How fast will this kill my battery??

[Micro469]

just picked up a small theroelectric fridge..1.7 C.F.. It's 115 volt, .95 Amps and 65 Watts.......My battery is a 115 amp batterry. If I hook these up with a 400 watt inverter between....How long can I expect to run the fridge before the battery dies?

I got the fridge for $10.00....my other idea is a beer cooler in the shed......

I hope someone answers, because my electrical math is non existant.
You might even call me brain dead.......

[jplock]

Micro469
I think a 110 volt \100 watt light bulb hooked to a (12 VDC to 110VAC) invertor pulls about 10 amps so I am guessing a 65 watt load will pull about 6.5 amps. Your 115 amp Hour battery may run up to 17 hours before complete exhaustion. But to be conservative with you battery maybe run it 7 to 8 hours to keep from ruining your battery. Anyone else have an idea on this ?
jplock


PS
I think a bag of ice in a ice chest would be more efficient and cost effective at maybe 2 bucks max! and no run down battery. The invertor idea would be great while traveling, the car alternator could be powering the invertor instead of the battery alone.

[madjack]

just picked up a small theroelectric fridge..1.7 C.F.. It's 115 volt, .95 Amps and 65 Watts.......My battery is a 115 amp batterry. If I hook these up with a 400 watt inverter between....How long can I expect to run the fridge before the battery dies?

I got the fridge for $10.00....my other idea is a beer cooler in the shed......

I hope someone answers, because my electrical math is non existant.
You might even call me brain dead.......

...in this case, there is a 10 to 1 diffrential between AC/DC...so that .95A becomes 9.5A...considering a 100% charge, you have 65 AH to 50% depletion...that's about 6.5-7 hours of run time...
......or......
65W divided by 12=5.5A(almost).....65AH divided by 5.5 = 11.5-12hrs run time.................

...all the above assumes 100% duty cycle on the TE fridge...........
madjack

[jplock]

What Madjack said sounds great to me there seems to be close guesstimates here!
jplock

[Micro469]

so... Is that 6-7 hours.... or 11 -12 hours....

[madjack]

so... Is that 6-7 hours.... or 11 -12 hours....

...YES...either way would kill the battery in less than half-a-day...you gave two different numbers for power draw(.95A/65W)...these 2 numbers did not match each other and the results were the two numbers given as answers...the discrepancies may/could be due to inefficiencies in the inverter itself.....
madjack

[jplock]

These are just guesstimates it may be trial and error for a while. Do you have a digital voltmeter? If you do let the refrig run on the invertor for several hours then check the voltage reading on your battery and compare to the state of charge chart provided on this website. The ratings on your tag may not be exact to what the actual discharge rate. The discharge rate could be different depending on how many times the door is opened or what the outdoor temperature is. The more the compressor runs the faster the battery will be discharged. Also the condition of your battery will affect the run time. See the below link for the chart. I hope this helps!
jplock


http://www.tnttt.com/viewtopic.php?t=11173
Scroll down to the Green Yellow Red chart that is the one I use, it's great.

[madjack]

...my question...does it havvta run off of the inverter or can it be run directly off of the 12vdc system...thereby saving on the inefficiencies of the inverter....

...JP, if it a thermo-electric unit, it has no compressor but rather a Peltier Chip, which is usually, a constant state device with no thermostat(100% duty cycle).........
madjack

[jplock]

I did not know about a Peltier Chip I was assuming it was like a regular refrigerator. Is this some type of RV refrig?
jplock

[madjack]

JP, ALL those 12vdc fridges/coolers you see at WallyWorld and in magazines/ezines which sell for under 100 bucks or so are thermo-electric fridges...they run on a solid state unit known as a Peltier Chip...a voltage run thru one of these chips will produce a cool side and a hot side...by using heat/cool exchangers, temps in an ice box can be controlled upto 40*s of ambient...

...a true 12vdc compressor fridge will start around 500+bucks for a ice chest sized unit and go up quickly from there...
...an RV, 3-way fridge which use a heat source(12vdc/120vac/propane) to run an ammonia based system start around 400 bucks for a cooler sized unit and go up in price very quickly as well...
...both of the latter are WAYYYYYY more efficient than the thermo-electric units........
madjack

[doug hodder]

John...while I know absolutely nothing about this type of unit, I still operate out of a cooler, I'd think it would be a good idea to plug it in and see if it cools and operates on the 110, you didn't mention if it did. The above numbers assume that it is a good working unit, at 10$ it just might not be. I could be wrong though and maybe you've done that. Doug

[Dean in Eureka, CA]

Take a generator along and as much gas as you need... Won't kill your battery one bit.

[Micro469]

When I got it, it didn't work. Found out the plug was faulty and put a new one on. Now it works...cools down to 40*. When I opened the back, it has an electronics board with all sorts of resistors and other gizmos attached. 115 goes in one side, but I think 12V comes out to power the fans, thermostat and led light. The reaason I say this is the wires are way too thin.......115 would probably fry them in a second..( I think). I suppose I could test that.
40* isn't really cold enough for beer....I just might rip the guts out the back, seal the hole, and get a sealed container of ice and just use it as a cooler......

[SlyTerry]

Just go back to your cpu fans and the block of ice John it really is a cool invention. Beer should float in ice water to be consumed with a gasp of delight anyway. Right

[Micro469]

Just go back to your cpu fans and the block of ice John it really is a cool invention. Beer should float in ice water to be consumed with a gasp of delight anyway. Right

Unfortunately, it leaks. When I got back from ADK, I found the bottom of my mattress was wet, and the only place the water could come from was my ice box. Yeah, I know it rained alot... but the galley was dry, and the wet spot started right behind the icebox......

BTW.. I was rolling past Brighton today, and thought of dropping in.... but you seem to want to keep your batcave location a secret..... sooooo....