Spare tire winch repurpose, ‘utility’ tray.

[Mbrooks420]

I’ve been planning to ditch my spare tire, I run 31s and it’s not really valid as a spare with the AWD. My original plan was to save my best 31 when I replace my tires, and make that fit. Lately, I’ve been thinking of making a tray to hold a few accessories, mainly a air compressor, small tank, and a second battery. I’d put the battery in a suitable battery box.

The tire winch would be used to raise and lower it, only. I’d snug the tray up against some sort of bushing, and hold it in place with clevis pins most likely.

Is this an entirely stupid idea? I’m planning on adding a large amplifier(in addition to at least 2 smaller ones for highs, and midbass speakers), I have a 1,000 watt power inverter, and I have a winch in a hitch carrier, and that a rear mount battery might be the ticket.

 

[CDW6212R]

That's not a bad idea. I carry a tire repair kit and a compressor almost always.

I have only needed a spare two times for my several vehicles. Once was from a big rock that three plugs wouldn't fix, and the other was my AWD Mercury, and the tires were nearly new(plugs void any warranty). I've repaired at least 50 tires while on my mail routes, never taking the tire off.

The space where the spare tire goes is big enough for many things, plus there is room above the cross member for some items. Here's my 99 showing the OEM air compressor, where it goes above the spare tire.

 

[SupaSwope]

I think it would be a cool idea.

 

[Mbrooks420]

I suppose I could mount the compressor up higher, and save room. The battery might be able to be positioned up higher than I had expected. I’m assuming a clean frame ground would be sufficient?

I understand a battery isolater is the way to go, and would be one of the most costly items. Also, I understand I need matching batteries.

With the isolator do I only need to size my cable for the full load available from the alternator? I currently have my amp and inverter running on a 4awg, and that’s definitely too small.

 

[CDW6212R]

If you put a battery back there, I'd run a big cable along the frame rail with the brake lines etc. If you have a power point already along the way, or wanted to move what you have, you could just place the new one on the frame(run cables that end at the isolator, the power point, and the front PDB terminal).

I've have 8 gauge wires running along there for a compressor I placed behind the left wheel(30amps continuous load).

 

[Mbrooks420]

I've got a wet location rated 2awg, but I'll probably get a 1/0 or 2/0 wire.

 

[CDW6212R]

That'll do, major circuits like nice big wires.

I used to get battery cables made from welding wire, but I've had some corrosion issues on the battery terminals that made me try going back to OEM new cables. I haven't started to plan my stereo amp wiring, hopefully I won't need much with two amps that need about 50-60amps.

I wish the new LiFePO4 batteries could handle more than 60amp alternators. Those are very small and could be mounted anywhere, but I don't think an isolator device can protect them from excess current. When that gets worked out, those will be very popular.

 

[Mbrooks420]

Looks like isolators are a lot cheaper than I expected. Looking through my gear I already have some of the fittings and distribution blocks I’ll need as well.

 

[CDW6212R]

Have you thought about how you will build the "tray" and how the tire winch will hook into it?

 

[Mbrooks420]

The tray would likely be built out of aluminum, and I’d probably drop the winch through a cutout in the base just like the rim is. I might use 8020, or one of the cheaper alternatives.

 

[CDW6212R]

I like it, saving space from the inside. I've got my consoles and back seats out of my trucks, for more space. I plan to build two consoles that are not much more than flooring and a few dividers(for mail stuff).

 

[Mbrooks420]

I like that I don’t need the vent free battery, and that it’ll probably help with center of gravity as well.

 

[toypaseo]

One thing I would worry about with a tray is all the dust/dirt/debris. When I drop my spare, there is always a good amount of small rock and lots of fine particle dirt on the top side, and I don't do a lot of driving on dirt roads.

I wonder if some sort of rigid spare tire cover would survive under there to hold stuff...

 

[Mbrooks420]

The battery would be in a box, and all of the terminations would be in some sort of dust/watertight container. The compressor would be rated for exposure as well.

 

[CDW6212R]

This got me looking at LIFePO4 batteries some more. I found an old 2014 thread where a guy put such a light battery in a motor home type vehicle, as an auxiliary to run a refrigerator. He and others managed to do it successfully, charging it with the stock engine etc, using a couple of relays and special charger etc. I might look into that more when I get to possibly moving my front battery out.

For others possibly needing secondary power, this could be very helpful;
ARB fridge with LiFePO4 in a dual battery setup - Page 4 - Expedition Portal

 

[Mbrooks420]

It’d be easy in a motorhome since most modern ones have power inverters as well as gen sets.

 

[CDW6212R]

True, but those were older kinds with normal systems like ours, and basic inverter stuff. They were wanting a battery to run things without the engine running, but still charge it when the engine comes on. I saw a $400ish battery that with the similar control/charging devices, could run with our systems. I think it was a 60ah battery weighing 20lbs, and a maximum 120amp charge limit. That limit is the part I learned was most important, older cars have much smaller alternators than current cars do.

 

[Mbrooks420]

What’s the advantage over a traditional deep cycle? More amp hours?

 

[CDW6212R]

The weight and lifespan. It looks to range from 10-20lbs for "decent" sized versions, and could last 10 years or more. The cycles limit is claimed to be in the 1000-2000 range, versus say 200-400 for lead acid batteries. So in short, if they can be managed(not over charged or run too low) properly, the cost is less in the end. I see decent options now, a while back it seemed far fetched. Foreign brands are popping up often, I think it's best to wait some more before trying it. There's an American brand, but theirs sound strictly limited to a 60amp charge limit, or a $750 version that says 120amps. I'd rather the margin for error(60a or 120a, versus our 140a alternators), be better, pricing too.

 

[Mbrooks420]

Started a parts list for this. Going to be a little more than I was thinking at first, so I’m going to build it in a few stages. First stage will be the structure, wiring, battery and isolator. I’m also considering Unistrut (might know it as kindorf) for the rails vs 8020.