Beginner needs suggestions

Bobby · May 2011

I live in the boonies and when the grid goes down it is usually a day or three before it comes back.
I have installed a battery back up power system that is about 1 year old that will take care of the necessities for about one day.

I am thinking of adding solar to the backup power that I already have.. I have an old C-Band dish pole to mount the new panels on and would probably try to make it track. I have been thinking of either two or four evergreen 200 watt panels. Any negatives for that brand of panel? I would appreciate suggestions on what would be best brand of panel and charge controller to buy.

If I do add the panels I will try to utilize the power to run the Deep Freeze and Fridge. I think both these together pulls about 400 watts.. probably 14 to 16 hours per day.

My backup power system now consist of.

6 - Energizer GC2 6 volt Golf Cart Batteries wired to give me 12 volts. I believe these are rated at 225 amp hours.

1 – 12 volt input 1000 watt Xantrex sine wave inverter. Used to run refrigerator and freezer, and a couple of lights when power fails.

1 - 3,500 watt 115/230 volt generator. Used when needed to charge battery bank plus run refrigerator and freezer.

1 – Hobart 12 volt charger, output 80 amps at 15 volts. This is an old charger originally used for electric pallet jack. I hope it is ok to recharge these batteries with this. It seems to work ok.

1 – Harbor Freight 45 watt solar kit. Used to just to keep batteries topped off when not in use. This is new. Installed about a month ago. The Harbor freight kit got me to thinking about more solar.

Note: I am not a rich man. I cannot afford to go off grid but I can afford a few panels.
Should I add the panels or use the money to add to my battery bank??

Cariboocoot · May 2011

Re: Beginner needs suggestions

Welcome to the forum. Wished you'd joined up before you started spending money.

For one thing, those HF panels are notoriously inefficient; rarely live up to their rating. I'd have to say that was money not well spent.
I'm kind of amazed you can run your 'frige off a 1 kW inverter, but Xantrex is known for having good surge ratings and good equipment.

Let's narrow the focus a bit and concentrate on what you want to do: add solar charge capability.
You've got three parallel strings of two of the 225 Amp hour 6 Volt batteries. That's 675 Amp hours at 12 Volts. That's a lot. That's about 4 kW hours of battery capacity. Are you sure you need that much?

Here's why I ask: you'll have a bit of an imbalance potential with three parallel battery sets, and the necessary solar to charge that much battery is in the neighbourhood of 1200 Watts. I'm sure you've already seen how expensive panels are. Plus, you'd need a big (aka expensive) charge controller because you'd be looking for more than 60 Amps of peak current.

My suggestions: first, get a hydrometer and check each cell of every battery. That will answer the question of how well they're being charged now. Chances are it's not good without a proper 3 stage charger. Second, get a Kill-A-Watt meter and check the actual power consumption on your essential loads. This will give you some real world numbers to base the battery bank and subsequent panels on. This should cost less than $50 for those two items, and worth every penny.

Remember; if you've got daily recharge potential (panels and generator) you only need to plan for one days consumption. I run the whole cabin off less than 4 kW hours daily.

Bobby · May 2011

Re: Beginner needs suggestions

Thanks for the quick reply. I agree the HF panels are not efficient but they educated me on how all goes together. And they seem to do ok as a trickle charger for the battery bank. I am 73 years old and still getting educated. Thanks

As for the 6 batteries, The original plan was they were just for backup power when the grid was down so I would not have to run the generator at night. I keep them full charged and ready for power outage. The thought to add decent solar panels came later as I was looking for a new project to keep me busy. LOL

I have a hydrometer and I will order a Kill-A-Watt meter tomorrow and start using it as soon as it arrives.

My HF charge controller cuts off at 14.5 volts. How often should I turn on the battery charger and bring the battery voltage up to 15 volts to stir up the electrolyte? Considering now I am not using this battery bank as long as the power is on.

icarus · May 2011

Re: Beginner needs suggestions

I suggest you read the following:

http://www.batteryfaq.org/

http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

These are probably the best information for beginners on these boards.
15 vdc is probably too high a voltge for a FLA battery.

