Float voltage question..

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wipe_out

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Just switched to AGM batteries and the manufacturer specifies float voltage of between 13.5V and 13.8V.. My charger is a Promariner Protech-4 30A charger which I believe is the US version of a Sterling charger.. The manual claims it is compatible with AGM and also claims a float voltage of 13.5V but when I connected it up today and measured the voltage I found that the float voltage was 13.3V..

How critical is the float voltage and will running at 0.2V below the manufacturer spec have any ill effect on the batteries?
 
With AGMs I think you have the reverse of a problem. What they don't like is over charging - I suspect that your charger correctly sensed the voltage and is acting accordingly.

But I'm not an expert - I've just read up on my own AGMs. I hope an expert will be along in a minute.
 
Once the rest of the charging cycle is correctly specced you will be absolutely fine.
 
Bulk charging seems spot on.. The spec calls for 14.4V to 15.0V and I saw 14.5 to 14.6 from the charger so happy with that stage, just saw a lower float.. I figured if anything slightly low is better than slightly high but though I would put it out to the forum and see what others felt.. :)
 
just a thought, are you certain your voltmeter is reading correctly?
Digital ones are prone to fluctuate with a flatish or cold internal battery
 
A lot of chargers use a float of around 13.8V, and battery makers often spec up to 13.8V
In my experience, you can ruin a battery by leaving it on a 13.8V float charge for months.
13.5 or less is more appropriate for 'permanent maintence float charging'
But 13.8V is great for a 'float' charging stage for a battery that's being cycled daily. Because the charger will flip into 'float' while the battery is still <100% charged, and the battery will be loaded before very long.

Then there are subtle tweaks according to what the lead is alloyed with (e.g. Calcium), and a fiddle factor for temperature.
 
wipe_out said:
Just switched to AGM batteries and the manufacturer specifies float voltage of between 13.5V and 13.8V.. My charger is a Promariner Protech-4 30A charger which I believe is the US version of a Sterling charger.. The manual claims it is compatible with AGM and also claims a float voltage of 13.5V but when I connected it up today and measured the voltage I found that the float voltage was 13.3V..

How critical is the float voltage and will running at 0.2V below the manufacturer spec have any ill effect on the batteries?
Click to expand...

Does your charger have temperature compensation? If so, is the temperature sensor near the battery? Charging voltages are, in the case of my Ctek, nominal at 25 degC, and go up with lower temperatures and down with higher.
 
Porthandbuoy said:
Does your charger have temperature compensation? If so, is the temperature sensor near the battery? Charging voltages are, in the case of my Ctek, nominal at 25 degC, and go up with lower temperatures and down with higher.
Click to expand...
No, I have seen no reference to temperature compensation on the manual so don't believe it is compensating for temperature..
 
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