Can I mix battery types?

[Ktholin]

My second Interstate 6V flooded battery has failed in less than 18 months since installing my solar system. The first battery died in 8 months, but was under warranty. Now the second battery is bad and, of course, is out of warranty.

I'm thinking of switching to Lifeline 6V AGM batteries. Since one of my flooded batteries is still good, can I combine one AGM battery with one flooded battery, or do I need to go with both AGMs?


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[55AS]

Pretty sure that is a no-no. I think they will not charge properly.

[Tincampers]

I would check first to see that your charging system is up to snuff. Sounds like your interstates were not getting fully charged resulting in early failure.

[idroba]

Throwing expensive AGM batteries into the box may not solve your basic problem. Although Interstate batteries are not the very best out there, you may have a charging issue with the original converter/charger, or may not be using and re charging the batteries properly. Do not mix AGM and conventional flooded cell batteries in any event.

If you have the original Parallax 55 amp converter charger in your rig now, it is not even compatible with AGM batteries and will quickly ruin them.

You may be doing everything right, and just have been having bad luck, but I would suggest you at least read this post to see if any of it applies to your usage.

http://www.airforums.com/forums/f449...ml#post1602327

Batteries are much more complex than most people think.

[switz]

If the original battery charger is in the trailer, it is totally incompatible with GSM batteries as well the new lithium iron phosphate batteries. A programable charger is needed for the more expensive batteries.

[m.hony]

idroba,
That is good information!
I am needing/considering purchasing new batteries. I would have never guessed that the converter in my trailer would be incompatible with AGM batteries. I guess a true upgrade would be a new converter and AGM batteries.

[Ktholin]

I do have the original converter charger in my Airstream. After the first battery failed, I began removing both batteries when I stored my rig and put them on a battery tender. When dry camping, I try never to let the batteries drop below 50%. I occasionally use a portable generator as well. Still, I had battery failure.

I think the smart play will be to upgrade the converter charger first, then go with two AGM batteries.

Would there be a big advantage in using AGMs vs a higher quality flooded cell, like Trojans?

Thanks again for everyones feedback

PS. I'm obviously not impressed with Interstate batteries, nor their one year warranty.

[JCWDCW]

AGMs and Flooded batteries charge to different voltage levels, so you cannot technically mix them and I believe the Fully charged AGM voltage is only about 85% of full charge on a lead acid battery.
I had very poor luck with interstate batteries. Switched to AC Delco and had them for over 5 years and still working very well when I finally let them go with the trailer.
My current battery is from UAP auto supply. It is an East Penn battery re-branded to the automotive supply store. Came with high recommendation from the store owner who uses the batteries for his fishing motors.
JCW

[tjdonahoe]

The interstates are very good batteries, don't let any one tell you otherwise , 6 years in the kenworth and still going, and averaging over 6 years in the airstreams....

[Airtandem]

Also,don't mix batteries of different age. When checking batteries , do a load as well as voltage.

[lewster]

Originally Posted by Ktholin

I do have the original converter charger in my Airstream. After the first battery failed, I began removing both batteries when I stored my rig and put them on a battery tender. When dry camping, I try never to let the batteries drop below 50%. I occasionally use a portable generator as well. Still, I had battery failure.

I think the smart play will be to upgrade the converter charger first, then go with two AGM batteries.

Would there be a big advantage in using AGMs vs a higher quality flooded cell, like Trojans?

Thanks again for everyones feedback

PS. I'm obviously not impressed with Interstate batteries, nor their one year warranty.

You're on the right track. NO BATTERY will last very long using the Parallax single stage converter unless you monitor it carefully and even if your do, your batteries will never see a full charge. All lead acid batteries require a minimum of 14.2 VDC (and as high as 14.8VDC) for both the bulk and absorption charge. After they are 'full', they then require a 'float' charge of 13.2-13.4VDC (depending on the manufacturer's requirements).

Regardless of how diligent you are about watching your Parallax as it slowly burns up your batteries, it's continual 13.6VDC output will never fully charge your battery and will never allow it to float if it ever does get a full charge.

There are many other quality batteries on the market, but after replacing several hundred battery banks over the last 15 years, I have found Trojan T-105s and their larger siblings to have the longest life for liquid lead acid types and Lifeline AGMs to be the longest lived AGM batteries. I won't get into discussing lithium phosphate batteries here.

