24 volt battery chargers in 2017?

softdown · February 2017

Another bottomless pit has claimed my off grid soul. 24 volt battery chargers........seems like the price at least doubles when 12 volt changes to 24 volt....for one thing.

Background: Have a 24 volt 1650 lb forklift battery feeding a large chest freezer in a cold (during cold weather) room. Six ~ 180 watt panels supply the energy via two charge controllers. Two panels to the south that kick ass. Four panels to the east that "suffer" from November through February due to 37 degree latitude.

The system...gets...by. I'm sure many are thinking this is under paneled to keep a forklift battery really happy. I'm sure that is true.

Long story short: Looking for an affordable 24 volt charger to help the panels in cloudy weather. The diesel genset can supply over 5000 watts by the way.

Would be doubleplus good if the voltage was adjustable to counter cold weather. In 20F weather, I would think optimal charging voltage would be significantly over 30 volts. This area has very cold winters.

The board has endless pages of posters lamenting somewhat similar problems. Have yet to find the post that says "Viva....I have found ze ideal solution!" It has been closer to "I still don't know what to do."

What about a transformer that can leach off power from my 48 volt system? I am generally over paneled a bit there. I suspect such a transformer would supply about 25 volts, maybe 25.5 volts, though. Not enough.

BB. · February 2017

At least in our area--Electric forklifts seem to go to scrap pretty often when the battery fails. Perhaps you can look around for scrap/scrapping/Craigslist forklifts and ask what is going to happen to the their battery charger.

Your 48 volt issue... An MPPT type battery charger connecting the panel input to your 48 volt bank and the output to the 24 volt volt bank should work fine. Some controllers will have "no problem" with direct connect to 48 volt battery bank (other than the normal fuse/breaker for over current protection)--Other folks have suggested that you put a low resistance power resistor in the positive lead from the battery to protect the switching circuits in the MPPT controller.

In either case, the two systems (48 volt and 24 volt) would share a common ground with the MPPT solar controller connection.

The Xantrex TC2 chargers are not cheap--But very nice:

http://www.xantrex.com/power-products/battery-chargers/truecharge-2-24v.aspx

Or get an Inverter/Charger (Outback, Magnum, etc.) and use that with the genset (if you can justify a new 24 VDC inverter).

-Bill

softdown · February 2017

Its almost as if being an electrician would be a decent background for solar....

I wonder what percentage of regular guys stumbled into solar and did a fantastic job with assembling a real off grid solar system. I suspect the failure stories > success stories. I'm not talking about a little 12 volt cabin system....

BB. · February 2017

Electricians have code experience with 120 vac and higher...

But there are enough electricians that have gotten buffaloed by lower voltage DC current and even things like medium sized shop air compressors/pressure switches/motor contactors--That I would not assume anything.

-Bill

mcgivor · February 2017

All electricans differ due to factors such as schooling, field experience and so on, personally I am an electrican, with most of my experience in the industrial controls and low voltage fields, fire alarms, building automation, access control, and security systems, my training was in railway signaling and telecommunications. Despite this there was still a learning curve adapting, however having low voltage and DC experience made that curve less steep. Some electricans have limited experience, for example house wiring, these skills do not nesesarally translate well to what is needed doing solar, but having some fundemental knowledge would be an asset.

Estragon · February 2017

I'm a regular guy who with no electrical training. I did a ton of reading before getting into solar, and did have a bit of a clue about batteries from my keelboat though. I also spent the first decade of my work life in remote northern locations where there isn't much choice but self-reliance.

My systems likely wouldn't pass an inspection, but in my location they would just give me funny looks if I tried to pull a permit. They work, and maybe more importantly I know how they work. If I had just hired someone to do it, I wouldn't understand all the design tradeoffs as well, and would be stuck when something went wrong.

softdown · February 2017

I live in the second coldest part of the Colorado mountains. Relying on a Big Buddy propane heater for my living area. Another for my bedroom. The average indoor temp during the winter is probably in the low 50's. I kind of hibernate. I'm also a prepper due to unsustainable, short sighted policies in DC. I would do a prepping board but they seem to be full of government Thought Cops that think that all is wonderful. That staggering debt and never ending war is *voila* good!

