Why are gas-powered battery chargers not more common today?

[Chance]

Why are gas-powered battery chargers not used more often? They may be more common in boats but rarely do I see then mentioned for RVs, not even newer RVs that have much battery and inverter capacity.

One example from Australia can be seen here:

http://toolmonger.com/2009/09/22/gas-po ... y-charger/

It's basically a small engine powering an automobile-type alternator, or else a DC generator.

Any thoughts on why AC power remains the norm for auxiliary power units even though much of the energy gets stored in DC form?

[GoProCowboy]

Have you seen this... Honda version out of Pacific NW cheaper..
http://www.altendc.com/checkout/cart/

[carringb]

Maybe because you could buy a Honda 1000 generator and a shop charger for less, but have something quieter and more useful?

Also that gas charger linked to would not meet CARB or Forest Service requirements.

[Chance]

Originally Posted by carringb

Maybe because you could buy a Honda 1000 generator and a shop charger for less, but have something quieter and more useful?

Also that gas charger linked to would not meet CARB or Forest Service requirements.

As I understand it (and I'm no expert on Hondas) the Honda 1000 or 2000 produces AC power at some frequency that depends on engine speed, then it gets converted to DC power and then the inverter in the "inverter generator" converts it to 115 Volts Alternating Current at 60 Hz. Then this AC power has to go through a converter or battery charger to convert back to DC at between 12 and 14 Volts to charge the batteries.

In many cases this kind of setup may indeed be better, but doesn't it sound like a very indirect way to get from point A to point B?

Regarding noise and CARB requirements, as long as a similar/equal engine is used then shouldn't these be non-issues? I get the particular unit linked is not approved, but why do you suppose approved units are not made for RVs? My guess it's due to low demand or the void would be filled.

[carringb]

Originally Posted by Chance

As I understand it (and I'm no expert on Hondas) the Honda 1000 or 2000 produces AC power at some frequency that depends on engine speed, then it gets converted to DC power and then the inverter in the "inverter generator" converts it to 115 Volts Alternating Current at 60 Hz. Then this AC power has to go through a converter or battery charger to convert back to DC at between 12 and 14 Volts to charge the batteries.

In many cases this kind of setup may indeed be better, but doesn't it sound like a very indirect way to get from point A to point B?

Regarding noise and CARB requirements, as long as a similar/equal engine is used then shouldn't these be non-issues? I get the particular unit linked is not approved, but why do you suppose approved units are not made for RVs? My guess it's due to low demand or the void would be filled.

You are right. The primary windings are 3-phase AC, plus seperate DC windings but that only does 8-15 amps depending on model. So yeah, way more complex electrically but it does more for less $.

For the few times I've needed to recharge the trailer batteries, hooking up the van worked out great and was much quieter than my old contractor-style generator.

[JWA]

Another guess is the majority of gas powered generators will be/are used in the AC form. Apart from marine applications DC-only generators would have limited use or appeal in the market segment serviced by gas powered equipment.

[Chance]

Originally Posted by JWA

Another guess is the majority of gas powered generators will be/are used in the AC form. Apart from marine applications DC-only generators would have limited use or appeal in the market segment serviced by gas powered equipment.

I agree that has been, and is still the case for the most part. Particularly for stationary power.

However, with large inverters becoming more affordable, to the point we can even run a camper's air conditioner off a 3000 to 5000 watt inverter, should it remain the normal design strategy? Why shouldn't the camper's inverter function in place of the inverter they incorporate in higher-end generators? The main reason for inverter generators is to allow the engine to run slower and thus more fuel efficient and quieter at partial loads. And we can't do that unless we have two inverters, or use DC charging, or else cycle generator on and off.

And as battery capacity also becomes lighter and less expensive, I think there is going to be a shift towards all-electric or mostly-electric RVs. If so, two scenarios jump out for auxiliary power. Either a very large capacity generator run off engine which can charge batteries in short order, or much smaller generator that can keep batteries charged over long periods of time -- much like has been discussed in fuel-cell thread.

I'd prefer the first, but not all vans have a second-generator option. And it would also add more cost due to needing more battery capacity to run AC overnight (like maybe 800 Amp-hours). On the other hand as long as batteries can supply starting surge, a small generator like the 55-Amp/800-watt unit linked above should be able to run a van AC without discharging batteries during night. Not suggesting that one -- would want a permanent generator tied to fuel tank.

Best of all the noise should be steady instead of generator surging every time AC compressor kicks in; which they may do a lot at night. That surging is what kept me from sleeping well with a 4 kW Onan I had. Steady background noise I can ignore easier.