3 Batteries

L

Labman2

Active Member
Well, this has proably been posted to death, did a search and all it would show me is "Batteries"!
I have the 1-2-both switch already, but with my HDS8, HDS7, Sructure Scan, Radar, S.M. 2150 AIS/DCS VHS and a MPS/C.D./Radio, I'm thinking it's going to draw a lot of AMPS!
I want to isolate the start battery (position 1), then wire the 2 house batteries together (position 2), just not sure how to do it. I plan on running tinned wire from the switch to a fuse block at the helm, strickly for the electronics, but how would one wire the 2 batteries together?

Regards;
Mark
 
All you have to do is wire them in parallel............Connect both Red terminals to each other and then attach the black terminals together with equal length wires. Once that's done you can treat it as a single 12V battery with twice the juice! lol Just come of the red and black of the same battery after that and you should be good. Lots of simple diagrams on google on this as well.......Cheers!
 
Great post labman...something I was also interested in doing was isolating a battery strictly for starting the motor, with the other 2 running my auxilerys and such.

tx
 
Exactly like reelslim said, all you need to do is add a second house battery by connecting the pos terminal on the new battery to the pos terminal on the existing house battery. Same for the neg terminals. So one new battery and two equal length cables and your done.

Usually it's a good idea to replace the existing house battery with an identical new one when you are connecting them in parallel. So two new house batteries with identical specs.
 
Make sure you use heavy gauge wire to go between the two batteries. No less than the gauge your main uses for the starter. Reason being if your starter battery dies you still want to be able to start with your aux batteries. If you don't use a heavy enough wire between the two batteries and then to the switch your starter might not be able to draw enough power to turn over even if the batteries are charged.
 
My 2 cents here. I'd also invest in a Blue Seas "Add A Battery" ACR (Automatic Charge Relay) system for the setup you've outlined above and get rid of the MBSS (Main Battery Selector Switch) setup that you've got. The ACR isolates your House and Start batteries when no charge source is present, and combines them for charging when a charge source is present, assuming that neither the house or start systems have any charging issues. The ACR will not allow the systems to combine if one system is faulty saving your alternator, chargers and expensive electronics a bunch of grief. It also has a start protection feature preventing a surge from frying your electronics at start.

I've put ACR systems into my last 2 boats -- first upgrade I did and would never own a boat without them.
 
Ok....Sorry.....Now my two cents....lol Although I do agree that there are many "automatic" switching relays on the market they are far from fool proof. As an E/I Tech. for 20 years or so I tend to be very cautious when I hear the word "automatic" it tends to let people believe that it is some sort of magic.....lol Automatic is good until the diodes crap out or some other fault occurs. After all.....you are just adding another piece of hardware in a marine environment. What could possibly go wrong......its automatic! lol Anyways......whether you go with a Blue Seas type sytem of stay with the old relaible switch......neither one will work if it's not used and maintained properly. Not a shot TenMile......just my view as an overcatious tradesmen! Although I have been called a "little" anal by friends..........Cheers!

Greg
 
Last edited by a moderator:
Man, that was quick!
Thanks all, and I am also very anal/overcautious, so I always have switched the batteries off when I left my other boats.
I plan on a Group 31 for the start side and 2 of the Group 27 for the House side. Other posts on here have suggested that the Kirkland brand is not too bad a battery and they are fairly inexpensive. The previous owner wasn't sure how old the batteries were when I bought the boat, but he was sure the one was newer, so out they go and 3 new ones will be going in!

I had originally considered going with 6 volt batteries, when I bought my 40' 5th wheel the dealer put 4 of those in, but the weight of four 6s, compared to the 2 group 27s is more than I want to deal with in the stern!
I am interested in a battery tender, something that can be plugged into shore power or my Honda 2000i gen-set, I figure it could be wired to charge the start battery and the Alt., could look after the house side once I was running. I have the updated 65 amp alt. on my 5.0 Merc., instead of the original 55 amp!

I bought 20' of the 14-2 tinned wire to run to a Blue Sea 6 circuit spade style fuse block, and I will be tying the 2 batteries together with the wire from a sacrificial set of jumper cables, just need to find the right size lugs for the cable/battery posts.

Thanks again for the info.

Good luck Fishin'

Mark
 
The Kirkland batteries are good, I'm using one now. I'd just go with 3 of the group 27 starting/deep cycle combo batteries. Use one for starting and two for house. 875 MCA and 120 amp hours of capacity. So you'd have 240 amp hours of capacity on your house side.

I think I paid about 110 bucks for mine. Best deal out there. Mine keeps a good charge when trolling all day running a fish finder and electric downrigger.
 
Mark -- you probably want a dual bank battery charger for what you've described. Either plug it into shore power, or your Honda generator and it will then charge both your house and start batteries independently without combining them. Your Honda generator has a build in DC battery charger, but it's only 8Amp so likely no better than your kicker. You can get Dual Bank marine chargers with 3 or 4 charging stages that are 20+Amps.

My system (and I put this in to reduce the risks after a couple of at sea battery failures). I only have a single bank charger -- the ACR negates the need for a dual-bank system.

Start Battery: Group 27
House Batteries: 2 x Trojan T105 6V with a total capacity of 225Ah (these will last 7-10 years if well cared for) -- one of the best deep-cycle batteries
1 x Blue Sea ACR
1 x Xantrex HF1000 Inverter + 3 Stage Charger (Bulk, Absorb, Maintain)
1 x TriMetric Dual Bank battery monitor (monitors State of Charge, Amps and Voltage from house, and voltage of Start battery -- gives me 100% confidence of the exact and actual % charge of my system -- no guessing...
1 x 85W (4.8A) Solar panel, +10A Charge Controller (we do a fair bit of extended trips, so this keeps the lights/fridge on and batteries up)
1 x Tohatsu 20Hp kicker with 15A Alternator WITH a pull start -- if all else fails, I can pull the rope...
 
Chit, forgot the Scotty's when I was trying to figure the Amp draw!
So, your're happy with the Kirkland 27's then, how long have you been running it?
 
Thanks for the lowdown TenMile.
So you did go with 2 6volt batteries for your house side then?
I toyed with the Solar Panel idea as well, I am getting one from C.T. to put on the roof of my 5th wheel. It has a built-in Onan/Cummins 5500 gen-set, but I like to have the batteries charged up, before I hook-up to my truck.
 
Labman2 said:
Chit, forgot the Scotty's when I was trying to figure the Amp draw!
So, your're happy with the Kirkland 27's then, how long have you been running it?
Click to expand...

Only had it for 3 months but it performs much better than the canadian tire brand starting battery it replaced. In fact the other day I forgot to turn off my depth sounder and left it on all night. The battery still had juice to start my motor in the morning. My motor is only 70hp though.
 
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