Solar almost seems like a second language during my winter hibernation. Strange. Sorry if I seem a bit disconnected these days.

mcgivor · February 2017

@softdown, are you suffering from cabin fever by any chance?

softdown · February 2017

Probably a bit. I always go into winter thinking it will be easier this year. By February I am gritting it out.

I try to go on a walk with the dogs several days/week. The snow has become weird. It supports your weight quite often and fails to quite often. Pretty disconcerting on extended hikes. My dogs have been known to injure their legs a little from trying to run through it.

The worst is over. The hibernation is coming to a close.

mvas · February 2017

softdown said:

Long story short: Looking for an affordable 24 volt charger to help the panels in cloudy weather. The diesel genset can supply over 5000 watts by the way.

What do you consider "affordable" ?

Here is one option:

(used) Fork Lift Battery Charger ... 240 Volt AC 1 Phase input, 24 Volt DC @ 120 Amp output = $250 (local pickup only)
http://www.ebay.com/itm/Barrett-Battery-1B12-4520-Industrial-Forklift-Battery-Charger-208-240-/321592945389?hash=item4ae06eeaed:g:7yIAAOSwAL9UbssQ

If delivery is an issue, then ask a local Fork Lift dealer to deliver a used / refurbished battery charger.
I think, at least 100 amps to put a minimum 50% load on the diesel generator.

Raj174 · February 2017

softdown,

NAWS has an Iota 24 volt 15 amp 3 stage charger that will do EQ with the additional AL1 charge control module.
It's 90 bucks plus 20 for the module. It doesn't state EQ voltage so you might want to ask them if it will meet your needs.

https://www.solar-electric.com/catalogsearch/result/?q=SDC1-120-24-15+AL1&_antispam=antispam_160

Rick

softdown · February 2017

Raj174 said:

softdown,

NAWS has an Iota 24 volt 15 amp 3 stage charger that will do EQ with the additional AL1 charge control module.
It's 90 bucks plus 20 for the module. It doesn't state EQ voltage so you might want to ask them if it will meet your needs.

https://www.solar-electric.com/catalogsearch/result/?q=SDC1-120-24-15+AL1&_antispam=antispam_160

Rick

Well I'll be damned. That was perfect in every way. Got to buy it from our host at a hella price and use Paypal for payment!

Thank You!!!

softdown · February 2017

Kind of a slow shipment on the IOTA, they had to order it. Arrived in good shape and needing cables going to the battery. Found a perfect use for those new 8awg battery jumper cables I had. Cut them in half and.....voila.....was in business,

Now I am perplexed as to why the charging voltage is always around 27.15 volts when I check. Second day of use. I unplug it when the sun weakens since 25 amps could drain my main battery bank. 27.15 volts seems way too low. I would prefer to think that IOTA has a reason for maintaining that level right now.

I am using it on a battery bank that is of "D+" quality right now...a few weak cells.

The equalizer mode on the accessory works after seven days in float. That is a separate issue............

littleharbor2 · February 2017

Sounds like a dead cell creating a situation that will never allow the voltage to get to 28.8 or whatever you are looking for.

softdown · February 2017

littleharbor2 said:

Sounds like a dead cell creating a situation that will never allow the voltage to get to 28.8 or whatever you are looking for.

No dead cells but ~three weak cells. I can disconnect from the battery and clamp unto a voltmeter. Still read 27.15 volts.

Still would likely tend to blame the battery. The charger isn't likely going to re-read the situation every few seconds....

Estragon · February 2017

Reading 27.15v unloaded sure sounds like float. Do you have the al1 plugged in? If so, what LED status indication?

softdown · February 2017

Estragon said:

Reading 27.15v unloaded sure sounds like float. Do you have the al1 plugged in? If so, what LED status indication?

Good question.....every time I look it is flashing. I would tend to call it a slow flash. Should be a fast flash for bulking considering the bank reads about 24.4 volts at approx. 15F....based on a few readings.

It is possible that low morning temperatures are having some type of impact.

Hooked it up to a healthy bank. Now it is reading 27.05 volts charging. However the overnight temperature dropped to ~8F. Some people also think that ground temp falls further than air temp.

Edit: The temp has warmed up by ~15F....to ~25. Now charging at 27.15 volts. Sitting in a battery box on the ground, the air temperature will take longer to reflect.

I am starting to suspect this unit...

