Battery Question

[kevino]

Hello All! New member here. My wife and I recently purchased an 05 Safari 25SS. A couple of the members have already been very helpful via email.

My question....

How long can I expect one 12v deep cycle to last while running the refer? I turned on my refer to pre chill on propane on Wed around 1:30 pm. When I went to the camper on Friday the refer was reading "check" and the battery was nearly dead. The only other 12v appliance running was the LP Gas Detector. Everything else was off. I usually turn the refer on the night before a trip but in this case I wasn't going to be able to make it to the storage lot on Thursday.

Keep in mind that I'm currently only running one deep cycle. The dealer shorted me a battery. I have since purchased a new deep cycle and was reimbursed by the dealer but I haven't hooked it up yet.

Thanks for your input,
Kevin

[john hd]

it depends.

is your fridge a 2 way or a 3 way?

if it is running on propane your battery should last quite a long time. many days if not a week or better.

if you are trying to run it on 12 volt only it could be as short as a couple of hours.

john

[kevino]

My fridge is a two way. I was pre chilling it on propane.

[john hd]

it also depends if your battery was fully charged to start with. has it been a long time since the unit has been on shore power?

john

[kevino]

Thanks John,

That's just it. We camped the previous weekend - hooked up to shore power. And I had to take the camper in for service on Wed - 1 1/2 hours each way. I would think the battery was charging during the 3 hour round trip. I turned on the refer when I parked it on Wed after the 3 hour round trip.

The dealer had to service the hot water heater. I know they did not have the camper hooked up to shore power and relied on 12v to run/test the water heater and they also had a light on inside - for about two hours. Could that have run the batt down considerably?

Kevin

[Toasty's Dad]

hi kevin,

a lot depends on the battery's size and the fridge fan's draw. but in my case, yeah, the fridge can darn near kill my battery in 48 hours. here's how:

a guy named phred has written quite a dissertation on batteries and charging systems. http://www.phrannie.org/phredex.html. while i'm sure many disagree with his assertions, i've found them to quite accurately describe the behavior of my own battery. ymmv.

anyhoo, phred sez that the rated AH of a battery is usually wildly overspecced by the manufacturer, and should be divided by 2. also, at any temp below 80 degrees, the capacity of the battery will fall well short of even that.

so, my 76AH NC-24 battery can likely actually deliver only around 40 AH. my AS-installed fridge fan uses about 1A, and the darned thing runs A LOT, maybe 2/3 of the time. so i'd assume that in 48 hours, the fan might consume 32 AH or even more, and easily nearly kill the battery.

phred also contends that you should draw no more than 50% of the battery's capacity before recharging if you want the battery to have a long life. so, i usually assume i've got about 20 AH to play with, which is a pitiful small amount of juice. therefore when shore power is unavailable....

whenever possible, i just take the stupid vent panels off to maximize ventilation, and unplug the stupid fan. it makes the side of the trailer look stupid, but lets me use my precious juice for more important things like the stereo. .

jon

[Toasty's Dad]

ooops engaged mouth before brain....

phred actually contends "that batteries are only 75-80% of their rated capacity". my own rule, which i misstated as phred's, of dividing by 2 was derived from my real-world testing of my own battery, when temps were in the 30's.

however, the fridge fan is still a killer, that i can accurately say from my own experience.

jon

[john hd]

jon

i would have to agree since there is a fan involved, less than a day would be right in the ball park with one battery.

disconnecting the fan may be an option. however, after speaking with some folks knowledgable about rv fridges in preperation for my fridge rebuild they said that airstreams seem to be tougher on cooling units due to the shape of the roof and the restriction of airflow.

i just ordered a new cooling unit for my excella to the tune of 500+ bucks! i am seriously considering a fan for mine. then again, the old unit made it 15 years with out one and always cooled well.

john

[kevino]

Thanks for the replies - however my fridge does not have a fan.

[Toasty's Dad]

>Thanks for the replies - however my fridge does not have a fan.

hmmph! well in that case, the fridge + propane + a measly little circuit board should draw nearly nothin'.

at this point, i'd be gettin out the ammeter and seeing where that stuff is going! you've gotta be losing somwhere around an amp somewhere. or the battery is just shot, one of the two. i can provide some help there if you wanna check draw and don't know how...

does the batt hold charge when the fridge isn't on and no shore power?

mystified,
jon

[john hd]

Thanks for the replies - however my fridge does not have a fan

yeah that's a puzzler!

i do remember lots of folks having trouble with newer trailers "battery disconnect switch" seems that they really don't disconnect the batteries even though the control panel says it is... i.e. propane detector etc.

that is why i like my old fashioned manual disconnect behind the couch! when it is off, it is off!

john

[lewster]

Originally Posted by Toasty's Dad

hi kevin,

a lot depends on the battery's size and the fridge fan's draw. but in my case, yeah, the fridge can darn near kill my battery in 48 hours. here's how:

a guy named phred has written quite a dissertation on batteries and charging systems. http://www.phrannie.org/phredex.html. while i'm sure many disagree with his assertions, i've found them to quite accurately describe the behavior of my own battery. ymmv.

