CTEK Build with factory leisure battery. How much to run a fridge?

[kjellman]

Hello guys!

I've searched a lot on the forum. Maybe I'm bad at searching. I apologize!

I have a factory leisure battery. I also have a new spare 90 Ah AGM battery at home that I am planing to use with Ctek d250se and smartpass, since I also have it at home. Plan is that the 90 AGM battery will power the fridge(alpicool THQ50) and 1-2 USB ports. And that the factory leisure battery will power some USB ports and lights. Will that work? And do you guys know how to hook it all up? Do you have some better ideas?

I want to use the 90 ah AGM with CTEK stuff since I already have it and on a budget.

Does anyone know if this will be enough to camp for 2-3 days?

 

[kjellman]

I have a plan of doing everything trough the starter battery and leaving the factory leisure battery. Wiring the lights and USB from that. And running the frige from the seperate third battery. Or is there any better budget way?

 

[Anakin]

If the separate battery is a typical 90Ah AGM, and you don’t have a smart battery to battery charger (i.e. factory leisure battery setup), then it will only get charged to about 80%. So when you start with a “charged” battery you only have 72Ah available. Guidance is to never discharge AGM batteries to below 50% of capacity, so you have 72-45=27Ah of charge to play with.

A fridge can pull 2A, so 27/2=13.5 hours before the AGM is safely depleted.

I personally wouldn’t pull anything from the starter battery when parked up.

 

[kjellman]

If the separate battery is a typical 90Ah AGM, and you don’t have a smart battery to battery charger (i.e. factory leisure battery setup), then it will only get charged to about 80%. So when you start with a “charged” battery you only have 72Ah available. Guidance is to never discharge AGM batteries to below 50% of capacity, so you have 72-45=27Ah of charge to play with.

A fridge can pull 2A, so 27/2=13.5 hours before the AGM is safely depleted.

I personally wouldn’t pull anything from the starter battery when parked up.

I understand. Maybe the best way is to install the CTEK to the oem second battery and replace that battery with a lithium one? And just use that to power the fridge, lights and USB ports?

Like this: T6.1 factory aux battery split charge relay upgrade & solar panel install.

 

[Anakin]

I understand. Maybe the best way is to install the CTEK to the oem second battery and replace that battery with a lithium one? And just use that to power the fridge, lights and USB ports?

Like this: T6.1 factory aux battery split charge relay upgrade & solar panel install.

That would definitely be much better. You would get a lot more useable capacity as you can charge the lithium to 100% and discharge almost fully.

Another low cost option, for completeness, is to fit an Ablemail trickle charger, that uses the leisure battery to top up the starter battery.

You can then fit solar at a later date if you want full independence from mains electricity.