Posts: 3,188
Threads: 216
Joined: Sep 2007
your truck engine may be able to handle the load ....the alternator may not .....there was a time in the boat cruising world where oversize alternators were popular ....to get the increased output winding wire sizes were reduced to produce the extra wattage ... the windings had a tendency to fail ...many cruises had to have them rewound - with the original 55 amp windings due to the extra heat produced...best alternators in stock form come from ambulances...130 amp (@12v) units (about 13 amps 120v not counting inverter losses) see "big case" alternators ....you will also need to upgrade the belts and pulleys .....bigger the alternator output = more turning resistance .....leece neville makes nice units imho
Posts: 14,074
Threads: 424
Joined: Aug 2012
I assumed the engine would be running
Most inverters don't like that because the voltage runs too high.
best alternators in stock form come from ambulances...130 amp
Also "police special" and "those kids with the thumping stereo".
Seems a truck engine should handle the same load a 10 hp 5kw generator would put out.
A truck also has enough capacity to carry around a proper generator...
Posts: 3,188
Threads: 216
Joined: Sep 2007
I am impressed with the new rechargeable power tools coming on market ....that may be a better option... I just bought a milwaukee m series combo that rocks - really fast recharge time .....
Posts: 7,714
Threads: 683
Joined: Jun 2011
Large inverters don't like long cables from the battery. What I did was put a deep cycle battery in my truck (Kirkland sells one with high cranking amps) when my regular truck battery needed replacement.
If I need to run the inverter I just screw the cables into the extra deep cycle posts they are already sized for.
This gives me two options, I can either leave the truck running if I'm powering a high load, or I can just run off the battery if it's a low load. It sort of turns the truck into an extra generator. Except it's quiet. I have a 4000 watt (8000 peak) inverter I can use to power the catchment pump. The bonus with the deep cycle is if I'm using more power than the truck can produce the battery can provide it. My battery has been used in this manner for 4 years (though admittedly not frequently) and it functions like new.
"Most inverters don't like that because the voltage runs too high."
Most of the inverters I have specify to leave the engine running so as to not damage the battery. So long as the alternator is wired to the battery it should even the voltage out, a decent inverter should have over voltage protection. My big ones additionally have fuses in the battery cables.
It's a better deal to get an inverter that comes with cables. My recommendation with inverters is determine how many watts you think you need, and then buy an inverter that is rated for twice that amount. If an appliance uses 1000 watts of pure sine wave power, it will use like 20% more of that on modified sine wave, and most inverters don't actually put out the power they advertise. Doubling is a good strategy, tripling is better if you think you might want to expand your needs later.
Posts: 3,186
Threads: 108
Joined: Jun 2010
Most of the 12v inverters I've used have handled 14.9 - 15.4 volts, YMMV. They are certainly designed to handle a vehicle alternator.
The 2-3x surge wattage is to handle the inrush current on motorized tools. I'd go 3x.
If you are using tools normally, you will only be at 25% duty cycle or something, so your alternator will have plenty of time to catch up the battery, even if it is undersized for peak load. Just use thick short cables everywhere you can.
Posts: 1,098
Threads: 71
Joined: Jan 2009
quote:
Originally posted by Rob Tucker
Thanks everyone. I kinda pictured not running off a truck battery. In my naivete I assumed the engine would be running. Seems a truck engine should handle
the same load a 10 hp 5kw generator would put out.
Am I wrong?
Not sure in your scenario, for sure. But one of my early (19 years ago virgin off grid fella) mistakes was to try to charge a small battery pack by hooking up my Prism (toyota sister ship) via cables to the battery pack. Shot stuff to hell, especially the alternator. I thought, shoots, if it can run a car, it can charge a few batteries, no?
No.
Some sort of electronically stuff.
Cheers,
Kirt (embarrassed )
Posts: 8,437
Threads: 1,031
Joined: May 2003
I've been so impressed with the lithium ion battery packs that I may just go that route. Perhaps a small inverter to charge batteries.....
Assume the best and ask questions.
Punaweb moderator
Posts: 7,714
Threads: 683
Joined: Jun 2011
I bought a small inverter that plugs into the cigarette lighter hole and it powers the ryobi charger no problem.
Posts: 14,074
Threads: 424
Joined: Aug 2012
a small inverter that plugs into the cigarette lighter hole
...easily moved to another vehicle, should the need arise.
