Float charge rate?

[brobox]

I noticed on another post that AGM's should not be float charged more than 13.3 volts. Mine are Float charging at 13.7.

I am keeping an eye on Wineman's MH while it is is storage. He had new AGM's installed last year and I noticed they have his float rate set at 12.9V.

Are mine being over charged and how do you change the setting if they are?

[hawgguy]

I will be paying attention to this thread. Mine float at 13.6.

This reference suggests that the ambient temperatures influence the recommended float charge rate.

FTA:
As with all gelled and sealed units, AGM batteries are sensitive to overcharging. These batteries can be charged to 2.40V/cell (and higher) without problem; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages).

2.25-2.3V/cell would be 13.5-13.8V

[twinboat]

I think with AGM batteries, owners need to do a little homework, to find out what float voltage their batteries need. Every manufacturer will probably have slightly different suggestions.

Many people buy them, hook them up and all is good. A few years latter, they are wondering why they're dead.

[TerryO]

It depends on the temperature. I've attached page 19 of the Lifeline manual.

[757driver]

Originally Posted by brobox

I noticed on another post that AGM's should not be float charged more than 13.3 volts. Mine are Float charging at 13.7.

I am keeping an eye on Wineman's MH while it is is storage. He had new AGM's installed last year and I noticed they have his float rate set at 12.9V.

Are mine being over charged and how do you change the setting if they are?

Chuck,

If you have the Discover AGM's (or any other brand) then you need to go to their website and get the charge graphs for your model of battery. If they are the Discovery EVGC6A-B then they can be floated at 2.27vpc at 25C. If the temperature is above this, the voltage will be less and greater voltage if below 25C because we have temperature compensation from the Magnum inverters.

12.9v is rather low for float voltage but each manufacturer is different, can't say without knowing the brand.

No, you are not over charging your batteries, in fact you are under charging them if they are set to AGM2 under setting 04 which gives an absorb voltage of 14.5v.
If you want to change the setting of float or absorb they you need to go into the settings menu on the Magnum inverters "04 Battery Type" and set this to custom. If you have the Discovery EVGC6A's then the Absorb setting should be 14.7v, float up to 13.6v (I have mine at 13.4v) and Equalize 14.7v (no you will not equalizing them). The 14.7v for equalize is so that if the batteries did get put into an equalize charge they would not be hurt by it. Also charge rate in settings "05 Charge Rate" should be 80% to best take advantage of generator run time when and if you use it.

[757driver]

Her is the link for Discover Batteries graph.

Product SearchÂ*|Â*Discover Energy

[brobox]

Thanks Don. I don't even know which batteries are in the Anthem. I have printed your post and it looks I need to spend a day checking it out. I also appreciate the link. I still don't understand all of the setting for the Magnums.

[MRUSA14]

Originally Posted by 757driver

Also charge rate in settings "05 Charge Rate" should be 80% to best take advantage of generator run time when and if you use it.

This is something I have been wondering about. Why not 100%?

[Randyman1]

I have the Magnum Inverter/Charger set for AGM batteries and my Lifeline AGM's Float at 13.0, I thought that was kind of high until I read TerryO chart. Randy

[twinboat]

You charge to 80% , on generator, because it takes hours for the last 20 %.
That is where a solar panel setup would come in real handy. Even a mid size array would top off the batteries.

That gets back to the AGM , wet cell issue. Wet cells tolerate being charged to 80% much better then AGM. Not an issue if you boondock a few day, then plug in, but not bringing your AGMs up to 100% often, will shorten their life's.

[MRUSA14]

You are referring to the level of charging, but I am looking at charging rate. My inverters came set up to charge at 50%, but according to the Lifeline chart posted by TerryO, you should charge as fast as possible.

[dpinvidic]

Originally Posted by MRUSA14

You are referring to the level of charging, but I am looking at charging rate. My inverters came set up to charge at 50%, but according to the Lifeline chart posted by TerryO, you should charge as fast as possible.

50% of what??

Normal charge rate is specified a x times Capacity (like 2C would be 2 amps for a 1 AmpHr battery).

I think most of the inverter manuals use % to specify when the charger switches between Bulk, Absorb, and Float. Each one gets less current (lower applied charge voltage.

Can you point us to the page where you see 50% charge rate?
This is from the Magnum Manual that I have.


Thanks,
Dan

[twinboat]

Thinking about what he said, I think the 50% number, may have come from the 120 volt AC load sharing settings on the inverter. They use that so they don't overload the generator or pop the breakers, when plugged into 20 amp shore power.

Could be wrong

[johnnyreno]