Hi ndiy,where do you connect charger earth lead when battery is on floor in shed ?

For last 50 years I’ve connected leads across battery with no problems.

I assumed connecting charger to chassis was due to electronics in modern cars

Maurice

Many car batteries these days are sealed, so they shouldn't vent hydrogen unless grossly overcharged. So no risk of explosion. I always connect my charger across the battery terminals.

Andrew

I have read all the above posts and note that none mentions this. All connections to the battery or other terminals should be made before switching the charger on. Then there will then be no spark. Explosion is very unlikely as there would need to be a substantial build up of hydrogen and oxygen trapped within a building or shed, garage. That sort of quantity of gases would likely build up after perhaps several hours of charging. However, it would always be best practice not to smoke inside a charging room and avoid sparks, naked flames, just in case…….

Edited By DMB on 12/07/2022 21:09:16

I had an incident when I worked at a motorcycle workshop. I removed a new battery from a Honda 90 which had been sold and put it on charge. There was a large two voltage charger and selected the 6 volt pair and connected and switched it on. Another worker placed a spanner on the same bench which disconnected one of the crocodile clips and caused a spark. I could see a flame travel up the clear plastic tube connected to the battery vent and ran. The battery exploded spraying acid etc over the new bike and other stock. No one was hurt but only just.

David

When I was a teenager in electroplating, we had a duff plating transformer rectifier which was attached to a 6V lead acid battery. The battery cells were about 1 gallon each, not a tiny car battery. I said to Ray, "try shorting the battery", so he did with a 1/4" diameter nickel plated rod out of the drying oven. As he shorted it, I was leaning over him to get a better look ans a cell exploded. All the acid and bits of the plates and separators and the top of the cell just dissapeared, and neither of us had a scratch. We could have been killed, that cell was about 300AH. We hastly concocted a plausible story and got away with it when the boss appeared seconds later.

I have had a healthy respect for batteries ever since.

Yep, I’ve done it safely for 60 years, or so, too. A friend had a battery explode – he was angle grinding the other side of his workshop. The gas from a battery is not just hydrogen. It is water that is electrolysed to hydrogen and oxygen – the perfect proportion for recombining it all back to water.

Charging a battery direct with a decent ctek charger would not really affect any fancy electronics – neither of our cars is like that. I’ve charged literally hundreds of batteries with anything from a trickle charger to a 100A engine starter. 10 starts (or more) on machines, in quick succession was the order of the day at one time. Batteries needed boosting to start the engines, then they were run a while to charge the battery from its generator.

The principle is still the same – that of keeping any sparking well away from the battery.

The sensible ones amongst us do not connect or disconnect the battery charger to the mains until after the leads are connected. Just another KISS principle to follow. The Ctek charger instruction is explicit in this respect. Common sense to those that understand there is a risk – but many are totally oblivious to it.

Even on a ‘modern’ car (both ours are modern but not that new) if the battery needs charging, it needs charging. Full stop.

The adaptive charging will be taken care of when the engine is running. Manufacturers make it difficult for even renewing the battery these days – must go to dealer for them to do it and they make a nice healthy charge for it.

Andrew

According to the technical blurb for my car, the battery management system controls normal charging so that it never charges the battery to more than 80% to leave headroom for regenerative charging. The system does seem to be pretty sophisticated, and, for example, if the battery charge is getting low, or drain is high, it progressively shuts down power consumers so that essential items are kept going as long as possible. It also adapts to allows for battery ageing. One complication is that when the battery is changed the relevant ECU has to be reprogrammed with the details of the new battery or the charging characteristics will be non-optimum. So unless you have the necessary software, a simple battery change turns into an expensive visit to the dealer!

Mike

And I think BMW may hold one of the answers to the original question. My old 5 Series (E39) had a small explosive device on the battery terminal that in the event of a serious accident would sever the battery connection to try to reduce the risk of fire. There were many dire warnings about jump starting and charging in the manual, I think it suggested all these things would be done via the dedicated terminals under the bonnet. The battery was in the rear wing.