Charging batteries with generator

[pcskier]

I am looking into buying a 1000W Honda invertor/generator to make sure I can keep my onboard batteries charged during cold weather dry camping when I may use the furnace (I intend on using a Mr. Heater Catalytic heater as much as possible instead, though).

This generator can output 120v that I'd plug into the shore power; or 8 amps of 12V DC that can be attached directly to the batteries for charging. With 120V shore power attached, what is the output from the stock converter that charges the onboard batteries?

Which would be more efficient in terms of generator running time to keep the 2 12V interstates charge: running the generator into the shore power outlet, or using the 12v 8A output directly to the batteries? Pros and cons to letting the converter charge them, vs. the generator doing so directly? Thoughts?

THANKS as always.

[Protagonist]

Originally Posted by pcskier

Pros and cons to letting the converter charge them, vs. the generator doing so directly?

That depends very much on your converter (single-stage or multi-stage?) and the generator's voltage regulator (almost guaranteed to be single-stage).

[Al and Missy]

But almost all converters will put out more than 8 amps to charge the batteries, right? My stock was 50A and replaced with a 60A. 85 Ah at 8 amps - more than 10 hours generator run time. Even at 40A converter, less than 3 hours.

Al

[Mrjkq]

Make it easy, just plug in to the generator & stop micro managing, there's more things in life.

[DKB_SATX]

If you don't already own the Honda 1000, look carefully at the prices for the 1k and 2k. Another $200 and about 15 lb heavier gets you a much more capable generator with the easy option to parallel with another 2k generator in the future if you choose to do so.

[pcskier]

Originally Posted by Protagonist

That depends very much on your converter (single-stage or multi-stage?) and the generator's voltage regulator (almost guaranteed to be single-stage).

My convertor is stock so I'm sure it's a single stage.

[pcskier]

Originally Posted by DKB_SATX

If you don't already own the Honda 1000, look carefully at the prices for the 1k and 2k. Another $200 and about 15 lb heavier gets you a much more capable generator with the easy option to parallel with another 2k generator in the future if you choose to do so.

Indeed, I've been debating that. I considered a 2,000 Watt since it's only $200 more; but then though, 1,000W is plenty for my low power needs, EXCEPT for AC. So a 2,000w might be a good hedge in that I could add a second one later if needed. I was leaning toward the 1,000w simply because based on my needs *now*, it does what I need, and is the most efficient.

Still will think that through the for sure, so thanks for the input.

[pcskier]

Originally Posted by Mrjkq

Make it easy, just plug in to the generator & stop micro managing, there's more things in life.

Indeed In this case though I was just wondering if there was a very definite advantage to one way or the other based on others' experience.

Thanks for your advice---well taken!

[WindyJim]

I'll start off with, "I'm no expert, but..."

The reason most generators have an 8-amp battery charge rate is that the rough guide lines for charging a battery is to charge at a rate that is approximately 10% of the battery's amp-hour rating. Thus for a single 80 amp-hour battery, that would be approximately 8 amps.

Now, you have two batteries, so hypothetically 16 amps would be a good initial charge rate, so an 8 amp charge would take about twice as long as you might otherwise need. Now guidelines also dictate that to keep from damaging your batteries you shouldn't let them go below 50% of capacity. So, if you have two 80 AH batteries (160 AH total), you should only be utilizing 80 AH from it.

I am in agreement with others though, in that Airstream has been building trailers for a long time and I would start the generator up and just plug it in to the trailer instead of trying to use the battery charge setup from the generator. I think the 8-amp feature is primarily for use if you have an external, stand-alone battery that needs a charge.

[CaCraig]

I don't think Honda generators have an automatic shutoff when the battery is full, at least my eu2000i doesn't. I've plugged a new computerized car battery charger into the generator and then to the battery when at Burning Man. The better option this last year was a 100W solar suitcase from Renogy. It charged my battery in a few hours. I never turned on my generator once, but I didn't use the furnace

[Mexray]

I retrofitted a 3-stage converter/charger (45 amp) in our 78 model...among with a digital voltmeter...

