Alternator-inverter-fridge?

[Naio]

I have an all-electric mini fridge (well, really it is a mini freezer, but I doubt that matters).

When driving, could I / should I connect the inverter directly to the alternator (isolator output) and power the fridge that way? Or is it better to have the house battery in the loop? Or a bad idea all around, for some reason I don't see?

Thanks much!

[pianotuna]

#4 or #6

You won't need a timer once the isolation relay is installed.

[Naio]

Thank you guys :).

Yes, I have no propane systems. (Except for a backpacking stove that uses those little canisters.)

My mini freezer keeps food frozen for 3.5 days when unplugged (opened once or twice a day, normal temps). I am thinking if I can give it a cooling boost for an hour or so when driving it might be good for longer/hotter.

I am not planning to run it off batteries when parked. Solar, maybe sometimes, if batteries are full and the solar is just sitting there unused.

Of course, plugging freezer in while driving and forgetting to unplug it IS something I could do. Will try not to. Maybe I need an inline timer switch!

Actually, that is not a bad idea for many things. I wonder if I can find a 12v gazillion amp one.

Pianotuna, I have not installed the alternator stuff yet. Would you care to recommend a gauge for me? 120amp isolator, about 6 feet to house batt and 12 to ice machine. I'm jealous of jrnymn's roll of 0 gauge :).

[pianotuna]

If you plan to do this, plan on upgrading the charging path with larger wire.

[wolfe10]

Unless your alternator has an external sense wire, you will want a SOLENOID-BASED isolator, not DIODE-BASED isolator.

Said another way, unless you have an external sense wire, the .7 VDC loss in the diode-based isolator will not keep your batteries properly charged.

[time2roll]

I think you are better off to wire the inverter to the house battery. Wire the house battery to charge from the alternator through an isolator. The house battery will absorb most of any start surge and provide power during any short stops. The isolator will prevent discharge of the chassis start battery.

[pnichols]

Naio,

You only have one house battery?

If so, as you know you'll have to "watch the battery charge level like a hawk" if you're going to rely on it for keeping food from degrading or spoiling. A compressor type refrigerator powered via an inverter from a battery consumes more battery energy than a propane refrigerator's battery powered electronic control board.

However, perhaps your DIY rig doesn't have propane on board?

[Naio]

Thank you, Mex :).

[MEXICOWANDERER]

No.

Connect it to battery Rectifier type isolators have a center bolt to attach the wire to. The center is the alternator connection.

This circuit has no battery or capacitor to smooth the extremely high ripple (pulsating DC current). So your inverter would be fed a diet of pure dirty power and it will hate you and get even for it.

Connect to the side that is directly connected to the battery.