Want to add battery to UPS to extend run time

I have a Cyberpower 1500 UPS attached to my Harman Advance that will give me 15 minuets run time on the supplied battery( 7 amp hour?). I also have a generator so If I am home I can hook It up If we loose power for an extended period of time. I am trying to cover all the bases and want to extend the run time so If I am away from the house for an hour or two and have a power loss I will be able to get home and run the generator. I have seen 100 amp hour deep cycle batteries that will do the trick for like $300.00. But before I spend that amount of money I am trying to figure If I could hook up an extra lawn tractor battery to do the job. The battery I have is a 12 volt 230 cold crank. For the life of me I cannot figure out how to convert amp hours to cold cranking amps. .Any help with this question will be appreciated.If I ruin the battery by doing this just one time It Is ok as Its an extra. I need about an hour more run time.
Thanks
Jim

 

www.batterystuff.com good site to fill you in on batteries. Let us know what you do.

Gary

 

Thanks Gary
Before I spend $300.00 for a battery I have to know If the tractor battery I have will work even If Its a one shot deal

 

I would do away the Cyberpower UPS or possible to add another 2-4 extra batteries(depending on length of time needed to run) but might run into recharging problems which is dedicated to one or two batteries max! I've built my own but my requirements is for a 24hr or more until I power up the generator. If you can find a Harman UPS and attach a marine deep cycle 27 series would be the cheaper way to go about it.

 

Ivanhoe I don't think It will be cheaper Harman UPS =$90.00 And Battery Is another $90.00
The Tractor battery I have Is free.
I just have to find out how much longer I will be able to run the stove with It attached
I have trouble doing 3rd grade math.
Jim

 

You have to ask yourself how long do you need the UPS on before getting the generator on. Then go from there on the requirements on the UPS system. Presently you have a very short time...

 

According to what I've read, there isn't a way to convert CCA to Amp-hours as CCA are not measured over a specific period of time. If you look at the batteries on this website you will see that there is no formula to convert CCA to AH.. There is a correlation though. So your 230 CCA battery probably has 12-14 Amp-Hours worth of Juice.. If you UPS, which is advertised as having an 8.5 AH battery here, only gives you 15 minutes, then your tractor battery will likely give you only 22-30 minutes more..

 

I live where the temperature goes very low so time is not on my side. The generator is there for long power outages

What I meant to say, cheaper than what I did. I'm no expert on the battery scenerio but length of time is measured on the battery CCA's. I got 2 6volt batteries in series(TROJANS). My inverter is only 600watts but adequate for lights and stove.

 

Stuckinthemuck
That Is exactly what I wanted to know
45 min. is all the time I will need
Jim

 

Show us a pic of the install when you get it done.. Assuming that you're going to hook up that other battery in parallel so the UPS keeps a trickle charge on it? Do you have a box to put that extra battery in just in case something goes wrong with it? Curious what your game plan is? Always less than an hour from the house so if you lose power, you can go back to fire up the generator? Do you have a system that advises you of a loss of power?

I use a diehard 750watt inverter hooked into the old batteries from my GMC. I put them on the charger before a storm and then use 'em for power when the lights go out. Blower on the Buck 81 draws 200 watts regardless of where the rheostat is set.. Not sure of how much time I'd get overall but the backup is to hook the inverter to the truck itself and run it every few hours to recharge the batteries.. This is my low cost solution until I get the cash for a generator.

 

Hi NH Jim,

I think i can help you out on batteries.

Time for battery school, worth a read if you are going to spend money on setups like this:
http://www.solar-electric.com/deep-cycle-battery-faq.html/
http://batteryfaq.org/



Lead Acid batteries are not all the same. There are basically 3 categories:

SLA (starting, lighting, accessories) which is what your tractor batter and the typical car battery is. These are made to produce a lot of amps in short bursts but are not designed to be discharged much at all. They are built up of lead plates that look like sponges and are optimized more for moving a lot of current. regularly running them down will kill them extremely quickly. Generally you dont want to use more than 20% of the capacity of a starting battery before recharging it.

They have two ratings

• CCA is Cold Cranking Amps, which is the number of amps they can supply without dropping under 7 volts at 0 F. This is the measure of how well they can supply the short burst load of a starter motor
• Reserve Capacity is measure in the number of minutes the battery will supply a load of 25 amps at room temperature before dropping under 10.5 volts. If you want to convert RC to Amp Hours use the formula AH = (RC/60) * 25. But note that this is not exact because the actual amp hours you can get out of a battery varies both with load (the slower you discharge the more efficient) and temperature.See pukert effect for details.

Deep Cycle - These are made for long term deep discharge use. They use solid lead plates rather than sponge, cant push the kind of short temp amps a starting battery can but will last a lot longer when deep discharged. 80% is the generally accepted discharge limit for a deep cycle. To size your battery for only occasional use use that 80%.... (Off grid and RV guys who charge daily use a more conservative 50% figure for sizing as this is the most economical tradeoff of capacity vs. replacement interval)


Deep cycle batteries usually list capacity in Amp hours, usually at the 20 hour rate (C/20). They usually have no CCA or RC ratings. Common examples of real deep cycle batteries are golf cart (T105), UPS batteries, PV off grid batteries. Capacities range from the little 3AH units in emergency lights to massive 500-1000Ah batteries used in PV systems, telephone company's and to run forklifts. So for example if its marked 100Ah @ 20 hrs, that means you can pull 5 amps for 20 hours. Note as mentioned above capacity varies with discharge rate so if you put a load of 100 amps on such a battery you will not get the full 100amh hours, maybe 60.

