Battery Charger Installation

[Phil23]

I am replacing a battery charger that has not worked for some years.
I have a starter bank of 2 batteries and a house battery bank of 2 batteries also all at 12 volt.
Each bank is on its independent switch.
The battery charger I am installing states the power leads (2) must be connected directly to an individual battery. The charger has battery analysis, charging and maintenance capabilities with a charge amps of 20.
My query is is there any reason I am not able to connect the pos. lead to the main stud in my fuse box and the neg. to the neg bar in the fuse box, thus being able to turn on the House Battery switch to select house bank charge etc.

 

[rgano]

Using your alternate method, how many connections do you think there are between the charger and the battery? Think voltage losses. Why would you not want to charge both banks? Seems like added complexity and a good chance to add human error.

 

[tiltrider1]

Voltage loss is much more serious than people want to believe. Most wiring on a boat meets a no more than 10% voltage loss. This is not acceptable for battery chargers. You need to size wire for no less than 3%. Most people think that 13.8v is enough to charge a battery. In reality if you can’t get to 14.2v your batteries will never be fully charged.

You can certainly take a short cut and it might work depending on how you use your boat but when enough short cuts are taken all kinds of expensive problems can crop up.

 

[Comodave]

First you need a fuse in each battery charger positive lead. The fuse should be a bit more than the total charger capacity. I would run a lead to each battery bank through a fuse from the charger. I assume the charger is a 2 bank charger. As stated above you want to go for a 3% voltage drop. Measure the distance to the battery from the charger and include both positive and negative leads. Use that distance on a voltage drop chart to see what size wire you need. It is a one time expense to get proper size wire and it will pay off every day when you charge the batteries. Good luck.

 

[O C Diver]

I think you should be fine doing it that way. Many inverter / battery chargers are wired that way. As already mentioned, proper fusing is important.

Ted