optimising fridge and battery

[khisanth]

hi all i am new to the whole using my campervan and fridge.

i have a fridge it seema to draw 5v when on. but i have found over a weekend my leisure battery is nearly dead i have a solar panel on the roof but as we generally get a lot of rain and overcast it cant charge my battery as fast as i would like. so what do people do to optimise the fridge ie do you have it on the lowest setting or put freezer packs ib the freezer and put them in the fridge to keep it colder longer. rinse and repeat. any advice be greatly appreciated

[Velocette]

When you say it draws 5V, do you mean the voltage drops to 5V?

First thing, what sort of fridge?

2nd thing, are you using the rear 12V Socket? If it has the standard Mazda wiring it will be too weedy for most fridges and coolboxes, only good for charging phones etc IMO which would account for the big voltage drop.

3rd thing Does your solar panel have a decent regulator?

[khisanth]

its a 12v fridge the voltage drops by approximatly 5v the cabling to the fridge and pms from both battery is a thick 3core wire not all the cables in it are being used 1 is earth 1 is live starter battery 1 is live leisure battery. the solar panel works really well when sunny the regulator looks to be an ok for the panels.

[Muzorewa]

Make sure the LB is fully charged before you go, ideally off the mains, not from the alternator as the mains takes it to a higher voltage than the alternator

Then fill the fridge the night before you go, have it on the mains overnight so you're down to temperature before you start. That should last you easily a couple of days unless the LB is beyond its best. Be economical getting things in & out of the fridge too, when you open the door all that cool air spills straight out - top-loading fridges are much better in that regard.

I'm assuming you have a proper conversion with split-charge relay etc and EHU. Never had to bother with ice packs or anything like that.

[Simon Jones]

Have you got a make/model number for the fridge? An electric cool box will flatten a battery in no time at all, but a compressor fridge should keep going to for a few days. Does it work ok when connected to mains hookup such that the battery is being charged at the same time?

[khisanth]

was was i was doing with EHU 24hours before the trip.

the only reason i mention ice packs is because there is a small freezer section in the fridge and a freezer pack would store the cold a bit better than empty space.

[briwy]

What size is your solar panel?
We could run the fridge, lights, radio etc for ages with the solar panel on our Bongo even with dull weather.
As I understand it you are losing 5v between the battery and the fridge?? I'm amazed that the fridge will even turn on with that low a voltage.

[khisanth]

its an indel cruise model number unknown but looking at the choice of models and comparing it too my fitting instructions it looks like the power consumption is 340 w/24h

[Diplomat]

Does the fridge have a motor in it? If so it could be a compressor fridge or a peltier fridge.

Compressor fridges are usually quite efficient and don't run all the time. Peltier fridges are worse than useless and rely on a semiconductor junction mounted on a heat sink blownb y a fan. If you can see or hear a fan going when you switch on it will be a Peltier.

If it is totally silent it will be an absorbtion fridge. These are quite good but are thirsty on 12 volts. If the voltage drops by 5volts they still work but even more inefficiently and will kill your battery as they use a resistor as the heat source and won't just drop out when the voltage falls.

Do you mean 5 volts or 5 amps? 5 or 6 amps is usually what absorbtion fridges draw (all the time) so they soon eat up your available ampere hours. for simplicity of manufacture they don't include a thermostat in the 12 volt circuit. I use a home brewed external relay unit which samples the state of the mains connector (which is thermostatically controlled) to switch off the 12 volt feed when the friddge is cool enough, thus saving my battery and preventing over cooling and icing, especially while driving.

As others have mentioned, you will get a large voltage drop using cigar lighter sockets. Heavy wiring is needed back to the battery.


frank

[khisanth]

it makes a little bit of a noise barely noticable it does cut in and out as it gets cold enough. but after reading the specs of it online i have no idea on type but it is defiantly hard wired to the battery with thick.3 core cable (mains of a house thickness)

[g8dhe]

It will be one of these http://www.indelwebastomarine.com/Produ ... N_2010.pdf
they all appear to be compressor fridges as they also have Ice compartments.
Normally you will get 2-4 days off a full charged L/B, provided the battery is in good condition.

[Simon Jones]

Sounds to me like the LB is goosed. As soon as you put any load on it, the voltage would drop right down. Where are you measuring the 5v drop? If you get 5v drop at the fridge AND battery ends, then it can only be a faulty battery or it's not being charged by the EHU or split charger. Any decent garage or motor factor should be able to apply a load test meter & tell you if it's knackered.

[khisanth]

i put a new battery on last night the volts did drop very slowly when the fridge was turned on by 0.01 volt at a time but did continue to drop did not wait to see how far it dropped to.

[Dodgey]

Be good to see a photo of your solar panel and regulator - it's not one of mine is it? If so it will easily power a compressor fridge in clear weather.