# Max charging for SLA battery?

What is the max current for a rapid sealed lead acid battery charger?

Most recommend 0.1C up to 1C where C = Ah rating. I have a max 30-32A regulated 13.8VDC power supply and the battery is 12V, 170Ah. Would charging the battery at the max 32A damage the battery?

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#### willib

I dont think that the battery will draw the full 32A , in fact i am sure it wont..unless it is past , way past , its prime..
13.8-12 =1.8V
1.8/(internal resistance of battery) approx(.3 ohms) =6 amps..
it should work fine, as it is...
note :: it may draw more or less depending on the actual internal resistance and the amount of charge it allready has ..

The power supply is current limited but I'm worried abt whether the 32A will cause damage to the battery(if fully drained)?

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#### willib

does your power supply have an ammeter built in ?

No but I can easily install 1

#### willib

what i mean is, if you were to measure the current , you wouldnt be damageing your Ammeter..?
If not ,then try it with the ammeter installed and see what current the battery is drawing..

so what is the max allowable current for charging? I can measure the current with a clamp ammeter.

#### willib

if you were to measure 6 A when when the battery is connected , you could leave it on for 28 hours ..
170/6 = 28 approx..
as you said at the beginning , 0.1c = 17A , but that is pretty high ...

#### GENIERE

... I can measure the current with a clamp ammeter.
DC?

...

#### GENIERE

The few times I charged my motorcycle battery with a charger designed for an auto battery, I put the charger in series with the headlamp. Of course the charge time is much longer.

#### willib

GENIERE said:
I was wondering about that myself..
but i'm sure cookiebar knows how to measure current..

#### Averagesupernova

Gold Member
I don't know why they wouldn't exist and I can't say I have actually seen one but using a hall sensor you should be able to measure DC amps with a clamp on meter. I have seen sensors that permanently go in-line for current measurement. They are a square donut type of thing that the wire goes through loosely. I can't see why this couldn't be adapted to a clamp on sort of thing. My two cents...

#### GENIERE

Averagesupernova said:
They are a square donut type of thing that the wire goes through loosely...
Yeah, that seems to jog my memory.

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