Fridge using up battery

kelbal

Hi guys,
I had thought my leisure battery was doing ok, can get 2\3 nights no bother out of it when parked up. However we decided to run the fridge yesterday for a a few hours (after plenty of driving the previous 2 days to top up battery), and this morning the battery seems fairly low. When running the fridge off gas will no hookup, is it heavy on the battery?

Thanks in advance

Yurp it's a battery and charger killer.
It shouldn't use power when in gas operation. Unless you dual power it with gas + electric.
Compressor versions use 2% of the power and are more reliable and controllable.

Absorption fridges are so poor at 12v operation the manufacturer recommends only wiring them from an ignition switched feed.
They're just as poor at gas and mains operation but these sources are more abundant so people don't notice.

I turned on my compressor fridge last July...haven't faddled with it since. It's still on, running like a fridge should.

kelbal

Sir Liamalot wrote: »

Yurp it's a battery and charger killer.
It shouldn't use power when in gas operation. Unless you dual power it with gas + electric.
Compressor versions use 2% of the power and are more reliable and controllable.

Absorption fridges are so poor at 12v operation the manufacturer recommends only wiring them from an ignition switched feed.
They're just as poor at gas and mains operation but these sources are more abundant so people don't notice.

I turned on my compressor fridge last July...haven't faddled with it since. It's still on, running like a fridge should.

Thanks, can I just check what you mean. Its running off gas though, that's where the led is showing. The other 2 options are mains, and then it runs on the battery symbol but only when engine is running. When running off gas when parked up with no hookup, would it still eat the battery?

It shouldn't.
Maybe your habitation electrics are using more than you expect and/or your alternator isn't replacing as much as you think.

On very poor setups the alternator wiring is so poor and the fridge is discharging the battery while driving.
On average ones it consumes >50% of the charge current available.

Best to have a battery monitor.

kelbal

kelbal wrote: »

Hi guys,
I had thought my leisure battery was doing ok, can get 2\3 nights no bother out of it when parked up. However we decided to run the fridge yesterday for a a few hours (after plenty of driving the previous 2 days to top up battery), and this morning the battery seems fairly low. When running the fridge off gas will no hookup, is it heavy on the battery?

Thanks in advance

Ok, so if the fridge is on while driving, it potentially diverts a whole lot of juice away from recharging the battery, good to know.
Thanks

kelbal

[quote="Sir Liamalot;110032797"

Best to have a battery monitor.[/quote]

So a battery monitor tells you what draw there is on the battery at any given time? Can you recommend one? Thanks again

autumnalcore

kelbal wrote: »

Ok, so if the fridge is on while driving, it potentially diverts a whole lot of juice away from recharging the battery, good to know.
Thanks

Fridge is probably 120w so drawing 9a to 10a from control panel. Cable from alternator to control panel is usually totally undersized so you get a significant voltage drop accross the cable proportional to the current drawn. Voltage drop decimates the charge going to the battery.

niloc1951

When on 12v a small under counter fridge takes apperoximately the same power as one headlight, the large fridge/freezer type take about 170w = about 3 headlights.
The alternator fitted to FIAT Ducatos is usually 120 amp = over 1,400 watts so a fridge is not a significant load.

When on mains or gas the 12v draw is zero except for the ignition spark when on gas and that's only milliamps.

It looks like you need the services of an auto sparks

kelbal

kelbal wrote: »

Ok, so if the fridge is on while driving, it potentially diverts a whole lot of juice away from recharging the battery

That depends on whether you consider <10A a lottov juice. My system maxes out at about 80A to the service battery.

kelbal wrote: »

So a battery monitor tells you what draw there is on the battery at any given time? Can you recommend one?

Charge. Draw and State of Charge.
Here is a good one.


Here is a cheap one.
I have one, it's cheap and janky, plastic wing nut, plastic threads, B+ on a feeble shunt, janky molex connector...:(
I haven't tested the accuracy yet, I'm not expecting a lot. I also don't expect the molex to hold up to vibration...I'm deleting the PCB or it'll lose accuracy when the pins start to waller out the connecting socket.

niloc1951 wrote: »

The alternator fitted to FIAT Ducatos is usually 120 amp = over 1,400 watts so a fridge is not a significant load.

