Keeping AGM's up???

[bgowdy 5,000+ posts]

This may be a noobish situation but, i currently have 2 AGM's in the back and one stock lead-acid under the hood right now. They are all ran together. The battery upfront is not in very awesome condition but is also not completely shot just yet. Seeing they are all tied together and the front batt isnt as strong i have DIE HARD Smart Charger that has AGM charge settings on it.

So at night(and only at night) i charge my batts on the AGM setting, set to a 2 amp charge, and when it reaches 100% it auto switches to maintain ONLY and holds them to 100%(will not let voltage drop under 13v or charge over while maintaining). i do plan on changing the stock battery to better battery(AGM) but dont have the funds to do it right now.

Will this hurt the AGM's?

thanks,

Click to read more...

 

[NASTY08IMPALA 5,000+ posts]

I think the beat up batt under the hood is in trouble not the agms

 

[bgowdy 5,000+ posts]

I think the beat up batt under the hood is in trouble not the agms

lol why do you say that?

 

[Side Show 10+ year member]

the agms are better than the crappy one under the hood, weakest link usually goes first

 

[NASTY08IMPALA 5,000+ posts]

I think the beat up batt under the hood is in trouble not the agms

Bc its so much weaker to begin with even if it was new let alone run down

 

[dbeez 5,000+ posts]

The front batt will drain the agm batts one bad battery can kill a whole bank in time best bet is to either replace front battery asap or isolate it or completlely bypass it for time being.

 

[bgowdy 5,000+ posts]

The front batt will drain the agm batts one bad battery can kill a whole bank in time best bet is to either replace front battery asap or isolate it or completlely bypass it for time being.

even if they are all kept on a constant charge?

 

[NASTY08IMPALA 5,000+ posts]

even if they are all kept on a constant charge?

Yes that weak wet cell will instantly bring down the resting voltage of.the agms

 

[Side Show 10+ year member]

yes! i'd take one of the agms out the back and swap it for the one under the hood, then get yourself a 3rd one

 

[bgowdy 5,000+ posts]

yes! i'd take one of the agms out the back and swap it for the one under the hood, then get yourself a 3rd one

cant they are g31's, there is no way in hell it will fit

 

[bbeljefe]

Even if there's no bad cell in the wet battery, wet batteries and AGMs have a different surface charge voltage, so as soon as you disconnect the charger, the wet battery will rob some of the surface charge on the AGMs. That won't cause any damage and it won't even cause a problem as far as starting the vehicle, unless the wet battery has a bad or shorted cell or two.

 

[bgowdy 5,000+ posts]

Yes that weak wet cell will instantly bring down the resting voltage of.the agms

how can it bring down the resting volts when i have them constantly on a maintain charge pretty much anytime the truck is off(i dont drive it very often, gas is to high lol) at 13v? honestly the lead acid battery rests at 12.8 or .9 with out the charger connected. it just doesnt take big loads well.

 

[bgowdy 5,000+ posts]

Even if there's no bad cell in the wet battery, wet batteries and AGMs have a different surface charge voltage, so as soon as you disconnect the charger, the wet battery will rob some of the surface charge on the AGMs. That won't cause any damage and it won't even cause a problem as far as starting the vehicle, unless the wet battery has a bad or shorted cell or two.

i mean resting voltage to me is meh. when i compete we can do it with the vehicle running. i never run my system with the engine off

 

[bbeljefe]

i mean resting voltage to me is meh. when i compete we can do it with the vehicle running. i never run my system with the engine off

Agreed. But since you posed the question, I figured I would explain the situation, especially since so many people wrongfully claim that lead acid and AGM batteries in combination will cause problems.

I've even read scare stories where people claim mixing wet and AGM batteries will cause fires...

Um no... but not knowing fvck all about batteries and handing out bad advise will, lol.

 

[dbeez 5,000+ posts]

The wet cell acts as a load constantly pulling on the agms just like what was happening when you had a batt that needed charged it made you think your alt was bad will do the same thing here