Problems with Renogy charge controller and AGM battery charging.

foolios · August 2014

I've been using a few batteries; 26ah+35ah+35ah+35ah+55ah = 186ah total in parallel.
And I've experienced two situations where the voltage has reached 15.2v and the batteries start to stink.
This Renogy charge controller has great reviews so I think it's of a good quality. Trying to figure out why it's failing me. That is if 15.2v is far too high for 12v battery charging. As I understand it, the batteries shouldn't hit over 14.6v and that's what the range is for the controller 14.4v or 14.6v, its one of the two.
I've read comments on the web that different capacity batteries are ok to use, not a perfect setup but ok.
Just something I am doing in the meantime as I build up to some more 55ah batteries and remove the smaller capacity batteries from the group.
Could it be a bad charge controller or the difference in capacity of the batteries that are affecting the controller?

Thanks in advance for any info.

westbranch · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

welcome, first you should disconnect he 26 and 55Ah batteries or you will overcharge some and possibly undercharge others.

second, 5 parallel batteries is not a good method. Always only charge batteries with the same Ah rating, recommended max is 3 in parallel.
third, do you have a remote temp sensor, if not and the CC will accept it get one

the smell is probably from a EQ like voltage and it probably is from sulphate on the plates or the H2SO4 is being broken down by the charge voltage...

hth

waynefromnscanada · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

An AGM battery that is "stinking" (gassing) is being damaged by having it's electrolyte "boiled" away and dried out by overcharging / over voltage. That lost electrolyte cannot be replaced, thus the battery is being ruined.
As mentioned, the max number of parallel batteries or parallel battery strings recommended is 3, and even that can be tricky.
Not familiar with your controller, but it sounds like either it's set up for Flooded Batteries and in EQ mode, OR if it has a setting for AGM batteries and is so set, it's defective.
Just now checking the Renogy web site, I see no indication these controllers are adjustable for AGM batteries - - - but it is 4:30 AM so I may not be reading things correctly.
Are all your batteries of the AGM type, or is there a mixture of AGM / Gell / Flooded ?? Any time batteries are wired in parallel, they MUST all be of the same type with the same charging voltage characteristics, and it is HIGHLY recommended they be very close in age, otherwise the newest ones soon degrade to match the condition of the oldest, poorest condition battery/s in the bank.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

This is the controller. I had checked to make sure it works with AGM.
http://www.amazon.com/gp/product/B00BCTLIHC/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
The batteries are only AGM type.
So, possibly only the smallest ah battery was gassing? Would you guess that maybe I only shortened the life on that one, or all four of the lower amp hour batteries than the 55ah.
Darn, I never ran into the rule of 3.
Not sure what to do with these batteries now. I've seen comments about people using 6 golf cart batteries. I guess that's what had me confused.
Does that mean they use two sets of 3 paralleled together?
Is there a way for me to parallel 3 55ah alongside the 3 35ah batteries or will I have to make a whole new configuration of 3? If that's necessary, I will probably discard(recycle) these batteries and upgrade to two much larger amp hour batteries.

Thanks for the information.

AuricTech · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

What is your system intended to do? In order to design a system that meets your needs, you need to define the "mission statement" for your system.

waynefromnscanada · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

Yes, what will your loads be, how many hours at night, how many during daylight?
Your best arrangement will be two, 6 volt batteries in series, OR 6 two volt batteries in one series string. Depending on your loads and needs, you could also use one single 12 volt battery. That way you'll have no parallel strings to cause trouble. Avoid parallel strings if you reasonably can, and if you can't tey not to exceed two parallel strings and never more than 3.
But the best and most trouble free will always be one single series string of batteries big enough for your needs.
Also keep in mind that flooded type batteries are generally the most forgiving of charging errors, are generally considerably cheaper and usually last longer. The downside? You have to keep an eye on electrolyte levels and they do gas off somewhat as they come up to full charge. Sparks around them is a no no. On the other hand, you can check the SG and easily see their state of charge.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

