Battery charging circuit

[geek_guy]

I'm curious about the set up on my newly purchased Legend 37.

There is the batt selector switch like usual. But when I tried to use it it didn't seem to be working. I replaced it, but still, selecting 1,2, all did not add or change the batteries. Looking closed I believe that the switch was used to select charging from the engine. Out to the batts.

Anyway my question is why. Wouldn't just sending charge out to all the batts accomplish the same thing as going only to half the bank?

Dave

 

[Stu Jackson]

It all dpends on how it's wired. Really.

OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101

These take it further:

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

 

[Benny17441]

Usually the switch is wired so that two battery banks can be operated independently to provide redundancy or combined to provide maximum power. The switch position determines the bank that will service the load and which will receive charge from the alternator. The switch provides the operator with the alternative to recharge with the alternator one bank or the other or both as he may deem appropriate. The regulator for the alternator does not recognize separate battery banks, to it is just one big battery and if you combine a depleted battery with one fully charged the regulator will recognize the average charge between the two and limit alternator output as such. This may result in the combined charge taking that much longer that if you were just charging the depleted battery by itself. With the switch the operator can choose the configuration that he deems best under different conditions.

 

[geek_guy]

Ah, Thanks Benny.

That makes perfect sense. So being able to pick only the depleted battery would make the charging more efficient.