NooB with a battery question

[mint_2k]

NooB here from Houston with a battery question?

I recently bought a 16-foot 1984 fish-and-ski boat (90HP Johnson ob) and everything was hooked up to the one marine cranking battery in the back. The things that were hooked up include the motor, small bilge pump, an older Hummingbird depth finder, horn, front and back safety lights, and a CD/radio deck with two small speakers. There is no trolling motor or stereo amplifiers? nothing I?d consider a major battery hog at this point. The boat came with an onboard 2-bank charger (Guest Charge Pro 2611) with only one bank being used. I generally only use the boat on weekends and leave it plugged in afterwards and everything was fine.

The battery is an Interstate 1000 Marine Cranking battery, with a 135 reserve (24M-XHD). It has a date code of May 2009, and after 3 trips out this month, it has gone out. It still reads 12.5 volts turned off, but it drops to 7.5 when I turn the key - it can barely turn the motor 2-3 times VERY slowly before it gives up. So I?m looking to replace it. Here are my questions:

Can I simply replace this with another marine cranking battery, and have everything I have hooked up to it now the same way without any problems, or should I buy a separate deep-cycle and put everything but the motor on it? Since I don?t have a trolling motor I didn?t know if getting a whole other battery and adding the weight just for the light stuff is overkill or not.

If I do get a cranking battery and a deep-cycle for everything else, will the charger I have work for both (since it is a 2-bank)? I was curious if you could charge different kinds of batteries (cranking and deep cycle) on the same 2-bank charger / maintainer.

For that matter, the charger reads ?Max Batt.: 200 Amp Hr, Lead Acid. Hopefully I can keep using it. Any tips or info would be very much appreciated.

 

[gm280]

mint_2k, :welcome: to iboats. Nice you could join us here...

Okay set's see if we can answer your questions. Yes you can simply buy another battery and use it exactly like you presently are doing without any issues. And you can even buy two batteries and use one for only the engine and the other for everything else. And your installed dual bank charger will work without issue to charge both batteries separately as well. They don't have to be the exact same types. Each bank charges its' own battery independently of the other. So it really depends on how you want to go with the batteries. Either way is doable and will work. JMHO!

 

[bruceb58]

Instead of buying a cranking battery, go to Costco and buy one of the marine deep cycle batteries. They are actually dual purpose batteries and can survive a deeper discharge than a cranking battery. They were the only batteries I ever bought for my 7.4L engine and if they can crank that, they can crank your outboard. The only time there is an issue using deep cycle batteries on an engine is in the case of fuel injection.

If you do go for 2 batteries, your charger is fine to charge them even if one is a crank battery and the other is deep cycle.

If you end up sticking with one battery, you can hook up both of the charger outputs to the same battery. You don't have to leave when disconnected. That way, it will charge at 10A instead of 5A.

 

[mint_2k]

This is awesome info. Thank you both so much for taking the time to offer up some advice. It’s good I can just keep doing what I’m doing with a new battery, not worrying about too much on it. And, I would have never even thought of added the other bank outputs to the same battery! That’s awesome! So I assume the charger would cut both banks together to a float / trickle if hooked up to a single battery. I wonder - would it be ok to constantly juice the battery @ 10 amps? Previous owner has had this current Interstate Marine Cranking battery since May 2009 and charged in @ 5 amps the entire time. That (to me) seems like a long life. Speaking of charging, does my 1982 Johnson 90 HP outboard actually charge the battery at all when running? I assume there’s no space for an alternator or generator under that motor cap.

My wife and I were out fishing last weekend (before we noticed the battery issues) and since we only ran 1 battery, I was hesitant to turn on the radio with the engine off. Surely one could listen to the radio with the motor not running for a while before causing a major drain, right? We’re talking about a relatively cheap car CD player radio deck and two 5-inch” full range speakers. I don’t have a Costco membership, but I noticed Academy nearby carried a Dual Purpose battery called “Exide” for ~ $80. I guess I could also drive over to Interstate Batteries and replace this one verbatim…

 

[bruceb58]

6 years for a battery is a good life.

The battery charger will behave as before in regards to what mode it is in. It will just be able to have a maximum charge of 10A instead of 5A. Everything else will be the same.

You should be able to listen to the radio for quite a long time before ever having to worry about starting your engine. Same goes for your fish finder. If you are worried about capacity, go up to a 27 series battery if you are currently running a 24. That will get you more capacity for just a little bit of weight gain.

 

[mint_2k]

6 years for a battery is a good life.

The battery charger will behave as before in regards to what mode it is in. It will just be able to have a maximum charge of 10A instead of 5A. Everything else will be the same.

You should be able to listen to the radio for quite a long time before ever having to worry about starting your engine. Same goes for your fish finder. If you are worried about capacity, go up to a 27 series battery if you are currently running a 24. That will get you more capacity for just a little bit of weight gain.

Thanks again. That's a very good idea. I have plenty of room under the rear deck for a larger battery than the current one.

 

[Fed]

When you got the 7.5V reading were you measuring right at the battery posts rather than the lugs or bolts?

 

[mint_2k]

When you got the 7.5V reading were you measuring right at the battery posts rather than the lugs or bolts?

I had the multimeter on the posts themselves. I've only had the boat out 3-4 times since I bought it, but the previous owner said he had not taking it out for a while, and left it on the on board maintenance charger. It was just this last time where I started noticing toward the end of the day that it was cranking slower and slower. It had been plugged in for 4 days prior. I'm just guessing since it's a 6 year old battery that it's due for replacement. I have to be able to trust it for sure, and right now - I don't :grumpy:

I'm leaning towards picking up a dual purpose cranking / deep cycle tomorrow and seeing how it does.:joyous:

 

[bruceb58]

I'm just guessing since it's a 6 year old battery that it's due for replacement.

Yes! I always replaced mine at 5.

 

[Grandad]

Yes, I agree with Bruce all the way. I have 2 Costco deep cycle group 27's that I use for starting and little else. Radio maybe. Once in a while to inflate a water tube. These batteries are more than adequate to start my 4 cylinder I/O. I have 2 only so that one is always sitting on standby and I interchange them regularly with my battery switch so I know they're both still good. I think the deep cycle may stand up better to infrequent use and irregular charging, should that happen. I've always replaced after 5 years, but may try to stretch this one more season to 6 years, but any sign of weakness from either one and they'll both be replaced. - Grandad

 

[Fed]

Good work on the testing.
Grab a genuine OMC pull cord (~$5) and learn how to use it, you'll feel a lot better on the water with that.