I have my cabin inverter system set up and running temporarily at my house. It consists of a Xantrex Prosine 2kW inverter and 4 Energizer 220ah GC2 Batteries in a series/parallel connection to feed 12 VDC to the inverter. I have some questions regarding the settings on the 100A battery charger built into the inverter. Here are the settings that the Charger defaulted to when I selected generic flooded cell and entered 440 ah battery capacity.

Bulk Charge
Max Current 10% of battery ah capacity (Defaulted to 30%, I thought that was too high)
Max Voltage 14.4V
Absorption Charge begins after a time delay of 3 minutes at or above 13.5V

Absorption Charge
Max Current 44A 10% of battery ah capacity (Defaulted to 30%, I thought that was too high)
Max Voltage 14.4V
Max Time 8 hours.
Overcharge begins after a time delay of 3 minutes at or below 2.5% of battery ah capacity

Overcharge ( This is not explained very well in the manual other than it is the second half of the Absorption step)

Overcharge and Float also have settings but I don’t want to get too long with this message.

One question is about the 13.5V setting to begin the absorption charge seems low. Any advice on a typical number there, on what is the overcharge part of the absorption step and any other advice from the gurus here would be appreciated.

Thank you,

Jerry

30% is NOT to high, if you lower to 10%, it will take +8 hours to get to absorb, restore the default

The 13.5 should be at or very close to the 14.4 setting, Bulk to Absorb transition happens when the Bulk voltage is reached and the the charger goes into constant current.

With your 10% value, the battery's will NEVER get to the 14.4v and go into absorb at 13.5 very bad

Also, make sure you are using temperature compensation, the voltages listed are all for a battery at 25C

Guppy

Thank you for the reply. I was under the impression, and could be mistaken, that I shouldn’t be charging my flooded lead acid batteries at over 10% of their 440 Ah capacity. If I set bulk charge to 30% of 440 Ah that is about 146 Amps. My charger will do 100A.

The charger has a temperature sensor and adjustable battery temperature coefficient.

Is it OK for the GC2 batteries to be bulk charged at 30% of their Ah rating? In my case less than that because of the charger 100A limit. I’m charging with a genset until I get PV panels up so I want to maximize the charge rate without excessively hurting the batteries.

Also, could you tell me if there is a place where I can find more info on charging a particular type of battery? The battery manufactures have some guidelines but not as it relates to 3 stage charging.

Thank you,

Jerry

100 amps is fine, if you have any concerns just check on them when charging the first-time and see if they get hot. I have 440ah and do 100ah all the time, battery's don't even get warm.

You have a very generic lead-acid battery, using 14.4 for bulk/float is fine

the 30% figure is pushing it for many batteries, but if watching it you could possibly get away with it. i advise 5%-13% as a precaution for many who do not watch or baby it, as many will not do that, and they don't know the manufacturer's highest recommended charge rate. when dealing with batteries always ask the manufacturer what they will allow for because of warranty issues as well as battery lifespan for this applies to discharging and charging rates for cycle life. higher maintenence will be a certainty when doing such percentages up that high. some poorly made batteries could heat up and cause the plates to move under some high charges/discharges.
i agree with sg to raise the absorb to 14.4v. this is the point that takes the charger out of bulk and amounts to a voltage regulation circuit that holds it at that voltage while the current tends to tapper. at some preset point many 3 stage chargers will throw that voltage setpoint down to a float voltage (around 13.5v i think, but varies per manufacturer) when the current shows to be low enough.