what gauge wire runs from alternator to bed in the Tacoma tow packge

I have 2008. (too much of a wimp on this very cold day to walk to my unattached, unheated garage to measure it).

 

The only wires that come from the alternator are the battery charge wire that goes to the positive post and the alternator signal wire that goes into the fuse box.

Do you mean the wires from the inverter under the center console to the 110v outlet?

 

Guess I will have to go take a look. When the camper was installed I was told they used existing wire to charge camper battery from the alternator. Previous truck owner had a trailer and maybe they added something.

 

Your camper is a tow behind or the kind that slots into the bed? It has it's own house battery? They may have used the maintain charge wire from the 7 pin towing connector or they installed an entirely new wire which is non standard.

If they used the towing harness it's roughly 14-16 gauge, if it's aftermarket it's anyone's guess.

Even if they did add a new charging circuit for the camper's house battery it shouldn't be run directly off the alternator especially with no additional sensor wire.

 

It is a slide in, as in the photo. The wire for towing connector I think is what they said they used and 12 gauge also sounds like what they said. And that explains why i am not getting much charging with 12 gauge due to voltage drop over that distance. So I may replace it with 4 or 6 gauge.

 

If it goes to “the bed” you’re fucked. Simple calculations: how many amps do to need at 13.8 volts to give you 12v over what length.

 

This chart might help.

 

In a van at work, we use 12v electric start air compressors that don’t have their own alternator. Some have an additional battery back there, some don’t. All have a circuit breaker, ideally mounted up close to the front battery, and use 4 gauge cable. A circuit breaker is definitely a good idea. At least once, someone mounted the circuit breaker too far back and nearly burned the whole thing down.

If you plan to do the work yourself, route it away from exhaust pipes and overly protect it from abrasion. Get more zip ties than you think you’ll need. If you need to go through a sheet metal panel, use rubber grommets. You could use rubber hose cut, slit and zip tied to completely cover the cable in areas you think it’s needed.

Theres company’s that make all sorts of things for your setup. Battery isolators, low voltage alarm, dc to dc charger, step up or down converters, solar charge controller, etc.

 

I currently measure 8 amps at the camper battery with truck running. So I am in the first row of that chart -dont know exact length but 16 should be close and with 12 gauge wire the 8 amps I measure is in cell 1-5. With a heavier wire the voltage drop will be less, and a lot less with 4 gauge and will give me a huge increase in amps to the battery. System currently has a Blue Sea ACR battery isolator.If I upgrade to lithium battery I will add a dc-dc charger.

 

If you are talking about an OEM 7-pin trailer connector, the power pin is on a 40 Amp fuse under the hood, I think. So in theory, it should be 8 or 10 gauge wire. But I doubt it. I cobbled together a "charging cable" from the 7 pin to locking battery terminals to charge an auxiliary battery in the bed while driving. The charge through the 7-pin barely kept up with my compressor fridge on the same Aux battery. I'm planning on a dual battery under the hood with a DC to DC charger instead, and running a dedicated 8 gauge to anderson plugs in the bed.

 

4ga sounds like it would do the job for sure. Do keep in mind the return path (negative). And absolutely add appropriate sized breakers or fuses at both ends where you have a battery on both sides (if not already installed)

 

What is the future total load you need (in amps)?

As example: I have a combined peak 50 amp ham radio and alternative DC/DC isolated battery charger in the compartment behind the rear seat. It is 11 feet of snake cable so I ran 8 gauge copper. (Similar to the chart). In reality I ran 6 awg so I can tap it if desired.

 

I believe what OP is needing info for is the CHARGE Cable. Therefor, the wire size will be dependent on CHARGE CURRENT from the alternator. Not accessory current from the battery.

I say this because the Tow Power is figured off of the Starting battery. And is fused for accessories. Not necessarily charging a separate battery.

 

Correct. Dealer installed new camper 5 years ago. On new trucks they run a 10 gauge wire to charge camper battery from alternator. They have done thousands of these and know how to do it right. I brought to them my used Tacoma and they told me they used existing wiring but I forgot the details. Had I understood the implications at that time I would have made sure they put in new wiring, and would have paid the extra for heavier wire.

Sort of moot issue now because the battery and solar panel is not enough for my needs so I am going to have them replace whatever is there with heavier wire. I did do a thorough workup of my amp hour needs. Current battery is AGM but should I go lithium that brings more issues to bear and have already analyzed those. It ends up being a cost-effectiveness decsion. I was quoted just under two grand do install a lithium battery+victron dcdc charger, 4 gauge wire, victron smaart solar controller and victron battery monitor. That seems like way overkill since the only thing that runs off the battery is a small 35 watt compressor fridge. So will likely just replace my battery with a pair of 6 volt GC2 that will give me twice the amps I currently have, plus better charging from alternator. That will let me camp off grid indefinitely.

 

First I’ve heard of someone in here using the gc2, which is surprising seeing how strong they are.

The only issue is you might have is if you don’t discharge/charge properly. I think they want to be down to 20%, then fully charged before being put back into use. I’ve seen them in electric pallet jacks not even last a year due to poor charging habits.

 

News to me, so I just found a few articles on this that said they should be discharged to 50-80%. Since my fridge is the only thing that uses it and it has a low voltage cutoff at 50%, the batteries would never go below that. Also recharging would usually be slow and not back to full very often so I need to research that as well.

 

I'll see if I can find something