nasty smell from batteries

[rockcrawler31]

Hi all

last night i noticed a nasty smell coming from my second batteries in the rear of the cab. sort of like a cross between a dead animal and rotten egg gas (hydrogen sulfide). the batteries were also pretty warm to the touch so i disconnected the earth straps and the smell went away.

first i'll explain the set up i have.

two cranking batteries in the front run all the cars normal wiring and electrical needs.

A fat earth and power cable running to the back of the car to a bus.

off the bus bar come power for the Amplifier, compressor, spotlights (220w of HID goodness ) and a feed for the SC80 Second battery controller

The SC80 feeds two sealed lead acid batteries off which the fridge is powered.

Earths come off the batteries and other loads to a common return line.

I havn't come across this smell before and i've had all sorts of stuff running off the main bus bar at the one time no problems. the batteries have been running the fridge no drama's at all.

So. Any idea what the smell was and what happened? have i cooked the batts? can i reconnect them? or was that just a normal smell of them being charged and discharging gas?

I really really don't want a battery explosion or electrical fire with the combined power of four HD batteries.

[drivesafe]

Hi Rock, what is the exact type of batteries do you have in the rear and how old are they.

It highly unusual to cook rear mounted batteries but you can get a cell failure that will cause all the symptoms you have but are both your batteries running warm?

[jet-6]

Have you tested you alt output lately?

Also could have boiled the top of a cell and the plates are now exposed a little(if its a lead acid type)

[rockcrawler31]

not sure exactly what type. i will have to have a look. as best as i can remember they are sealed lead acid batteries, that are specifically deep cycle and not cranking batts. i know i have 14 or so volts on charge but i don't know what kind of amperage the alt is putting out.

what's the best way to test the rear batts?

[drivesafe]

Hi Rock, don’t worry about the amps as the batteries themselves control how many amps they will draw.

The fact that your rear batteries are playing up and your front batteries are ok points to a specific problem with one or possibly both batteries.

Either one of the batteries could have failed and caused both batteries to stuff up.

Try disconnecting all cables form both batteries and let them sit for a while, say a few hours and then check the voltage of both batteries.

Go chance one will be low and the other will have about 12+ volts.

This will tell you which battery is stuffed.

[barbz]

Also be worthwhile sitting a multimeter on each rear battery separately while you have a load on them and see how much they drop.

[rockcrawler31]

thanks guys

[dillza_69]

have you checked charge voltage? voltage reg may be shagged overvoltage will make them smell like rotten eggs