Battery Choices (House vs Start)

[ALX357]

I have to replace my starting battery, series 24 size, and still would like some reassurance that using a deep cycle battery would be just as good.

I already have a three battery system, two deep cycle batteries forward, dedicated to cabin usage and exterior lights, and the starting battery under the galley seat, dedicated to starting. Large jumper cables run to the motor, and also three cables forward to the house batteries. There are combiner/isolators between the two house batteries, and a A/B/AB/OFF switch there, and then another combiner/separator between the motor battery and the house batteries.

Upon finding the starter battery dead, I jumped the two busses, the starting buss and the deep cycle buss, with a short 6-inch battery cable, and was able to instantly start the motor. Ran the motor for about a half hour, and then put a smart charger on the motor battery overnight.
The next AM, it was dead again, and the smart charger was signaling a bad battery. But the thing I learned is that the deep cycle battery could easily crank the motor, at least in 90 degree weather.

Would it have trouble in 30~40 degree temps. ?
Would it have trouble with being used primarily as a starting battery ?

It would be satisfying to have three identical batteries, even if used differently.

[Catigale]

If your motor starts easily (less than 2 seconds of cranking) then I would say by all means go to three deep cycles - a starting battery is overkill on a small outboard imho..

[Frank C]

Agree that any deep-cycle should be fine for starting our little outboards. OTOH, since you already have a big double-bank for the house, not sure there's much advantage to carrying another single-deep, either. Unless it's approximately the same capacity as the double bank, so you can alternate, where's the advantage? (referring to odd/even strategy, discussed elsewhere).

A deep-cycle dedicated solely for a starter bank seems as wasteful as carrying an automotive starter battery. Your starting duty will never drill down into either of them, so either one will spend a fat & lazy life. You'd be as well-off with a garden tractor battery that's lots cheaper, at less than half the weight. The house bank still serves as a backup to the little starter battery.

[Boblee]

You could have the starter battery connected direct to your motor but have a separate wire going through a low voltage cutout back to the "perko" switch.
This would allow you to take the starting battery down to 11.8 v or whatever the cutout is set for, leaving plenty of power for emergency starting and still being able to extract the top 40-60% of the battery capacity for house use.
The batteries then would all charge from the motor or when the other batteries are charged from another source if the "perko " is set for multiple batteries.
Note if the cutout is rated at 20amps you would need a 20 amp fuse or better still a resettable circuit breaker in the line.
There are commercially made setups for this but they are usually waaaay overpriced and providing your batteries are the same type ie all deep cycle or all wet cell they can be left looped together permanently.
If you are using different types problems can develop and they need to be separated except when charging.
Agree completely with Frank and Catigale a deep cycle battery and especially a marine type will start our little motors with ease at any normal temperatures (it is not normal to be on the water below freezing).

[50/50]

have a small motorcycle type starting battery mounted at the pedastool which is wired to an isolator switch there. this is then connected to a Voltage sensitive relay.

http://www.bepmarine.com/showproduct.cfm?productid=12

The VSR ensures the starting battery receives the charge until fully charged and then changes to the house battery.

Basically the starter battery only requires a top up charge because the Yam dosen't require much to start it. I like the security that this simple system delivers.

The house battery is constantly monitered by a Nasa battery monitor.

http://www.yachtbits.com/nasa/nasa_clip ... system.php

The house battery is only 75amp capacity. I have just returned from a 300 mile 8 day cruise of the Scottish West Coast and although we used quite a lot of power (laptop charger, 300w inverter, stereo, lighting etc) the system coped amply with the usage and never need shore power.

[aya16]

Im with the just have two batt. crowd. perko switch the two house batteries
and run the starter wire to the perko. Starting the motor takes only a few seconds and the motor charges the house battery as you drive so I just have the two deep cycles in mine. If you really need a back up get a switch from cabela's that will not let one house battery die enough so it wont start the motor. or carry a portable jump starter. I have one of those and used it a couple times. Mostly on other boats at the ramp.

[Frank C]

... A deep-cycle dedicated solely for a starter bank seems as wasteful as carrying an automotive starter battery. Your starting duty will never drill down into either of them, so either one will spend a fat & lazy life. ...

I should prolly clarify slightly ...
There IS a good reason to add a new, single Deep-cycle battery, even though it might be less capacity than the pre-existing House bank. As long as your daily DC demands can be serviced by that new deep-cycle battery, then it can indeed be a good choice for "alternating" battery management (such as ODD/EVEN).

Wallymart now sells a Gp31 Marine Deep battery (@ $65) with 115 AmpHrs. capacity. That's good for a daily draw of 50 AH, which is ample for my daily electricity demands. Even though a pre-existing double-bank may have deeper power reserves, the new bank can still supply a day's worth of DC demands.

The general principle that I'm advocating (learned in an ASA Sailing Class) is that Alternating Battery Management is a better approach than Functional Battery Mgmt (Starter vs House). This logic path is based on several factors:

• 1. Our dedicated Starter Battery receives way too low a duty cycle to be used effectively;
  2. Starting amps are easily met by the House bank 'du-jour';
  3. The "Alternate" battery is always available as a backup;
  4. Alternating demands across 2 different banks more effectively "life-cycles" both banks;
  5. Alternate banks need not have matched capacities, if each meets the daily demands.