I would like to power about 20 amps @12v of power for about 4 hours each night.
20x12=240 watts an hour, 240x4=960 watts.
I figured that would be about an 80 amphour battery requirement, but at only 50% use, that's gonna be a 160 amphour battery.
But on top of that there's only 75% efficiency, so really I would require more like a 200 amphour battery to do what I desire.
Unless I have this wrong somewhere but this is where I have gotten so far.
My bank was slowly working its way towards that goal until I ran into this unknown problem that recently revealed itself. Something that I thought I understood to not be
an issue until recently told otherwise here.
So, now to fix this with the least amount of monetary loss if possible.
Does this seem in the ballpark?

waynefromnscanada · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

I would like to power about 20 amps @12v of power for about 4 hours each night.
20x12=240 watts an hour, 240x4=960 watts.
I figured that would be about an 80 amphour battery requirement, but at only 50% use, that's gonna be a 160 amphour battery.
But on top of that there's only 75% efficiency, so really I would require more like a 200 amphour battery to do what I desire.
Unless I have this wrong somewhere but this is where I have gotten so far.
My bank was slowly working its way towards that goal until I ran into this unknown problem that recently revealed itself. Something that I thought I understood to not be
an issue until recently told otherwise here.
So, now to fix this with the least amount of monetary loss if possible.
Does this seem in the ballpark?

You're on the right track - - - assuming you have enough sun and panels to totally recharge your battery bank each and every day. If you need to plan for a day, or 2, or 3 without sun, that changes things - - - for the worse financially.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

Do you have a recommendation for two 6v golf batteries?
I am going to do some research now on some new batteries.
Unless someone can come up with a savy way I can salvage what I have...

I forgot to mention I have 4x100 watt Renogy panels.

Thanks for the help thus far.

Edit:
Watching this video: https://www.youtube.com/watch?v=tGNMenyNqwU
and reading the comments has me confused.
If I have 2x12v 200ah batteries, I'll get 400ah
but if I have 2x6v 200ah batteries, I'll have 200ah at 12v?
Is that right? Whoa, that makes the 6v batteries waaay more expensive!

BB. · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

When you add batteries in series, you add voltages:

12 volt @ 200 AH + 12 volt @ 200 AH in series = 24 volts @ 200 AH

If you add batteries in parallel, you add Amp*Hours

12 volt @ 200 AH + 12 volt @ 200 AH in parallel = 12 volts @ 400 AH

The energy stored in either case is the same:

24 volts * 200 AH = 4,800 Watt*Hours
12 volts * 400 AH = 4,800 Watt*Hours

And you can have series/parallel connections... You add the two 6 volt @ 200 AH in series for a 12 volt @200 AH string. Then put two the two 12 volt strings in parallel for 12 volts @ 400 AH (4x 6 volt @ 200 AH batteries).

In general, a 12 volt @ 100 AH battery is about the same price, size, and weight at a 6 volt @ 200 AH battery bank. As they both store the same amount of energy (Watt*Hours).

It is easy to get confused if you only look at AH ratings... AH is only a "partial description" of the battery's capacity... You need to know the voltage too:

AH * Voltage = Watt*Hours

Watt*Hours is the "complete" description of the battery bank's capacity.

Sort of like talking about pumping water... 10 Gallons per Minute is the flow rate--But without knowing the water pressure--You don't know how much energy it will take. I.e., pumping 10 gallons per minute from a lake to a tank may take a few PSI (roughly 2 feet of water lift per PSI--pounds per square inch). However, pumping water from a 500' deep well--A lot more pressure (~250 PSI just to get the water to the top of the well)--And a lot more energy to lift the water that far.

-Bill

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

So if I want ~1000 watts a day for my setup.
1000/12=83ah
83*1.25=~100 amphour with inefficiencies
So I can get away with a 200 amphour battery to do this task while not dipping below the 50% mark for most of the time.
That helps a lot.

Now I know what size battery(12v) or combination of two batteries(6v) to get to fulfill my needs.

Is there any way I can salvage the setup I have or keep it in the battery bank after adding a 12v 200amphour battery? Or am I just better off Craiglisting these puppies?

BB. · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

The 100 AH of load and 2x for 50% maximum is probably "close enough".

Several issues though... Note that your discharge rage is actually C/8 or you would need to find the C₈ discharge rate for your battery.

The 200 AH capacity may be closer to 180 AH (depending on brand/model of battery) when discharged at a "faster rate".

