# Battery question



## paulrad (May 10, 2016)

I'm feeling like my battery is giving up sooner than it used to. I just use it to run my gps and my TM. I've even taken to starting my motor with the pull cord instead of electronically just to save on battery power. I did some experiments recently. I charged it up until the charger said full and then measured the voltage on the battery. It was 12.7. Then I measured it again a couple hours later - nothing was powered up, but wires were still attached - and got 12.5. Then I powered it up again until the charger said full again, and remeasured voltage. This time I got 12.6. I pulled all the wires off the + side of the battery and waited a few hours. I then got a 12.5 again. 

Would this be considered "normal"? Any better tests I ought to do? The charger works fairly quickly, but maybe it's not really giving a full charge up to the batteries?

Any wisdom you'd be willing to share would be appreciated.


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## MariettaMike (Jun 14, 2012)

Take the charged battery to AutoZone, Advance, NAPA, Reilly,.... and have them do a load test for free.


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## jay.bush1434 (Dec 27, 2014)

X2 with what @MariettaMike said. Testing with a voltmeter won’t tell you much. Load test will tell you the batteries health.


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## paulrad (May 10, 2016)

Ok. Took it to get tested. It said "Battery fails to meet industry specifications". It listed potential causes of premature failure as these:

1. Excessive vibration due to improper holddown.
2. Excessive power drain.
3. Faulty charging system.
4. Repeated severe discharge.

I have it on its side in the bow of my boat. It's clamped down. But maybe the bow hitting waves caused problems??

I don't know what constitutes excessive power drain or severe discharge. I use it fairly consistently and I'm generally pretty good about charging it back up right after I use it. I did buy a solar panel with a trickle charge controller to just leave on it all the time when I'm not using it. Haven't hooked that up yet.

The faulty charging system possibility does kind of worry me. I have a black and decker battery charger. It supposedly has the intelligence to figure out what kind of battery and controls the charge and whatever. But it is really old. Wondering if maybe I ought to get a new one. 

Good thing is that the battery has three year free replacement. I will employ my secret weapon to accomplish that one though - the wife will relentlessly pursue this type to thing to a degree that most people can not even imagine. She is ferocious is these situations. hahaha... I'm confident she will bring me a new battery this evening.


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## SomaliPirate (Feb 5, 2016)

Maybe someone smarter than me will chime in, but I believe AGM batteries are less susceptible to vibration/impact damage than the flooded lead ones? Might want to swap out to one of those after you use up the free replacement?


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## paulrad (May 10, 2016)

The one was an AGM. Probably should have mentioned that.


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## Finsleft258 (Oct 7, 2018)

SomaliPirate said:


> Maybe someone smarter than me will chime in, but I believe AGM batteries are less susceptible to vibration/impact damage than the flooded lead ones? Might want to swap out to one of those after you use up the free replacement?



Correct. They also have a lower self-discharge rate.


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## jay.bush1434 (Dec 27, 2014)

I'm not sure what kind of load test reads out "failed to meet industry standard" but in any event, it sounds like the battery has a bad cell. AGM's aren't really affected by vibrations or odd mounting angles. A battery with a bad cell with still take a full charge and will show full voltage when tested with a voltmeter. However, once a load is applied to it, it the charge with tank and the voltage will rapidly fall off to below 10vdc which is essentially a dead battery.


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## paulrad (May 10, 2016)

Woopwoop!! I got a new Interstate battery under warranty! The secret weapon worked! The place where I originally got it went out of business, so the pucker factor was a bit elevated. But she came through for me at the distributor! hahaha

They asked what charger I was using, and recommended a battery tender 5 amp model for it. I bought it so if this happens again they won't have any excuse. I'm pretty excited.


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## jasonrl23 (Jul 27, 2009)

paulrad said:


> Ok. Took it to get tested. It said "Battery fails to meet industry specifications". It listed potential causes of premature failure as these:
> 
> 1. Excessive vibration due to improper holddown.
> 2. Excessive power drain.
> ...


I just went through this. My charger was only charging one bank. Ruined a new battery.


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## paulrad (May 10, 2016)

jasonrl23 said:


> I just went through this. My charger was only charging one bank. Ruined a new battery.


Wow! I think the guys at Interstate were suspicious of my charger too. They really wanted me to get the new battery tender one. I'm glad I got it. 

One thing about my old charger. It had option to charge at 4, 10, 20, or 40 amps. I would frequently charge at 10 and sometimes at 20. I have come to find out that this might have been bad. New one won't go over 5.


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## LowHydrogen (Dec 31, 2015)

paulrad said:


> I would frequently charge at 10 and *sometimes at 20*.



You wanna go low and slow, like good BBQ. Charging fast = higher temps, higher temps = less longevity for the battery.


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## jasonrl23 (Jul 27, 2009)

paulrad said:


> Wow! I think the guys at Interstate were suspicious of my charger too. They really wanted me to get the new battery tender one. I'm glad I got it.
> 
> One thing about my old charger. It had option to charge at 4, 10, 20, or 40 amps. I would frequently charge at 10 and sometimes at 20. I have come to find out that this might have been bad. New one won't go over 5.


I made the mistake of trusting the charger that came with the boat. It was a 2015 10 amp charger. Bought a dual bank Minn Kota with 5 amps per bank plus maintenance mode which I think is 1.5 amps per bank. Worth the money for sure.


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## TwitchAO (Feb 18, 2019)

If you are using an onboard charger I would go with a Promariner ProSport 6 amp. One of the best marine onboard chargers for the money out there. Has a maintenance just like the tender but is built a little better for the harsh environment of salt water and air. I am still using the same one I bought 8 years ago.


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