Ok, thanks. I'm wiring up a second battery bank, tied into the start battery with an automatic combiner. I was thinking of adding a battery switch to bypass the combiner to allow me to start off the second bank in an emergency. I need to know amps for wire sizing and to see if the main fuse I installed for the second bank can handle the starting current.
Oh....I see now. I believe what your after is a switchable dual battery set up with an isolator. As with boats the alternator will see any number of batteries hooked up to your rig as one battery and charge them all as if they were one. This will cause the battery or batteries with more charge in them to over charge hence the isolator. It allows the charging system to sense more than one battery and charge them as individuals and not as just one big battery.
Here's a diagram that shows the circuit. Your battery leads should be #8 wire for a run of 4 feet or less. Hope this helps out.
PS If you have marine parts access I would recommend a decent Cole Hersey isolator.
Cap'n, that's exactly what I'm talking about, minus the POS diode based isolator. I'll be using an ACR (automotic combiner relay). I do boat wiring and electronics for a living so this side of auto work is pretty straight forward for me.
Yup...me too for bout 30yrs. I own both Mountain Marine & Nauticare Marine Services for decades. I don't do much marine work anymore but I'm happy to help out when I can.
Here's a handy DC Marine wire gauge chart that might come in handy.
Small world. I own Starfish Marine. My primary market is Orcas, but get over to the other islands periodically. I've only been doing this, professionally, for 10 years, but been boating my whole life. I've seen a lot of change in 10 years, but I imagine it's nothing compared to 30 years. It used to be simple, like trucks used to be. Now we've got computers everywhere, problems with ground loops and interference, etc. It makes it nicer for the user, until something breaks.
Edit to add: If you have an iOS device, check out the app from Blue Seas. It has a lot of good calculators built into it. More and more vendors are providing apps to support us in the field. Another example is Gemeco's app for transducers. It lists all the models, has installation diagrams, wiring diagrams, even includes a built-in level for measuring hull angle for transducers.
Hahaaa...I was gonna send the Blue Sea 1st but, didn't know if you had the capability to use the apps. I too grew up in and on the water along the FL. gulf coast. I founded Mountain Marine & Nauticare in Lake Tahoe and grew it to 3 locations ( Tahoe,Carson City & Lake Lahontan) back in 85 just before the big drought that lasted for 7years. Eddie Williams who now owns the Hot Shop (sells hot sauces) here in Friday Harbor used to work for me back then. Prior to that I co-owned Dry Dock marine in Tahoe. We restored old wooden classic run-a-bouts from waaay back in the day. in 90 I shut down all operations as my company was the last surviving marine service business still alive at the height of the big drought. Eddie re-upped in the Navy (dessert storm) and I packed up all my toyz and moved up here. Now that I think about it...that's over 40 years total...christ it's hell to get old. I operated Nauticare up here as a marine maintenance service while still working full time at yah sure yensens as their main tech for about 7 years. Raised my daughters here til it was time for them to go to college. They pick schools in the northeast so in 97 we packed up and moved to upstate NY. I took Mountain Marine off that back burner and founded Beast Custom Cycles back then. Stayed there for about 11 yrs. and also was the only Vessel Assist towing operator in the region (of both Lake George and Lake Champlain, NY). I was also doing a ten year stint with the USCG at the time and still do to a more minor extent with the USCG Aux. as a past commander among a list of other things. In 08 I moved to my home state (and transfer to) Ft. Myers, FL. for a 23 million dollar marine redevelopment project for a couple years while working out of USCG Cutter Sta. Ft. Myers Beach. Payed good and was able to move my motorcycle shop there as well.
After that area tanked due to the economy and the project was finished my wife and grown kids all wanted to move back here...so...here we are. We've been back 3 yr.s this next spring with the motorcycle shop. Still piddle with boats for old friends once in awhile but my day to day time is spent at our motorcycle shop. I jump in here now and again to learn a few things and help out if I can. Currently I'm boatless...first time in a longtime. Guess I finally smartined up huh? LOL!