This is all hypothetical but lets say that I have a bank of 8 6v Costco golf cart T105 batteries, hooked up to produce 12v output. With the right converter, how long would it take to charge this setup using the right generator?And what would these 'right' converters and generators be?

all depends on budget I guess, how much do you have to spend on the "right" generator and converter?if money's no object, wire them as a 48 volt system and run a pair of Magnum 4248 hybrid inverter chargers ... 250 amps at 48 volts (typ), run a small 30 amp 12v converter off the inverter for your 12v loads, or get a DC-DC converter. alternately, you could use 2 or 4 standard 100 amp 12v converters, I think some of the nicer ones let you slave them together, with a control panel to force them into absorb modeedit: forgot the time ... the magnum solution should recharge your bank from dead to full in about an hour, provided you can supply 30+ amps AC to the chargers. going the converter route 2-4 hours depending on how many converters you use and how well they parallel together.

You get diminishing returns from going up in charger amps, but with 8 batteries that won't be an issue unless you use multiple 100ampers :)The charging amps a generator can run depends on the VA rating of the gen, not its named watts size. A Honda 3000 does 2800 VA. Also chargers can be non-Power Factor corrected or corrected. The generator can run more amps with a power- factor corrected charger drawing the same VA.Ok, so here are some times using various size chargers on two batts so just multiply those times by four to get your eight batt times.( You double the time with the same amps if you double the battery bank size; but you do not halve the time by doubling the amps on the same battery bank--that is the diminishing returns part of this)

4 6-cell banks are going to have the ability to absorb several hundred amperes of controlled charge rate. BFL's chart is reality. So is listening to and babysitting a generator for hour after hour. I would be skittish about generator noise and neighbors.I would choose a 3,000 watt Honda because of the low noise factor. Purchase a 100 amp -minimum- size charger. If that ends up satisfying you, great. If it charges too slow for your taste purchase a 2nd one.Other than 12 volt battery banks are great for use with inverters and solar homes but an RV requires 12 volts - a lot of it.The inevitable question: Why so many batteries?

Thanks for the feedback guys.Although those Magnum inverter/chargers are expensive, looks like an elegant solution. I only found a model called MS4448PAE which appears to be equivalent to what was mentioned above and each cost about $2200.Adding to this picture, what happens if I add NINE 160w solar panels? Can I still use the same components?My daily usage is expected to be around 370Ah (I realize it is a lot) and obviously, those panels isn't enough to cover my usage hence I'm going to be using a generator during the day. I'm thinking a quiet Honda 3kw generator - it appears to be the quietest generator at this rated level. I cannot keep the generator on 24/7 and shorter time the better.

The Honda 3000 like mine can run about 130amps of non-PF corrected chargers, but can run maybe 160 amps of PF corrected chargers.The 150amp charger in the fancy inverter chargers is usually PF corrected, so that would work.

Time to charge a bank of 8 6v batteries using a generator

46 Replies

Acei
Explorer
Oct 24, 2014
Thanks for the info guys. I'm going to have to re-read the whole thread as it appears to be quite complicated! Not complaining though... lol.
time2roll
Nomad
Oct 24, 2014
14.2 is plenty fast IMO.
Otherwise there is always Victron or Mastervolt.... hope you have a fat wallet.
BFL13
Explorer II
Oct 24, 2014
The Iota 90 is not PF corrected, and costs more than a PowerMax 100

The Iota drops to 14.2 right after it gets the batteries to 14.6v ( Iota at 14.8 then) The PowerMax does the same thing only it drops to 13.6 instead of 14.2.

Neither one of them has a boost button that you can use to maintain the higher voltage 14.6 so it won't drop down. There is a version of the PowerMax out now with an external voltage adjustment knob, but that is not "automatic" if that is what the user wants. There is a 120amp sized one of those (they are called PMBC )

There is a PD 80 amper which is also not PF corrected, but does have the boost button so you can make it stay at the high voltage (but that is only 14.4) and you really only get 75 or 70 amps during Bulk unless you wire it special, difficult in an RV.

It appears you have to spend more money to get what you want, such as the 150 amp charger in those fancy inverter/chargers which can be programmed to do the charging profile you want or get the PowerMax 120a PMBC with manual adjustment
MEXICOWANDERER
Explorer
Oct 24, 2014
180 amperes bulk charge rate is not inappropriate. But the Iota's optional "smart" 14.2 volt voltage absorbsion limit is .6 of a volt off the mark for minimizing generator run time while maintaining a safe charging voltage level IMHO. 14.8 volts can be used in a time limited meaning definitely user monitored charging protocol to render a significant reduction in generator run time each recharging cycle. The 14.8 volt at absorbsion time limit has to be established by the user custom tailored for his bank.

Advantage? About 30 to 40 percent LESS generator run time to fill batteries from 50% to 95%. Subsequent recharges can be done using a spring wound timer.

The quandary comes when a supplemental charger is used and the converter leans on a shovel and squeals it is simply maintaining it's advertised 14.2 volt bulk charge setting.

The specifics are obvious: The amount of amperage differential between 14.2 and 14.8 volts charging.

I believe BFL 13 can chime in with a valuable second opinion on this subject.
09FLSTC
Explorer
Oct 24, 2014
smkettner wrote:
Acei wrote:
This is all hypothetical but lets say that I have a bank of 8 6v Costco golf cart T105 batteries, hooked up to produce 12v output. With the right converter, how long would it take to charge this setup using the right generator?

And what would these 'right' converters and generators be?

Best shot is two 90 amp IOTAs with a parallel IQ controller.
Take about 3 to 5 hours to get a good charge in from low.
Maybe 10 hours to 100%.

Probably 4000 watt generator minimum.

Not a bad idea either.
09FLSTC
Explorer
Oct 24, 2014
jrnymn7 wrote:
I inquired earlier today regarding the pm3-75:

Jrnymn7: Hi, are the powermax pm3-75 units you sell PFC?
(I noticed you have two separate listings for the pm3-100's, pfc and non-pfc.)
Thanks!

AdventureRV: The PM3-75 is not PFC. The PM3-100 and the PM3-100 PFC are 2 different units.

They appear to think I can't figure out the two 100's are two separate units? Anyhoo, they claim to have pm3-75 and 100's that are not pfc.

And if the 75 IS non-pfc, then what will it draw, if the 45's are near 10a ???

See why at the end of the day you call Randy at bestconverter.com.. The guy gets it.
time2roll
Nomad
Oct 23, 2014
Acei wrote:
This is all hypothetical but lets say that I have a bank of 8 6v Costco golf cart T105 batteries, hooked up to produce 12v output. With the right converter, how long would it take to charge this setup using the right generator?

And what would these 'right' converters and generators be?

Best shot is two 90 amp IOTAs with a parallel IQ controller.
Take about 3 to 5 hours to get a good charge in from low.
Maybe 10 hours to 100%.

Probably 4000 watt generator minimum.
GordonThree
Explorer
Oct 23, 2014
mena661 wrote:
GordonThree wrote:
Have you read about the "boonhauler"? I think the builder is active on this forum but detailed his custom boondocker trailer build elsewhere.
Found this.

BoonHauler Project

nice job finding it Mena... check that thread out OP, I think it's similar to your grand plan
mena661
Explorer
Oct 23, 2014
GordonThree wrote:
Have you read about the "boonhauler"? I think the builder is active on this forum but detailed his custom boondocker trailer build elsewhere.
Found this.

BoonHauler Project
jrnymn7
Explorer
Oct 23, 2014
Maybe the OP should just get a 3000i and two pm3-75's (and mod them) and call it a day.