House Battery Monitoring

John,
My Tom Cat 255 also came with an unusual battery configuration. I changed the wiring to some extent. You want to be able to use switches or relays to isolate the house batteries and starting battery. You are correct that one engine start is plenty to start the two engines which you own. But there is a risk that the house/engine start could run down, and the other start fail (very slight)--but I do like to isolate two starting batteries, and then have a separate house bank. You may have noted that I carried a U1 battery (Garden tractor) extra battery fully charged. One of these has plenty of power to start an outboard--probably would start two. It is better than one of the "jump start" kits, and cheaper.

Good luck with your decision--no matter what, you will do well.
 
Regarding the battery/motor start situation. Our #1 is a starting battery, #2 is two house batteries. We have brought the jumper-battery along on previous boats (didn't need it, but used it for charging cell phones, anchor light on our little sailboat with an electrical system, etc.). We figured the Honda generator would be our "back up" on the C-Dory. If we somehow managed to run down all the batteries, we'd fire up the generator to run the battery charger.

Best wishes,
Jim B.
 
Beware!

Battery Back-up Overkill can boarder on an obscessive-compulsive disorder!

And excessive worry won't lower your blood pressure or count as therapy time!

I went overboard on this one when I added the engine mounted electric trolling motor:

Batteries 3 and 4 added under the forward dinette seat. (Two more Group 27's)

Honda 1000i generator on the ready/standby.

Emergency battery start pack under floor of helm station.

I've used the 1000i to recharge when trolling for over 4 hours continuously, but never the emergency start pack, and have never run the 4 27's down enough that they wouldn't start the Yamaha 90.

Still, I know I won't be paddling my C-Dory anytime soon!

Joe.
 
I stumbled across this battery monitor. Thought it might make a nice, cheaper alternative to the link systems. "Only" $60. I have not ordered one yet but am thinking about it. Thougth I'd wait and get some opinions first.

r102_r300.jpg


http://www.rc-electronics-usa.com/ammeters/rv-battery-monitor.html
 
Pretty neat monitor there. It also appears to integrate over time (kWh) so you'd be able to quickly calculate capacity changes. However, (the infamous 'but'), it has to be located in-line with your current draw/charge to the battery. There-in lies the problem on a boat. It would have to be mounted somewhere back by the battery(s) [unless you ran some helacious wires to carry the current all the way to the dash...!]. Also, with that light wiring, I doubt it would carry the amps to put in line with your engine's charge/starting line -- or at least I wouldn't want to try it for fear of damage to either your engine or a fire in this unit. Did it say how much current it can safely handle?

You could just put it in line with your cabin power at a feed point back of the dash, then you'd be able to monitor the current drain at least. Then just don't worry about the recharge cycle or times. You'd get 80% or more of what you need to know for most of your boat usage (IMHO).

Looks more practical for like an electric car where the battery(s) are located closer to the dash and all. Still, neat monitor for sure.
 
Dora~Jean,

Your probably right about it not working so well as an amp meter but I thought it would work just fine as a volt meter. Of course it would probably be something that I would just have wired to the battery so I'd have to look in the lazarette but that's better than my current system of trying to hook up my handheld multimeter.
 
Looking at the specs, it appears to have a shunt (negitive), which carries the current, built into the meter. I agree that you cannot easily mount it remotely--ie on a console, because it has to be inline with the negitive wire or the circuit. Looking at the dimensions, it is much smaller than the "normal" shunt used in one of the link systems. It looks like a great gadget--but I wonder how practical it would be considering where it will need to be mounted (access to read, weather protection etc).

Bob Austin
 
We use a Link 20 on Naknek, and are very happy with it.

On one trip, Chris (Rana Verde) shared his technique. Run on two batteries, and when you stop for the night switch to one battery; even if you drain the single battery lower than intended, you still have a fully charged battery to get you going the next morning.

Even with that in mind we have never come close to running a (single) battery lower than recommended 50%. Run your Wallas, XM radio, VHF radio, etc, low wattage anchor light, low wattage reading lights with wild abandon and still have plenty of power the next morning.

The thing I like about the Link 20 (or Link 10) is that it allows you to know the state-of-battery charge ... no guessing.

Buy one - you'll like it if you're doing overnights away from a marina with power.

Casey
C-Dory Naknek
 
Offhand I don't know the amp hours (and we're in Panama City - Naknek is in AZ...).

The original Interstate batteries were series 24, and when we replaced them a year ago the Interstate dealer asked if I wanted the same battery, or did I want to upgrade? For an additional $10/11 per battery I opted to upgrade to the higher capacity series 24 battery ... but (sorry) I don't recall the capacity.

We're currently in Panama City Beach (FL) recouping from some traveling "Adventures," but hope to be back on the road to Key West in a couple weeks.

Casey
C-Dory Naknek
 
I agree with you Casey, nothing like peace of mind with the Link 10/20 monitors. I have twins, so 1 battery each motor, I just choose which of the 2 batteries will be my house battery for the trip, usually lasts several days, about the same usage/equipment you have, never below 70% capacity.

My batteries when new were 120 amp-hr capacity (I think group 27), but now at over 4 yrs old I'd imagine they're down 10-20% capacity from new. Plan to replace them this spring before heading to Alaska, just because.
 
I have an electric car conversion, with 15 8 volt Interstate deep cycle flooded batteries. It has a Link 10. I like it and am glad I have it. On my CD22, and the way I use it, I don't have the need for one.

Two things to consider:
If you really demand a lot of your batteries, either add another battery or two or bring a charger. If you went wild and bought a nice Trojan J-150 12 volt, instead of a Link 10, you'd have some real value.

If you don't know what a buss bar is or a kWh, the Link 10 is not for you. It is not what you are interested in.

Another issue. Last fall I forgot to unhook my Link 10 when I disconnected my battery pack, and when I reconnected, the repair cost me $90. They are delicate.

To watch my batteries, I bought a digital voltage display that plugs into my cigarette lighter outlet. WalMart, $15, in the battery charger area. It's terrific. It gives me an idea of what the level of charge is, and when running, it lets me know that the alternator is charging properly. It is in line with the simplicity of the C Dory.

Dave
 
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