I have a 1994 F-150 I'm thinking about putting in a power inverter and dual batteries. Anyone have any experience with this? Do's Don'ts any advise?

Jeff

 

A couple of things I would suggest. First would be a 3G alternator swap. Next would be a battery isolator, that way if you draw down the power too much on one battery the other will still start the truck. The rest is basic stuff you will probably doing anyway, new cables, big wires, etc.

 

3G alternator?

 

https://www.ford-trucks.com/forums/1...doing-one.html
Here ya go. Read all about it.

 

I may be misunderstanding the application, but regular auto start batteries aren't suited for deep discharges at all. Power inverters should be coupled with "deep cycle" batteries typically much larger and heavier and can handle repeated discharges. Many modern AGM batteries may work for this purpose though. Just be sure to use the right battery for this purpose.

 

Most power inverters I've used won't let the batteries discharge low enough to kill the battery, but they will be low enough they will no longer start the vehicle. That being said, the batteries I used were heavy equipment batteries. Not really in the same ballpark. A pair of jell batteries, or at least the one being discharged, may be a wise investment.

 

The issue isn't discharging deep enough to kill the battery, the issue is the design of the battery itself. Starting batteries are designed to give up a high amount of current over a brief period of time. Deep cycle batteries are the opposite; they give up a small amount of current over an extended period of time. The design of the plates within the battery is different. Starting has lots of thin plates while deep cycle has a fewer number of thick plates. Using a starting battery as a deep cycle battery will kill it far faster, even if it isn't deeply discharged.

As to separation, look for ACRs, or Automatic Combiner Relay. These are devices that will combine batteries (via a high amperage relay) when there is charge voltage, and disconnect them when the charge voltage level disappears. Avoid traditional diode based battery isolators as they will result in the both batteries being perpetually undercharged which will lead to premature death.

Basically you will want to create two separate electrical systems, except with a common ground. You will want the ACR to bridge between the starting battery and the new deep cycle battery. From the deep cycle battery you will want to have a fuse circuit leading to the inverter. If you want to power more than the inverter, you will want a fused circuit leading to a fuse block with the various load leading from that. Properly done you will be able to safely run auxiliary loads (like the inverter) without worrying about discharging your start battery.

And yes, a 3G upgrade is VERY strongly recommended.

I work in the marine world, so my resources tend to be marine based. Here is a white paper that will describe what I'm talking about: https://www.bluesea.com/support/arti...harging_Relays

Feel free to ask if you have more questions, which I'm sure you will. It isn't a simple subject. But done right you'll have an installation that will serve you well for years to come.

 

Just for future reference, this topic has been covered for quite sometime, but I'm guessing you haven't found the Fourm search yet.

Here ya go
https://www.ford-trucks.com/forums/1004186-dual-battery-setup.html

 

YES. Yes yes yes. That is what I was talking about but couldn't explain. Thanks for bailing me out, Jim!

 

And because I have to have 10 characters, here's a second

 

I just got done putting dual batteries in my 93 F250.

I got the isolator from: Hellroaring Technologies, inc., Manufacturer of Solid State Dual Battery Isolator / Combiners

The owner, Mike, is very helpful.

Got the dual battery tray from: http://http://www.wranglerpower.com/...20Products.pdf

I used a blue sea 6 circuit fuse box and ANL fuse from blue sea too.

Here's an article that helped walk me through the process: http://http://www.fourwheeler.com/pr...#__federated=1

 

This is exactly the type of isolator to avoid. They use blocking diodes which cause voltage drop across them. The alternator thinks it's putting out the correct voltage, but the isolator eats up some of that resulting in the batteries and the electrical system getting less voltage than they should. Under voltage causes undercharging which results in shortened battery life. The other major downside to these isolators is that in the process of eating up the voltage they generate heat. That's why the have massive heat finned cases to them.

This technology was great in the 60's and 70's, but like everything else improvements have come along. And like many things, the improved versions perform better for less money. The Blue Sea ACRs through Amazon are roughly 1/2 the price of these diode bridge isolators for 120 amps and about 80% the cost for a 500 amp version compared to the 300 amp, without all the attendant downsides.

 

I did do a search. I didn't find this.
Thank you for posting it.

Jeff

 

I would like to thank everyone for all the help.
I will post my progress as I go. Will be a few weeks before I can get started.


Jeff

 

I used the NW Wrangler system from the Fourwheeler link in my '95 F-150. I was happy with that. It electrically separated the batteries when the truck was shut off, connected them directly (no diode voltage drop) when running, and gave a manual switch to either force them to be always connected (which would draw power) or always disconnected.

Here's the link again, but I just copied it from the thread Puddy already linked in.
1992 Ford F-150 - Electrical, Battery Upgrade - Four Wheeler Magazine