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# When a SLA battery specifies a range of charge voltages, do you choose the high or low end?

## When a SLA battery specifies a range of charge voltages, do you choose the high or low end?

(OP)
Typical example:

The label states that the charging voltage is "14.6-14.8V". I have a computerized hobby charger (similar to the iCharger 206B) that does CC-CV charging where the voltage of the CV stage can be set to an accuracy of 0.01V per cell.

So, the question is, what's the best voltage setting, and why? Should I target the low end (14.6V) or the high end (14.8V)? I'm inclined to target the low end as I feel it would reduce positive plate corrosion and electrolyte loss.

What would happen if I use the conventional FLA voltage of 2.4V/cell (14.4V total) for this SLA?

Lastly, since it states a "maximum" current of 10.8A, is it a good idea to set the CC current to 10.8A... or would a lower current setting give longevity benefits? (The charger is not a limiting factor, it's rated for 20A. CC current can be set in 0.1A increments)

In short, I'd like some pointers from more experienced engineers to maximise the life and performance of SLAs within the limitations written by the manufacturer, since they provide a range rather than a fixed value.

P.S. If it makes any difference, the application will be occasional backup power. This battery will be stored open circuit, given a topping charge every few months, and only used occasionally for a long deep discharge, powering an inverter every time there's a power cut (couple of times a year).

### RE: When a SLA battery specifies a range of charge voltages, do you choose the high or low end?

It's all about the 25C. Note the -30mV/°C

The temperature is way more important than those 200mV. You live in a warm place so I'd typically go for the lower value.

If your charger belts out a lot of current then racing up to the higher value would be fine since it will be there only briefly before cutoff.

If your charger tapers off then the lower one would be more applicable because the peak voltage would be applied longer.

You do not want sealed batteries off-gassing. Very bad for them. Note the 10.8A MAX. Above that and the system can not recombine the gasses fast enough to keep them in the battery.

When the battery charges it heats up so the battery will at a higher temperature than ambient near the end of charge.

Keith Cress
kcress - http://www.flaminsystems.com

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