Need help finding a charger to charge an eight battery bank system

Off-grid Texan

I have an eight battery bank wired in series and parallel for 12v. They're 232Ah Interstate golf cart batts. I currently charge my batts whenever the gen is running to keep them up when the suns not out but the digital display on the charger never EVER shows a charge of more than 60-63% (about 12.2v) when the charger quits. The charger I'm using is one I had in my shop. It's a Schumacher 10A/20A. I've read on the NAWS site that I might need upwards of 26-60 amp charger to get a complete charge. Thoughts, comments, suggestions, recommendations?

Thanks!

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

Has anyone yet mentioned that having four parallel battery strings is not a good idea? I know it would be a further outlay but you should consider going to a 24 Volt system if at all possible.

A bit about why: http://forum.solar-electric.com/showthread.php?15989-Battery-System-Voltages-and-equivalent-power

That said, you have 4 * 232 Amp hours or 928 Amp hours @ 12 Volts. Ideally you should have a peak charge current around 92 Amps for that. Which isn't going to happen. There's no single charge controller that will produce that kind of current. In terms of a stand-alone charger this big Iota comes close: http://www.solar-electric.com/ioen12vo90am.html

In solar panels you'd actually need like 1440 Watts of panel and two MPPT controllers to handle it. Another reason to investigate going up to a 24 Volt system.

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

Has anyone yet mentioned that having four parallel battery strings is not a good idea? I know it would be a further outlay but you should consider going to a 24 Volt system if at all possible.

A bit about why: http://forum.solar-electric.com/showthread.php?15989-Battery-System-Voltages-and-equivalent-power

That said, you have 4 * 232 Amp hours or 928 Amp hours @ 12 Volts. Ideally you should have a peak charge current around 92 Amps for that. Which isn't going to happen. There's no single charge controller that will produce that kind of current. In terms of a stand-alone charger this big Iota comes close: http://www.solar-electric.com/ioen12vo90am.html

In solar panels you'd actually need like 1440 Watts of panel and two MPPT controllers to handle it. Another reason to investigate going up to a 24 Volt system.

Again, thnx...looks like I'm going 24v.
Like Edison said..."Those who never made mistakes are people who never tried anything new!"

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

Blackcherry04 wrote: »

Actually you have 4 , 6 V GC-2 's batteries that are 232 Amp hrs each.

Could have sworn he said "an eight battery bank". That would be four parallel strings of two in series giving 928 Amp hours @ 12 Volts as they are 232 Amp hour 6 Volt batteries (probably the same East Penn PS2200's I use).

Blackcherry04

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

Could have sworn he said "an eight battery bank". That would be four parallel strings of two in series giving 928 Amp hours @ 12 Volts as they are 232 Amp hour 6 Volt batteries (probably the same East Penn PS2200's I use).

You are correct, My Error !! Post Deleted.

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

That said, you have 4 * 232 Amp hours or 928 Amp hours @ 12 Volts.

Why would it be 4 * 232 and not 8 * 232?

vtmaps

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

Has anyone yet mentioned that having four parallel battery strings is not a good idea? I know it would be a further outlay but you should consider going to a 24 Volt system if at all possible.

And here's a short discussion of why parallel batteries are problematic.

Cariboocoot wrote: »

That said, you have 4 * 232 Amp hours or 928 Amp hours @ 12 Volts. Ideally you should have a peak charge current around 92 Amps for that. Which isn't going to happen. There's no single charge controller that will produce that kind of current.

The midnite Classic is rated 96 amps. (but I'm not suggesting you use it in this situation... operating any controller at its maximum rating continuously will shorten its life). As Cariboocoot mentioned, you should be reconfiguring your system to 24 volts.

Cariboocoot wrote: »

In terms of a stand-alone charger this big Iota comes close: http://www.solar-electric.com/ioen12vo90am.html

Off-grid Texan, what generator do you have? The Iota charger has poor power factor and huge inrush currents... not a problem if you are powering it from the grid, but may be a problem if your generator is not larger than you think it needs to be.

