36 LRC battery wiring?

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chicagocat
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36 LRC battery wiring?

Postby chicagocat » 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
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Screen Shot 2018-06-26 at 3.39.15 PM.png
PDQ 36052 - 1996 LRC - "Anne Z" - Chicago
and 2001 PDQ 36 Classic (Tall Rig)- "Cat Tales" - Punta Gorda, FL

Jwood1
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Re: 36 LRC battery wiring?

Postby Jwood1 » Tue Jun 26, 2018 10:53 pm

Hey Chicagocat
I have a 32LRC but I believe my batteries are wired the same way: 2 starting batteries in the port cockpit locker with not one, but two 1-2-Both switches! 4 6V golf cart batteries in starboard locker for house bank with their own 1-2-Both switch. The two banks are separate: port alt charges the starting batteries and the starboard alt charges the house bank. Solar and wind gen are also wired into the house bank. There is no way to connect the house and start batteries except by jumper cable. While the boat is on the hard, I have connected the house and start bank with jumper cables so the solar can keep both banks topped up.

I find myself wondering why I really need two starting batteries. One battery should easily be able to start both engines. If that battery dies, you can always jump it with the house bank. This would save a lot of weight.
Terrapin
1997 PDQ 32 LRC #26
Punta Gorda, FL

http://terrapinsailing.com/

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chicagocat
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Re: 36 LRC battery wiring?

Postby chicagocat » Wed Jun 27, 2018 8:19 am

Thanks,
That sounds very similar to my set up. Except for the even stranger fact that you have double 1-2-both switches for the starting batteries.
Yesterday, I messed with the 1-2-both switch settings at the starting batteries. In the "both" position, both engines started. In the 1 position, they both started. In the 2 position, only the starboard engine started. And in the off position (naturally), neither started. Very strange wiring setup indeed.

BTW, when you are on the hard and run jumper cables to the starting batteries from the house (which seems like a good idea), how do you run the cables from inside to outside? There's no way I think I could do that except through the companionway or a hatch, which would allow for water intrusion.
Of course, in Florida you may just be on the hard for a few days for bottom paint. In Chicago, I'm on the hard for months!
I've never had trouble starting up even after a long winter, though.
PDQ 36052 - 1996 LRC - "Anne Z" - Chicago
and 2001 PDQ 36 Classic (Tall Rig)- "Cat Tales" - Punta Gorda, FL

Jwood1
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Re: 36 LRC battery wiring?

Postby Jwood1 » Thu Jun 28, 2018 2:05 pm

On the 32 LRC both sets of batteries are in the cockpit lockers where the outboards would be in the Classic. My starting batteries are on the port side and the house bank is on the starboard side, so it is easy to run the jumper cables across the cockpit. Terrapin is on the hard all summer long due to those pesky hurricanes. I will be putting in a higher output alternator this year and doing a bit of rewiring to simplify things. I'm also thinking of installing an echo charger to keep the starting bank topped up without needing to resort to jumper cables.
http://www.xantrex.com/power-products/p ... arger.aspx
Terrapin
1997 PDQ 32 LRC #26
Punta Gorda, FL

http://terrapinsailing.com/


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