Estragon · February 2017

Slow flash about 1 flash/sec s/b absorb at 28.4v. Fast flash for bulk is about 2/sec.

IIRC, Iota is not temp compensated. If it was, voltage would comp higher with cold bank, so non-comp absorb charging will be slow. Still, it should be at 28.4 if in absorb. In bulk, trying to get there, it should be fast blinking.

I wonder if some cells were extra low SG and are frozen? Can you measure current?

softdown · February 2017

Estragon said:

Slow flash about 1 flash/sec s/b absorb at 28.4v. Fast flash for bulk is about 2/sec.

IIRC, Iota is not temp compensated. If it was, voltage would comp higher with cold bank, so non-comp absorb charging will be slow. Still, it should be at 28.4 if in absorb. In bulk, trying to get there, it should be fast blinking.

I wonder if some cells were extra low SG and are frozen? Can you measure current?

The worse bank can get a little bit of slush at the top of the weak cells when it is both ignored for awhile and very cold.....like 0F. It is my third string 24 volt battery bank for "what the hell" purposes.

The charger is behaving identically on the healthy bank.....slow blinking at 27.15 volts. I feel like I should give it a couple more days of testing to be fair. Perhaps we will figure out what the problem is....

Our host had an almost half price deal on 24 volt IOTA's. We all know what can mean at times....

Estragon · February 2017

I've had mine get slushy as well. I think as long as they don't freeze hard, it actually slows down the effects of not being fully charged. Mine charged okay from that state though.

The charger may well be faulty, but I doubt host would knowingly sell them faulty. Too much hassle with returns and not worth the reputation risk. Testing for another day or to sounds like a good plan.

Maybe also unplug and reinstall al1, like a cold reboot?

softdown · February 2017

^^^The host had to order from the manufacturer...thats why shipping was slow. Agreed that our host would not knowingly sell such a defect. It gets unplugged in the afternoon and re-plugged in the morning. Sprung for the 25 amp unit....would be a significant overnight battery drain.

I'll reserve further judgement until we have studied the problem more...

Estragon · February 2017

Do you turn off the DC as well? I think my controller thing stays powered when AC is unplugged. Also wondering about the connection to the charger. A phone jack type on mine - sometimes they get crud in the jack.

softdown · February 2017

Estragon said:

Do you turn off the DC as well? I think my controller thing stays powered when AC is unplugged. Also wondering about the connection to the charger. A phone jack type on mine - sometimes they get crud in the jack.

Good point about turning off the DC. Since I have tried a different battery bank, with the same outcome, that would not appear to address the root of the problem.

softdown · March 2017

A fresh start this morning. Initial charging voltage was, again, 27.05 volts which settled into 27.15 volts...again.

Initial wattage was about 450 which settled into 50 after a few hours. Approx numbers are being used....they fluctuate.

Initial voltage available, when turned on initially, was 119 volts. Now back to 121 volts. My power supply is good.

It has never shown any mode but the slow flash of absorption. In spite of deploying a float voltage level.

I am giving it another day or two.....then contacting the seller. This unit is doing a few things wrong:
Max charge voltage is 27.15 volts.
Always claims to be in absorption mode.....blinking slowly.

Estragon · March 2017

Is something likely to change over the next day or two?

softdown · March 2017

Estragon said:

Is something likely to change over the next day or two?

It is somewhat possible that someone will pop in with a bright idea. Pretty sure I have a month to figure this out...

I'll leave it plugged in overnight since it is only snatching 42 watts. After 24 continuous hours, I feel like I have given it a fair chance.

A lot of products get returned that were fine. There is at least a 1 in 500 chance that this one is fine....

Estragon · March 2017

The only thing I can think of to try is to check the connection between the charger and the al1 controller. I remember back in the dialup modem days that crud and corrosion on rj11 were sometimes the culprit in flakey connections, and my techs didn't always think to check for the low tech stuff.

softdown · March 2017

Estragon said:

The only thing I can think of to try is to check the connection between the charger and the al1 controller. I remember back in the dialup modem days that crud and corrosion on rj11 were sometimes the culprit in flakey connections, and my techs didn't always think to check for the low tech stuff.

Yep.....that was it. Bad connection with the al 1. Was charging at 29.5 volts when I shut it down for the day. It is almost 5pm here.

24 volt battery chargers in 2017?

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