Need a new House Battery - suggestions?

[papab]

Originally Posted by booster

The big question would have to be how you are using and charging them. There are very specific parameters for getting long life out of any AGM battery. Walkdown to 80% is very common in all batteries as it is around the place where they get charged to with poor charging control.

Originally Posted by cruising7388

I think your experience is unusual and without more details like typical depth of discharge levels, shoreside charging equipment, alternator characteristics etc. it's difficult to entertain a diagnosis. Which model(s) do you have?

BTW, Concord's warranty is pretty generous. Free replacement within one year and prorated replacement for five years. IMO, warranty replacement will put you money ahead of using another brand.

150 amp hr. xantrex truecharge 60 amp. 160W PV on roof, + 50W portable. trimetric charge controller and battery monitor. I can use the xantrex while driving or on shore power.
I try to charge until amps drop below .75 amps, at 14.3V, temperature compensated. I haven't been below 70% SOC all year except for capacity tests. Last year, rarely below 70%, probably 60% minimum. I have had some periods when I didn't get back to 100% for 10-14 days, when it cycled between 70 - 95%. Last fall I took a trip to BC and might have been more than 2 wks without full charge.
When I started with this system I was only using the alternator to charge, which puts out well over 100 amps, but is regulated to about 14.1V. I thought this was close enough, and it probably is in warm weather, but not in cool weather. The xantrex was recommended by lifeline, but it's a challenge since it goes to float when current drops below 6 amps. I switch to gel mode, and fool it into cold which keeps it at 14.3V. Of course when on solar only, the voltage is lower than desired until late morning or mid day usually,but I can keep the volts correct all the way, I actually err on the high side and set it to 14.6V, also temp compensated.
I was pretty ignorant when I started and thought that since lifeline said the battery could take huge current and my alternator has plenty of output that I could charge up quickly driving, but it takes a long time to get to 100%.
I think what killed it was the extended days at partial state of charge.
I was talking to lifeline about getting it replaced, about $200, but the guy I was talking to hasn't called back after numerous messages and I gave up and decided to put money elsewhere.

[booster]

I don't really see anything in what you have done that would kill of a battery that quickly. You are charging to amps on a (mostly) regular basis. Only a couple of times of 14 days without a full charge, and even then not being all that low. The 14.1v on the alternator in the cold is fine warm, as you said, but even when cold it shouldn't be all that bad, just a bit slower.

About the only thing left would be if somehow the battery is seeing absorption voltage (or anything above float) for a long time after it is already full. Solar chargers can do this sometimes, as our Blue Sky does it occasionally, and the non amps controlled ones can destroy a battery quickly if they cycle onto a full battery for a absorption time every day,

The same thing can happen with the alternator if you do a long drive after coming off a full charge from shore power. Long periods of high voltage will dry out an agm and oxidize the anode if done on already full batteries.

Other than those possibilities, it looks like you kept better track of the charging than 99% of folks that got longer life than you, so very strange.

[papab]

It's never been left at absorption voltage after its fully charged. I was worried about that from the beginning so I installed a switch so I can disconnect it from the van 12V system. Lately since it's been taking so long to finish, I started using the finish stage option in the trimetric, which boosts the voltage for the final charge. Lifeline approves of conditioning the battery for 8 hrs at 15.5 v, so it would seem that it would take a very long time of overcharging to cause damage.

[booster]

I have spoken to Lifeline about the "conditioning" charge, and they say it does dry up the electrolyte some, but since it is used to recover lost capacity in a battery that has walked down or otherwise lost capacity, the benefits outweigh the negatives. AGMs have some reserve water capacity in them, but can't be replenished. I would certainly think that they should be replacing your battery, although they probably will trying a conditioning charge first. I have seen where quite a few folks have managed to get their capacity back, or much of it, by conditioning. IMO, they should not get off the hook so easily, as this is way early for the way you have used them.

[canoe22]

This may be too late to help but I just ordered two Exide Stowaway batteries model 27MDCST at $69.99 each at Tractor Supply. Same specs as Duracell SLI27MDC at Batteries Plus but about $20 cheaper. At that price I don't need the top of the line at 3x the price.