Anyone ran a secondary battery cable to a second battery for an inverter??

[91stranger]

Trying to get ideas for a mobile power center.
So I want to run a secondary battery cable to a battery either mounted in the bed of the truck or run the wires to an outlet of some sort to the bed so I can charge a secondary battery. I have a 2000w inverter and I want to be able to charge the inverter battery off the engine. This would be used for camping or working. I kind of like the thought of running the wires to an outlet in the bed and just make a plug for the battery to be able to plug into the bed and charge when needed. Is this even safe? Do-able? I've got plenty of 10 gauge wiring I was going to use or double up or even triple up since this is a 2000w inverter with 4 gauge wiring.

My initial plan was to build a power box attached to a dolly and have a battery (or two) mounted inside a vented box with the inverter and have a power center on wheels kind of deal but not sure what road to take.... Anyone on here have inverters mounted to their trucks or have an inverter setup, if so how is it set up? Just want to get some more info on this so I don't fry anything or burn my truck to the ground.

More on the power center on wheels:
1 or 2 batteries
2000w inverter (4000w peak)
Is it possible to make a charging system for this out of an old alternator and a motor?

I got a lot of ideas in my head but just don't know how to execute them properly and haven't played with inverter enough to know what's good and what not to do and would hate to ruin a nice inverter. Currently I have about $50 in the inverter, alternator and battery so I'm not in it very deep at all..... yet.

 

[RonD]

What you want is a portable generator

Using a vehicle's engine and alternator won't be very cost effective, and wouldn't work that well in any case at idle RPMs

No reason to reinvent the wheel IMO, I would watch craigslist and other local sources for used generators that you can repair

2000watts at 12volts is 166amps, so it would be hard for any alternator to keep up, charging batteries while using equipment
The more batteries you have the better as the 120vac inverter would be drawing 16.6amps at 2000watts
So amp hour rating of the batteries come in to play
Deep cycle have better ratings, CCA is not what you care about, just amp/hours
So you could run the inverter off the batteries only, then recharge them as needed with smaller generator

You can make a generator with a smaller engine and alternator, use pulley size to get alternator RPMs higher for its max amp rating, at best engine RPM, which depends on alternator and engine HP

 

[sgtsandman]

There is some info in the tech section about dual battery setups. I do know that you want an isolator block so the system you are powering doesn’t drain your main battery.

Like mentioned above, you’ll want a battery designed for deep cycle or it won’t last very long.

Beyond that, I can’t help much. 4XOverland and Ronny Dahl on Youtube show their layouts and what they use. Very similar, if not identical to what you are looking to do. That might be a place to start beyond the tech section.

 

[Josh B]

Here's a few ideas,

Power Inverters

I know there was a thread on here about PI's but I can't find it. Just wanted some info on what you all are running size wise for sawzalls, drills, ect. I want to put one in dad's truck just not sure what the best option is between that and a cordless. Thanks all Joe

www.scrapmetalforum.com

RonD's probly right though, as you'll read on post #2 here,

Portable Power Generator - Page 2

Who can recommend a good, cost effective portable power generator. I am looking to get one for when I am on a job, and need electric for power tools, but no where near a outlet.

www.scrapmetalforum.com

 

[Josh B]

I studied a write-up about a solar generator/inverter once too that was very interesting

 

[RonD]

I forgot to ask how long would you need the 2000-4000watts at a time?
If you will only using it maybe 2 or 3 hours at max watts and would be driving around a few hours between use you may be able to build a battery "bank" to store the needed amps and then recharge while driving

And yes you would want an isolator installed between engine battery and inverter batteries, not just a solenoid switch
An isolator acts line a Diode, it only lets voltage travel one way, if the inverter batteries were low and you just uses a solenoid then when key was first turned on the engine battery's voltage/amps would be sucked down to inverters batteries level
Isolator prevents that from happening

 

[91stranger]

I'm well aware of isolators since I work at an RV dealership. I was just wondering if anyone had any inverter setup's. My sole purpose is for shits and giggles pretty much. Got the inverter dirt cheap ($20) so I want to use it.... I think it would be nice to be able to run power tools out in the woods or at a junk yard. I know deep cycle batteries would be better but I already got a good battery from my truck and can get more batteries for $25 if needed. I would probably only use it for an hour at most I would imagine so not very much draw. It's like I have brain constipation...… Lots of ideas in my head but just can't get them out. Is there x-lax for the brain? ahahahaha

 

[4x4junkie]

You don't want to use a diode isolator, the voltage drop associated with the diodes won't allow proper charging of the batteries (mosfet ones are not much better). You want an isolator relay (250-500A relay) that operates via the ignition (connects the batteries together while ignition is on, disconnects the batteries when you shut engine off).
And no, a drained aux battery is not going to immediately suck down the engine battery if the two are connected together during starting (it only takes a few amps before the voltage of a discharged battery rises up above 12V). However you certainly can still wire the relay to a circuit that's live while key is "On", but not during "Start" if that'll give peace of mind (if you're creative with electronics, you could even put a time-delay on it before the relay engages, like 20 seconds or something. You might even be able to buy such a device, I haven't checked).

#2 AWG would be the minimum wire to use if mounting the aux battery in the bed (you'd need to bundle up about 6 or 7 #10 wires to be roughly equivalent to a #2 wire... not sure how much wire you got on hand). More than about 0.3V drop will also affect charging of the battery.


As for inverters, I have a 1500W (3000W surge) MSW unit (I forget the brand... Statpower, I think). I keep it stored away when not using it. It has #4 cables which I put heavy-duty battery cable clamps on the ends (like jumper cable clamps). I've found it will not power medium-large power tools such as a circular saw (the startup current is too much for it), but it will power things like drills, sawzalls, and even an angle grinder no prob.. Maybe the extra 500W (1000W surge) of a 2000W-rated unit would make the difference, not sure.

I've also used it for making waffles in camp (1200W waffle iron).