Also--When you are recharging a 50% discharged battery, you need both enough sun+solar panel energy plus enough time (Lead Acid battery have a reducing charging current phase called "absorb" in the solar industry). So, you may take 4 hours to "bulk charge" and another 2-4+ hours to fully recharge the battery bank--Which may not give you enough hour of sun in the day to fully recharge the battery bank (or you may need to increase charging voltage for faster charging--Which can stress a battery too).

If this is occasional use (weekend cabin), then the less than ideal absorb time is recovered during the middle of the week. If full time off grid--You may end up needing more generator time to help with charging and getting >~90% state of charge once or twice a week.

You may want to get "cheap" 6 volt golf cart batteries (2x 6 volt @ 220+ AH) to start with and see how it works out before you get "really nice" expensive batteries. If the golf cart batteries only last you 1-3 years, you are not hurt too badly (they should last 3-5 years in normal service).

I would get rid of the other batteries--Just going to add more confusion/issues.

Not sure Craig's List will allow batteries on their listings (hazardous materials?).

-Bill

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

If anyone can provide a listing to "cheap" 6 volt golf cart batteries (2x 6 volt @ 220+ AH) , I'd appreciate it.
O ya, I should have said, some local listing for pickup.
Thanks for the advice.

I'm wondering since the other batteries are AGM if I couldn't use them in a south facing room with a panel in a bedroom window to supplement some miscellaneous gadget charging.

Photowhit · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

If anyone can provide a listing to "cheap" 6 volt golf cart batteries (2x 6 volt @ 220+ AH) , I'd appreciate it.
O ya, I should have said, some local listing for pickup.

Cheapest tends to be Sam's Club or Costco, around $80 each plus a core, Sam's Club tends to be very liberal with what cores they accept, I used a lawn mower battery as an acceptable core, about 2 years ago. That's the size of your 35 amp AGM. If your in Missouri I have another option that might be cheaper, but since You might live in Belize... Might add where you live to your profile.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

Oh nice! Discount with the core. Great thinking!
Is that price for an AGM battery?

Photowhit · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

No Discount, a core is required, batteries are worth around 30 cents a pound here, golf cart batteries run 60 lbs.

I don't recall seeing an AGM battery at Sam's club. They tend to be more expensive and less forgiving.

If you or a friend, don't have a Sam's club card/membership you might be able to 'arrange' a 1 time purchase without becoming a member. One way around this was to buy a Sam's club gift card at WalMart, and go to Sam's club to redeem it. I think I read about something similar at Costco, sometimes you can get a trail membership also... You can likely find more info by with a Google search.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

Thanks for the info. Great ideas.

vtmaps · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

Thanks for the info. Great ideas.

On your way to pick up the batteries, make sure to buy a digital voltmeter, an hydrometer, a pencil and a logbook, and a jug of distilled water so you can properly commission your new battery bank. Do you have any questions about how to commission a new battery bank?

--vtMaps

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

I've never heard of this commissioning. But seeing as you're mentioning a hydrometer. I'm assuming commissioning must be for flooded, wet batteries? I would love to be able to use those because of the price point, but since the batteries have to go into the garage, I'll have to ante up the extra cost for AGM's.
Unless there's something I am missing?
I am going to sit here with my fingers crossed hoping you are going to blow my mind with some added info.

Maybe I should consider a box vented to the outside? Practical?

Photowhit · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

... but since the batteries have to go into the garage, I'll have to ante up the extra cost for AGM's.
Unless there's something I am missing?

If it's designed to park in, I wouldn't worry about flooded batteries. Hydrogen will pass through most any material (it's a tiny atom) I personally wouldn't bother with a battery box, but a battery box vented to outside would be a tad safer, I don't smoke, but would suggest keeping an open flame out of the immediate area, but with just a couple? batteries your really pretty safe.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

That definitely gets me interested in flooded/wet lead acid batteries again.
The garage is not drywalled, plenty of air gets in through soffits that then go up through the roof. There is a bedroom upstairs but I did add insulation on the garage roof/bedroom floor, still haven't drywalled it yet.
Hmmm... But I think the biggest concern then is, when it freezes out, the batteries are gonna get mighty cold. And from what I've been reading AGM can handle the cold pretty well vs how poorly flooded deal with the cold.
I guess I could take the system offline during the cold months. My small setup isn't really going to do me much good in the winter.
But how do you safely store lead acid batteries? Plus I gotta keep them on trickle charge, eesh, I dunno...

