power inverter

[asmith]

not sure if this is the right place but it is for my truck. Looking to add an inverter to my truck. dont need anything insane. i would like it to charge tool batteries, and run a laptop occasionally, maybe if i dont have to get too big of one (read expensive), one capable of running power tools, but that is not necessary, just a want. anyway was trying to read about them and am getting confused. not sure what the difference between pure sine and modified sine is, and if it really makes a difference? also how much power do you think i would need? does anyone have one in their truck? what brands are good? i would rather spend a little more now for something that is going to last.

 

[79jasper]

You can get them big enough to run a fridge, so most power tools shouldn't be a problem. Maybe 100 amps max??

I would get one that hooks directly to the battery. Not the cigarette lighter/power socket type.

 

[fuzzy1626]

This may help:
http://www.ehow.com/facts_5804865_difference-modified-sine-wave-inverter.html

 

[asmith]

You can get them big enough to run a fridge, so most power tools shouldn't be a problem. Maybe 100 amps max??

I would get one that hooks directly to the battery. Not the cigarette lighter/power socket type.

i was definitely going to get one that comes off the battery. also i know they make them big enough to run power tools and stuff, it will just be my budget that is the limiting factor in how big of one i get.

This may help:
http://www.ehow.com/facts_5804865_difference-modified-sine-wave-inverter.html

Thank you. that does help. after reading it, do you think, or anyone else for that matter, that i would need a pure sine wave one for power tools. it mentions variable speed motors as doing better on them. kinda sounds to me like that is what i should be looking at.

 

[OLDBULL8]

Get this one, it'll do anything you want to run including electronics.
Power tools don't care if it's pure sine wave or modified, you'll never know the difference when running them.
Just remember, the more power you use out of the inverter, you suck 3 to 4 times that much out of the batteries, so you better have damn good batteries or you'll be left stranded. Batteries are rated at Amp Hr output.
http://www.harborfreight.com/5000-watt-continuous-10000-watt-peak-power-inverter-96706.html

 

[spg]

Having experience with an Inverter in my motor home I can offer the following advice. Figure the most power you will need and buy the next size larger Inverter. Remember watts divided by volts equals amps or any combination of the formula to figure one of the three parts. 10 amps at 12 volts is only 1 amp at 120 volts plus the waste or inefficency of the inverter. you will need multiple batterys for anything over 1000 watts. And the engine running to recharge the batteries for any exteded use mainly with power tool usage. I use 3 group 31 btteries for the 2000 watt inverter in my motor home. A 10 cubic foot Fridge of less than 600 watts will run them down in weekend if they are not charged during usage. Electric motors take about twice the starting watts as they do running watts.

 

[jaluhn83]

I'd get a true sine wave, and all of the advice above is sound too, especially sizing and considering the life of your truck batteries.

Power tools and some electronics should do ok on modified square, but some electronics, particularly computers and some speed controllers will blow up on a modified square wave.

Also remember that auto batteries are not deep cycle - that is, they're designed for a high load for a short time and immediate recharging. You really want deep cycle batteries (marine trawling, golf cart, etc) since they are designed for a moderate load over a lengthy time.

Not only do you stand a good chance of sucking your batteries down to where you can't start the truck fairly quickly, but anything more than occasional use will drastically shorten the lifespan on the batteries, especially if you don't immediately recharge them.

Additionally, consider the wiring from the unit to your batteries. Anything over about 150 watts is too big for a cigarette lighter. A 600 watt unit will pull 50-60 amps at full load and would need #4 or #6 wire.

To put some numbers out here, typical large auto batteries are ~60 amp/hr, so you've got about 120 amp/hr total. But, you've got to leave enough to start the truck, and if the batteries aren't brand new it'll be less. Say 50 amp/hr usable. That's 50 amps for one hour, or 10 amps for 5. Remember too that the inverter is not that efficient, so for a 100 watt load (typical laptop) you'll actually probably be pulling ~150 watts from the battery. So that's ~12 amps. So you could run the laptop ~4 hours with no other loads in an ideal world.

Depending on how much space you have any what you're planning to do I'd look into installing a dedicated auxiliary deep cycle battery wired to the truck charging system through an isolator and with the inverter directly wired to it with heavy gauge wire. With this system you get a proper high capacity battery and don't have to worry about not being able to start the truck, and probably need less expensive heavy gauge wire.

 

[asmith]

man there is some good advice and info here thank you. jaluhn that is a good idea about a separate battery for it. most of the time i would be driving the truck while using the inverter, so i dont have to worry about it too much, but it sure would be nice to be able to run a saw or something real quick on a jobsite without having to start up the truck or worry about killing the batteries. besides oldbull8 anyone have any recommendations on what brand to get? oldbull i am looking into that one now, so dont think i am dismissing your recommendation. just like to have choices.

 

[OLDBULL8]

I've got a small 250 watt inverter in my truck, only use it for a computer with the autoenginuity scanner and to charge my drill batteries.
Damn, just thinking, that may be turned on and running my truck batteries down, don't drive it much, gotta check it today.

 

[fuzzy1626]

I am using a Cobra 1500 at the race tracks to run a crockpot or Foreman grill and a fan this summer.

 

[Agnem]

I've had a Triplite 550B in the Moose Truck since the mid 80's. Not sure if they make that one anymore, but it's a good one. It is also a battery charger, so if you goof, you can just find another source of 110V power, and plug it in, and put back what you took out. It's older technology, and hums menacingly, so your not likely to forget that it is on. Some of the guys who have been to rallies know of the funny story I tell about my wife and the hair dryer.

As an aside, maybe a lot of you don't know this, but you can take most corded electric drills and hook them directly up to your battery, and they will run, albeit slowly. Drills have what are called "universal" motors and run on AC or DC.

 

[jaluhn83]

I am using a Cobra 1500 at the race tracks to run a crockpot or Foreman grill and a fan this summer.

You probably already thought of this, but make sure you use a big enough wire to connect it - probably a minimum of 2 awg. Having too small of a wire will cause excessive voltage drop under load, causing voltage regulation issues and the unit to draw more current and stands a good chance of blowing the inverter up.

Don't know much about brands, but I would suggest saying away from the cheapy ones unless all you're running is things like tools and motors. My experience is with heavy duty house power inverters - my parent's house is on a 3500 watt trace which is an awesome unit, but weights about 100# and cost well over $1000. On the other hand, it's designed to run full load making very clean regulated power for years on end.

I'd be surprised if you could get much out of a motor running it off 12 volts dc. I think the universal motor is more meant to run on 120 vac or vdc.