VMax trolling motor/wheelchair battery as house battery for modest power needs

[Smoky]

Though I thought I measured correctly, I was disappointed to discover that the VMax 127-100 battery I bought as a second battery for my 2007 Chevy Silverado Classic doesn't fit in the auxiliary battery tray I installed. I'm firm on wanting to mount the battery in the engine compartment rather than anywhere else. Unfortunately, after a LOT of searching, I haven't been able to find a single 100 AH or better battery that will fit in the Silverado's second battery tray/space located in front of the passenger seat. The closest I've been able to come is a VMax Extreme XTR34-75 (75 AH rating). This is a true deep-cycle battery which VMax says is appropriate for trolling motors and wheelchairs. I'd plan to use this battery in my truck cap camper to charge my laptop, run a small fan, and run LED lights...and to occasionally power a fridge during short trips (max 4 days). I'd be interested in what folks think about using a deep-cycle wheelchair/trolling motor battery as a house battery, and about whether this is enough battery for my fairly modest needs.

Thanks, in advance...Smoky.

 

[Smoky]

Charging plan

Recharging will primarily be through the Silverado's alternator. I also have a Yamaha 2000W generator and plan to pick up a good battery charger to use with it. There's always shore power when available, but I'm not considering solar at this time. I have a Blue Sea Systems ML-RBS Remote Battery Switch mounted and ready to go as soon as I install the second battery.

 

[dwh]

I seem to recall some guys saying you have to get rid of a bracket that runs diagonally across over the battery tray.

But maybe that was some other truck.

 

[Smoky]

dwh...that's correct. I did remove that bracket but the battery was still too tall. Length was a problem, too.

 

[john61ct]

Yes the available volume will limit the AH capacity.

Sounds like that battery will be OK, but I think the fridge will be pushing the AH limit.

If you are more careful about measuring, maybe build a box from cardboard to confirm, and look up the BCI form factors, like "group 27" and "group 31", maybe get more choices.

Another option is check out "drop in" 12V LiFePO4, much higher energy:density ratios, but expensive.

And of course modifying or replacing the tray, cheap if you have a friend handy with a welder.

Finally consider going under the chassis, a big AGM will fit sideways.

 

[Smoky]

Thanks john61ct. The primary limiting factor involves the other structures in the engine compartment where the battery has to be placed. For example, the second battery tray sits on the wheel well so I'd have to remove some wheel well, which I don't want to do. I actually did cut out a cardboard pattern to use to confirm the dimensions in the engine compartment to make sure the VMax would fit. It will but just barely. I looked at dozens of group 27 and 31 batteries and their dimensions, and none that were reputable would fit so I'm kind of stuck with the VMax 34-75. I also thought about a frame mount, and I'll go that route if the evolution of my traveling preferences suggests the VMax will limit me too much.

 

[jonyjoe101]

The 75 ah vmax will work fine for your modest needs. All the agm's deep cycle are basically the same, even if they say its recommended for trolling motors, they make good aux battery. I was using a car audio agm for my aux battery for 3 years with no problems.

Just try not to let it get too low. Below is the graph of what the lowest voltage to never go below, this applies to all agm's.

 

[Smoky]

Thanks jonyjoe101...appreciate the info!

 

[chuppie]

Have you looked at the Trojan Battery web page? They have dozens of unusual batteries sizes you can special order.

 

[SSage]

Engine heat will shorten the life of your house battery, you might be better off making room for a better location. I would hate to put a nice battery in the engine compartment. I just use two cheap Group 27's under the hood of my truck, top the water off occasionally and charge them every couple weeks to 100%. Put the deep cycle house batteries in the camper or somewhere with less heat. Its hard to beat golf cart batteries for value, flooded or AGM.

Maybe two AGM GC2's near the spare tire or inside? You could get a real 110 AH or 50% of whatever your total 20 hour rate is. Sam's Club sells Deka AGM Golf Cart batteries in 6 and 12 volt Duracell versions fairly cheap for a decent battery designed for deep cycling. I think the 12 volt GC12 is 140 AH or so, it weighs around 90 lbs though.

12 volt batteries in general have very thin plates no matter what they claim, just a glorified starting battery unless its a huge GC12 like deal. Lifeline and the other premium brands have deep 12's, but they are expensive for what you get. Vmax is a Chinese AGM right? Never tried one myself, I only got 3 years from my Chinese internals Deka, but they are less money than a Lifeline. Trojan has the true deep cycle 1200 discharge rated T1275 12 volt, but its around $380. I rather stick to the two 6 volt GC2's myself. Easier to handle them and they last and last if you don't abuse them too bad. The small 12 volt batteries won't last even a 1/4 of the cycles of two decent GC2's.

 

[Smoky]

chuppie...I already pulled the trigger on the VMax. Perhaps next time.

 

[Smoky]

SSage...appreciate the input but I already pulled the trigger on the VMax 75AH. Plus, I don't really want to spend the time and effort to move things around in the engine compartment, especially since there's not much room in there anyway. If I see that battery life is shorter than it should be, or that the 75AH bat isn't enough, I'll probably do a frame mount next time around to accommodate a bigger battery.