Picking out a generator and battery charger. Any Ideas???

nobody928 · October 2013

Let me start off by stating that I would prefer to be on the cheap side.

I was thinking of getting the champion 1500 watt generator from Amazon @ $199 dollars. I am looking for good gas
consumption/tank size and easy cold starting. I only will be using it to basically charge my battery bank and maybe power the tv as well.

There are multiple full size and compact chargers around 100 dollars. I want one that will charge my battery bank fast but im not sure how many amps I can charge my AGM batteries with. Any ideas or suggestions with any reasonably priced would be helpfull.

My system consists of; 3x140 watt UL solar panels. I have a c40 xantrex pwm charge controler, 4x 105 a.h a.g.m. batteries. And a 1500 watt sine wave inverter.

Cariboocoot · October 2013

Re: Picking out a generator and battery charger. Any Ideas???

Okay what you're looking at here is 420 Amp hours of battery. Normally you'd want to charge that at about 40 Amps peak, which is roughly (40A * 14.4V) 576 Watts. Call it 600 because there are losses and power factor to be considered. Normally you'd want to run the gen at 50% or more of its capacity for maximum efficiency. So that's a 1200 Watt gen for full charging power. 1500 Watts is close enough to this to not argue about, especially if you have it pick up loads while charging. (People who obsess over small amounts tend to have systems with no operating margins. These invariably fail.)

You will need a stand-alone battery charger unless your inverter has one built-in (doubtful). You do not have to pick a 40 Amp charger; you could go as low as 20 Amps or as high as 60. But all things considered a 40 Amp charger and a 1500 Watt generator looks like a good match for that battery bank.

Champion generators. Several people on the forum have them. They are cheap, yet reasonably dependable. They aren't "prime power" candidates. They aren't "maximum efficiency" like an inverter-generator. They aren't going to last forever. But they are cheap and reasonably dependable. Perfectly suited for occasional use in a small off grid system.

jcheil · October 2013

Re: Picking out a generator and battery charger. Any Ideas???

I have that same Champion model. Well technically I have the one from two years ago that was rated 1400/1800 but simply math based on THAT engine size determined that it would never produce 1400 watts. It basically would do about 1100 and after that thevoltage and waveform were really messed up. This new 1200/1500 model is the EXACT same motor/alternator that I have but they just got smart and derated it to realistic numbers. And mine would not run an IOTA DLS-55 (12v) charger (likely due to inrush and crappy power factor).

All in all it is a GREAT basic/cheap generator. I run a 550watt A/C unit on mine and it will run for about 10ish hours on the 1.4gallon fuel tank. Pretty much in line with the fuel usage of the Honda 1000i not too much louder than the honda 1000i when NOT in econo mode with the same sized load on it.

Just change the oil EVERY 50 hours or when you see it starting to turn black. It only takes less than a half a quart of oil so it breaks down really fast. Mine is 2+ years old now and doesn't burn a drop. My neighbor bought one at the same time and (against my advice) just "tops off" the low oil and only changes it every few months and his only lasted just over a year before it would burn so much oil that the low oil shutdown would kill it in less than an hour.

And their service department is great in that if you have a problem, they will send you the parts to repair yourself if you want. You don't even have to bring it to a service center unless you want to. And I mean ANY part. I got a piston/ring/crank set under the 2 year warranty for a 3500 model 3 or 4 years ago back before I realized how important it was to change the oil more frequently than their recommended 100 hours.

techntrek · October 2013

Re: Picking out a generator and battery charger. Any Ideas???

Cariboocoot wrote: »

Okay what you're looking at here is 420 Amp hours of battery. Normally you'd want to charge that at about 40 Amps peak, which is roughly (40A * 14.4V) 576 Watts. Call it 600 because there are losses and power factor to be considered. Normally you'd want to run the gen at 50% or more of its capacity for maximum efficiency. So that's a 1200 Watt gen for full charging power. 1500 Watts is close enough to this to not argue about, ...

I agree he needs to load the genset above 50%, preferably up to 80%, but I must be missing something in your math. If he has a 600 watt load, a 1200 watt genset would only be right at the 50% mark. He should go a bit smaller to load it up a bit more. Assuming it would handle the starting surge.

Cariboocoot · October 2013

Re: Picking out a generator and battery charger. Any Ideas???

techntrek wrote: »

I agree he needs to load the genset above 50%, preferably up to 80%, but I must be missing something in your math. If he has a 600 watt load, a 1200 watt genset would only be right at the 50% mark. He should go a bit smaller to load it up a bit more. Assuming it would handle the starting surge.

I thought he was planning on running some other things at the same time.
And if jcheil's analysis is right this gen is really 1200 Watts (some companies like to put the peak number on instead of the continuous).

mike95490 · October 2013

Re: Picking out a generator and battery charger. Any Ideas???

techntrek wrote: »

I agree he needs to load the genset above 50%, preferably up to 80%, but I must be missing something in your math. If he has a 600 watt load, a 1200 watt genset would only be right at the 50% mark. ....

There is also the power factor & efficiency to consider. The alternators rating is only valid at their designed PF (usually 1.0)
And if the 600 watt charger pulls 700 watts to deliver the 600, then that loss needs accounting too.

icarus · October 2013

Re: Picking out a generator and battery charger. Any Ideas???

In my experience, cheap is not always less expensive in the long term.

Tony

Picking out a generator and battery charger. Any Ideas???

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