--vtMaps

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

Why would it be 4 * 232 and not 8 * 232?

You put two 6 Volt 232 Amp hour batteries in series to get 12 Volts: the Amp hours does not add up with a series connection, only the Voltage does.

You put four of these 232 Amp hour 12 Volt strings in parallel to get 928 Amp hours @ 12 Volts: the Amp hours add up in parallel, the Voltage doesn't.

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

You put two 6 Volt 232 Amp hour batteries in series to get 12 Volts: the Amp hours does not add up with a series connection, only the Voltage does.

You put four of these 232 Amp hour 12 Volt strings in parallel to get 928 Amp hours @ 12 Volts: the Amp hours add up in parallel, the Voltage doesn't.

GOTCHA! I did not know the amp hours didn't add up when in series. I'm assuming they do in parallel??

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

Off-grid Texan, what generator do you have? The Iota charger has poor power factor and huge inrush currents... not a problem if you are powering it from the grid, but may be a problem if your generator is not larger than you think it needs to be.

--vtMaps

You think my gen could be an issue? I thought a gen was a gen only dif being output. I have a harbor Freight special 4000W peak 2300W nominal...so far that bad boy runs everything on my property.

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

GOTCHA! I did not know the amp hours didn't add up when in series. I'm assuming they do in parallel??

Yes: series connection adds Volts but not Amps, parallel connection adds Amps but not Volts.

The generator issue vtMaps is one of power factor PF: 92 Amps * 12 Volts is 1104 Watts on the DC side, but with a poor PF the draw on the generator can be a lot more than 1104 Watts. In fact it can be around 1400 Watts. If the generator can't supply that it will be overloaded.

vtmaps

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

You think my gen could be an issue? I thought a gen was a gen only dif being output. I have a harbor Freight special 4000W peak 2300W nominal...so far that bad boy runs everything on my property.

The generator can probably handle that Iota, there's really only one way to find out... try it. One thing for sure: the Iota will use up most of the capacity of that generator... you may not be able to power anything else other than the Iota.

--vtMaps

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

Yes: series connection adds Volts but not Amps, parallel connection adds Amps but not Volts.

The generator issue vtMaps is one of power factor PF: 92 Amps * 12 Volts is 1104 Watts on the DC side, but with a poor PF the draw on the generator can be a lot more than 1104 Watts. In fact it can be around 1400 Watts. If the generator can't supply that it will be overloaded.

I knew the voltage and amperage changed w/ series vs parallelling but I didn't know amp hours changed. Thanks.

In regards to the gen's power output even at the 1400 watt range it's still within the gens limits easily and many times we've ran the gen soley to charge the batts with no other load. Or am I missing something here?

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

The generator can probably handle that Iota, there's really only one way to find out... try it. One thing for sure: the Iota will use up most of the capacity of that generator... you may not be able to power anything else other than the Iota.

--vtMaps

I know those Iotas aren't cheap...any other alternatives? I want quality of course. (Buy nice or buy twice! Right?)

vtmaps

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

I knew the voltage and amperage changed w/ series vs parallelling but I didn't know amp hours changed. Thanks.

In regards to the gen's power output even at the 1400 watt range it's still within the gens limits easily and many times we've ran the gen soley to charge the batts with no other load. Or am I missing something here?

I think you are missing something. You have been charging with a SMALL schumacher charger... not much of a load.

Also, the Iota may draw 1400 watts (probably closer to 1250 watts), but the VA may be much higher. Your generator needs to have a watt rating higher than the VA of the Iota.

--vtMaps

vtmaps

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

I know those Iotas aren't cheap...any other alternatives? I want quality of course. (Buy nice or buy twice! Right?)

Actually, the Iotas are cheap. and rugged. But they are not PF corrected and may be a problem with generators. A high quality PF corrected charger will cost three times as much as the Iota.