Tony

Cariboocoot · May 2011

Re: Beginner needs suggestions

Now here's where it gets tricky. Trojan actually recommends an Absorb Voltage of 14.8, which is higher than what we usually expect. Interstate likewise has high Voltage charge specs. I don't know what Energizer's specs are. So ... check the Specific Gravity. If that's consistent and the resting (no charge or discharge for at least 3 hours - preferably overnight) Voltage is good you don't do the 15+ Volt Equalization cycle.

Here I'll throw some battery FAQ reading at you: http://www.windsun.com/Batteries/Battery_FAQ.htm

One problem I see with your existing charge set-up is that it likely doesn't do the stage charging; just throw current at the battery to bring the Voltage up. The important missing step is holding that Absorb Voltage for an hour or two (at low current). Deep cycle batteries really need that extra step for longest life.

As for how to spend the money, consider this: to properly charge those batteries would require at least 5% of the Amp hour capacity. That's 32 Amps @ 14.4 Volts = 460 Watts of panel, not including derating factor. A couple of the Evergreens would fall short of this, even at 205 Watts. Unless you could reduce your battery bank capacity. Or you could add enough panel to "maintain" the batteries and recharge with the generator as per usual. This is likely to run $1000. Or you could invest in a good 3-stage battery charger: http://www.solar-electric.com/dls-30.html You'll still have to fire up the gen to make sure it works, but a charger like the Iota can sit there plugged in to grid power and keep the batteries ready for use with little fuss. Just check the water level regularly.

Photowhit · May 2011

Re: Beginner needs suggestions

icarus wrote: »

I suggest you read the following:

http://www.batteryfaq.org/

http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

These are probably the best information for beginners on these boards.

This will help a bunch, Lots of good information.

icarus wrote: »

15 vdc is probably too high a voltge for a FLA battery.

FLA (flooded Lead acid like your 'golf cart' batteries) are the only batteries that should be taken this high, When they are young, they won't need to have an equalizing charge(a delierate over charge to mix electrolite and equalize the SG- specific gravity) as often as when they are older, but 3-4 times a year wouldn't hurt. After a couple years a monthly Equalizing is common, I do it myself. For a couple hours at 30.4V's in a 24 volt system, information will be in the FAQ's.

stephendv · May 2011

Re: Beginner needs suggestions

Cariboocoot wrote: »

As for how to spend the money, consider this: to properly charge those batteries would require at least 5% of the Amp hour capacity. That's 32 Amps @ 14.4 Volts = 460 Watts of panel, not including derating factor.

I don't think the 5% rule necessarily holds true in this case because the OP is not going to be cycling the batteries daily and he has a much longer time available to charge the batts. If he gets a good AC charger then he'd have generator and/or grid available for charging the batteries, so he could probably get away with less solar.
Also since the batteries will only be used in the rare emergency situation there is a lot more time available to recharge them, so panel capacity as low 2-3% of battery capacity would be able to charge those batts. (over a longer period)

In my opinion, first get a good AC charger like the IOTA 'coot suggested, then you could start off with a pair of evergreens and see how well they work in your setup. Then add more panels if necessary at a later date. Remember to choose a charge controller with enough spare capacity to handle extra panels at a later date!

niel · May 2011

Re: Beginner needs suggestions

in the case of trojans even going as low as 5% may be pushing things too far no matter how much time you have to charge the batteries as the electrolyte needs stirred up. if one could occasionally hit it with a high charge rate to stir things then maybe a 5% rate would suffice. going lower than 5% for trojans i would not recommend just because one has more time to charge.

stephendv · May 2011

Re: Beginner needs suggestions

The stirring of the electrolyte only happens after the voltage has reached the gassing point of 2.4V, and by then it's lower than 5% in any case. According to the trojan user guide in the last stage ( > 95% SoC) of absorb the current should be between 1-3%, so as long as the battery spends some time here, it should gas and mix enough.

niel · May 2011

Re: Beginner needs suggestions

we could be splitting hairs on this subject, but i would still not recommend bulk charging at less than 5%. remember that this represents at least 20hrs of charge time and that would be many days when talking solar and that's discounting any potential cloudy times making the charge time too drawn out if much lower in charge rate % and sulfation could easily set in. obviously it cuts back in the absorb stage, but is not good for a bulk stage if that low.

