Quick quistions about caravan Battery

[Freaakyy]

Hello guys,

First off, im new. from the Netherlands, so excuse any spelling errors.

I got a quistion about discharge rate of our battery in our caravan. It's a hankook xv24mf 12v 80ah battery.

If im correct, this battery should not be used under 11 volts?

We bought it, charged it and hooked it up. We tried testing it with 2 led strips and a fridge hooked up, at that point it pulls 6 Ampere. The battery dropped from 12.7volt to 10.7.

What i want to know is how much Ampere should i be able to pull before it drops under 11Volts? I tried googling this stuff but coundt find what i wanted to know.

Also im not sure if the battery was fully charged. I think our charger might not fully charge the battery. Could that cause the low voltage when only pulling 6 ampere? Or is this just to much asking from the battery? Also, what is the best way to check if the battery is fully charged?

Thanx for any help!

 

[Woodentop]

It sounds as though your battery charger or power supply is not working when the mains electricity is connected.

A fully charged battery immediately after the mains-powered charge is removed will usually show around 13.6-13.8V. Leave it an hour off load and it will droop and settle at about 13.2V or 2.2V per cell.

In industry a battery is defined as flat at 1.8Vpc or 10.8V across six, but most caravanners consider a battery flat way above that level, usually around 11.5V.

Your fridge should not be connected to the caravan battery as it draws substantial current: run it on mains if available or otherwise use gas.

Someone will come on here and say your battery needs replacing but I would suggest you get it fully charged first, then see how it survives under load. Also make sure it is not low on water.

 

[Freaakyy]

Thanx for your quick response.

What is it the fridge draws to much? Doesnt this directly translate to Amperage? I dont know much about electricity in gerenral but shoundt it just be the case that a battery has a maximum discharge rate? Say like you could pull 10A at one time no mather what is connected to it? (Lights, friedge etc.)

Our fridge is just an camping 12v coolbox thing. I gues this is a fridge that should be able to hook up to a caravan battary?

And we have a battery that is able to deliver 80 Ah, shouldn't that be it's max instead of just pulling 6?

I also just looked up the stats of our charger. Its an ctek mxs 5.0 charger. its capable of charging 110ah battery's. Our battery currently shows 12.58V when not hooked up to anything. I gues this means its like halfway full?

 

[Woodentop]

You need to look at the label on the coolbox to see how much power it is using. Dividing watts by 12 will give you the approximate current (amps.)

If you have an 80Ah battery then in theory if it starts fully charged and your fridge draws 5A (assume 1A for the LED lighting that is switched off for the purposes of this example) you should be able to run it for 80/5=16 hours. In practice it might be only 75-80% of that on a good day.

The charger you have is a so-called smart charger that, having a model number with a 5 in it, suggests its maximum output is 5A. That would mean for a 'flat' battery it would need 80/5=16+20% or about 20 hours to fully charge the battery with nothing else drawing current throughout. Once the battery is charged you can leave the charger connected as it will trickle charge the battery to counteract the self discharge that all batteries suffer.

In terms of demand current, the battery is capable of delivering 100A or even much more depending on its construction, albeit the higher the current drawn the less will be the total capacity. 80Ah is quoted on the basis of a 10 hour discharge rate, i.e (in theory again) 8A for 10 hours.