Battery in caravan

Submitted: Saturday, May 17, 2003 at 09:00
ThreadID: 4959 Views:2315 Replies:5 FollowUps:7
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I was so disapointed, with the instalation of my batteries in the previous van, that when I ordered our new one, I deleted the requirement.

The new van has now arrived, and the battery when installed will be used to mainly power the Dometc fridge when we are rolling. My understanding is that it will draw 10 amps at 12 volts.

On the tow car, I have a piranha DBE 150S MK2, which previously on a days running, would fully charge the two 80 amp hour deep cycle batteries, in the van. As we only have three 10 watt and two 20 watt globes in the new van, and to also reduce weight, I was going to fit a single 80 amp hour battery in the new one.

I intend to run two heavy wires, from the anderson plug at the rear of the car, and take them direct to the battery. I was going to hook the fridge and lights, through fuse protection direct to the battery.

I was also going to fit a low voltage cut out at 11.6 volts, to protect the battery, if for some reason it discharges that low.

My electrical man, who is going to do the final instalation, has suggested that instead of running the fridge on 12 volts, that it would be better to purchase a inverter, which should come with low voltage protection. This would mean that the fridge during transit would run on 240 volts and at 120 amps, which should give better performance. As a large inverter would not be needed, say 400 amp, the instalation should not be that much more expensive.

He has also suggested that instead of a wet battery, that a Mat/Gel battery would be a better way to go. However I have heard that they do not like being in the same circuit as the wet battery in the car. However my instalation is in series, and maybe this comment only applies when wired in parrel.

Before I plonks down my money, does any one have any feed back.

Thanks

Col Tigwell
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Reply By: Dozer - Saturday, May 17, 2003 at 09:50

Saturday, May 17, 2003 at 09:50
Hi Col
It has been my experiance that the 3 way fridge will keep cold without being connected to power at all if it is chilled down over the previous nite and you are only travelling from town to town.
I run mine on 12volt whilst in transit mainly because i can and it is there,but it makes very little difference putting it on or not unless you are going to travel all day, and then 12 volts only maintains the status quo.( i have a battery in the boot and thick wire to the fridge and car with one of those old 7 pin council steel plugs dedicated to the 12 volt connection between van and car- 3 pins for plus and 4 for neg). I found this to be true after forgetting to put the catch on the fridge one day. 2 hrs later, the fridge was repacked, but the food never got cold again till the gas was out back on :-0
I believe 240 is more efficient and controls better with a thermistat in the system to supply temperature based feedback, but remember, that fridge doesnt like being efficient once it is out of level by one puffteenth of a bubble, even on gas, so its up to you. Give the inverter a go, it may pull 6 amps at 12v to give you your wattage at 240, and you can also run the fume evacuator off it aswell as the 240 lights if you wish.
Just remember safety first with 240. Put an elcb in the system, or use your 240 lead and plug it straight in to the power inlet. (all new vans are reqd to have an elcb std)
Happy times
Andrew Wollongong
AnswerID: 20286

Follow Up By: Autolec - Saturday, May 17, 2003 at 10:30

Saturday, May 17, 2003 at 10:30
Dozer your basic mathematics is seriously flawed "it may pull 6 amps at 12v to give you your wattage at 240"
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FollowupID: 12996

Follow Up By: Dozer - Saturday, May 17, 2003 at 10:40

Saturday, May 17, 2003 at 10:40
Autolec, it was a generalisation seeing as though we dont have the relavent information to do the equasion (like efficiency of the inverter)
Lets agree to disagree and let today be a new day :-)
Andrew
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FollowupID: 12998

Follow Up By: Dozer - Saturday, May 17, 2003 at 11:37

Saturday, May 17, 2003 at 11:37
Sorry Col and Autolec.
After rereading the posts, i think i shouldnt have said 6 amps, and you were correct to point it out Autolec.
The thing is Col,you will need to compare amperage draw of both and then work out if it is worth the extra outlay to have it on the fridge and the extra convenience of lights and fans/radios etc in the camping area.
Remember the parks charge 5-20 dollars a night extra for power depending where you are....that way the inverter will pay for itself over if you leave the van hooked up in the overnight stay bay more than a few times.
I also have an inverter, but it is a power supply aswell. It supplies 240 volts from mains, if power is disconnected, the light doesnt go out! it inverts. When power is restored, depending on battery charge, it recharges the battery for next time. This is not how i use it, but it gets used manually when i camp. It works automatically dependant on battery charge if im at a powered site.
Most inverters are hard mounted to the battery because they draw high current. Mine draws 120 amps at full load of 1000 watts, thats quite efficient. Yours may not be as efficient. 80-90% is the norm with pure sinewave or modified sinewave inverters. My last mod sine wave was a 500 watt, and powered my t/v in camp areas much to the thrill of the back packers:-0
Andrew
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FollowupID: 13000