Marine - Your typical boat battery. These are actually a hybrid that are not true deep cycle but are not pure starting battery either. This is what you will actually find labelled as a deep cycle if you go into Walmart, AutoZone, etc. Often has a CCA rating and an RC rating, sometimes an AH rating.


It gets more complex if you consider also the different ways batteries are constructed (flooded wet lead acid, sealed wet lead acid, AGM, gel cells) but for now we'll skip that and just focus on the basics.


----


So having said that, my recommendations to you:


1 - DON'T bother trying to use that lawn tractor battery. Its run time driving your pellet stove will be very, I mean very short (think minutes) as in deep cycle use it probably has less usable capacity than whats in the UPS and used like that you will probably kill it in 50 discharges or less (real deep cycles can go 500-1000 charges).

2- DON'T hook up a lawn tractor battery to the UPS. First off the charger in the UPS doesn't push enough current to charge the extra capacity fully. Secondly the UPSs battery is an AGM, the tractor is a flooded battery, and they have slightly different charging voltages. This is an especially bad idea if the tractor battery is the type with caps to add water as the UPS charger might over voltage it and boil off the electrolyte.

In general trying to use that UPS for what you are doing is not ideal as its made to run computer electronics and setup up for very short run times. The best bet long term if you want serious run time is to get a real deep cycle, a small inverter and a dedicated 12 volt battery charger& maintainer.

Inverter:
To figure out what to get, first off you have to figure out what your load is. looked up the advance manual and the start wattage is 480, run wattage 275. So based on that I would look for an inverter of about 600 watts to handle the start up load. You might be able to get away with a cheap modified sine wave inverter (probably $50 ) but if you want to be extra careful with the control board you can get a true sine wave inverter. Norther tool carries a good selection of inverters.

Battery:
Next to you have to size the battery. Using our run load of 275 watts at 120vac we get 275/120 = 2.3amps. When the inverter converts this to 12 volt it becomes 23 amps, however inverters are only about 80-85% efficient so lets use 27 amps.

Now you want to run for 2 hours. 27amp x 2 hr = 54 Amp-Hour. We dont ever want to run our deep cycle down more than 80% so 54/0.8 = 68 Amp-Hours minimum deep cycle battery capacity. Now again remember that above I mentioned that usable capacity reduces the faster you discharge so a battery that will give you 68Ah over 2 hours is going to be more like 100 when listed in the spec sheet at 20 hours. So guess what your original 100Ah deep cycle battery guess was right!

100Ah should not cost you 300, and I would also strongly suggest using an AGM rather than a flooded battery (dont have to worry about adding water, works in freezing cold, safer indoors with no issues about venting hydrogen when charging). Here is one option that I would recommend at $180. You can search Amazon and maybe find it cheaper locally.

Charger
Next you have to get a charger. Don't just use an auto parts store car battery charger. For best life of this expensive battery you want a good 3 stage charger and maintainer that will keep it full and on a float charge. I like the NOCO Genius line, but they are not cheap. The 7amp NOCO G7200 they make would be enough at $100 if you can live with the fact it would take all night to recharge 100Ah. If that's too slow you can step up to their 26amp model at $250. Expensive for sure but these are a very handy tool and can be used to charge your car battery and have modes to de-sulfate and revive old tired batteries.

Wiring.
One last point... Don't cheap out in cabling. running at close to 30amps continuous you need some fairly heavy gauge wire to connect the inverter to the battery. The DC wire sizing tables suggest 10 gauge, and if you have a long wire run to the battery (say 15 feet or more) maybe even go up to 8.

All in, expect to be around $500 to really do this right and get a setup that works reliably and wont frustrate you. I know that's not cheap, which is why most of us just break down and get a small generator for duties like this. A little bit more money will get you a nice 1000watt inverter generator that will be whisper quiet and run all day on a gallon of gas running a load like that.

 

jharkin's post is spot on....that being said, not everyone has the $ to do it this way.

I say if you've got the battery give it a whirl and parallel it up, any addition of time is better than none.

Now, if it were me and I was doing it on the cheap, I'd go to walmart and buy a marine battery for $125-150 and be done.

 

If it was me I would buy a wood stove and not worry about having power.

Or install a whole house diesel gen set... bought at auction for less than the cost of a deep cycle battery.

 

Thanks Gang for all the replies
Jim

 

Mixing batteries is a no-no! In which I should of brought up to your attention but mistakenly overseen by me, The zombie effect when working the graveyard shifts Jharkin has worthy words to ponder about.

 

Jharkin gives good info.Have seen the battery backup thing beat to death on websites,is not efficient,may help not getting smoke inthe house ina poor installation.Not going to get into the battery thing,I live whee power goes out a lot.Years ago I installed 2 dv35? empire direct vent heaters.If I am not home,they come on(thermostat) but no blower,so the eff. is down,but the cabin stays warm.The more electrical you add to a pellet stove,and then add on a backup/charging system,the more the eff goes away,you have to draw a line somewhere.but if you are looking for total comfort put in NG.

 

Agree with this, but it's geared more towards batteries in series. Picture a 1a fuse in line with a 15a load

 

A little cheaper for the battery:

http://www.batteryclerk.com/store/p...6B7H2dN_nm23u_yL4C6NNrhTH3CcCyEv6YRoCSL7w_wcB

This is the charger/maintainer I use for my storage battery:

http://www.amazon.com/Schumacher-SEM-1562A-CA-Charge-Battery-Maintainer/dp/B0009IBJAS/ref=sr_1_2?s=automotive&ie=UTF8&qid=1413509381&sr=1-2&keywords=battery chargers schumacher