looking for battery info for new Exeltech inverter

[Bearingman]

Just finally purchased an Exeltech XP1100 12-volt for our Harman pellet stove. We are more interested in info about what kind/size Marine deep cell batteries to get - how many - and how do any of you who have this set-up, charge them? Always slow charge, and if so, how long to charge? We are planning to use it for the pellet stove at home and then possibly duel use it at work for a few of the computers and phone system.
We are still smarting from Sandy when we had no power at all at home and at work for about 10 days.
One more thing - we have a 6.7K grid tied solar system in the backyard. During the day, is there a way to connect a charger (outside) so that we won't have to be continually running the generator? (the solar is about 200 ft from the house)

 

[WoodPorn]

Is your solar strictly a backfeed sys or do yo have battery storage?
You can buy a seperate solar charger for your batt, just make sure you find a good charge regulator for it.
A decent charger will shut down/trickle charge automatically

 

[Bearingman]

No storage on the solar. It just provides power to the house and then back through the grid for what we don't use. The issue of concern is if we had a long outage, how long does it typically take to recharge those deep cell batteries?

 

[WoodPorn]

My deep cycle marine will recharge in 5 or so hours

 

[Bearingman]

What size is that battery? And what size charger? Sorry for the dumb questions but this is all new to us.

 

[WoodPorn]

I believe the battery is a 800ish CCA and the charger is variable rate

 

[briansol]

a grid-tie system is useless when the grid is down. I don't know why people do that set up. IMO, convert that to be a grid or off grid system. That's the best thing you can do for yourself.

 

[Bearingman]

a grid-tie system is useless when the grid is down. I don't know why people do that set up. IMO, convert that to be a grid or off grid system. That's the best thing you can do for yourself.

Because the state paid 60% of the system, that's why! And we would have to change out our inverters to ones that would feed to batteries, we were told.

 

[Bearingman]

I believe the battery is a 800ish CCA and the charger is variable rate

What is a CCA? Can you give me in amps?

 

[briansol]

cca = cold cranking amps.

its a useless measure for storage batteries, really. That's a better figure for regular non deep cycle batteries.

what you care about is Amp/Hours. usually marines are in the 100ah~ ish range but there are some 60's and some huge 200 ah batteries.

 

[Bearingman]

cca = cold cranking amps.

its a useless measure for storage batteries, really. That's a better figure for regular non deep cycle batteries.

what you care about is Amp/Hours. usually marines are in the 100ah~ ish range but there are some 60's and some huge 200 ah batteries.

Okay, I think I'm getting it. Would something like this be appropriate?

(broken link removed to http://www.atbatt.com/product/24124.asp)

 

[briansol]

I don't recommend any regular cell batteries if they will be indoors. Lead acid types need to be vented outside, as charging them emits poisonous gasses. That's why you see those battery boxes with exhausts outside/etc.

For just one or two, its better IMO to get the AGM sealed type. If you're going to keep it outside all the time, it doesn't matter. but you'll get more use life out of a warmer battery (stored in doors in the winter).

ie, this one at 138 ah (similar to the one you posted) is about 100 more.
http://www.wholesalesolar.com/products.folder/battery-folder/concorde.html
its also 6 volt which lets you get 2 in a series/parallel hook up for more amps per volt. using 6v golf cart batteries is pretty common these days. .

 

[Bearingman]

I don't recommend any regular cell batteries if they will be indoors. Lead acid types need to be vented outside, as charging them emits poisonous gasses. That's why you see those battery boxes with exhausts outside/etc.

For just one or two, its better IMO to get the AGM sealed type. If you're going to keep it outside all the time, it doesn't matter. but you'll get more use life out of a warmer battery (stored in doors in the winter).

ie, this one at 138 ah (similar to the one you posted) is about 100 more.
http://www.wholesalesolar.com/products.folder/battery-folder/concorde.html
its also 6 volt which lets you get 2 in a series/parallel hook up for more amps per volt. using 6v golf cart batteries is pretty common these days. .

Okay. This one is $114.88 at SAM's Club.
What do you think of this one?
Duracell® AGM Deep Cycle Marine and RV Battery - Group Size SL34MAGM

• 20 amp hour rate:55
• BCI Group Size:34M
• CA at 32 degrees F:955
• CCA at 0 degrees F:775
• Reserve Capacity:120
• Volts:12

 

[Bearingman]

And then I have another choice -

Duracell® AGM Deep Cycle Marine and RV Battery - Group Size 31DTMAGM
$179.32
Description

Features:
Marine AGM batteries are specially designed for engine starting and the long deep discharges typical of marine applications. The maintenance-free AGM* design immobilizes the electrolyte making them spillproof and leakproof, so they’re safe to use no matter how much your tiny ship (or luxury yacht) gets tossed. They are available in all popular marine sizes with abundant cranking power for quick, easy starting and all the reserve power necessary to keep your auxiliary equipment running strong.

