Recharge time

[ericfx1984]

So I have 4 Duracell gc2 wet acid batteries... There's six volts configured to 12 volts

I've had quite a few gray days lately and as a result I've had to use my generator in the morning to charge up the batteries and potentially in the evening as well

The inverter charger can do up to 100 amps continuous of charge.. it is an Aims power one of the things I have noticed about the generator when it's used in charge mode is that it seems to charge significantly longer than it really needs to

Oftentimes it will be in fast charge mode for upwards of 4 hours when the batteries have only been discharged to 12.6 volts.. but for my calculations even at 70 amps it shouldn't take more than two or three hours and if I decide to turn it to the hundred amp setting it shouldn't take but 2 hours at most

So I'm trying to understand why the inverter charger seems to be so heavy on the charge when it doesn't seem to need it

There have been a few times that I've shut the generator off technically ending the cycle early only to find out that the batteries are resting somewhere at or above 12.9 volts

 

[circus]

I found my lead acid batteries determine the charge rate, not the charger. That last 5% takes the longest time. It doesn't matter on a plug in charger, it just draws less current but does matter when feeding fuel to a gas generator. Do you actually know the amps going in?

 

[ericfx1984]

thank you for the reply..

Well.. you can adjust the output and that 100% output it puts out 100 amps or at least it can... Course when you draw it down to the lowest setting I think it's only about 10 or 15a

I suppose I need to get a clamp meter on it.. this morning after running the heater all night it's a propane heater with a blower motor built into the RV I was down around 12.6 or 12.7 volts... And I went ahead and set the charger to its Max rate and it charged in about an hour and a half and switched over to float mode so maybe the dial is not completely accurate..?

Either way I figure at 12 volts that's about 450 amp hours give or take so if it was down at 12.6 or so if it charges within 2 hours that's right around 100 amps

 

[circus]

There have been a few times that I've shut the generator off technically ending the cycle early

Maybe that's smart. Even on grey days solar probably produces the low wattage needed after bulk charging.

 

[Short_Shot]

Just to be sure:
How big are these batteries that you're trying to do as much as 100a? Lead is usually charged no faster than 0.3C as I understand it.

GC2 size batteries are usually 200 to 225 or so ah in my very limited 6v experience, so 4 of them @12v should be around 400 to 450ah, with you using around 200ah capacity?

This should be fine to handle 100a charge if so.

So with that said, you still won't get that charge rate throughout the whole capacity. As they fill up the charge rate will drop a lot. This will draw out the "fast charge" (which is really just a higher voltage bulk mode) much longer than the straightforward calculation.

 

[chrisski]

Just to be sure:
How big are these batteries that you're trying to do as much as 100a? Lead is usually charged no faster than 0.3C as I understand it.

That is exactly what I was thinking. I have four tall golf cart batteries (GC2H) that are charge no more than 60 amps.

My flooded lead acid Trojan batteries say to charge no more amps than 13% of the 20 hour rate. I have four GC2H, which compared to a GC2 are length and width is the same, but the height is less than an inch taller for a marginal increase in capacity. My 2S2P are 458 ah.

Some GC2 batteries are as low as 180 ah, so those would be 2S2P 360ah.

I don’t know what happens when you exceed amperage, but I doubt its healthy. I need to watch my charging with those. My system can push up to 74 amps, but charging has always been done well before it reaches that.

 

[STW]

My 2 Interstate GC2’s will start accepting charge at about 50amps (on a 70amp charger). They will slowly start taking less and less amps as the voltage rises. At the end they are only taking a few amps. As stated the last 5% takes along time to fill up.

Charging at too high rate for too long will cause more gasing. You will be adding more water.