dberladyn

Installing Auxiliary Batteries was one of the first thing I should have done. It would have saved me a tremendous amount of headaches and losses. I am coming close to purchasing factory auxiliary battery mounts. It is one of the few things that seems to make me happy. Having this truck to set up that is. It's... just spending the money is the only thing that really stops me. I have had lots of plans.

Anyways, what are your thoughts on this switch? I think I like it. I need to spend more time reading and thinking about it, but so far nothing but good points considering the information they provide.

http://www.inpowerdirect.com/docs/PDS-119D.pdf

mountainmanjoe

Interesting. No diodes or solenoids so what does it use? Seems they're trying to keep it a secret, but such a small package would suggest silicon (transistors?). That entails power losses so you're just burning up energy as heat. I prefer solenoids since they have very low resistance.

$200+ USD seems like a lot. I got my Surepower 1314 for around $80 CAD and it works marvelously.

StanVan

And a simple isolating relay is even cheaper. They can be had for $15 to $20. I'm leaning towards this one;

https://www.google.com/shopping/prod...cTaDusQ8wIIxgI

dberladyn

Thanks for the replies. Originally I have been planning on something like this hooked in to the RAP or the RUN Circuit. Maybe that's what I will still end up doing. I'll decide after I buy the mounts and the batteries. Which I should I do soon as I have a lead on cheap brand new batteries. Originally I was going to go with Optima Batteries, then I decided I should for bigger ones, now I am back to Optima. Just Keep it Simple Stupid, right?

If I install two banks of auxiliaries, I will probably use an isolator to keep them separate. One bank for multiple amps, charging tablets, laptops, cellphones, accessories, another bank for really heavy inverter work. Or even just being able to switch back and forth between the two of them. If I am not working and pulling a trailer to get away, I am sure extra on board auxiliaries would come in very handy for remote stops. Speaking of such, there's some really good deals on trailers here locally right now. Clean 26 footers for $2000 each. It would be hard to go wrong. I have fight myself off from jumping into that too.

mountainmanjoe

I think there are major benefits in having some electronics to monitor voltages and control the relay. That Stinger is cheap because it's wimpy. It won't even give you 1000W.

If you want simple then just put in a switch. But it will leave you stranded one day when you forget to flip it.

StanVan

Your idea of wimpy and mine differ.

mountainmanjoe

It's fine if you just want to run a laptop.

Inverters have really come down in price. You can pick up a 2,000W unit for about $250. Personally I would rather spend a little more to be able to run power tools, a beer fridge, kettle, microwave, or whatever else I need. I mean, that's why we bought vans right?

StanVan

First, the isolator is for charging the battery, not for running stuff. And a 4000 watt inverter draws between 30 and 35 amps. And last, it you're powering a fridge and a microwave, you don't want a van, you want an RV, and they usually come with generators.

mountainmanjoe

Sorry I got a little carried with inverters. But ...

#1- I have a 140A alternator charging my battery.
#2 - If you're running a lot of devices, you will sometimes want to use power from the alternator for those too.
#3 - What if something happens to your starting battery, and you want to use your house battery to start the engine. That's 120-200A
you need to push through.

That's 30A on the high side, Stan. You're forgetting that the inverter is changing the voltage.

Most 120V appliances are designed to run on a 15A circuit. Let's consider a heavy load ... a 1500W kettle for example. Inverters aren't magic and you can't get something for nothing. (In fact there are significant losses).
POWER IN = POWER OUT.
POWER = VOLTAGE x CURRENT.
On your 12 V side, CURRENT = 1500W / 12V
That's 125A @ 12V for one device.
I won't even get into inductive loads and inrush current.

So why would I cripple myself just to save a few bucks on an isolater. They're really not that expensive. (in the grand scheme of things)

No I don't want an RV. A small fridge and microwave fit nicely in full size vans.

I actually built an auxiliary power system, which I used to for years, and now I'm designing a better one. I'm not just armchair quarterbacking here.

StanVan

The 4000 watt inverter I looked up said the input line was protected by a 30 amp fuse.

But more importantly, NO. Power does not equal voltage times current. Ohm's Law is based on a triangle of voltage, current (amps) and resistance. You must know 2 of these to calculate the 3rd.

To find the Voltage, ( V )

[ V = I x R ] V (volts) = I (amps) x R (Ω)

To find the Current, ( I )

[ I = V ÷ R ] I (amps) = V (volts) ÷ R (Ω)

To find the Resistance, ( R )

[ R = V ÷ I ] R (Ω) = V (volts) ÷ I (amps)