Also remember that Lifeline offers a 5 year pro-rated warranty for their AGM batteries when placed in RV use.

It's interesting that I usually replace most Interstates right after the one year warranty period is done (IF they last that long) and that they are replaced over a shorter duration than any other battery.

With regard to mixing batteries, most of the points have been covered:
• ALWAYS use the SAME TYPE batteries in a battery bank
• NEVER mix battery types
•*ALWAYS try to buy batteries with the same manufacture date from the same lot
• ALWAYS keep your battery terminals clean and tight at all times
• Check water levels in liquid cells often and on a regular basis. Re fill using distilled water only!
• ALWAYS recharge your lead-based batteries to 100% soon after discharge using a proper 3 or 4 stage automatic charger to prevent plate sulfation
• Try to keep your use above the 50% depth of discharge level for maximum longevity

The less you stress your batteries by repeated deep discharges, the more charge cycles you get which translates into longer battery life.

I'm done now….

[Airtandem]

There is/was a theory that batteries would "take a set" if not discharged to low levels.Is this still true? By set, if a battery was only discharged to a give %, the battery would remember this (set) and that would become the max use. Another idea was that the harder used, the longer they would last; if the battery was not used often, they would "die" sooner.
Is this true with the NEW batteries?

[idroba]

Originally Posted by Airtandem

There is/was a theory that batteries would "take a set" if not discharged to low levels.Is this still true? By set, if a battery was only discharged to a give %, the battery would remember this (set) and that would become the max use. Another idea was that the harder used, the longer they would last; if the battery was not used often, they would "die" sooner.
Is this true with the NEW batteries?

No, No, and no.

Some of those things may have been true of NiCa tool batteries, but never flooded cell batteries.

[lewster]

Idroba nailed it. Just make sure you never place your batteries on concrete either!!! (NOT!)


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[acstokes]

My second Interstate 6V flooded battery has failed in less than 18 months since installing my solar system.

Another observation. You didn't say what size solar system you have, but you should be receiving enough solar power to keep your batteries charged (assuming your trailer is exposed to sunlight and not under a canopy or in a garage). If not, your solar system is either under-sized or has a problem that's keeping your batteries from being adequately charged. What are some specifications of the solar system you have installed?

[OTRA15]

If you need to charge/store your batteries above a concrete floor due to space limitations, which is typical for a garage or commercial shop, you can set them up on wooden spacers (1 1/2" thick or more), as long as it is not a moist area, as I understand it. Better up higher on a wooden shelf. I assume that setting them directly on soil/sand/earth is also a no no.

[idroba]

Lewster, never say things in jest! LOL. See what it gets you?

[acstokes]

Probably father to son advice!

[Rich W]

Originally Posted by JCWDCW

My current battery is from UAP auto supply. It is an East Penn battery re-branded to the automotive supply store. Came with high recommendation from the store owner who uses the batteries for his fishing motors.
JCW

East Penn makes Deka brand batteries, available at Lowes stores. (farming stores, boat marinas, etc.) Order online and they ship to the store. Take an old battery to avoid the "core" charge and you're in business. Deka batteries are reasonably priced. Go to the East Penn web site for details about the company, privately owned, family company: East Penn Manufacturing – The world's largest single site, family-owned lead-acid battery manufacturer

The Ranger boat I purchased in 1994 came with Deka trolling motor batteries and I have always replaced them with Deka. They have given me excellent service over the years and I would recommend them for any flooded battery application. It's also easy to use Lowes as the purchase location, they have them just about everywhere. The web site says about a week but when I ordered a new ignition battery on a Monday, I got an email on Thursday that I could pick it up, just before leaving on a fishing trip. (Perfect timing)

The manufacture date shows that they are always fresh, usually only a month or two old. Some stores keep batteries on their shelves for months, very bad for battery life.

Although Deka is a good battery, replacing the converter and purchasing Lifeline batteries for my Airstream has made a remarkable improvement in battery charging. I'd recommend the Lifelines but Deka is an excellent alternative.

[OTRA15]

Originally Posted by lewster

Idroba nailed it. Just make sure you never place your batteries on concrete either!!! (NOT!)

Originally Posted by idroba

Lewster, never say things in jest! LOL. See what it gets you?

I stand corrected, but the route to figure this out was not short, thank you very much . . .

http://www.airforums.com/forums/f449...tml#post538511