be bumped up to speed initial charging. Limiting the current reduces free hydrogen levels and prolongs the life span.

In the field, voltage is usually set using this back-of-napkin calculation

1 cell 2.3-2.5 VDC (charging)

1 cell (depletion) 2 VDC

or Vout = N x 2

and charge

Vin = N x (2.3..2.5)

a 12VDC SLA battery for instance, is comprised of 6 cells, for a total charge voltage of between (2.3 x 6) and (2.5 x 6), or 13.8 - 15VDC

Perhaps~~ some iron phosphate lipo chargers **might** be usable on a temporary basis, (they have similar characteristics to lead acid in charging...) but I'd stick with something designed ((or set up) to charge lead-acid chemistry batteries for best return..

SLAs btw, underline> when appropriately set in both voltage and limit-current <end-underline, tend to self-limit to full charge. That is, as they charge, they'll draw less and less current. No special consideration needs be taken except for always remembering to ventilate, at least while charging, even if you think "why? this is just a small ups battery. be safe. If you want to go the extra mile, monitor the charge current and when it drops to about 0.1amp, be sure to turn the voltage down to the lowest (Nx2.3) voltage for a sustained trickle charge. (if left idle for a an extended duration)

Downunder35m3 months ago

It is always best to charge batteries individually unless you can sure they are all identical - electrical and chemically.
A lipo charger works quite different to a proper lead acid charger but then again not that much different to a cheap chinese charger off Ebay that claims to charge your lead acid batteries.
The case is far from ideal but for a while it will work just fine.
I would keep an eye on the discharge levels and the gassing when charging.
Sealed batteries are not really fully sealed but if for some reason they gas too much the battery can blow up like a balloon and finally burst.