What do we need to charge our battery bank with a gas generator?

[bernadinenewland@hotmail.]

We are beginners and have watched dozens of videos and read so much our heads are spinning. I have searched this site and still am not sure.​

We have a PREDATOR​

9000 Watt Max Starting Extra Long Life Gas Powered Generator. We would like to use it to charge our battery bank and maybe have some solar. We are considering Lithium Iron batteries and need to know how to hook up the generator to the charge controller, which charge controller is best for this or does it matter, and what other things we need to consider. Thanks.​

 

[John Frum]

We are beginners and have watched dozens of videos and read so much our heads are spinning. I have searched this site and still am not sure.​

We have a PREDATOR​

9000 Watt Max Starting Extra Long Life Gas Powered Generator. We would like to use it to charge our battery bank and maybe have some solar. We are considering Lithium Iron batteries and need to know how to hook up the generator to the charge controller, which charge controller is best for this or does it matter, and what other things we need to consider. Thanks.​

You want an ac2dc charger to charge your battery bank via generator.
Since you will very likely need an inverter too its a good idea to combine them.
An inverter/charger is very likely what you want.
You need to determine the continuous watt rating for the inverter in order to size the battery bank.
See my signature for a link to an audit tool.

 

[HRTKD]

You need an AC-DC converter. Most of those come with a plug on the end of the cord that allows you to plug into a standard 15 amp outlet.

You'll size the converter based on your battery bank and how fast you want to charge that bank. The generator should easily handle most 120Vac converters.

 

[bernadinenewland@hotmail.]

You need an AC-DC converter. Most of those come with a plug on the end of the cord that allows you to plug into a standard 15 amp outlet.

You'll size the converter based on your battery bank and how fast you want to charge that bank. The generator should easily handle most 120Vac converters.

Ok we are thinking of one 200 amp lithium iron battery for now. We may go with two of them but is there any danger of charging too fast? I'm sorry for all the questions but how long would it take to charge one battery or if get them two batteries? Do the Converters or inverters have fuses in them? Or do we need to purchase them separately?

 

[HRTKD]

Ok we are thinking of one 200 amp lithium iron battery for now. We may go with two of them but is there any danger of charging too fast? I'm sorry for all the questions but how long would it take to charge one battery or if get them two batteries? Do the Converters or inverters have fuses in them? Or do we need to purchase them separately?

You need to check the specifications for your batteries to know how many amps they can be charged at. The general number is that you charge at no more than half the Ah rating. So a 200Ah LiFePO4 battery could be charged at .5C or 100 amps.

A 200 Ah battery, at a low state of charge, would take about two hours to charge when charge at 100 amps. AC-DC converters rated that high are not common, but do exist.

A converter usually has fuses, but those are to protect the converter. A breaker or fuse on the wire between the converter and the common bus bar (or the battery) is there to protect the wire.

 

[bernadinenewland@hotmail.]

You need to check the specifications for your batteries to know how many amps they can be charged at. The general number is that you charge at no more than half the Ah rating. So a 200Ah LiFePO4 battery could be charged at .5C or 100 amps.

A 200 Ah battery, at a low state of charge, would take about two hours to charge when charge at 100 amps. AC-DC converters rated that high are not common, but do exist.

A converter usually has fuses, but those are to protect the converter. A breaker or fuse on the wire between the converter and the common bus bar (or the battery) is there to protect the wire.

Thank you so much. We are working hard to understand all this. your advice is really appreciated.

 

[deeuubee]

What do you plan to do with the battery?
Only for emergencies?, Power a shed?
What do you want to power with it?

With just one battery, I would get a 100 amp charger and charge it from the generator.
Done in an hour or so depending on state of discharge.

With basic solar 2-400 watts, probably most of the day to charge it.

 

[Drooling Piston]

I see this thread is a few months old but, it seems I can only find ac to dc chargers up to about to 50 amps DC, that can still plug in to a standard 110v outlet. Above that rating, they need 20+ amps of AC and thus heavier wiring, breakers and plugs

 

[HRTKD]

It's not much more, but I have a 55 amp charger from IOTA Engineering. You're right that once you get much above that amp rate, it requires a 20 amp AC source.

 

[chrisski]

I see this thread is a few months old but, it seems I can only find ac to dc chargers up to about to 50 amps DC, that can still plug in to a standard 110v outlet. Above that rating, they need 20+ amps of AC and thus heavier wiring, breakers and plugs

How much power are you looking for? 50 amps would be fine for my four GC2 golf cart batteries.

