36 LRC battery wiring?
Posted: Tue Jun 26, 2018 5:02 pm
OK, I've finally decided to get a deeper understanding of the battery wiring for the 36 LRC with Yanmar diesels.
I've attached a picture which is commonly represented as what a "1-2-both-off" switch does on a boat. This is not what the salon 1-2-both-off switch does on the LRC.
Say, the house bank is battery 1. Normally, you have a common post on the switch, which can be switched to "1" so that the alternator charges the house bank. In that case the house bank would also start the engine. If the switch is on "2" you are starting the engine with the starting battery AND running the panel (lights, etc) with the starting battery. If switched to "both", both banks are in parallel acting as a big battery. People usually think that using "both" is not a good idea, because you can run down both your house bank and starting bank and be stuck with no way to start the engines.
This is NOT the way the LRC is wired. The "1-2"-both-off" switch in the salon refers to the house bank only. The house bank is made up of 4 golf cart batteries. Call them A,B,C,D. They are 6 volts each. A and B form a single 12v battery. That's battery 1 on the salon switch. C and D form a single 12v battery. That's battery 2 on the salon switch. The starting batteries outside in the cockpit are not connected to this switch at all. I can see no reason not to just leave this switch on "both", since you can't run down the starting battery by doing so, and you want all the house power you can get.
Outside, in the cockpit, there are two 12v starting batteries. These are also connected to a "1-2-both-off" switch. In the "both" position, it appears that the two 12v batteries are in parallel and the starboard engine is charging both starting batteries. Meanwhile the port engine charges the HOUSE batteries. That's clear from watching the house voltage. It goes up when the port engine is running, but not when the starboard is running.
This design seems very strange to me, since there is no way to switch to the house bank to start the engines, in case either starting battery were to die. You would have to resort to jumper cables or a portable generator.
Does anyone with a 36 LRC have the same wiring system? Am I missing something?
Thanks,
Brendan
I've attached a picture which is commonly represented as what a "1-2-both-off" switch does on a boat. This is not what the salon 1-2-both-off switch does on the LRC.
Say, the house bank is battery 1. Normally, you have a common post on the switch, which can be switched to "1" so that the alternator charges the house bank. In that case the house bank would also start the engine. If the switch is on "2" you are starting the engine with the starting battery AND running the panel (lights, etc) with the starting battery. If switched to "both", both banks are in parallel acting as a big battery. People usually think that using "both" is not a good idea, because you can run down both your house bank and starting bank and be stuck with no way to start the engines.
This is NOT the way the LRC is wired. The "1-2"-both-off" switch in the salon refers to the house bank only. The house bank is made up of 4 golf cart batteries. Call them A,B,C,D. They are 6 volts each. A and B form a single 12v battery. That's battery 1 on the salon switch. C and D form a single 12v battery. That's battery 2 on the salon switch. The starting batteries outside in the cockpit are not connected to this switch at all. I can see no reason not to just leave this switch on "both", since you can't run down the starting battery by doing so, and you want all the house power you can get.
Outside, in the cockpit, there are two 12v starting batteries. These are also connected to a "1-2-both-off" switch. In the "both" position, it appears that the two 12v batteries are in parallel and the starboard engine is charging both starting batteries. Meanwhile the port engine charges the HOUSE batteries. That's clear from watching the house voltage. It goes up when the port engine is running, but not when the starboard is running.
This design seems very strange to me, since there is no way to switch to the house bank to start the engines, in case either starting battery were to die. You would have to resort to jumper cables or a portable generator.
Does anyone with a 36 LRC have the same wiring system? Am I missing something?
Thanks,
Brendan