[tangentair]

This seems a continuation of the thread in the performance and tuning board so I will again raise the issues

if a novice were to mix battery types (wet/gell/agm) in circuits that allow cross connections and charge them at the same rate or from the same source such as the engine alternator I believe that this would shorten the battery's life cycle
and
using deep cells for rapid discharge/high current uses like starting even for short periods can also shorten their life cycle. Yes some motors turn over easily without much effort, but not all do and as battery voltage falls off due to age or current use, it requires more current to start the motor.

And I suppose that mounting the gell and AGM battery is not so much an issue because it would be difficult to get them overheated if they are in the bilges, but I have heard that extended usage in temps over 80 are a factor in shortening the newer type batteries' lifespans.

and while I do not keep a jumper battery on board, I have wired the stationary vhf with a double throw switch and a 12 volt dry cell mounted up under the cabin roof, so if I am ever swamped and the main batteries are flooded out - yes they are supposed to work submerged but I doubt if the factory fuse will hold up if it goes swiming in salt water, I can switch over and still get off a Mayday.

[Frank C]

Where, in either thread, did anyone propose mixing the battery types among Wet/Gel/AGM? In fact, mixing battery types is specifically excluded in the other thread, and not discussed in this one, until now.

What HAS been proposed ...

• - that alternating batteries is a good managment scenario;
  - that differing duty-cycles (Marine vs. Automotive), by bank, does not defeat that scenario;
  - and that differing capacities, by bank, does not defeat that scenario.

Finally, since most owners here have banks that are isolated by VSR, I'm not convinced that an AGM battery is necessarily excluded from an Alternate Battery system. The weaker bank will always receive the initial topping charge, at whatever amperage it can accept, upon which they will both be charged. I believe any compromise of the battery life-cycles will be miniscule ... especially as compared to the inefficient life-cycling of a dedicated Starter battery.

At least on my boat, the "working" battery will generally be on the alternator while the "alternate" remains topped-off and resting. They should rarely be on the alternator together. As long as the "shore-power charger" is smart enough, I wouldn't hesitate to swap either bank to AGM when I next need a replacement.
(Note: Gel batteries are still excluded, at least from my consideration ... YMMV).

As for excessive amperage demanded by starters ... I contend that is a MYTH ... simply not true for the vast majority of outboards owned by this membership. Outboard engines are frequently motorcycle engines (majority manufactured by Yamaha or Suzuki, et al), and at 800 to 1100 ccs, they are half the size of automotive engines, or smaller yet.

• - Have you ever seen the battery used in most motorcycles?
  - Do you really believe these starters can overwhelm a marine deep cycle battery?
  - I do not, but YMMV. Caveat Emptor, conclusions belong to each reader.

Up to now, I've judged AGMs too costly.
However, the fact that an AGM continues to operate when submerged ...
Might mean that an AGM comes aboard at my next opportunity;
(even if that requires direct wiring to a VHF panel, with an elevated fuse).

[vkmaynard]

2 House batteries from Walmart with a 1-1&2-2-OFF switch ($25). You don't need a starting battery for 50-70 HP motors.

Victor

[argonaut]

Trojan makes AGMs that run about $100/battery.
Not spiral technology like Optima but you end up with a sealed battery and the other AGM benefits. My system is two of these in separate banks with three simple open/closed switches.
An Off/on for the motor battery, off/on for for the house, the third switch connects both loads together. It's the Westmarine dual bank system.
Plenty of start power for a 50, and the motor's generator quickly puts back what is uses.

[Paul S]

got to love the 3 switch system.



I still prefer wetcell batteries (I think I am the only one that does now-a-days). Cheap, powerful, reliable, great power per lb. Got 2 group 27 batteries

never had an issue in over a decade with our powerboat with a wetcell, or the last few years with our M. If I get to a point where the batteries are upside down and start to leak.. I suspect there will be a lot of other issues that will need my attention!!

[Catigale]

I have 2 Group 24 wet cells that I got with the boat in 2002...one of them is weak and will only just start the motor. I guess we dont have a lot of power requirements on our 5 days cruises....no nuke or major electrical appliances to speak of. We dont use much in the way of cabin lights as as soon as the sun goes down (930 nautical twilight in our LAT) we are already in bed....

[Boblee]

I think unsealed wet cell batteries are probably not a good choice below deck but unless fast charging from flat there should not be any ignition or pollution problems, that was my excuse anyway.
If mine were above deck I would prefer to use them and throw them away IF they break down earlier, the economics would be far better.
As it is when I am sleeping my batteries are slowly discharging and when they are recharging fast (motor 25 amps) I am hopefully above deck, when charging slow (solar) they shouldn't be a problem.
I agree that if they are upside down and leaking they will be the least of our problems.
Ideally sealed marine type batteries (heavier plates) would be superior and Optima would be at the top end sadly my budget does not run to them.
Every time I Bring Out Another Thousand dollars for the BOAT world war 3 breaks out.

[aya16]

I too dont use much power, I like candles and have a battery operated
Coleman lamp. But when its movie time or some big drain I just start the engine let it idle.

Bob lee whats up with your aussie girls? I keep meeting them here.
you guys run them off your Island or what. Every time I turn around
I meet one. They are all Blonde and young and tough. Cute too. I have to say one thing that stands out with them They have personality....
and a deep love for Australia. I want to go to the factory there where you guys make them.
Mike