Battery Question (1 Viewer)

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My current battery setup is two group 34 yellow top Optimas. They have worked out OK for me. When I camp, I sometimes wish I had more battery capacity for the fridge and such. Well, I'm needing a new battery in my tractor and so was thinking about moving the accessory battery out of the cruiser into the tractor and putting something bigger in there.

I'm looking at the deep cycle / starting type AGM batteries. My second battery tray is an ARB unit and will just not hold a group 31 without major modification. I'm now looking at a X2Power 27M battery, which is only 10% less capacity than their group 31 (90Ah vs. 100Ah). This is still much more capacity than the yellow Optima, which is only 50Ah. Even this 27M battery will require modding of the battery tray, but much less.

My question: Is there any problem running batteries of different sizes? Both are deep cycle / starting AGM batteries. My battery management system is a simple A, B, both or none switch. TIA.
 
I run Odyssey batteries with different sizes since 2017. no issues. hope it helps
 
A lot depends on the output of your alternator. I recall that AGM batteries need quite a high charging voltage (14.8 +). That said I doubt the difference would be huge. Main thing is that you don't have a modern smart alternator. That would almost render you auxiliary battery useless without a DC/DC charger.
 
I'm running a Sequoia 150 amp alternator using Photoman's bracket and small pulley. Seems to work well so far. I'm seeing about 14.5 volts when actively charging and then it drops to 13.7 or so. I believe that is good, right?
 
I run Odyssey batteries with different sizes since 2017. no issues. hope it helps
Would love to run one of these but I just can't squeeze in a group 31 and they don't seem to a dual purpose battery that is in the 12.5" length and has lots of capacity. At least, I didn't find one on their site.
 
Don't just fixate on AH, another very important parameter is how the battery handles a deep discharge. Standard wet cell batteries do not like to be discharged much at all without losing battery life and capacity.

So, I'd check how they handle deep discharge in their datasheet/spec or call and ask.

I'd also suggest you run solar if you aren't already. With a 100W or more panel and sunlight most of the day you should be able to run the fridge 24/7 without the need to start and drive the vehicle.

cheers,
george.
 
Don't just fixate on AH, another very important parameter is how the battery handles a deep discharge. Standard wet cell batteries do not like to be discharged much at all without losing battery life and capacity.

So, I'd check how they handle deep discharge in their datasheet/spec or call and ask.

I'd also suggest you run solar if you aren't already. With a 100W or more panel and sunlight most of the day you should be able to run the fridge 24/7 without the need to start and drive the vehicle.

cheers,
george.
Totally understood. This is why I'm looking at a "dual mode" starting / deep cycle, marine / RV battery. These should be able to handle discharges as well as starting duty. The battery I'm looking at is a rebadged Northstar. The datasheet on the battery shows 400+ cycles at 80% discharge. Here's the data sheet:

X2Power Data Sheet

I totally would love to go the solar route. However, there is no room on the roof and with two large dogs and a wife, space is at a premium. Plus, my Optimas are now 7 years old, and while they have shown no sign of problems, I thought I would use this opportunity to upgrade. And we also don't tend to make camp and stay for a week. A couple days tops and we're ready to move on to the next spot.

Input is always appreciated.
 
Folding solar panels are what I use. Doesn't take much room when they are folded/stashed in the back and then you can deploy as needed and pointed at the sun etc if the vehicle is parked in shade. You can make up an extension (just use SB50 andersons everywhere) to reach further from the vehicle if necessary. Of course in heavily treed areas you're out of luck :)

Also battery capacity/size will depend how long you camp in one spot. A day or two or a week...

cheers,
george.
 

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