Cariboocoot · May 2011

Re: Beginner needs suggestions

stephendv wrote: »

The stirring of the electrolyte only happens after the voltage has reached the gassing point of 2.4V, and by then it's lower than 5% in any case. According to the trojan user guide in the last stage ( > 95% SoC) of absorb the current should be between 1-3%, so as long as the battery spends some time here, it should gas and mix enough.

That's what they say.
Real world results, however, may vary.

Continual low charge rates on deep cycles shortens their life. They don't like to exist in a perpetual state of Float; they like to be discharged and recharged at least occasionally. They do like good, strong, fast recharging. They also start to bubble the minute the current gets strong, not at any "ideal" Voltage point. And they seem to prefer charging from solar rather than from a charger. My guess is this is due to the difference in applied current: the solar brings the current up over time then tapers off again whereas a charger hits them with full Amps to begin with and then declines. I suspect the solar charging produces less internal heat over-all.

Just my experience. Anyone and everyone is free to disagree and do whatever you like with your batteries. Mine are fine managed my way. :cool:

stephendv · May 2011

Re: Beginner needs suggestions

Maybe we are splitting hairs. Keep in mind that the OP already has a battery based system working fine without any solar because it's purely a backup system, that's hardly ever discharged. IMO any amount of solar will be better than the current setup.

'coot, I've watched my own bats during bulk charging, when throwing 60A at them from the generator at the start of charge, I can see the odd bubble every now and then, but after it's been in absorb for an hour or so the current is reduced to only about 20A (2% of C20) and there was a lot more bubbling going on!
This agrees with the principal of an EQ charge to cause excessive gassing: i.e. it's a charge with a high voltage. Not a charge with a high current.

Bobby · May 2011

Re: Beginner needs suggestions

Well Thanks everyone for all the discussions on this thread. As I read threw the slightly different opinions it became obvious to me that there is no cut and dried rules to batteries.
I did read the recommended battery documents with interest and learned a lot. Thanks

At this point I would like to tell you how I have handled my battery bank up until now.

In a 3 day power outage I have pulled the battery bank down to about 50% charge then crank the gas generator and turn on the Hobart max 80 amp Charger. It begins at about 60 amps and tapers off as the voltage comes up. I usually leave it on until the battery voltage comes up to about 13.5 to 14 volts. This will carry the fridge threw the night and make coffee in the morning.

After the power comes back on I run the Big Charger until the voltage comes up to about 14.5 to 14.8 volts and shut it down. If the sun shines the Harbor Freight 45 watt panels will maintain the batteries at a max of 14.5 turn off and comes back on at about 13.5
My question here is am I damaging my battery bank by doing this.

I can see the advantages of a 3 stage charger and will probably buy the recommended Iota DLS-30 Would you recommend the IQ4 plug in with it?

But if I decide to put in a couple of solar panels I assume the charge controller will maintain the batteries about the same as the Iota charger as long as the solar is able to bump the 14.5 volt range every few days. Is my thinking right here?

In emergency power situations I would still use the Generator and Hobart charger as above to bring the battery bank back close to full charge. Your opinions appreciated.

Cariboocoot · May 2011

Re: Beginner needs suggestions

Are you damaging the batteries? No. Shortening their potential lifespan a bit.

The Iota DLS-30-M 12 V has the IQ4 built-in. It's a good option as it will keep the batteries charged while the grid is functioning and will recharge from the generator when it's not. The trouble with solar panels is that they only work when the sun shines, which may not be an option if foul weather is what has taken the grid down. Otherwise either would recharge the same way. But the solar panels & controller will cost more for the equivalent charge potential. The more/longer you are without grid power the more solar panels make sense (as opposed to lots of hours on a gen with the mounting costs of gasoline and maintenance).

Beginner needs suggestions

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