Battery Bank Sizing

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solarman said:
How old are they and what is the make, I will let you know the equalize interval.
Solarman... our batteries are six months old, manufactured by East Penn and are 105 AH Group 31s. They are identical to the OEM batteries I just replaced. FYI, our Magnum 2812 inverter/converter has programmable settings for different types of batteries, but the equalization settings for type1 and type 2 AGM batteries were disabled at the factory.

Several years ago, when researching whether or not AGMs should be equalized, I found a variety of responses from different manufacturers. East Penn doesn't directly address the issue, and Trojan conspicuously leaves out equalization settings for its AGM batteries. Lifeline says their AGMs can be equalized, but they also say it's problematic, because there's no way to determine how much electrolyte escapes through the valves, no way to replenish the electrolyte if it does and typical equalizing voltages can damage AGMs.

I'll be interested in hearing what you recommend.

Kev
 
GC2's are popular due to cost of amp hours per dollar. Cheaper to buy two 6 volt GC2's than two 12 volt to provide comparable amp hour rating. (Talking true deep cycle, not RV/marine dual purpose)
 
I am intriqued by the used Tesla car battery packs after watching the "Mortons on the Move" video
blog. The battery pack is 24v with a 5.2 kw capacity and only weights 65lbs. Being Li you can
discharge down to 90% if I'm not mistaken without damage to the battery. That would give you 4.5kw
a day to work with. Pricing wasn't bad either at about $1400 plus shipping.
The problem I see is that you have a bunch of other (controls) to install to make its use pratical
and safe. I'm just exploring all of the options right now. You can see the videos on their website
if interested.
 
Side note, I was on briefly on Trojan?s site today and noted they have a version of the T105 specifically designed for solar/renewable energy - the T105RE. They state the RE version has thicker plates.
 
butchiiii said:
The problem I see is that you have a bunch of other (controls) to install to make its use pratical
and safe.


And, as Kevin mentioned above, the temperature restrictions. Like Kevin I could not use lithium as I also travel in areas that are both well above, and well below, the max and min temps required by lithium. And no room to move them inside.
 
Kevin Means said:
Solarman... our batteries are six months old, manufactured by East Penn and are 105 AH Group 31s. They are identical to the OEM batteries I just replaced. FYI, our Magnum 2812 inverter/converter has programmable settings for different types of batteries, but the equalization settings for type1 and type 2 AGM batteries were disabled at the factory.

Several years ago, when researching whether or not AGMs should be equalized, I found a variety of responses from different manufacturers. East Penn doesn't directly address the issue, and Trojan conspicuously leaves out equalization settings for its AGM batteries. Lifeline says their AGMs can be equalized, but they also say it's problematic, because there's no way to determine how much electrolyte escapes through the valves, no way to replenish the electrolyte if it does and typical equalizing voltages can damage AGMs.

I'll be interested in hearing what you recommend.

Kev

Just curious what batteries you had..

there are a few manufacturers who specify equalization for agm,  East Penn is not one of them, so you will not need it.
Trojan is a no also, Concorde/Lifeline have an equalization spec and it is yearly, Yuasa did at one time.. it was to 15.5 volts

so it's a moot point for you..



 
Sun2Retire said:
Side note, I was on briefly on Trojan?s site today and noted they have a version of the T105 specifically designed for solar/renewable energy - the T105RE. They state the RE version has thicker plates.

it's a very good battery. the plates are 300% thicker than a normal SLI battery.
5 year warranty and good cycle life. They do have higher internal resistance.
good choice for serious boon-docker if you have the space.




 
solarman said:
it's a very good battery. the plates are 300% thicker than a normal SLI battery.
5 year warranty and good cycle life. They do have higher internal resistance.
good choice for serious boon-docker if you have the space.


Also close to double what I paid for the Costco (Interstate) GC2 batteries I got in St George UT this year. Ouch!  They'd have to last over 10 years for me to break even.
 
it's a very good battery. the plates are 300% thicker than a normal SLI battery.

But not, I think, 300% thicker than the standard T105 deep cycle. None of the T105 series of batteries would be considered an "SLI" (Starting-Lighting-Ignition) type. They are designed for deep cycling and thus have much thicker plates than an SLI type.

Trojan seems to be secretive about plate thickness and other design specs, but 3rd party reports indicate the vanilla T105 has plates about 0.110 thick. Other brands of 225 AH GC2 batteries run from 0.105-0.115, while the lesser 200-210 AH may be down around 0.090.  A typical automotive SLI battery would be around 0.040, so any decent quality GC2 will be nearly 3x the plate thickness.