--vtMaps

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

I think you are missing something. You have been charging with a SMALL schumacher charger... not much of a load.



--vtMaps

You have a point good Sir.

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

And if you're changing to a 24 Volt system spend the money on an inverter-charger; the built-in chargers they have are much better than the stand-alone units in terms of PF and programming for charge profile.

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

Actually, the Iotas are cheap. and rugged. But they are not PF corrected and may be a problem with generators. A high quality PF corrected charger will cost three times as much as the Iota.

--vtMaps

I tell you what...this solar biz is gettin' more and more expensive! Freedom definately costs more than a buck o' five!

vtmaps

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

Also, the Iota may draw 1400 watts (probably closer to 1250 watts), but the VA may be much higher. Your generator needs to have a watt rating higher than the VA of the Iota.

I just looked at the Iota spec sheet... it can draw up to 21.8 amps from your generator (maximum inrush current = 40 amps) and Iota recommends that it be powered from a circuit with a 30 amp circuit breaker. I wouldn't make a bet that your generator can handle that.

--vtMaps

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

And if you're changing to a 24 Volt system spend the money on an inverter-charger; the built-in chargers they have are much better than the stand-alone units in terms of PF and programming for charge profile.

I haven't even began to investigate those combo units or anything at a 24v setting. Care to help me save some time since I am going to swap over to 24v and recommend a good combo to look into??

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

I just looked at the Iota spec sheet... it can draw up to 21.8 amps from your generator (maximum inrush current = 40 amps) and Iota recommends that it be powered from a circuit with a 30 amp circuit breaker. I wouldn't make a bet that your generator can handle that.

--vtMaps

Yup...20 amp breakers. Good call.

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

vtmaps wrote: »

I just looked at the Iota spec sheet... it can draw up to 21.8 amps from your generator (maximum inrush current = 40 amps) and Iota recommends that it be powered from a circuit with a 30 amp circuit breaker. I wouldn't make a bet that your generator can handle that.

--vtMaps

Yep: 21.8 Amps @ 120 Volts is 2616 Watts as far as the generator is concerned. Or in simple terms "ouch".

Off-grid power is very expensive. It's even more expensive if you have to do it twice before getting it right.

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

I haven't even began to investigate those combo units or anything at a 24v setting. Care to help me save some time since I am going to swap over to 24v and recommend a good combo to look into??

How big is the inverter you have now?
Do you need 240 Volts?
Have you got a budget?

Basically the Outback FX series or the Magnum line offer very good inverter-chargers for the money. Have a look at our host's listings: http://www.solar-electric.com/oupooffgrand.html and http://www.solar-electric.com/maensiwainac.html

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

How big is the inverter you have now?
Do you need 240 Volts?
Have you got a budget?

Basically the Outback FX series or the Magnum line offer very good inverter-chargers for the money. Have a look at our host's listings: http://www.solar-electric.com/oupooffgrand.html and http://www.solar-electric.com/maensiwainac.html

I currently have a 2000W nominal inverter. I'd like 240v but I have that on my gen if I need to run my water well to fill my tank for a short period or run the dryer if need be. It's not a deal breaker.

Cariboocoot

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

I currently have a 2000W nominal inverter. I'd like 240v but I have that on my gen if I need to run my water well to fill my tank for a short period or run the dryer if need be. It's not a deal breaker.

There's more than one way to supply 240 VAC, but if you only have a couple of items to run at that Voltage and are happy with using the generator to do that you can skip the 240 Volt inverters and autotransformers.

Outback's built-in charger works better than the Magnum's, as it ramps up from zero current rather than starting out at maximum and adjusting downwards.

I may sound like a broken record but Outback's inverters are functionally superior to the others. They were designed by very smart people (who now run MidNite).

Off-grid Texan

Re: Need help finding a charger to charge an eight battery bank system

Cariboocoot wrote: »

There's more than one way to supply 240 VAC, but if you only have a couple of items to run at that Voltage and are happy with using the generator to do that you can skip the 240 Volt inverters and autotransformers.

