Battery charging in situ

[Alakefic]

Hi All 

is there any problem with changing my 3 batteries without disconnecting them?

and is it possible to charge from a neg and pos point inside the control panel? 
from inside the boat 

thanks 

Alakefic

[Jen-in-Wellies]

11 minutes ago, Alakefic said:

is there any problem with changing my 3 batteries without disconnecting them?

None at all. This is normal.

11 minutes ago, Alakefic said:

is it possible to charge from a neg and pos point inside the control panel? 
from inside the boat 

Depends. The thinner the wire and the longer the run, both on the positive and negative wires, the greater the voltage drop and the more risk of the batteries being under charged. In extreme cases, it could overload the wires, but there should be a properly rated fuse in there somewhere I hope. What are you planning to use as the charge source? What current can this supply? How long is the length of the wire run and what cross sectional area are the cables?

Using crocodile clips to connect a charger is frowned on by the boat safety scheme. Too much risk of one becoming detached and causing a short.

[Alakefic]

Hi 

it’s a small smart charger 240v which will run happily off my genset or the hook up point, the battery’s are 1.5 M from the point inside the boat where I can pick up the pos and Neg, both cables are 16 mm tri rated .

[Tony Brooks]

1 hour ago, Jen-in-Wellies said:

None at all. This is normal.

Depends. The thinner the wire and the longer the run, both on the positive and negative wires, the greater the voltage drop and the more risk of the batteries being under charged. In extreme cases, it could overload the wires, but there should be a properly rated fuse in there somewhere I hope. What are you planning to use as the charge source? What current can this supply? How long is the length of the wire run and what cross sectional area are the cables?

Using crocodile clips to connect a charger is frowned on by the boat safety scheme. Too much risk of one becoming detached and causing a short.

 

He siad:

 

1 hour ago, Alakefic said:

 is it possible to charge from a neg and pos point inside the control panel? 

from inside the boat

 

That is far from clear. Does he mean the domestic distribution/fuse/MCB board, or can he get at the back of the engine control panel from inside the boat.

 

That talk of 16 sq mm CCSA cable suggest this is probably the domestic distribution panel and if so the vast majority of modern boats, but not older ones, should have a main fuse in the supply close to the batteries. However, that fuse would be rated to protect the 16 sq mm CCSA cable, not the one from the charger to panel, so perhaps a smaller fuse in the charger cable close to the connection point.

 

If it is the engine control panel, then it would not charge the domestic bank unless a duel sensing VSR is in use.

 

Also, if you turn the master switches off when leaving the boat doing as suggested would isolate the charger from the batteries.

 

[Jen-in-Wellies]

1 hour ago, Alakefic said:

Hi 

it’s a small smart charger 240v which will run happily off my genset or the hook up point, the battery’s are 1.5 M from the point inside the boat where I can pick up the pos and Neg, both cables are 16 mm tri rated .

Thanks. What current can the charger output? See also Tony's questions above.

[blackrose]

2 hours ago, Alakefic said:

Hi All 

is there any problem with changing my 3 batteries without disconnecting them?

 

How does one change a battery without actually disconnecting it? 

[Alakefic]

6 minutes ago, blackrose said:

 

How does one change a battery without actually disconnecting it? 

Obviously meant charge ,

[Tony Brooks]

8 minutes ago, blackrose said:

 

How does one change a battery without actually disconnecting it? 

You just leave it connected to the bat's circuits and then connect a charger and turn the charger on. The topic title shows it was a typo or autocorrect.

 

The OP seemed to be concerned over putting a battery on charge while it was still connected and powering the boat's circuits. For any normal charger, that will do no harm at all.

Edited June 26, 2023 by Tony Brooks

[Alakefic]

Thanks Tony 

[blackrose]

4 minutes ago, Alakefic said:

Obviously meant charge ,

 

Ok I see. It wasn't obvious to me.