Max Charging Current for SLA Batteries: Avoiding Damage

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Discussion Overview

The discussion revolves around the maximum charging current for sealed lead acid (SLA) batteries, particularly focusing on whether charging a 12V, 170Ah battery with a 30-32A power supply could cause damage. Participants explore various aspects of charging rates, internal resistance, and measurement techniques.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests that charging at 32A may not damage the battery, as it likely won't draw the full current unless it is significantly degraded.
  • Another participant mentions that the internal resistance of the battery could limit the charging current to around 6A, depending on its condition and charge state.
  • Concerns are raised about whether the power supply's maximum current could harm the battery if it is fully drained.
  • Participants discuss the feasibility of measuring the charging current using an ammeter, with one suggesting the use of a clamp ammeter for this purpose.
  • There is mention of previous experiences charging batteries with different types of chargers, indicating variability in charging practices.
  • One participant proposes the use of a hall sensor for measuring DC current, indicating a potential solution for monitoring charging without direct connection.

Areas of Agreement / Disagreement

Participants express differing views on the maximum allowable charging current and its potential effects on battery health. The discussion remains unresolved regarding the exact implications of charging at higher currents.

Contextual Notes

There are uncertainties regarding the internal resistance of the battery and how it affects the charging current. Additionally, the discussion does not reach a consensus on the maximum safe charging current for the specific battery in question.

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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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I don't 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 already has ..
 
The power supply is current limited but I'm worried abt whether the 32A will cause damage to the battery(if fully drained)?
 
Last edited:
does your power supply have an ammeter built in ?
 
No but I can easily install 1
 
what i mean is, if you were to measure the current , you wouldn't 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.
 
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 ...
 
cookiebar said:
... I can measure the current with a clamp ammeter.

DC?


...
 
  • #10
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.
 
  • #11
GENIERE said:
DC?


...
I was wondering about that myself..
but I'm sure cookiebar knows how to measure current..
 
  • #12
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...
 
  • #13
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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