Can you decipher this on my Leisure battery please?

I've been having some (issues) with my LB and I've just taken it out to get the shop to give it a test.

On the Battery:

Platinum Leisure.
Pt No 685L
V - 12v
AH(20h) 75 amps

Does this mean I have a 20amp/hr battery?

 

No its a 75 amp/hour
The 20 hours is the standard test time

 

http://www.dcbattery.com/faq.html

 

Ok, cheers guys. My battery will give 75amps for 20 hours?

If that's so, then I've bought the wrong battery to run a propex and fridge haven't I?

 

The Amp hour rating denotes the amount of energy that can be taken from a battery before the terminal voltage falls below 10.8 volts. This test is usually carried out over a 20 hour period (20 hour rate). Thus a 50 Amp hour battery can be discharged at 2.5 amps for 20 hours before the voltage drops below 10.8 volts (i.e. 20 x 2.5 = 50). With leisure batteries Amp hours is often abbreviated to amps

 

No idea? What rating is your fridge? The propex will be running on gas?

 

No it will give 75amp for one hour

Depends on what fridge you have if its a 2/3 way fridge these take 15amps and should not be run off the battery without the engine running and it will flatten the battery in no time
A propex should run for a weekend as it is not running all the time unless you have the door open and have it running flat out all weekend.

 

A 75amp/hour battery with give 3.75amps for 20hours (75/20=3.75)

 

Ohhhhh Electrikery gives me a headache.

The fridge is a Waeco coolmatic and says 45 Watts

The few times we've tried the propex it's lasted a hour or two and then cuts out with the low voltage warning light on.

The fridge is very quiet so the only way we can tell it's on is by checking the light when we open the door. The light comes on but to be honest it hasn't kept the food very cold at all.

 

A 45 watt Waeco fridge sounds like on of their compressor fridges. They generally only need to run the compressor for about 1/4 of the time in order to maintain the cool temperature.

45 watts is 3.75 amps (45w/12v), so for simplicity round that up to 4amps. Running quarter of the time would be 1 amp, and so 1 amp running on a 75 amp hour battery should in theory let your fridge run for 75 hours.

We have a Waeco compressor fridge and it will normally last a good long weekend away running on the leisure battery. Of course if you run the engine at all it will top the battery up and keep it going even longer...

Hope that helps.

Nick.

 

Just re-read your last message.

If the propex only works for a couple of hours before your battery goes flat, that strongly suggests either a bad battery or that it isn't ever getting charged properly.

The propex only takes a tiny amount of power and so should last for ages.

 

Cheers Nick
Does your fridge keep stuff properly cold?
How about the Propex, surely that should run for more than a couple of hours. It switches on and off ok to maintain a temp but even with the thermostat turned really low it still quits after an hour or maybe two with a low voltage warning.

 

Double post there, The charging system works ok and with the engine running I get 13ish volts at the leisure fuse box input.

 

Yes, our fridge keeps things VERY cold. We've had two different compressor fridges in different vans and they have both been great.

Again the fact that yours isn't getting very cold suggests to me bad battery or it not charging properly.

You can hear compressor fridges (just like one in a kitchen) and although not loud you will hear the compressor cutting in and out.

If the power is low the light will still work but the comprssor will not kick in and so it won't get cold.

Nick.

 

Try putting the fridge on while the engine is running and listening for the compressor noise.

If the charging system is working Ok then definitely sounds like a bad battery that isn't holding it's charge anymore.

 

Cheers Nick, I'm going to get my LB checked at the motorhome place I bought it from but it looks from all the other LB threads that I should be looking for a 110amp/hr low height battery.

Oh, and thanks for doing all the sums for my fridge power.

 

Although 13ish volts sounds a bit low to charge properly to me - woukd expect charging voltage to be nearer 14.

What is the voltage across the main battery when the engine is running? Voltage across the leisure battery with engine running should be the same. I think the van alternators should give anywhere between 13.6 and 14.2 volts - although someone may correct me here...

 

That's a good plan. I'm going to call it "Plan A" and I'll give it a go when I refit the battery.

 

Yeah it is 13.something but I'll check that as well.

 

A 75 battery is the smallest one you can get and a bit small for running that lot
Also make sure you have decent size wires feeding the fridge the instruction book that come with the fridge gives the size wire needed against the length of run