Battery Query

[Moorings]

Having recently bought a 5 year old boat (on the original batteries) I decided to check the electrolyte levels. All were fine and didn't need topping up, except for one of the four 110 Ah leisure batteries. This was extremely dry and took at least 500 ml into one cell alone to get the level above the plates, at which point I suspected a leak and decided not to top up the other cells until I'd consulted the knowledgeable here! However, the area around the battery remained dry and there is no sign of acid damage to the paintwork in the area.

 

So, what might be happening? All the connections are firm, 14.3V is present at all four leisure battery terminals when being charged via the Victron or the alternator, so why is this one battery so dry?

[WotEver]

So, what might be happening? All the connections are firm, 14.3V is present at all four leisure battery terminals when being charged via the Victron or the alternator, so why is this one battery so dry?

Does that battery have the connections to the rest of the boat on it? Is it at one end of the bank?

 

Tony

[Moorings]

Does that battery have the connections to the rest of the boat on it? Is it at one end of the bank?

 

Tony

 

It is indeed at one end of the bank - the one furthest away from the connections to the rest of the boat.

 

Ken.

[WotEver]

... the one furthest away from the connections to the rest of the boat.

Odd - I would have expected it to be the other end.

 

Regardless, your battery wiring is incorrect. At the very least the two connections to the boat should be at diaginal opposites of the bank. The negative connection going to the hull from one battery, and the positive connection going to the isolator from the battery at the other end of the bank.

 

See here for more esoteric solutions, and an explanation as to why yours is wrong.

 

As for the 'dry' battery - top it up and keep your eye on it.

 

Tony

[Moorings]

Odd - I would have expected it to be the other end.

 

Regardless, your battery wiring is incorrect. At the very least the two connections to the boat should be at diaginal opposites of the bank. The negative connection going to the hull from one battery, and the positive connection going to the isolator from the battery at the other end of the bank.

 

See here for more esoteric solutions, and an explanation as to why yours is wrong.

 

As for the 'dry' battery - top it up and keep your eye on it.

 

Tony

 

Thanks for the link. It is indeed wired as per Gibbo's Method 1 in that link and I can now see that it is wrong. What I've also just noticed is that the charging cables are connected to the battery adjacent to the dry one, not to the terminals where the load is taken from. Surely that can't be right? (To clarify, if we have batteries numbered 1 to 4 connected in parallel where 4 is the dry one, then the load to the boat is connected to 1 and the charging cables to 3 if that helps).

 

Ken.

[WotEver]

Surely that can't be right?

No it's not. Folk sometimes think that they'll "share the load around" but Gibbo explains why that's wrong.

 

Your batteries will thank you for correcting it all

 

Cheers,

Tony

[Robin2]

It is indeed at one end of the bank - the one furthest away from the connections to the rest of the boat.

 

Ken.

 

Perhaps it was moved to its present position before you took delivery of the boat?