vehicle battery maintenance

[j-top paj]

i got a deep cycle battery in my GU as my aux battery in october last year
and all it has been doing basically is run the fridge.
the last few months i havnt really been driving the trol as much but the fridge is still in there runing.
this afternoon i noticed that the fridge went warm so i looked at the voltage and it was down to 10 something volts.
so i had a look at the battery and the water was down to just above the plates.
i havnt even looked at it since i got it as i didnt think i would need to on a newish battery.

how often should i be topping up the water?
i thought the water would only need replacing if the battery got overcharged or something

[drivesafe]

Hi j-top paj, any wet cell battery will loose water while being used, overcharging will just accelerate the water lose.

Most of us a guilty of not checking the water level in our wet cell batteries but in your case, the level of water is not a problem as the plates are still covered.

What would be a problem is that the battery voltage is so low. Wet cell batteries should never be taken below 11 volts and even when the fridge has an automatic cut of 10.5 volts, as this would normally occur while the fridge is operating and as such, the battery is under load, straight after the cut-out you would see the battery settle back to at least 11 volts.

In your case, the battery is quite obviously way too low.

I would suggest that you get it on a battery charger as quickly as possible and that you adopt a regime of both checking the water level regularly but more importantly, as you leave the fridge running, to have a battery charger connected to the auxiliary battery when ever the vehicle is not used.

Leaving any type of automotive battery at State of Charge ( SoC ) level of less that 75%, which is around 12.35 volts, for any length of time is going to have a detrimental effect on the battery’s ability to to hold a charge and to the battery’s operating life span.

Cheers.

[j-top paj]

yeh the fridge only runs off the aux battery. the starting battery is only there for the car.
i have connected a charger to the battery overnight and i will take it for a drive sometime today.
i think my next aux battery will have to be a sealed one i think.

[drivesafe]

Hi again j-top paj, the info above pretty well relates to any form of battery.

A battery with a terminal voltage reading of 10.5 is dead flat and that’s a NO NO for any type of battery so unless you have another specific reason, you might as well save your money and stick with what you already use.

Cheers.

[j-top paj]

i know not to let the voltage drop that low.
maybe i just need to not be lazy after a weekend away and take the fridge back out