inetdog · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

Photowhit wrote: »

If it's designed to park in, I wouldn't worry about flooded batteries. Hydrogen will pass through most any material (it's a tiny atom) I personally wouldn't bother with a battery box, but a battery box vented to outside would be a tad safer, I don't smoke, but would suggest keeping an open flame out of the immediate area, but with just a couple? batteries your really pretty safe.

FWIW, I would be more concerned about the possibility of a spark from working on the battery bank (or a fuse or breaker activating) igniting gasoline vapors near the floor of the garage than any risk from hydrogen gas.
To avoid that problem there are two simple precautions you can take:
1. Mount the battery bank so that the lowest point in the DC wiring is at least 18" above the floor.
2. Open the garage door and air the place out a few minutes before working on the battery and other wiring.

inetdog · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

That definitely gets me interested in flooded/wet lead acid batteries again.
The garage is not drywalled, plenty of air gets in through soffits that then go up through the roof. There is a bedroom upstairs but I did add insulation on the garage roof/bedroom floor, still haven't drywalled it yet.

If the foam is closed cell, that should help. Recent studies show that carbon monoxide actually diffuses remarkably freely through ordinary drywall. I would be much more concerned about CO than about H₂.

Just be careful that actual acid mist and/or acid spatter from the batteries during vigorous gassing does not hit anything that might be damaged by it. A simple cover will usually take care of this without any need for outside venting.

westbranch · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

If your FLAs are fully charged and hooked up to your CC they will NOT freeze, same chemistry as AGMs....

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

YOU GUYS ROCK!
Showed me how to resolve my concerns AND
AND
AND
Saving me hundreds of dollars to BOOT!!

Thanks so much for the info and help resolving this. I was so upset that I dumped $200 into batteries I can't use and to think I needed to spend another $500.
I will prolly get away with only spending $200 instead.
And maybe I'll still find a use for the 55AH AGM battery in one of my south facing rooms/window upstairs. Thinking of getting a 50 watt panel and hooking it up with the extra charge controller and just using that for charging gadgets in the tv room up there.

Does that sound like a reasonable thing to do? Any concerns there?

waynefromnscanada · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

I think the biggest concern is, when it freezes out, the batteries are gonna get mighty cold.

Mine have been in an outside unheated shed for heading for 13 years. Temps here can and do drop to minus 25C to minus 30C overnight and I've never had any problems. Yes, mine are flooded. Now if you were to let then go dead, that's a whole different thing and the batteries would likely freeze, split their cases. and be ruined.

vtmaps · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

waynefromnscanada wrote: »

Now if you were to let then go dead, that's a whole different thing and the batteries would likely freeze, split their cases. and be ruined.

If you let the batteries go dead, they are ruined whether or not they freeze.

--vtMaps

waynefromnscanada · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

vtmaps wrote: »

If you let the batteries go dead, they are ruined whether or not they freeze.

--vtMaps

Hahaha How true! That's what I get for posting while half asleep - - something it seems I've been doing too much lately.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

No problems with that. I'd rather have a half asleep answer than none at all.

foolios · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

One more question about switching to flooded batteries for the garage.
What if I want to get a hybrid/electric plugin vehicle?
Will that change the scenario for whether I can use the flooded batteries in the garage while that car is charging?
ugh...

ya, i'ma gonna have to vent it out. i think i'll add a 12v fan to the load terminals of the charge controller and place it at an opening i may have to carve out somewhere

AuricTech · August 2014

Re: Problems with Renogy charge controller and AGM battery charging.

foolios wrote: »

One more question about switching to flooded batteries for the garage.
What if I want to get a hybrid/electric plugin vehicle?
Will that change the scenario for whether I can use the flooded batteries in the garage while that car is charging?
ugh...

The best solution, regardless of whether you get a plug-in hybrid or an EV, would be to put the batteries in a battery box and vent the battery box to the outside.

Problems with Renogy charge controller and AGM battery charging.

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