To me these 120 VAC 15 amp chargers do not seem very efficient. I don’t know why. You would think a 120 volt to 12 volt 50 amp converter would only pull 5 amps and 600 watts, maybe 10% more for inefficiencies, but this seems to max out the 15 amp jack, which is around 1800 watts. There’s got to be some reason why it’s so inefficient.

 

[Drooling Piston]

In the scenario spelled out by the original author here, The sun is shining, your solar array is charging, then you turn on the generator to run the roof mounted air conditioner. The generator will send 110v AC to the new 55amp battery charger, that is connected to the same batteries the solar is charging already. Which charger will "win"? or will the AC charger sense the higher voltage of the solar charger already running and not do much at all? I ask because the AC charger will be able to push higher amps than my small solar array does and my goal is to recharge those batteries every day. So if one charger is going to stand down, when we have the generator running anyway, I would prefer it be the higher amp AC charger.

 

[chrisski]

It’s got something to do with the voltage also.

My solar panels carge at 14.5 and are capable of delinverting 45 -60 charging amps. My RVs converter charges at 13.6 but can only deliver 15 amps. I set the voltage for my PV on my SCC for what my 4 golf cart batteries need. The RV conever is a fixed voltage, 13.6, and designed for a single battery.

In that case, the higher voltage should win, especially because the PV has so many more amps to back the voltage up.

I’ve never tested this in full sun. I’ve only ran the generator on cloudy days once or twice. When I did, the PV was not producing many amps, maybe 5 to 10, and the generator and RV DC converter still produced 15 amps.

If I have the solar invert powering AC, I leave the DC converter circuit breaker tripped to prevent the batteries from charging itself. I forgot once and in addition to pulling 750 - 1000 watts, sounded like the self resting circuit breaker was clicking. When I charger off the generator, I disconnect the PV inverter, and get AC directly from the generator.

 

[Drooling Piston]

That makes sense. In my case I do not have an inverter. We live in Western Washington (the wet side of Washington) I don't know how effective my solar will be. I will be happy if it just recharges my batteries.
I have recently learned, it is my fault that my RV batteries haven't been lasting very long. I have been discharging them too far. I did put 2 new 6v lead acid golf cart batteries in this year. For about the same price as a second set of those Lead acid, golf cart batteries, I put together a 200 watt solar array with a 40amp MPPT controller (that should allow me some growing room to a second set of panels) to silently re-charge my batteries throughout the day. I really only run into trouble when it is cold and we want to run the furnace in the travel trailer. It takes a lot of battery to run the furnace fan. These newer trailers seem to have a lot of power drain even when it seems nothing is running. Things like the circuit boards for the refrigerator & water heater, USB plugs to keep mamas phone charged up, rechargeable lights etc.

I have upgraded my converter/charger to this unit I bought from Amazon

https://www.amazon.com/gp/product/B00F8MC440/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

I can set the charge voltage between 13.2 & 14.4, capable of 55amps. So I think, in my case, this charger would win. I am ok with that because, If I have to listen to the generator run, I want to make the most of it.

 

[chrisski]

To run my furnace nd the stuff you mention on a cold night, I need 4 golf cart batteries for my 35’ RV. Days I don’t use the urn ace, the same batteries will last days without recharging.

On a 12 volt system, each golf cart battery has 110 ah of energy, 55 ah is usable until it is at 50% and will die quickly. My furnace fan draws 6 amps and will be running most of the night on the coldest night of the year, which in sunny Arizona may be in the high 20s. Those are also the shortest days of the year, where the sun is not shining many hours.

My overnight greatest usage was 165 ah. So I’m in the point I need 4 golf cart batteries. If you don’t have an inverter, than perhaps 2 will be OK on a cold night with the furnace running all night. Most of the draw I mentioned was DC.. The TV and other AC items use a small Portion of power compared to the furnace running all night.

 

[Drooling Piston]

That is what I'm hoping for. My new batteries are rated at 75amp for 120minutes. I'm not sure how to do the math to convert that to amp hours. I was told they are 220amp hour batteries. 50% of that quote should give me 110amp hrs useable.

Currently, since I only have 2 100watt panels, and I expect they will be partially shaded by tree branches, throughout the day, How do I determine the more effective configuration? In series or parallel?
My seat of the pants guess was put them in series. That is why I bought the MPPT controller to take advantage of the higher voltage. A couple of "Y" cords are cheap enough, if I would get more power wiring them in parallel.

 

[chrisski]

Try getting WIll Prowse’sbook, “Mobile Solar Power”. If you have kindle unlimited it’s downloadable at no extra cost. Also, take a look at the blue print up top.

For what you’re doing, putting as many panels as fits on your roof could be a good idea.