beneteau battery layout

[cmedsailor]

In a standard beneteau battery layout (with the general switch and the two batt 1 and batt 2 switches), if you switch off any one of the batteries (1 or 2) while the engine is running will this damage your alternator?

 

[KeithH]

I hope that someone knows the answer to this question. My friend has an Oceanis 281, and we cannot work out the logic of the General ,1 and 2 switches. They dont seem to function as you might expect. However, it is possible that a previous owner might have altered the wiring, so an answer of "what Beneteau intended" would be useful.

 

[StugeronSteve]

Provided that the black? isolator is in the on position and one battery is "live" you shouldn't do any harm to the alternator by turning the other off. On long passages I always isolate the cranking battery, just to make sure that I don't discharge it.

 

[alan]

On my 311 the two red switches were wired (in factory) as #1 for engine battery, #2 for service battery; these two were paralleled when in the "on" position ( a short piece of cable on the back of the switches). The "general" switch (not fitted on the 311) is the earth breaker; both the earths from the batteries are routed via this switch to the main engine body earth point.

Alan.

 

[alan]

No, on my 311 this is how I used to manage the battery charging/discharging manually.
General switch "on"
Batt1 switch: "on" for starting, Batt2: "off"
Batt1 and 2 : "on" for charging (engine running)
Batt 1: "off", batt 2: "on" (services when sailing/anchored)
All : "off" when leaving boat unattended.

[General switch (earth) is for isolating everything in emergency situation]

Alan

 

[Phoenix of Hamble]

Thats my approach too.....

 

[cliffb]

Generally speaking this is also the procedure I use. However - I'm not 100% convinced that Batt 2 wouldn't charge if the switch is off whilst the engine is running. Without a doubt though, if both switches (i.e. bats 1 & 2 ) are off whilst the engine is running I would think there's a good chance the alternator wouldn't like it.

 

[cmedsailor]

Alan is correct, I know this myself. Batt 1 is for the engine and batt2 is for the services. If you have only batt 1 on no services will function, however, I think, if you have only batt 2 on you can still start the engine.
But the question remains. What happens if either battery is off while the engine is running.

 

[alan]

I don't think you can start the engine with only batt #2 on as the parelleling cable is on the "output" side of the switches (or at least it was on mine).

Switching off one battery whilst the engine is running will not damage the alternator, you still have the load of the other battery.

Alan.