Batteries

[BillG]

I was out in my sister's new boat this weekend and noticed that the battery charger, which is a smart charger, failed every time to go into bulk charging.
Her house bank is an 8D and is on it last leg and she is hoping to finish the season before replacing.  Am not sure of its use and charging history but assume that it was discharged beyond 50% on a regular basis and undercharged.  My question is whether a battery is this shape could trick the smart charger into skipping the bulk stage and going right into absorption mode or could there be something wrong with the charger itself.  there is also a starter battery but it is separated with the house bank.

[KWKloeber]

I was out in my sister's new boat this weekend and noticed that the battery charger, which is a smart charger, failed every time to go into bulk charging.
Her house bank is an 8D and is on it last leg and she is hoping to finish the season before replacing.  Am not sure of its use and charging history but assume that it was discharged beyond 50% on a regular basis and undercharged.  My question is whether a battery is this shape could trick the smart charger into skipping the bulk stage and going right into absorption mode or could there be something wrong with the charger itself.  there is also a starter battery but it is separated with the house bank.

lacking a lot of details to guess what's going on. 
what batteries,
type
age
what charger
her sailing and charging profile
battery profile set on charger
etc, probably missing others on the list!


But one (but maybe not the correct one in this case) short answer is that the charger may be doing it's job and sensing a shorted cell or other fault.  Or the batt is up to voltage but there's no depth of charge left in 'er.  What's the voltage reading when on and taken off charge.

kk

[Ron Hill]

Bill : See if you know anyone that has a battery load checker/tester - to see that batteries' status.

I believe that Harbor Freight has a low cost load tester.  An 8D battery is a critter that you only want to have to move once!!

A thought

[mainesail]

I was out in my sister's new boat this weekend and noticed that the battery charger, which is a smart charger, failed every time to go into bulk charging.
Her house bank is an 8D and is on it last leg and she is hoping to finish the season before replacing.  Am not sure of its use and charging history but assume that it was discharged beyond 50% on a regular basis and undercharged.  My question is whether a battery is this shape could trick the smart charger into skipping the bulk stage and going right into absorption mode or could there be something wrong with the charger itself.  there is also a starter battery but it is separated with the house bank.

If the battery is heavily sulfated the sulfate covering the plates will cause voltage to rise prematurely and very quickly. This is essentially creating a surface charge on the plates but not really charging the batteries well. If bad enough it can essentially zoom through bulk in less than 1 minute... The voltage rises so quickly the charger begins limiting voltage to the absorption setting and the battery charges very slowly... With a charger sized at roughly 20% a healthy battery should remain in bulk for 1.5 to 2 hours..

Here is what it typically looks like, with a healthy battery.

125Ah Group 31 "Deep Cycle" battery fed a 20% of "C" charge rate, or 25A, after being discharged to 50% SOC. It took 1.7 Hours in bulk or constant current charging to hit absorption voltage. If your batteries come up to limiting voltage, with 20% of "C" faster, then there is a voltage or battery issue.

2 Min = 12.59V / 25A = BULK / Constant Current
10 Min = 13.0V / 25A
20 Min = 13.12V / 25A
30 Min = 13.22V / 25A
40 Min = 13.33V / 25A
50 Min = 13.45 / 25A
60 Min = 13.6V / 25A
70 Min = 13.76 / 25A
80 Min = 13.95 / 25A
90 Min = 14.16V / 25A
100 Min = 14.39 / 25A
102 Min = 14.4V / 24.5A = ABSORPTION VOLTAGE / Attained Voltage Limiting

[BillG]

thanks for the responses.  Unfortunately I don't know the history and age of the battery, as it is in a case and I can't see the date stamp and the boat  was only purchased 2 months ago by my sister.  It is an interstate 8D and the charger is a Newmar PT40CE. The surveyor did tell them the battery  was not good, but would last the season.  not sure if he did a load test.  What I do know is that the surveyor failed to discover that the Xantrex Pathmaker, (a battery combiner) was not working and therefore this battery was never being charged while underway.  That is why I can say that the battery was probably being deeply discharged( beyond 50%) on a regular basis and is  probably sulfated beyond redemption. I think that mainesail may have hit it in that the voltage is rising so quick that the charger is limiting the voltage,  I have yet to see it rise beyond13.7 or 13.8. Plans are to replace this battery and I have suggested to them to use
four 6volt deep cycle batteries instead.

[mainesail]

thanks for the responses.  Unfortunately I don't know the history and age of the battery, as it is in a case and I can't see the date stamp and the boat  was only purchased 2 months ago by my sister.  It is an interstate 8D and the charger is a Newmar PT40CE. The surveyor did tell them the battery  was not good, but would last the season.  not sure if he did a load test.  What I do know is that the surveyor failed to discover that the Xantrex Pathmaker, (a battery combiner) was not working and therefore this battery was never being charged while underway.  That is why I can say that the battery was probably being deeply discharged( beyond 50%) on a regular basis and is  probably sulfated beyond redemption. I think that mainesail may have hit it in that the voltage is rising so quick that the charger is limiting the voltage,  I have yet to see it rise beyond13.7 or 13.8. Plans are to replace this battery and I have suggested to them to use
four 6volt deep cycle batteries instead.

Keep in mind that while those Newmars are reliable work horses they are rather dumb "egg timer/dip switch" chargers with pathetic voltage control options. You essentially have only two options GEL = 14.0V or Lead Acid = 14.2V both options are far too low for just about any flooded battery, or AGM for that matter.....

Replace the Pathmaker (these were pretty glitchy) with a Blue Sea ACR, or Yandina, and consider a smarter charger before investing in new batteries...

[BillG]

you are right, there are only 2 options for charging on the newmar, and that is exactly what I installed 2 weeks ago, a blue seas ACR, (during Connecticuts only heat wave of the summer)