• ONLY AVAILABLE IN AL, CT, DE, FL, GA, IL, IN, KY, MA, MD, ME, MI, MS, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, AND WV

Specifications

• 1 amp hour rate:68.2
• 100 amp hour rate:110
• 20 amp hour rate:105
• 3 amp hour rate:85
• 5 amp hour rate:86
• 6 amp hour rate:87.4
• 8 amp hour rate:90
• BCI Group Size:31
• CCA at 0 degrees F:800
• MCA at 32 degrees F:1000
• Minutes at 15 amps:348
• Minutes at 25 amps:210
• Minutes at 5 amps:1265
• Minutes at 50 amps:87.4
• Minutes at 75 amps:53
• Minutes at 8 amps:706
• Reserve Capacity:200
• Volts:12
• Core Charge may apply

 

[briansol]

The stoves don't use a lot of power, once on. a couple hundred watts. the igniter takes a lot though. sometimes up to 1000 watts. consult your manual.

some of this math is tricky, and i'm probably doing it wrong... someone correct me if so.
but assuming an average of 250 watts at 120 volts is about 2 amps.
when you drop that back to 12v power, it's suddenly 20amps.

so if you have a 100 ah battery, /20 you in theory can get about 5 hours out of it.

But you can't drain a battery to death. if you go below 20-30%, you'll never come back. So you really only have 70 of those 100 ah's to work with So, 3-4 hours of use.
on average. without an igniter running. And that assumes a constant 250 watt load, which will not be the case (augers don't spin constantly) so its probably closer to 4 hours..

If you want to make sure you can make it a full winters' night (14 hours (5pm - 7am) you're going to want at least want 400 ah. and a way to re-charge it in one 8 hour of sun day (it will take a couple good solar panels to do that) or on day 2 you're cold again. If A sandy-like event is the fix case, it's not going to cut it without a several good panels, a quality charge controller, and batteries to hold it all.

And that assumes the sun is out! lol



That seems high to me, but I can't be certain.... I have limited experience with this stuff. I'm looking into it for my next house when I move in a couple years



My ups (in sig) runs my stove for about 45 min to an hour on medium settings. 12 min if the ignition cycle is part of it. it has an 12v 8.5ah battery.
It then takes 8 hours to fully recharge-- plugged into the wall.

going to 100 ah should in theory be about 10 times longer, or 10 hours then, give or take.
but consider the charge time too... if my 8ah takes 8 hours in the wall, what will 100 take from the sun?

 

[briansol]

At the end of the day, get a pure sine UPS like I have and a generator. solar is just super expensive. the pure sine and line convertor will let you run a crappy loud cheap generator through it and not hurt he stove. Plus, for the 90% of power outages that are 5-10 min, you're not interrupted, and after a half hour, you have time to go out back and start up the generator.

 

[Bearingman]

At the end of the day, get a pure sine UPS like I have and a generator. solar is just super expensive. the pure sine and line convertor will let you run a crappy loud cheap generator through it and not hurt he stove. Plus, for the 90% of power outages that are 5-10 min, you're not interrupted, and after a half hour, you have time to go out back and start up the generator.

Now you have me really confused! I was asking about a deep cycle battery for the Exeltech XP 1100 that we just bought. I don't think I need a UPS for this...

 

[jharkin]

For all you ever wanted to know about deep cycle batteries read:

http://www.solar-electric.com/deep-cycle-battery-faq.html
http://batteryfaq.org/


In a nutshell:

• Any battery that lists CCA is a starting (SLI) battery, and not meant for cycle (repeated charge/discharge) use.
• A true deep cycle battery is meant to recharge many times and will have a capacity listed in Amp-hours. usually quoted at a 20 hour discharge rate; or "reserve capacity" quoted in the number of minutes it can supply a steady 25 amps.
• A "marine battery" is actually a hybrid that can do both starting loads and cycle use but is not ideal for either. True deep cycle battery's are of the types you get for golf carts, forklifts and off grid solar
• For any lead acid battery, the faster you discharge it the less capacity you get. So a battery rated at 100Ah @ 20 hours (5a load) might only give you 60Ah total if you double the load to 10amp, and maybe as little as 30-40 if you try to pull 100amps.
• For any lead acid battery, the deeper you discharge it on each cycle the fewer charge cycles you can get out of it. You might get 1000s or recharges if you only use 30%, but use 80% and it might be dead in a hundred cycles. Solar guys like to use 50% as an average discharge as the best balance between life and cost.
• How you charge a battery also affects how long it will last. The best chargers are whats called "3 stage" that do a bulk charge at about 1/10~1/3 the amperage of the 20hr Ah capacity of the battery, then a constant voltage absorption charge to fill, and then a 'float' aka continuous trickle. A good inexpensive brand of 3 stage chargers is NOCO Genius. Cheap auto store chargers only bulk charge and will not fill the battery to 100%.
• Lead acid batteries like to be storied fully charged. If you leave them discharged they sulfate and die. So always recharge right after use. If its a wet cell you also want to leave it on constant trickle, this is less of an issue with AGM.
• the most common battery construction are wet flooded and sealed AGM (fiberglass mats soaked in acid). AGM are twice as expensive but no maintenance, dont loose their charge as fast and eliminate most of the safety concerns.