Powering the fridge is a lesser issue to charging a battery at the correct voltage and rate.


What good is a 100hp water pump with a 1/4" pipe outlet?
Why doesn't the 20A split "charge" fuse ever blow?
120A x 14V = 1.6kW however they derate 15% pretty quickly and i'd be very surprised if it produces >40A in normal operation.
What size are the cables coming outtov your Sterling B2B charger?

niloc1951 wrote: »

It looks like you need the services of an auto sparks

Why? Who do you think signed off on that install in the first place?

Auto-sparks are not ELV fitment experts.

niloc1951

Sir Liamalot wrote: »

What size are the cables coming outtov your Sterling B2B charger?

70mm² or thereabouts.

I understand very little of the tech stuff you talk about. All I do know is that in 15 years I've never had a shortage of 12v for my 170w fridge, the beer has always been nice and cold and the frozen food still frozen after a drive.
My pair of leisure batteries have lasted about seven years each (pair) and are worked quite hard with lighting, tv, sat decoder, water pumping, etc.etc., I do mostly off grid.
For when the engine isn't running I have 200watts of solar running through a quality MPPT charge controller with a four-stage charging regime, not a cheapie wannabe.

You fitment is far better than standard Niloc.
You will not get a 120A alternator to produce more than 15A to the service battery (which is good by standards) over the usual 2.5mm² cable.
Big pump + small pipe = low output.

niloc1951

Sir Liamalot wrote: »

You fitment is far better than standard Niloc.
You will not get a 120A alternator to produce more than 15A to the service battery (which is good by standards) over the usual 2.5mm² cable.
Big pump + small pipe = low output.

That's why I have a big pump + bigger pipe = no shortage

Exactly but likely Kelbal has inherited an unmonitored system with a large pump and an anemic convoluted pipe, as has every user who hasn't upgraded their system. This is normal, coach fitters and auto-sparkies are still installing 80s tech for habitation electrics.

Hands up who needs a fuel gauge?
Keep your hands up everyone who has a battery monitor!?


...rummage...

Here 'tis

I'm not promoting Sterling. Their hardware is unreliable and overpriced (personal opinion). You can improve a standard system times 8 with a cable, routing and contactor upgrade (unless you have a "smart" alternator).
Should you want to improve that a further 50% when the time comes and you have oodles of cash by all means then get one, they perform well until they fail, you can do better but difficult to find ones as aggressive....sez the guy who runs one and likes it very much, except I only use mine between November and March.

PS my fridge is 60watts and runs at aboot a 15 times lower duty cycle.

PPS I heart the way Charles derates the competitors' product...tehehe..
Hey Charles! Why does my Sterling 120A battery to battery charger only output 80amps continuous???

"So I don't know how you get 26A down a 20A fuse" said the engineer to the classroom...



EDIT: If you put your glasses on Charles you'll see it's 25A max DC output.

CelticRambler

kelbal wrote: »

However we decided to run the fridge yesterday for a a few hours (after plenty of driving the previous 2 days to top up battery), and this morning the battery seems fairly low.

That sounds suspiciously like the problem I had in recent years, discussed here, where the fault lay in the split charge relay causing the fridge to draw power from the leisure batteries while driving even though there was no 12V supply.

If it is that, keeping the fridge on while driving makes it worse. One of those "easy to diagnose, easy to fix" problems - once you know where to look. I have bought in to the idea of installing a normal fridge ... in the future. Need to save up for additional solar panels, an inverter and a fridge first!

CelticRambler

CelticRambler wrote: »

I have bought in to the idea of installing a normal fridge

Look at it as a free inverter. Normal fridge + inverter = same price as a camper fridge.

The better you insulate it the less solar you need.

CelticRambler

Sir Liamalot wrote: »

Look at it as a free inverter. Normal fridge + inverter = same price as a camper fridge.

Long-term, yes; but it's all new up-front cost vs. a camper fridge paid for a long time ago. In addition, the new fridge-freezer has to be of a certain capacity (150l) and fit between the two existing wardrobes, so limited options for additional insulation. All this at a time when my usage patterns have changed for reasons not entirely outside of my control, but enough to make 12V + gas a cost-effective fuel option for the immediate future.