Generator charging house battery bank. How much?

I see many posts stating they use the genie for an hour or so am charge the house batteries and top it off with solar. Using a 4kw genie, how much can I expect to charge ( amp output?) ? 4 GC2 in series, parallel.
Thanks, Pat

The issue is really about the charger.  A 75 amp charger will charge much faster than a for instance 40 amp charger.

You might want to use a plug in charger like you would use for a car battery to augment the charger built in the converter. 

HueyPilotVN said:

The issue is really about the charger.  A 75 amp charger will charge much faster than a for instance 40 amp charger.

You might want to use a plug in charger like you would use for a car battery to augment the charger built in the converter.

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In the case of having four GC 2 golf cart batteries a 75 amp charger would make little or no difference.  I have 4four GC 2 batteries and a Progressive Dynamics PD9260 converter/charger, and I never seen a charge rate of more 45 amps for more than a few minutes.  I suppose if my batteries were way below 50% state of charge, I might see a higher charging rate for a longer period of time.

There is also the charge acceptance rate of the batteries to consider, you can't just put a bigger charger on the batteries to charge them faster without also shortening their service life.  A correctly sized charger will take about 4 to 5 hours to fully charge a deep cycle battery that has been discharged to the 50% capacity level, note that charge acceptance rate slows considerably on about the last 20% of the charge.  In other words depleted to 80% charge goes fairly fast, then that last 20% takes a long while.

Blues Driver said:

I see many posts stating they use the genie for an hour or so am charge the house batteries and top it off with solar. Using a 4kw genie, how much can I expect to charge ( amp output?) ? 4 GC2 in series, parallel.
Thanks, Pat

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A charger putting 50amps of 12V dc into a battery is only using 600watts, so even considering the inefficiency of the charger a 1000watt generator would charge the battery and run the lights, flat panel TV and gas elect fridge running on gas. 

You mention a 4000 watt generator.  I'm assuming you are talking about the cheap contractor generators.  Do you really want to listen to the extremely loud noise these generators make.  Not to mention if you are within 1/4 mile of your neighbor they are going to be really unhappy with your noise.

For a camping generator you want the small portable Honda, Yamaha, Westinghouse inverter type generators.  They are relatively quiet.

The problem with the subject line is that your RV has a CONVERTER. Mine is 80 amps. draw (With dead and I mean DEAD batteries) is about 1,000 watts.  With the converter properly matched to the batteies it's well To make math easy let us use 100 amp hours of battery and a 30 amp converter

50% state of charge (50 amp horus) you will need about 2 hours at 30 amps possibly 3 as the converter tapers off to reach 90 percent then another 2-4 horus for the last 10 percent.

If you put a 6,000 watt generator in place of the 1000.. NO CHANGE

4-6 hours to bring it from half full to full up.  PERIOD.

IF you add more battery (IE Doubler to 200 amp hours) but do not upgrade ther converter

Add mroe time in the BULK stager. absorption does not changer much.

So in the example 4-6 beomes 6-8

AStravelers said:

You mention a 4000 watt generator.  I'm assuming you are talking about the cheap contractor generators.  Do you really want to listen to the extremely loud noise these generators make.  Not to mention if you are within 1/4 mile of your neighbor they are going to be really unhappy with your noise.

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Why would you assume anything? The generator in question is an Onan 4kw built into a Winnie. As a contractor of 37 years I usually ran Hondas. $$$ but good and Quiet!

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John From Detroit said:

The problem with the subject line is that your RV has a CONVERTER. Mine is 80 amps. draw (With dead and I mean DEAD batteries) is about 1,000 watts.  With the converter properly matched to the batteies it's well To make math easy let us use 100 amp hours of battery and a 30 amp converter

50% state of charge (50 amp horus) you will need about 2 hours at 30 amps possibly 3 as the converter tapers off to reach 90 percent then another 2-4 horus for the last 10 percent.

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Thank you John, I should have been more specific. .  4k Onan in a Winnie. All info is good and your example helps . This whole subject has a lot of variables and suppositions. It is a crapshoot at best. Maybe it wasn't even a fair question.
  I would like to not use the gene at all but it appears necessary.  I plan to use it for an hour or less  for breakfast appliances and whatever charge I get is a bonus.  On a good day solar will finish the job.
I am conscious of the noise and plan to be considerate as I hope others will be.



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If you don't already have one, a battery monitor that tracks amp hours in and out can tell you just where your batteries are and how long to run the genset if at all.  Takes all the guesswork out of it.

Mark B.
Albuquerque, NM

Blues Driver said:

Why would you assume anything? The generator in question is an Onan 4kw built into a Winnie. As a contractor of 37 years I usually ran Hondas. $$$ but good and Quiet!

Moderator added missing end-quote tag

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Sorry, Bluesdriver. Though it is true that the type of generator was not mentioned anywhere in your post, I too was thinking portable generator, not built-in. And I think many of us have had the unfortunate circumstance of sharing a campground with someone using a contractor style generator. I think AStravelers was just trying to be helpful.