Bad smell and hissing noise from battery

[horizontal kipper]

Driving back from leicester yesterday Gill could smell a bad smell inside the van, me having a bunged up nose at the minute could not really smell it. Today i drove the van 5 miles and when stopped at the lights i could here a hissing sound pulled over and found it to be from the battery compartment under the seat the top of the battery was very hot. Checked the second battery this was hot. Am i right in thinking this could be down to a fault with the alternator voltage regulator? had one pack up before but that just did not charge, i put a new one in and its been ok for the last 6 years until now.I Put a meter on each battery and got readings of 15 volts this did not change with lights, wipers, etc even when at 3,500rpm, i thought that the voltage would be higher at lower revs after start up then decrease to around 13v-14v at around 3,500rpm. I will do most things myself but sparky stuff scares me. Any advice on checking it please.

Thanks

Paul

[pocolow]

Best to get the alternator output checked by an auto electrician, also how old is the battery?

[horizontal kipper]

Both are 74amh bosch silver less than 2 years old.

[pocolow]

Sounds like the batteries are being overcharged hence the acrid smell, have you checked all the wiring for burning or loose connections?

[California Dreamin]

Hiya mate....I had exactly the same thing happen to me a couple of years back, turned out the battery had boiled dry and then after clever clogs topped up the cells the plates shorted internally. Very dangerous mate....all that hydrogen gas and heat.

Now I don't want to lead you up the garden path here so the first thing that struck me with your info was this unusually high voltage reading of 15 volts.....The regulator is set at 14 volts approximately so you should be seeing around 12.6 volts approx with the engine turned off, rising immediately to around 14 volts with the engine running (ignition light off)
Voltage does not decrease with revs it stays pretty constant from just off idle to full rpm. Load (lights/heated rear windscreen/blower) will lower the voltage slightly (from the 14 volts down 0.2/0.3 volts) roughly.

Bad smell is hydrogen gas, and hissing is excess production of that gas (bubbles) heat is over charging or shorting plates..potentially dangerous so be careful dirsconnecting (make sure you allow to cool and properly ventilate the area (you wouldn't want to see an exploding battery)

Take the leisure battery out of the equation first by disconnecting it (remove the positive terminal but keep it away from the body) now carry out the before and after voltage readings on the starter battery (with/without engine running)
If you are getting 15 volts then it's a pretty safe bet the regulator is up the creek.
Just be mindful that all that OVER charging may well have boiled cells dry and or warped battery plates.

Martin

[California Dreamin]

Ah! modern Calcium Silver SEALED batteries.....great until you need to top them up.

Paul...was it just the leisure battery that got hot?

Was also going to add, when mine did the same it melted the split charge relay closed (as in permanently connected the two batteries)

So if just the one battery was HOT? this one could be up the swanny, however, Bosch Silvers carry a minimum 3 year warranty....just be sure you don't mention the circumstances around it's failure (if it has gone).

Martin

[horizontal kipper]

Ok thanks for the replies Pocolow and Martin i will give it a try in the morning. It was the starter battery that was the hottest the one i use as a leisure battery was warm. I did try the a 54 amh bosch silver off the polo in place of the sarter battery but this also got warm within 3 mins on the drive. At least it never happened last weekend driving in Holland.

[California Dreamin]

Ahhh there you go then mate....sounds like the brush pack has gone breasticles up....
About £13.00

Martin

[ghost123uk]

Just to add, don't use / drive it like this = VERY dangerous Like Martin says, an exploding battery is summat you NEVER want to see. They can go off like a bomb and shower every thing in hot Sulphuric acid. People have been blinded / scarred for life etc. Take great care here !

Oh, of lesser importance, any voltage that rises to 15 or over can burn out your stereo, ignition amp, alarm and bulbs etc too.

[1664]

Ah! modern Calcium Silver SEALED batteries.....great until you need to top them up.

Slightly off topic but does anybody know where/if you can still get UNSEALED batteries anymore? I hate these sealed 'maintenance free' (meaning throw away and buy another after only a few years) as I know a properly maintained lead acid battery will last a good 30 years - they use them to power emergency lighting systems in Hotels etc and still use them on ships because of their reliability and longevity.

Wouldn't surprise me if good old 'elf & 'effin safety have poked their tenticles in and decided us lesser mortals can't be trusted to top a battery up

[horizontal kipper]

Ok today i replaced the voltage regulator brush pack then took readings at both batteries with ignition off starter battery now a 54AH off the polo gave a reading of 12.7 v (the boiled 74AH starter one was giving a reading of 13.2 even after being left in the garden overnight, not reconnected it)
The other 74AH i use as the leisure battery gave a reading of 12.5v with ignition off.
Engine running 54 AH starter reading 13.8v and 74AH leisure reading 13.5v

Should i not be getting the same readings from both batteries when the alternator is charging

[300CE]

Paul, just curious to know if your battery light on the dash has been glowing at all and whether it still lights up when you turn the ignition on? I'm sure the chaps will be along shortly with advice on your last post

[horizontal kipper]

Paul, just curious to know if your battery light on the dash has been glowing at all and whether it still lights up when you turn the ignition on? I'm sure the chaps will be along shortly with advice on your last post

Hi, battery light on dash had not been glowing at all. Came on when turned the ignition on but as soon as engine started it went out. It did start glowing before i replaced it the first time on this van 6 years ago

[Oldiebut goodie]

Ah! modern Calcium Silver SEALED batteries.....great until you need to top them up.

Slightly off topic but does anybody know where/if you can still get UNSEALED batteries anymore? I hate these sealed 'maintenance free' (meaning throw away and buy another after only a few years) as I know a properly maintained lead acid battery will last a good 30 years - they use them to power emergency lighting systems in Hotels etc and still use them on ships because of their reliability and longevity.

Wouldn't surprise me if good old 'elf & 'effin safety have poked their tenticles in and decided us lesser mortals can't be trusted to top a battery up

I have had several of these die due to lack of water - I have resurrected one by drilling the top and filling up with water and sticking it on the de-sulphater for a couple of months.
Annoyingly the little green eye always says that they are good - but that is only one cell!

[Oldiebut goodie]

Should i not be getting the same readings from both batteries when the alternator is charging

Differing lengths/resistance of cabling/relay will explain that.