Thread: DBS - 4 sealed smaller batteries? how to?

Hi jsp, first off, those batteries you have are not good for current loads bigger than 10% of each battery’s total A/H capacity, so each battery is only good for use with loads up to 1.8 amps.

As your fridge draws around 5 amps while the compressor is running, ( you need to check the exact current requirement ) so you need to use at least three of those batteries in parallel to keep the current load under the maximum tolerance of each battery.

In your case, just permanently connect all four batteries in parallel and treat all four batteries as if they were just one 72 A/H battery and you can charge this set up off your alternator.

To connect the four batteries in parallel, you only need to hard wire each battery’s positive terminal to the next battery’s positive terminal and so on and then hard wire each battery’s negative terminal to the next battery’s negative terminal.

You then just connect your positive cable coming from your cranking battery to any one of the positive terminals and he same with the negative from your cranking battery.

A word of warning, a 78 A/H battery will power your fridge but it is still only a small battery and as such will not power your fridge for too long, you will need to test to see how long it can power your fridge but you must not let these batteries be discharged below about 11.75 volts or they will be stuffed.

Most of those types of batteries usually have relevant charge and discharge info on the side of the battery.

thanks mate!

Its a CF32UP waeco.

I have been told it only draws around 2 amps running at full pelt? doesn't seem like much!

Its got an 18AH battery built in, and I have learnt it can run the fridge (set to 2 degrees celcius) for about 36 hours in cold weather 16C / car not in the sun, but only for 2 to 3 hours on hot days 35C with the car in the sun.

So no extra fusing required for the multi battery setup apart from the 20A inline fuse I have allready about 6 inches from my cranking battery? Should I put a fuse at the back of the car also on the line from the cranking battery?

I just have a high current relay with a voltage thing so it trips at 13.2 I think it is and goes off at 12.5 but I think I might wire it into the ignition so its off when the ignition is off irrespective - is that a good idea also?

Hi again jps, you do need another fuse or circuit breaker at the rear.

As far as the voltage settings go, they are fine, you don’t need to do anything different.

Originally Posted by jsp

thanks mate!

Its a CF32UP waeco.

I have been told it only draws around 2 amps running at full pelt? doesn't seem like much!

Its got an 18AH battery built in, and I have learnt it can run the fridge (set to 2 degrees celcius) for about 36 hours in cold weather 16C / car not in the sun, but only for 2 to 3 hours on hot days 35C with the car in the sun.

not sure how you you have come about your figures. i'm guessing you are working on 90amh/h total, to get 36hrs run time would mean draining the batteries to next to nothing which would be be too good but in saying that your fridge will cycle on and off and you will not be using your 2amps/h

re: hot weather, the fridge max current draw is 2amp/h therefore it will still run for 36hrs, i am not sure how hot weather will reduce run time, hot weather will reduce the ability for the fridge to maintain temp without moving the thermostat, in this case its a good chance the fridge will not cycle off which will mean a current draw of 2amp/h

other than that you are heading down the right track.....