The right Alternator/battery/inverter combo for 3000 Watts

[toadshade]

I am a welder and I have just experienced hurricane Irma and a loss of power for a week. I have been looking into a decent sized inverter (3000 watt) so I can run my welder for short periods on some smaller stuff. If I can run 20 amps 120V, I am good. The idea came from needing power for my house more than anything. I would buy a generator, but I need my welder on the road very often and it would be nice to just plug into the truck. I am worried about the strain on the alternator. I have the Slee conversion for a second battery. I have the massive marine switch and Blue Sea ACR and breakers but I have not bought the deep cycle yet. Should I just get the biggest one that will fit in the battery box? Any drawback to too big a battery?? I know this answer is out here on Mud somewhere and I looked around. If anyone has a link to a good thread I would appreciate it too.

I would hate to run the truck as a gen set for a period of time and I do not intend to unless I am in a rare situation as I was during the hurricane. That is another reason I would hate to have/maintain a generator. I also forgot that since I work out of my truck, I will intend to use the inverter for charging this new awesome DeWalt power source/four battery charger I just got. I am worried that the alternator will have too much load on it if I try to charge four 60V batteries at the same time. The biggest reason I do not want a separate generator, especially for the Lion battery charging is that I need to do it on the road from point to point while driving.

Sorry for the long as hell post

 

[scottryana]

I think your difficulty might be finding an inverter that will put out 3000w to a single outlet. Most have like 4 outlets and 2 are 15a and 2 are 20a. If you do it I would upgrade both batteries to the largest size you can fit. Do the 150a alternator upgrade, be very diligent about your belt tension and see how it goes. You will likely need a hand throttle as well as most alternators don’t make max power at idle.

 

[toadshade]

As long as I have a real 20A at the outlet I am fine. Something I just noticed with a small 2000W Honda Gen is that it was not happy when I started up the welder. It would balk at an immediate call for high amps. Will the inverter give me a good strong 20A right off the bat? Thanks for the info on the 150A alt. and the hand throttle.

 

[george_tlc]

3000W output from nominal 12V (call it 'maybe' 13V with engine running and voltage drop to the inverter) and let's assume say 90% efficiency means you will be pulling 3000W / 0.9 / 13V = 256A from you 12V system. That's a lot... You would need good quality large wires and kept short (to the inverter). You would need to be certain the inverter could handle the higher load while striking an arc.

I'd suggest the money would be better spent in a decent genset rather than trying to get these energy levels out of a 12V system. Even if having the genset is somewhat painful to carry around. Many modern gensets (small sizes in the low kw range) are inverter based. You would need to ensure they can handle the initial arc striking load - test them before committing to purchasing them.

An alternator (even beefed 150A) will get extremely hot trying to put out that level of current for any period of time. Heat is the enemy of electronics and such an alternator will have diodes and onboard regulator.

Obviously welders that do 'portable' welding for any period of time have welding units with a built in generator - cost is of course higher... something not 'too' expensive -> FREE SHIPPING — Hobart Champion 145 Welder Generator —145 Amp DC, 4,500 Watt AC Power, Model# 500563 | Engine Drive Welders| Northern Tool + Equipment (can be used as a welder or as a generator for power).

That dewalt unit only has 'smallish' batteries (4AH, 20V) so even 4 of them will not be a big issue to charge from the vehicle alternator. Don't mistake their spec's power 'output' for what it draws while recharging.

cheers,
george.

 

[bajaphile]

Just remember power (watts) is Amp x Volt. If you're on a 12v system, to get 3000 watts, you'll need 250 amps. I think best option for you would be to get a generator.

 

[Tools R Us]

For quick, emergency type welding, why not buy or make a battery welder?

 

[western flyer]

For quick, emergency type welding, why not buy or make a battery welder?

Yes, this.

I have a Ready Welder II: Fully portable. It functions with 2 or 3 typical vehicle deep cycle batteries as the power source. I built a welding cart and several other small items with mine (I use a Millermatic 252 in the shop). You would not be able to lay a lot of bead with just two vehicle batteries without recharging, but you would be able to perform common field repairs. Bring a third battery (or fourth) for more weld time or power. I suggest three deep cycle batteries for your battery welding scenario, and keep the 80 starting battery fully charged and out of the welding plans.

Ready Welder » Model 10000 Ready Welder II

 

[gummycarbs]

I'm also interested in being able to weld on the go. I've heard in the past of pulling AC current off an alternator before the rectifier.

If you Google "ac welding alternator", you'll get some relevant results. The first one is a PDF about modifying a GM 140 amp alternator. I'd paste it here, but I'm on mobile.

 

[nukegoat]

Don't weld on the 3000w inverter - even assuming it was built to deliver that sustained power (and load), which it isn't, the reasons others have mentioned will kill that option.

 

[Desert Dino]

Bay a portable gentator if you need to work


For emergency use only on the trail you can use the primitive way
Use 2 12V batteries in series use good jump start cables + electrodes or if you have a welding handle with cable combine it into the red neck setup and there you go.

If you need something more elegant use 2 12V car batteries in series and a kit like:

Pirate4x4.Com - The largest off roading and 4x4 website in the world.

 

[toadshade]

Damn. My hopes are diminishing for welding. I was afraid of that. I do have a 3000 watt generator that I thought about adding an electric clutch to and shoving it in there some place. Sounds like that might be a better option. Still not easy though. Someone also told me about high amp generator alternators. But they ain't cheap. I was hoping to move past quick emergency field repairs and actually use 3/32 rods for a few minutes at a time with my small Miller inverter.

 

[Desert Dino]

Using a 3000W converter 12VDC to 110VAC is wasting more then 50% has heat. And the full sine wave are very expansive.

 

[toadshade]

Yeah that is the impression I got. Too bad. As for the sine wave, I am not really sure it matters too much with my inverter. All it wants is power. 3 phase, 480, 220 110V doesn't matter so I would think an imperfect wave would not affect it too much. Just my guess though.