anyhoo, phred sez that the rated AH of a battery is usually wildly overspecced by the manufacturer, and should be divided by 2. also, at any temp below 80 degrees, the capacity of the battery will fall well short of even that.

so, my 76AH NC-24 battery can likely actually deliver only around 40 AH. my AS-installed fridge fan uses about 1A, and the darned thing runs A LOT, maybe 2/3 of the time. so i'd assume that in 48 hours, the fan might consume 32 AH or even more, and easily nearly kill the battery.

phred also contends that you should draw no more than 50% of the battery's capacity before recharging if you want the battery to have a long life. so, i usually assume i've got about 20 AH to play with, which is a pitiful small amount of juice. therefore when shore power is unavailable....

whenever possible, i just take the stupid vent panels off to maximize ventilation, and unplug the stupid fan. it makes the side of the trailer look stupid, but lets me use my precious juice for more important things like the stereo. .

jon

Jon,

You might try a small solar panel to power that fridge fan. Look on the motor for the amp draw. They CAN'T be that much! One of the MFG's makes a solar fan unit, but who needs to spend $75 for it when a 5 watt panel will probably do the trick anyway (guess on the draw here). Plus, those fans are not really effective anyway! There IS a good design for a fan set-up for the fridge from Snyder's Refrigeration. I have one of these on my CCD but have not had the unit on in the extreme heat yet (that will change in about a week!) I'm looking into the solar option and will let you know what I find.

[Killo1]

Originally Posted by kevino

Thanks for the replies - however my fridge does not have a fan.

Are you sure? It's not actually part of the fridge. Airstream adds it to extend the life of a fridge. It seems very unlikely an 05 doesn't have one.

[kevino]

You're right John...the battery disconnect switch doesn't disconnect everything. The LPG detector still runs with the switch off. I disconnect my negative battery terminal between trips just like I did on my previous campers.

[kevino]

I'm almost positive my refer does not have a fan.

We're talking about a fan that would be mounted somewhere behind the refer correct?

I'll stick my head in that access panel on the side of the trailer and have another look around but I'm pretty sure it doesn't have one.

[Toasty's Dad]

fwiw,

the 16' CCD has two plastic access panels, one at the bottom and top of the fridge, on the outside of the coach. Behind them is all of the fridge "stuff" - tubing, burner, etc.

at the top of all that are tubes surrounded by a dense row of aluminum cooling fins. on one of those fins, AS (poorly) mounted a buttom thermostat, which controls a computer-style fan that sits right behind the vent.

the thermal coupling between the fins and the fan looks to me poor at best. and yeah, the fan draws a full amp. measured it myself.

if you've run the fridge much, i'd think you'd have heard it by now - the fan AS supplies is NOISY as well as inefficient!

i've been and still am looking into improvements, so all suggestions welcome.

jon

[rseagle]

Hi Kevino,

Check out this book. I found it very helpful for managing my battery usage:

http://www.campingworld.com/browse/s...=SRCH&tcode=37

[Killo1]

Originally Posted by kevino

I'm almost positive my refer does not have a fan.

We're talking about a fan that would be mounted somewhere behind the refer correct?

I'll stick my head in that access panel on the side of the trailer and have another look around but I'm pretty sure it doesn't have one.

Yes. There should be 2 access panels. It should be near the top of the refer on the uppermost access panel. (should be near some fins) You can tell Airstream added it by the fit and finish compared to the fridge. Also, on the the inside of the coach you should have a "refer fan" switch.

[jcanavera]

This was a great thread which originated with my unhappiness back in 2002. You might find it worthwhile to read.

Battery life thread.

Regards,

Jack

[lewster]

Originally Posted by Toasty's Dad

fwiw,

the 16' CCD has two plastic access panels, one at the bottom and top of the fridge, on the outside of the coach. Behind them is all of the fridge "stuff" - tubing, burner, etc.

at the top of all that are tubes surrounded by a dense row of aluminum cooling fins. on one of those fins, AS (poorly) mounted a buttom thermostat, which controls a computer-style fan that sits right behind the vent.

the thermal coupling between the fins and the fan looks to me poor at best. and yeah, the fan draws a full amp. measured it myself.

if you've run the fridge much, i'd think you'd have heard it by now - the fan AS supplies is NOISY as well as inefficient!

i've been and still am looking into improvements, so all suggestions welcome.

jon

The fan that is supplied by Airstream is 'supposed' to help the evaporator section (fins) work more efficiently in very hot weather. These fans are a JOKE!! Given the position and the mounting of them, they will do nothin except make noise and run your battery down.

I have installed a unit fron Schnieders RV Refrigeration that really seems to work. It uses a piece of PVC gutter with a very quiet ball bearing fan pointing up at the fins. The unit sticks on to the back of the fridge with industrial stickey tape. It has it's own termostat for on/off and blows the air UP at the fins and OUT the top access door. WAY MORE EFFICIENT!!!

I think that they are $39 plus shipping. I have 3 in stock if anyone needs one .

I'l try to get a shot up in the classifieds tomorrow.