Mounting a auxiliary battery on rear frame?

[Pskhaat]

I have started to accessorize, and putting a fridge and my ham radio (mobile) unit in the rear of the vehicle. In Cruisers prior, I have always had under-hood auxiliary battery setups. Alas, with all my accessory electric load now in the rear, why not mount a battery underside & outboard the rear frame area? There appears to be enough space. I fear road grit/grime but there are battery boxes available. I would, yes, likely run a switched positive lead from the primary battery under the hood.

Anyway, anyone else done this? If so how and if not why not?

 

[bamabrock]

why not an AGM battery in a box inside?

 

[Pskhaat]

why not an AGM battery in a box inside?

Space is at an absolute premium. Need to be able to carry 6 persons (4 children, but they ain't so small anymore) and gear, et cetera. And also trying to keep things as clean and clutter-free as possible.

 

[gungriffin]

I haven't come across something like you are referring to. If space is at a premium in the cabin, the how about in the engine bay?

 

[Whiskerz]

At a former employer we used to use frame mounted boxed to add extra batteries to shuttle buses since space was at a premium under the hood. Never had an issue with them.

 

[gungriffin]

At a former employer we used to use frame mounted boxed to add extra batteries to shuttle buses since space was at a premium under the hood. Never had an issue with them.

If there is space in the engine bay, would there be any advantage to instead going frame mounted that you can see?

 

[Whiskerz]

Shorter cables are about it. Potentially moving weight to the back should help a little with weight distribution a hair. Big cables can get into real cost. Find a place that sells truck parts. Trucks tend to have heavy long cables. A lot of truck parts places can make up new ones in whatever length you need. Welding cable works as well.

 

[J1000]

I also wanted a rear mounted house battery setup but also to maximize usable space inside the vehicle. I added a house battery bank with 3x 16Ah LifePo4 batteries, a 400watt inverter, A Steca 8A solar MPPT charger into my truck. I snuck them behind the rear quarter interior panel where the (2nd) factory DVD player was. They ended up fitting perfectly in the cavity and I made a little battery box from some aluminum angle. In total these will give me about 615 watt-hours or 48 Ah of total house battery capacity. Not a huge amount, but enough to charge my drone, a laptop or two, run my fridge, and power any LED lights but most importantly will run an electric blanket all night! I probably won't use the solar input much if at all but since I had it I wired it in anyway. The battery bank can always be expanded if I figure a clever place to hide more batteries.

I chose Miady batteries as they were the cheapest LiFePo4s I found: https://amzn.to/2SBNJUo These batteries have build in BMS that manages cells, have over and under voltage protection, thermal protection, over current protection, charge protection, etc, etc. So basically I can just hook them all up together in parallel and forget about em! Also used a little fuse block to keep the wiring tidy.

I used a Blue Sea Systems fuse box to keep the wiring tidy and isolated from the vehicle 12v system: https://amzn.to/2GJolJt

Added dynamat to the inside fender to block some noise since I'm opening this area up a little but also to prevent dents if the batteries move a little bit.

Dynamat: https://amzn.to/2FaEDKZ
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I used a Victron DC-DC charger and manually activated by a switch through a Bosch 75A relay. Also reorganized the area and modified the stock plastic shelf to hold the equipment a little nicer. In the future I want it to be automatically switched just not sure exactly how I want to accomplish that yet.

Victron DC-DC charger: Amazon.com: Victron Energy Orion-Tr 12/12-18A (220W) Isolated DC-DC Converter: Car Electronics
Bosch 75 amp relay: Amazon.com: - Pins, 12 V, 75 A, Bosch 0332002168 Normal Open Power Relays: Automotive
Cool LED voltmeter gauge with built-in USB charger: Amazon.com: Digital Meter Panel, DROK 2pcs Automotive Voltmeter Battery Level Monitor, 5V 2A Dual USB Port LED Battery Electric Quantity Indicator Voltage Tester Volt Detector Multimeter for Auto Car: Industrial & Scientific

All this and now I have reached my ultimate goal of.....ELECTRIC HEATING PAD!

Electrowarmth 12v heating pad: Amazon.com: Electrowarmth Twin, Heated Mattress Pad, Non-Fitted, Size 36 x 60, Model# T36 12V Used in Trucks, RVs, Campers: Automotive