You don't have to do a lot of tech research to get a handle on relative plate thickness - just compare battery weight. For a given size battery case, a heavier battery will have more lead, i.e. thicker plates.
 
Frank B said:
Also close to double what I paid for the Costco (Interstate) GC2 batteries I got in St George UT this year. Ouch!  They'd have to last over 10 years for me to break even.

true, they cost more but then the key here is to look at the warranty..

the duracell/interstate el cheapo golf cart battery is a hybrid and not really a true deep cycle, it has less lead in it and therefore will not last
as long as a true deep cycle like the T105RE.  warranty period for T105RE is 5 years pro rated, the Costco is 1 year.

basically, the more lead the better...

also in real world use you will find the Ah capacity of the el cheapo to drop off MUCH faster than the Trojan.


 
Gary RV_Wizard said:
But not, I think, 300% thicker than the standard T105 deep cycle. None of the T105 series of batteries would be considered an "SLI" (Starting-Lighting-Ignition) type. They are designed for deep cycling and thus have much thicker plates than an SLI type.

Trojan seems to be secretive about plate thickness and other design specs, but 3rd party reports indicate the vanilla T105 has plates about 0.110 thick. Other brands of 225 AH GC2 batteries run from 0.105-0.115, while the lesser 200-210 AH may be down around 0.090.  A typical automotive SLI battery would be around 0.040, so any decent quality GC2 will be nearly 3x the plate thickness.

You don't have to do a lot of tech research to get a handle on relative plate thickness - just compare battery weight. For a given size battery case, a heavier battery will have more lead, i.e. thicker plates.

correct, not 300% over it's brother T105, but i never said that.

The 105RE uses their carbon technology and is a little thicker, it helps to reduce sulfation and increase cycle and calendar life.
the trade off is higher internal resistance, but that should not be an issue in a correctly designed system.

 
Solarman:

true, they cost more but then the key here is to look at the warranty..

Yes.  I've never tried to collect on a battery warranty from Trojan, but I have tried from Home Depot on their lithium tool batteries. Too many variables and entirely too much 'wiggle room' for the warrantor.  I would think it would be even more complicated using third party chargers, and trying to prove  you kept the cells topped off with distilled  water or not.

also in real world use you will find the Ah capacity of the el cheapo to drop off MUCH faster than the Trojan.

And that is entirely possible.  But will I get any better performance than I would by replacing the 'el cheapo' batteries with a new set after 3 years?  I typically get 5 to 7 years out of mine before their declining performance bothers me.

I dunno. I do believe in the general principle of you get what you pay for.  And if they were 30% more expensive, then sure.  But almost double?  My jury is still out.  ;D

 
Wow. 

Just when I was thinking that an upgrade to the more expensive AGM batteries would be money well spent. 

Just when I was thought I knew what the ideal maximum battery discharge should be when boon docking. 

Just when I was beginning to think I finally had a pretty good handle on my planned DIY inverter install. 

Just when I was beginning to think I had picked up enough information to do a limited solar install. 

Great thread.  Should be required reading for anyone who has a battery in their RV. 


 
 
garyb1st said:
Wow. 

Just when I was thinking that an upgrade to the more expensive AGM batteries would be money well spent. 

Just when I was thought I knew what the ideal maximum battery discharge should be when boon docking. 

Just when I was beginning to think I finally had a pretty good handle on my planned DIY inverter install. 

Just when I was beginning to think I had picked up enough information to do a limited solar install. 

Great thread.  Should be required reading for anyone who has a battery in their RV. 


Yeah, I too have been humbled by how much I do not know.  ???
 
Gary, my thoughts exactly. I'm also closely following this and a couple other threads.

BTW, we got home Sunday. What a trip!

Tom
 
butchiiii said:
It looks like I stirred up the pot here with my initial question  :) :) :)


Indeed! But I think we're all happy about it. There's a lot to learn in this thread.  We hope that somewhere along the line you will actually get an answer to your initial question!  ;D


Frank.
 
I have to admit that when I was reading through some of Solarman's math, I realized that's it's been awhile since I sat down and ran the numbers on some of these things. Almost every time one of these discussions goes in depth like this, I learn something that helps me improve our setup.

Now, if I can just figure out how to catch trap/apprehend/kill/intimidate/offend the little bas---d mouse that got into our coach, I'll be a happy man. He got into one of my drawers and chewed up two pair of my underwear. Not socks, not T-shirts... underwear. (You'd think that would have done him in.) Smart little jerk. If I don't get him soon, I'm gonna back the RV out of the garage and set fire to it. (The RV) I'll show him! ;)

Kev
 
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