Battery Upgrade

by Greg Zimmerman

It was time to upgrade the battery and I wanted more capacity without jumping to a group 31 which requires modifying the hold down (they’re really big and heavy). Trojan batteries are made in the USA. They normally supply much larger batteries for golf carts, mega yachts, and big trucks. The 27-TMX deep cycle has to be ordered from a dealer and when it showed up it was the smallest thing in the warehouse. Just like a Casita at a campground!

The only customization required was to cut off the threaded post on the terminals because they stick up too high to fit in the battery compartment. A pair of off-set terminals are used to give the required clearance.

TIP: Don’t forget that the white and green wires are negative and the black is positive!

The TMX-27’s capacity at a 20 hour discharge rate is 105 amp/hours which is quite a bit more than the 87 amp/hour rating of the original Interstate battery.

Just fits!


Gary Wells January 28, 2019 - 12:01 pm

Great job on the battery change out. What size wire from the battery to the distribution posts. And the batter disconnect (RED) block – what size? Or were these items already on the Casita?


Greg Zimmerman January 28, 2019 - 1:09 pm

It’s 8 gauge wire. It was included in the Little House Customs battery disconnect kit along with the terminal block and connector.

Gary Wells January 31, 2019 - 12:39 pm

Thanks Greg.


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