one battery gone bust

[Surfacesub]

Will be getting some new normal lead acid with proper screw on caps so that I can check and top up juices onto them.

V.

Just a thought does the charger have a different battery type selector? As you may be aware the selection is critical to the characteristics of the battery. To ignore this, yes all batteries will be charged but as to what happens to a battery with the incorrect setting is very much open to conjecture!

VAS, I think you will have difficulty in sourcing a Lead Acid battery. My understanding is that for obvious reasons Lead in batteries is band!

As for being able to top up (distilled water) a new composite design with caps (non gel battery) may also be problematical given the new materials. e.g. what medium does one use for a top up?

 

[gjgm]

Wow!

How well ventilated in the area in which your batteries were charging? It looks to me almost as if you've had a hydrogen explosion. If the batteries were knackered when they were put on charge, they would be venting hydrogen. You only need about 4% in any atmosphere to create a real explosive risk.

Have you any switchy things (relays/contactors) in the vacinity that could have been a source of ignition?



Some chargers I have come across just internal temperature measurement (thermistor on the PCB). This is presumably on the grounds that the charger tends to be close to the batteries, and generally runs slightly hotter than the batteries anyway, so the charge regime can be very crudely adjusted in line with the charger's internal temperature. It's not perfect, but its probably better than no temperature compensation at all.

Someone told me that the temp sensor is not a safety device, but is only used to adjust the power according to air temp (ie hot day/cold day) ?

 

[annageek]

Someone told me that the temp sensor is not a safety device, but is only used to adjust the power according to air temp (ie hot day/cold day) ?

Correct. As the temperature of a battery increases, the voltage that you need to charge at must be decreased. If not, you risk overcharging and putting the battery into thermal runaway. This results in explosive hydrogen gas being vented.

The temperature sensor is really therefore a reliability device rather than a safety device, but its operation does indirectly impinge on safety.

That said, I think some chargers implement a maximum temperature, such that if it is exceeded, charging is stopped completely to avoid. The last thing you want to do to a dangerously hot battery is give it more energy!

On a boat, temperature compensation is more or less vital if the battery is to remain on charge for any period of time.