Running a load from an inverter, with conversion losses figure that for each 1amp AC you will pull 10amps DC. Figure how many hours you need and multiple that by your amps for Ah. Then double that number to figure the size of battery you need to never use more than 50%. You will get a BIG number I bet. Also figure on 6-10 hours to fully recharge a battery and you might need a big expensive charger.

 

[Bearingman]

"so if you have a 100 ah battery, /20 you in theory can get about 5 hours out of it."
Looking at those two SAM's club batteries I posted, I can't tell what they are. The group size 34 says 20 amp hour rate:55
And the group size 31 says

• 1 amp hour rate:68.2
• 100 amp hour rate:110
• 20 amp hour rate:105
• 3 amp hour rate:85
• 5 amp hour rate:86
• 6 amp hour rate:87.4
• 8 amp hour rate:90

How do I find out what the ah of these two batteries are?

 

[briansol]

see the post above yours. draining is not 1:1. different loads will kill a battery faster or slower. There's a distribution around its efficiency range., potentially bi-modal (2 humps). you'll probably draw about 20 amps so the 105 rate is right there where you want to be at/near the rated of 110.

 

[Redbarn]

Surely this thread belongs in the Green Room.
There are people there who know a lot about this stuff.

 

[jharkin]

"so if you have a 100 ah battery, /20 you in theory can get about 5 hours out of it."
Looking at those two SAM's club batteries I posted, I can't tell what they are. The group size 34 says 20 amp hour rate:55
And the group size 31 says

• 1 amp hour rate:68.2
• 100 amp hour rate:110
• 20 amp hour rate:105
• 3 amp hour rate:8585Ah
• 5 amp hour rate:86
• 6 amp hour rate:87.4
• 8 amp hour rate:90

How do I find out what the ah of these two batteries are?

Something is messed up about that spec sheet, I cant make any sense of it. A group 31 battery is usually in the 100Ah (20hour) range. Here is a typical spec sheet for a G31 battery - (broken link removed)

20 hour rate - 5amps (20x5=100Ah)
10hr rate - 9.3A (93Ah)
5hr rate - 17A (85Ah)
1hr rate - 60A (60Ah)

Also notice the cycle life chart - full discharges will give you ~200 recharges, half will give you 500, 1/3 will give you 1200! recharges.


If you are serious about getting a set of batteries with solar charging that can run this load for days you are going to end up spending some real $$. You might find out a small inverter generator is cheaper in the long run. If you do go battery and solar I highly recommend doing a lot of research first, read the entire battery FAQ I posted and also post on the solar forum at Arizona Wind-Sun for some advice from guys who have done this before.

General rules of thumb for solar:
* Figure your max daily Ah usage and double it to size the battery (full off grid setups go even bigger to have a 2-3 day reserve for bad weather but that should be good for an emergency setup)
* Size your solar array for at least 1W of panel per Ah of battery

see the post above yours. draining is not 1:1. different loads will kill a battery faster or slower. There's a distribution around its efficiency range., potentially bi-modal (2 humps).

Its actually a relatively linear relationship, the faster your discharge the lower the efficiency, directly proportional to the internal resistance of the battery. What happens is that

for faster discharges more current gets converted to heat overcoming that resistance. There are formulas to calculate it based on a constant called the Pukert coefficient. Some high end battery manufacturers (Like Crown, Surette, Concord, etc) publish that number.

Because the state paid 60% of the system, that's why! And we would have to change out our inverters to ones that would feed to batteries, we were told.

Its not necessarily that you need different inverters, but you do need a lot of other equipment that adds a lot of cost. These setups rarely get certified for subsidized installs and cost a lot more.

In an off grid system, the panel DC output feeds a charge control that charges the battery, and then the battery is connected to the inverter to feed AC loads.

In a grid tie system they cut a lot of costs out by removing the charge controller and battery and just feed the inverters directly. Since there is no battery they just backfeed the grid to get rid of excess generation. Grid tie systems are designed to shutoff when the power is out because if they didn't they would backfeed a dead grid and possibly injure a lineman just like when some idiot backfeeds with a generator through his dryer outlet with the main breaker on.

To build a grid tie with backup, you would need to take the entire grid tie setup, also add batteries and a charge controller, and an automatic grid disconnect of some sort to decouple from the grid when its down to prevent a backfeed. You might also need control logic to prevent the inverter from draining down the battery when the grid is live. This adds a lot of expense to an already expensive system.