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Author Topic:   Battery Size
Florida15 posted 03-14-2003 11:17 AM ET (US)   Profile for Florida15   Send Email to Florida15  
Is it possible to have too much battery or is bigger better ? I need a new battery for my 1981 50 hp Johnson. I was looking at the Stowaway brand. One is a dual purpose with 700 marine cranking amps and 525 cold cranking amps. It's at Academy for $49.95.
The other is a Stowaway Tournament model.
It is rated at 800/1000. It is $54.95 at Sam's. Both are group size 24. Would the Tournament model be better ? Or , another way to put it : Can too much power hurt my motor ?
ShrimpBurrito posted 03-14-2003 12:10 PM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
A battery with a greater current capacity than your motor requires won't hurt the engine, as the motor and anything you connect to it will only draw as much current as it needs. In fact, you'll be able to run more equipment off of it.

However, the alternator may not be big enough to adequately charge it. If it's bigger than what's supposed to be in there, the alternator is going to be working harder, which can lead to premature alternator failure.

triblet posted 03-17-2003 01:21 PM ET (US)     Profile for triblet  Send Email to triblet     
The alternator won't really be working any
harder to charge the badder battery, it will
just take longer.

Either of those should be fine with a 50. Much
smaller than that, and you can think about a
motorcycle battery, esp. if the motor also
has a pull rope. I know several folks doing
that on inflatables. And Adm. Linda's big
Suziki bike probably has more HP and more
compression than your Johnson 50.


Jerry Townsend posted 03-17-2003 01:43 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
As Triblet (Chuck) mentions, the bigger battery will not damage the alternator. There is a voltage regulator in the charging circuit that limits the voltage to the battery - and aside from that, the battery is a good regulator, by itself. Either battery should be fine. The bigger battery will give you more capacity. Being in Florida, you don't have a cold weather problem - which might suggest the bigger batter. --- Jerry/Idaho
ShrimpBurrito posted 03-18-2003 11:55 AM ET (US)     Profile for ShrimpBurrito  Send Email to ShrimpBurrito     
Oops. I stand corrected. Sorry for passing on bad info.
Florida15 posted 03-18-2003 12:23 PM ET (US)     Profile for Florida15  Send Email to Florida15     
Thanks for the info guys. I'm going with the
Stowaway Tournament model.
Sal DiMercurio posted 03-19-2003 12:06 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
You will never have to much battery, it's like money in the bank, when you need extra power, it's usually there.
The only thing is, I believe that engine only puts out 6 amps, not enough to "charge" any battery, but usually enough to maintain a "charged" battery.
Group 24 is about as small as you can buy for a full sized battery.
You can tell if your buying a good battery buy just picking it up, the heavier, the better.
For instance, my 200 Evinrude "requires", twin group 29s, 1 group 29 weighs about 3 times as much as 1 group 24 battery.
As I noted, your engine has a small rectifier & is only capable of "maintaining" any battery, be it large or small & would take just about 6 hours straight of running at a minimum of 4,000 rpms to charge any battery.
Nothing is worse then tyrning the egnition key 10 miles from your harbor & click, click, click, then you will wish you paid $100 for a larger battery.
Get the biggest one you can, [ even a group 29 ] you wont be sorry.
Florida15 posted 03-19-2003 10:35 AM ET (US)     Profile for Florida15  Send Email to Florida15     
Thanks for the advice Sal. I don't know that I have seen a group 27 cranking battery. Most of the big ones I have seen are either deep cycle or the Stowaway dual purpose. How do the dual purpose batteries rate? I'm thinking about getting a cranking battery for the motor and then get a dual purpose for the trolling motor and electronics.

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