Reply By: Autolec - Saturday, May 17, 2003 at 10:25

Saturday, May 17, 2003 at 10:25
Herkman maybe you had better find another electrical man.
The performance with the 12vDC versus the 240vAC is identical. The issue with the 12vDC is that normally they are not wired correctly with heavy enough cable. The technical manual for Dometic/Electrolux show performance between the 12vDC and 240vAC to be around 3%. Some models the 12vDC is up to 3% better and on some models the 240vAC is up to 3% better. In the majority of cases they are close to being the same.
The two heavy wires need to be 6mm2 twin sheathed cable. Re-reading your post it appears you already have an Anderson plug fitted to your vehicle. It is essential that it is wired with a minimum of 10mm2 twin cable and preferably 12mm2 twin sheathed cable.
I am not at all fussed on the mat or gel batteries. We prefer to fit the normal wet cell lead acid battery from one of the known quality brand manufacturers. The mat or gel batteries are on average 3 times the price, usually less capacity, larger in physical size and last around the same length of time. You can fit the battery in a transparent food box with lid and vent it to the outside with plastic pipe. If you post an e-mail address I can e-mail you some pictures. All batteries should be fitted in enclosed vented box.

You can get a low voltage cut-out from KMart for $20 that works well if you decide you really need one. Personally I would not bother fitting one. A voltmeter/indoor-outdoor temperature/clock from Jaycar is a better buy. This will allow you to see the battery voltage and you will soon learn to know what capacity is left by the voltage. The thermometer will allow you to run the fridge at the correct temperature and not have it turned up to high or low on gas. On 12vDC with the correct wiring, you may find at times you will need to turn the 12vDC supply off as it gets to cold.
The part number from Jaycar is XC0116

If you are the forgetful type, you can fit a relay in your caravan that energises when the vehicle is started that will bring the fridge on 12vDC into circuit. You can use one of the spare pins in the trailer plug to control the relay. This will prevent you from inadvertently leaving the fridge on 12vDC when you park up.
AnswerID: 20288

Follow Up By: Paul - Saturday, May 17, 2003 at 22:06

Saturday, May 17, 2003 at 22:06
Hi Autolec,

I'm interested in this and would like to see your photo's of your battery and setup, can be emailed to: valentyn@airnet.com.au

Cheers

Paul
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FollowupID: 13022

Follow Up By: philippe - Sunday, May 18, 2003 at 21:56

Sunday, May 18, 2003 at 21:56
autolec,
i'm also interested in the same info. could i trouble you to email the photos & any details to: philippe1@bigpond.com.au

regards

philippe
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FollowupID: 13057

Follow Up By: Paul - Monday, May 19, 2003 at 20:22

Monday, May 19, 2003 at 20:22
Hi Autolec,

I'm interested in this and would like to see your photo's of your battery and setup, can be emailed to: valentyn@airnet.com.au

Cheers

Paul
0
FollowupID: 13112

Reply By: herkman - Saturday, May 17, 2003 at 12:17

Saturday, May 17, 2003 at 12:17
Thank you for your kind help, would appreciate any photos you have

herkman@optusnet.com.au

Regards

Col Tigwell
AnswerID: 20295

Reply By: herkman - Saturday, May 17, 2003 at 16:27

Saturday, May 17, 2003 at 16:27
Got the photos they were a great help.

Your instalation will save me much money, and still give me what I want.

Really appreciate your kind help.

Regards

Col
AnswerID: 20312

Follow Up By: Paul - Monday, May 19, 2003 at 20:21

Monday, May 19, 2003 at 20:21
Hi Herkman,

I'm interested in this setup and would like to have a look at the photos. please forward to valentyn@airnet.com.au

Cheers

Paul

0
FollowupID: 13111

Reply By: strider1532o - Tuesday, May 20, 2003 at 16:22

Tuesday, May 20, 2003 at 16:22
Hi Autolec, could I prevail on your patience and request a copy of your email on the dual battery set up. Thanks and regards, Neal

nmclary@printnet.com.au
AnswerID: 20566

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