Outback's built-in charger works better than the Magnum's, as it ramps up from zero current rather than starting out at maximum and adjusting downwards.

I may sound like a broken record but Outback's inverters are functionally superior to the others. They were designed by very smart people (who now run MidNite).

Cool. I was kinda partial to the Outback (not sure why, maybe the reviews and price) but good to know they run MidNite.) Thanks again for all your help!

Hogan

Re: Need help finding a charger to charge an eight battery bank system

If your inverter is working for you, and your batteries are still in good condition, all you really need is a decent automotive battery charger like the wheeled jobs you can buy at Sears. With a 40a or 50a quick charge, a 2a slow charge and a 200w "start" charge setting, you can get your batteries back in shape.

The best choice is their deluxe wheeled unit, as it has the higher charge voltages and also gives you a 6v setting. Not many choices on these kinds of units anymore, unless you don't mind spending $500 at your parts house. Look for a sale or figure on about $200 for the best wheeled shop charger at Sears.

Charge the battery from your generator. Can split your battery cabling into 2 sets of 4 when you get a holding charge of 12.6 or higher. Might take a couple to several hours when charging all eight at 50a rate. When your charge/spec gravity is at about 90% you can equalize one-half of your eight using the 250a charge function. Once the batteries are highly charged, the charger will not overheat and you can get an hour or more at the highest rate. Might need to do that now and afterwards, every 3-4 months. Lots on this site about when to Equalize...

24v is "better" but, this idea might be all you need to get the most out of the gear you now have and take time to learn more about all the electric principles that go into sizing and making optimum use of your investment.

vtmaps

Re: Need help finding a charger to charge an eight battery bank system

Hogan wrote: »

all you really need is a decent automotive battery charger like the wheeled jobs you can buy at Sears. With a 40a or 50a quick charge, a 2a slow charge and a 200w "start" charge setting, you can get your batteries back in shape.

The best choice is their deluxe wheeled unit, as it has the higher charge voltages

Most automotive battery chargers do NOT have appropriate charge profiles for deep cycle batteries. They may be adequate for bulking up the battery bank, but they do not have high enough (or adjustable) absorb voltages for deep cycle batteries. What is the model number of their deluxe charger with the higher voltages?

Hogan wrote: »

Can split your battery cabling into 2 sets of 4 when you get a holding charge of 12.6 or higher.

What do you mean by "holding" charge? If there is a charge imbalance (measured with DC clamp ammeter), then it is a good idea to charge each 12 volt battery while it is disconnected from the rest of the bank.

Hogan wrote: »

When your charge/spec gravity is at about 90% you can equalize one-half of your eight using the 250a charge function. Once the batteries are highly charged, the charger will not overheat and you can get an hour or more at the highest rate.

This doesn't make sense... usually by the time the batteries are at 90% SOC their charge acceptance is reduced. Equalization is done at a higher voltage than absorb, but NOT at high current. Also, equalization should not be done until the batteries are as fully charged as they can get at normal absorb voltage, and even then equalization should only be done if one or more cells in the battery have not reached 100% SOC as determined by measuring the specific gravity.

--vtMaps

jcheil

Re: Need help finding a charger to charge an eight battery bank system

Off-grid Texan wrote: »

Cool. I was kinda partial to the Outback (not sure why, maybe the reviews and price) but good to know they run MidNite.) Thanks again for all your help!

I just installed an outback VFX3648 this weekend, replacing a stand-alone inverter and an IOTA charger and I gotta say I LOVE IT.
The Iota was great, but with the PF/inrush, it would kill my 3500 generator if anything else was running.

With the Outback, I even set it up to use my little 1400 generator and not once did it trip the generator circuit breaker nor bog down due to overloading.

Wish I had made that investment a year ago when I went from 12v to 24v. Lesson learned.