AGM Battery Charging

[Jim28730]

If I replace my house batteries with AGM, and set the system to charge AGM's, what about my chassis batteries? Will the charging system work on the new setting if I retain my Interstate chassis batteries or do I need to replace them with AGM's as well?

[wa8yxm]

The difference is like .01 or .02 volts. I'm not sure which is higher but by the time you figure in line loss. You likely won't notice.

Now: Why are you downgrading to AGM's. True Lifeline (And that is brand specific) AGM's do feature faster recharge, but the difference is very slight and you need on heck of a converter to manage it.

But so long as you can mount them "This Side Up" there is no real advantage that I can see to AGM's.. Same amp hours (Save for Optima which have less) Shorter life and higher cost.

Cost: From retailer's websites
Life: From battery manufacturer'sweb sites, battery specifications, number of cycles before death.

Now if you have to mount them odd-side up.. THEN you need AGM's. but so long as you can go this side up.. Maintenance free cost way less, is also low-gasing, Low (not free) maintenance, and should, in theory (Per the web pages) last longer.

[jepeed]

I replaced my house batteries with AGM (Lifeline) and did not change the batteries for the chassis. I have had them for about a year & that is the best thing I ever did on my coach. No more battery fill system & no more checking water levels. No more corrision, and less work.




2005 Alpine FDQS
2007 Chevy Crew Cab

[Jim A]

Same as Jepeed for me, except mine are not Lifeline and I have had them for 3+ years. If they died tomorrow, I would buy AGM's again without hesitation. In many cases I am willing to trade cost for convenience. One less thing to spent time on while on the road. And no corrosion.

They say with bicycle parts they can be strong, light weight, inexpensive. Pick two. In the case of RV parts, I will often pick reliability and convenience over cost.

[OldForester]

Jim, when I replaced my wet cells with Lifeline AGMs and set the charger to charge AGMs at 880 AH three years ago I left the Interstate Chassis batteries as-is and haven't had any issues. They have been great and I wouldn't go back to wet cells again No corrosion, no hassle.

[Dale777]

wa8yxm,

I know that AGM batteries are expensive, but so is a Motorhome. Relative to the cost of the Motorhome, the extra cost of AGM over flooded cell batteries is very small. The relative benefit is enormous.

In a motorhome, those benefits have nothing to do with whether the batteries are mounted right-side up or not. And, the inverter/charger installed in Alpine Coaches is more than adequate to handle the demands of charging the AGM batteries.

I have 8 Lifeline AGM house batteries (6 volts each for a total of 880 amp-hours) and 2 sealed wet cell starter batteries (12 volts each) which have been installed for 5 years. I have done absolutely zero maintenance on either the AGM house batteries or the sealed wet cell starter batteries. For the AGM house batteries, there is no corrosion, no out-gassing, no spills, no mess, no watering, faster recharging time (due to less internal resistance), slower discharging time, and longer life.

Since the sealed wet cell starter batteries don't go through repeated deep discharge and re-charge, they too have no out-gassing, watering, spills, or mess.

Monthly, or sometimes more often, I check the battery compartment just to make sure the batteries are still there. Occasionally, I blow out the battery compartment with compressed air, just to keep the dust off the batteries.

I don't worry about splashing acid on me, bending over in a tight space, peering in with a flashlight to see if any watering is needed, then watering, or trying to get an automatic watering system to work properly. You can tell that I am sold on AGMs!

[two-niner]

Dale: A great post. Very clear and concise.

Kerry

[Norm4015]

I have used the same set of Lifeline AGM batteries in two motorhomes. They are 9 1/2 years old and still going strong. My chassis batteries are wet cell and are 6 years old so charging both AGMs and wet cells have not harmed the batteries. If my AGMs every die I'll replace them with more AGMs.

[WheelingIt]

Like the others we replaced our house batteries w Lifeline AGMs and left the chassis as is. Sooooo happy with the AGMs. They charge fast and never any checking or mess. Love em!

[az bound]

Dale
Another plus is they will not freeze and if disconnected only loose charge at a rate of 1-1.5% of charge per month. No charge maintainer needed.
Love those AGMs.

[wa8yxm]

Dale, I did not recommend Flooded wet cells (though they do give the best bang for your buck) but Maintenance free

Maintenance is a VRSLA battery (Valve Regulated Sealed Lead Acid) same as the AGM, the only difference is the liquid is not contained in a glass mat.

You still get the low maintenance, the low gassing, no "Fill kit" or adding water and such.. The only difference is they have to be mounted "This side up" like a flooded cell (Since they contain free liquid)

And of course 1/3 the cost

Compare those two types and see how they stack up

I'll be replacing my AGM's (Yes I have some) with Maintenance free when I replace them, and they need it, The you youngest, and deadest, batteries I have.

[Jim28730]

Great information as always. Thanks....I'm sold!

[takepride]

Quote:

Originally Posted by wa8yxm Shorter life and higher cost. Cost: From retailer's websites Life: From battery manufacturer'sweb sites, battery specifications, number of cycles before death.

Great idea. Re-read the manufacturer's information on lifespan, cycles and discharge depth. Then get back to us.

Aside from that hooey, AGM's are more expensive, and worth it. The lifespan of mine have already repaid any savings over the maintenance-free ones I had on my last coach.