Electrical – Can a house battery share common ground with the starter battery without interference

When a truck battery, most probably 2 open type lead acid batteries,is at the end of it's charging cycle. Meaning completely charged to 2x 14,4 volt then the batterie start to boil thereby relasing water and with that sulphuric acid.

This might be the reason of the corrosion here.

Furthermore only cleaning is not enough. After cleaning the battery poles must be protected with something like vasiline to eliminate the risk that the sulphuric acid vapor can reach the poles. Make sure the poles are in good order and well attached to the poles. Normally the battery poles and connectors are made of lead. If different you are also in for corrosion problems.

Corrosion can also come from a galvanic path between the body of the truck and the poles. This has also to be kept clean. If the old battery has been boiling over due to a faulty alternator regulator the bottom of the housing should also be checked and cleaned if required.

So there are some tasks to be done.

1. Clean the battery poles and protect them
2. Clean the battery housing and maybe place an isolator underneath the batteries.
3. Verify if the alternator indeed supplies a max of 28.8V and not more

Note: If the batteries are 2 x 6 V making 12 V then the above is only 14.4 V

Aswer to a:

The car is not earthed trough the tires. Remember that sometimes someone get a static shock when leaving a car.

Answer to b:

Some people purchase and install a special flexible wire (carbon strap) that lays on the ground removing static charge. You can most probably find it in a car shop.

Answer to c:

Since the current drops to zero everything seems to be ok. So dont worry.