Using our 2KW Honda genny, i can recharge out 3 gp-27 batteties each morning while monitering the voltmeter...

When i notice the voltage drop from a charging rate to the 'float' voltage of 13.4 volts - i know the battery bank is fully charged again...

I plug the shore power cord directly into the genny - i can then also quickly fire it up to run the microwave, etc. When needed as well...

[mojo]

The bonus of plugging the power cord directly into the generator is that you can enjoy all of the onboard conveniences loke lights, microwave, TV and heat while your batteries are charging.

[pcskier]

Went ahead and pulled the trigger on a 2000w Honda for $899, no tax, free shipping (that's the price everywhere online right now). While I don't 'need' that much power for my intended purposes 'now', just $200 more seemed to make sense in case I ever want to use AC and could add a second gen.

Thanks for all the advice folks.

PK

[DKB_SATX]

Originally Posted by pcskier

Went ahead and pulled the trigger on a 2000w Honda for $899, no tax, free shipping (that's the price everywhere online right now). While I don't 'need' that much power for my intended purposes 'now', just $200 more seemed to make sense in case I ever want to use AC and could add a second gen.

Thanks for all the advice folks.

PK

It'll make life easier... since you won't be near the generator's peak output for the first couple of minutes you won't need to be as scrupulous about shedding/preventing load before you start the generator. (e.g. turning the fridge to LP-only, etc.) It should "just work" and should run at the quieter low-RPM "econ" mode while it's charging your batteries.

[JBinKC]

You'll need to accessorize that Honda generator. You need an adaptor for 30-amp to 20-amp, maybe a short 20-amp extension cord if you don't want to drag out your 30-amp cord, plasticized cable and heavy lock, gas can, high-test ethylene-free gas, stabilizer, oil and oil-changing apparatus, etc., etc., etc. And you'll need to run that generator every month for 15 minutes, year round. If you don't, it won't start when you need it. Hauling a small generator or two is no small commitment in time, energy and cash.

[DKB_SATX]

Originally Posted by JBinKC

You'll need to accessorize that Honda generator. You need an adaptor for 30-amp to 20-amp, maybe a short 20-amp extension cord if you don't want to drag out your 30-amp cord, plasticized cable and heavy lock, gas can, high-test ethylene-free gas, stabilizer, oil and oil-changing apparatus, etc., etc., etc. And you'll need to run that generator every month for 15 minutes, year round. If you don't, it won't start when you need it. Hauling a small generator or two is no small commitment in time, energy and cash.

No need to make things more complicated than they are. It can be hard to find ethANOL-free gas at the drop of a hat, but if you burn all the gas in the tank before storage it's not a big issue. (One reason I prefer Yamaha generators is that they all have fuel shut-off valves so I can easily burn all the gas out of the carburetor at every shut-down.) If by "high-test" you mean high octane, I don't think that matters at all for any of the consumer-available generators. I burn the same regular unleaded in my Yamaha that I put in the F150.

Yes you'll need an adapter from the 30A twist-lock to a 30A RV socket, and a cable and lock is a great idea if you'd like to keep it, but you need that for a good bicycle as well.

[J. Morgan]

I am currently using a charger, but I have a new converter that I will install when I get home.

I installed the charger because I had it and I was being cheap, but overall it was a bad compromise and generally a bad idea.


Brevi tempore!

[larryglarson]

I see Battery charges on special for very little money. Yes, I would get a 2000 and then plug the Battery charger into the generator after reading A/S instructions for charging batteries.

[pcskier]

Test

[Wingeezer]

I think you'll be happy you bought the 2000 watt.

I bought mine for use power the trailer when needed but have also found it handy in teh event of power failures at home, and also to use in places where 110v is not readily available to run power tools up to and including a small 140amp mig welder I have.

I have ever used the DC 8 amp output - I just plug the trailer into teh gennie and use teh 50 amp charger in the trailer.

Incidentally we also have just the basic charger in the trailer as originally equipped and so if we camp any place on shore power, I disconnect the batteries to avoid any chance of
"cooking" them with the the trailer's charger.

Brian.