Battery Charger Question

stopngo

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This is the Battery Charger

Minn Kota Mod MK 105 P..........1 Bank .5 Amp......Output 12 VDC 5 Amps

No problem on most batteries.....meaning that when put on charge the charge light comes on and when charged the fully charged light comes on.

Problem is on one of my batteries which is less than a year old. When charger connected the yellow charge light comes on but within 10 seconds it flashes back and forth between the yellow charge light and the green fully charged light..

Any ideas???
 

stopngo

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Answer to both of your questions is NO. And this battery while in the RV is being maintained by the onboard charger converter in the warmer months and stored in a heated garage in winter.and it cranks the engine with absolute vigor....no sign of weakness. It cranks and cranks without slowing down yet showed only 12.45 V when I put the charger to it. .I get the above described problem.

New development.........Used my other charger and charged at 2 amps for a few hours. 2 hours after disconnect still reads 12.92V hmmm. You mentioned letting it sit 20 minutes and there is definitely no problem there.

My next Question.......Should the 12.6 to 12.7 hold indefinitely provided there is no draw on the battery? After sitting a few days it goes to 12.45.
 

alldodge

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2 hours after disconnect still reads 12.92V

After sitting a few days it goes to 12.45.

I'm leaning toward your meter is defective
 

bruceb58

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My next Question.......Should the 12.6 to 12.7 hold indefinitely provided there is no draw on the battery? After sitting a few days it goes to 12.45.
It should not drop that much in a couple days.12.45V means it has dropped capacity over 10% or it never got charged completely in the first place. Is the battery disconnected when it drops it's voltage or is there some parasitic draw on it like the engine ECU or radio?


battery.png
 

MH Hawker

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sounds like a bad cell, thats how every one i have had for the last 6 years have failed. i have had to replace mine ever year
 

bruceb58

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sounds like a bad cell, thats how every one i have had for the last 6 years have failed. i have had to replace mine ever year
If you have to replace a battery every year, something is very wrong.
 

stopngo

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It should not drop that much in a couple days.12.45V means it has dropped capacity over 10% or it never got charged completely in the first place. Is the battery disconnected when it drops it's voltage or is there some parasitic draw on it like the engine ECU or radio?


battery.png

Battery is completely disconnected during my observation. Earlier I stated that using the other charger it read 12.92 2 hrs after disconnect. 6 hours after it reads 12.88.
 

bruceb58

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12.88 is pretty much impossible with a lead acid battery once the surface charge dissipates. Now I am questioning your meter. You aren't using a cheapy meter are you?
 

stopngo

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12.88 is pretty much impossible with a lead acid battery once the surface charge dissipates. Now I am questioning your meter. You aren't using a cheapy meter are you?

No I don't think so . My other 2 batteries show 12.6 to 12.7. After 9 hours the subject battery now reads 12.85. As for the accuracy of the Multimeter it does read 1.5 volts on a new 1.5 volt flashlight battery if that is any indication,
 

bruceb58

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Weird. Best test at this point is a load test. That will tell you a lot.
 

MH Hawker

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If you have to replace a battery every year, something is very wrong.

i have about the worst conditions for battery's, a 10 hp motor with a 4 amp charging system on a slip kept boat with out 120 v for a on board charger, it never gets a hard charge to clean the cells, i do give it one at the end of the year but i am sure its not enough so if i get a year out of one thats how it is
 
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bruceb58

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Probably because the battery stays in a discharged condition for a long time. How often do you run your boat?

Do you have a battery switch that you turn off every time you use your boat?
 

stopngo

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Probably because the battery stays in a discharged condition for a long time. How often do you run your boat?

Do you have a battery switch that you turn off every time you use your boat?

I need to let the cat out of the bag. The battery of which I speak is my RV Cranking Battery which has never sat around in a discharged condition nor subjected to cold winter conditions and is less than a year old.
 

bruceb58

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I need to let the cat out of the bag. The battery of which I speak is my RV Cranking Battery which has never sat around in a discharged condition nor subjected to cold winter conditions and is less than a year old.
Sorry, I was replying to MH Hawker. That is what happens when you get two stories going at the same time.

As far as YOUR battery is concerned, some times sh_t happens. I have had batteries only last a year in my car that I use every day and never discharged.
 
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