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AGM Battery Life Expectancy

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Jun 4, 2011
26
Hunter 31 Panama City
Shakedown trip on a newly acquired 31' Hunter (1984) turned up battery issues. I have a starting battery (no issues with this battery) and a 3 battery bank of AGM batteries. The batteries are maintained on charge 24/7 while in the slip. We left the slip, motored for one hour, sailed for 4 hours and motored for another 30 minutes to our anchorage. While under sail, we ran our Adler refrigerator, the radio, electronics (GPS, Autohelm on but not used, depth sonar and one small 12 volt fan in the v-berth). While at anchor we used the refrigerator, radio, water pressure pump, one fan, anchor light). My the morning, the house bank of 3 batteries were dead.

On my last vessel I could easily go 24 hours or longer on a single house battery.

Right now I'm not sure if I left the electronics switch on or not. This would include the auto pilot. The GPS was off and stowed. The depth sonar may have also been left on as well.

Based on past experience, I would expect a bank of 3 batteries to last more than 24 hours with charging occurring at two intervals, one for an hour and another for 1/2 hour during that time frame.

One other issue with these batteries is that they are very hot when on the charger. The wood on the seat above the batteries is very warm to the touch. Is this normal?

I have added pictures of my charger and the labels on the batteries if this helps in offering a reply.

Thanks in advance for advice.
 

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Are you sure that you are running off the house bank and not the starting battery?

I would disconnect the connections and test the three batterys seperately as well as a bank. You may also want to have the batteries load tested. Every boat is wired differently so be sure you are not chasing a dead horse.
 
Nov 26, 2006
381
Hunter 31 1987 Fly Creek Marina Fairhope,AL.
As Steve mentioned, I would test the batteries individually. I had 2 AGM's in my H-31 I purchased in Sept of last year that had one went bad. However , they were installed in Sept 2004 so they lasted 6 yrs. Due to the foot print and performance, i replaced with same brand and size.

Solved my issues. Also night consider running a test at the dock and leaving the anchor light, refer running all night and check it the next morning if practical.
In regards to the heat issue, i suspect a bad cell .
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Did you check a monitor while sailing? I have found that the autohelm can really suck the amps depending upon the weather.
 
Nov 6, 2006
8,571
Hunter 34 Mandeville Louisiana
Make sure the Charger is set to AGM's ... I agree that it sounds like maybe one or more bad cells, but running the reefer full time could be the thing using all the power. Do you know the ampere draw and duty cycle? If the fridge evaporator is air cooled, check the air passages to and from the evaporator and check that the evaporator fan (if there is one) is running ..Stuff as benign as dust bunnies and/or spider webs can really increase the amp draw by restricting air flow. If it is water cooled, check the strainers and stuff for correct flow.. but ass mentioned, check the batteries first.
 
Jun 4, 2011
26
Hunter 31 Panama City
Thanks for the feedack thus far. It seems that one battery is hotter than the other two. I will do some troubleshooting by taking the system off charge and leave a few things on over night and check in the AM. I have read that the life expectancy is 4-7 years and this set is 5 years old. To replace any one or all three with the exact same battery will set me back about 750 bucks! Considering the rapid drain it's likely the problem is all the batteries, rather than just one. Again, I'm not sure if the autopilot was left on all night. Does anyone know if the power consumption for the autopilot is high when on or just when in use? I will also troubleshoot this if needed. Tonight I will leave a couple lights and the fridge on and see what the morning holds.

Thanks for the assistance.
 
Jun 4, 2011
26
Hunter 31 Panama City
Steve Dion said:
Are you sure that you are running off the house bank and not the starting battery?

I would disconnect the connections and test the three batterys seperately as well as a bank. You may also want to have the batteries load tested. Every boat is wired differently so be sure you are not chasing a dead horse.
Where would one have a battery load tested? In what state of charge should this be done?
 
Nov 6, 2006
8,571
Hunter 34 Mandeville Louisiana
Auto parts places can do a rudimentry check that would tell gross problems.. The autopilot if in standby (and working correctly), draws less than one ampere.. so it should not be a problem..
 
Jun 4, 2011
26
Hunter 31 Panama City
Ed Schenck said:
Did you check a monitor while sailing? I have found that the autohelm can really suck the amps depending upon the weather.
I didn't check the monitor on the trip out as I expected better battery life with three house batteries vs. The one I have used for several years without issue to be a non issue. On the way home it didn't matter because they were fully discharged. But in retrospect, it was something I should have monitored...lesson learned!
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Load testing should be done with a fully charged battery. Most automotive garages or auto parts stores can do this for you.

If you end up with one battery out of 3 that is bad, you can just remove it from the bank and you will be good to go. You do NOT want to add a new battery to the bank.
 
Jun 4, 2011
26
Hunter 31 Panama City
kloudie1 said:
Make sure the Charger is set to AGM's ... I agree that it sounds like maybe one or more bad cells, but running the reefer full time could be the thing using all the power. Do you know the ampere draw and duty cycle? If the fridge evaporator is air cooled, check the air passages to and from the evaporator and check that the evaporator fan (if there is one) is running ..Stuff as benign as dust bunnies and/or spider webs can really increase the amp draw by restricting air flow. If it is water cooled, check the strainers and stuff for correct flow.. but ass mentioned, check the batteries first.
The charger is set to AGM and there are 3 "temperature" settings on the charger which s currenly set to hot. I need to pull the manual on the charger and educate myself on the settings, etc. I will also need to check the fridge documentation. I know that the fridge s a conversion job from an ice box. It is an Adler model and since it is a marine mode I expected it is designed to be "efficient". My last fridge was a Norcold unit which could run all day and not drain one house battery so I just made an assumption that I would have no problems with this unit...I may be wrong, we will see as I get to so of the suggested trouble shooting.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
If you put a NEW battery in an old bank it will take you new battery down to the level of the other batteries. That is why I suggested that you just remove the single battery if it turns out to be the issue.

This is a different boat and different fridge unit. I would suggest that you try to monitor the usage at the dock with the AC disconnected to see what is going on. It does NOT seem reasonable that your fridge would take the batteries down this fast. Once you get your batteries tested you can make a better evaluation.
 
Jun 4, 2011
26
Hunter 31 Panama City
I disconnected the starting battery and turned off the charger and there is no charge on the house bank which has been on charge for 72 hours. Only one if the three batteries is hot to the touch.

I will pull all three batteries and take in for a load test on each. I like the suggestion of pulling the bad one and not replacing it as these puppies are not cheap! I hope not to have to replace the whole bank of batteries or I may need to sell off one of my kids to cover the cost.
 
Feb 6, 1998
11,165
Canadian Sailcraft 36T Casco Bay, ME
I disconnected the starting battery and turned off the charger and there is no charge on the house bank which has been on charge for 72 hours. Only one if the three batteries is hot to the touch.

I will pull all three batteries and take in for a load test on each. I like the suggestion of pulling the bad one and not replacing it as these puppies are not cheap! I hope not to have to replace the whole bank of batteries or I may need to sell off one of my kids to cover the cost.
You actually got decent life out of them. Wet cells for 1/3 the cost can also last 5+ years.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Actually you can change out the entire bank to a flooded type. They can either be 6v or 12v. The only real downside to flooded batteries is the gasing and maintenance required but they are much cheaper.

I don't like to mess with my batteries, so I have been using Gel's for about 15 yrs. The last set I had lasted for over 10 years.
 
Oct 6, 2009
129
Newport Newport 28 MKII Jacksonville, FL
You might look at the refer thermostat setting to see if it is cranked all the way to max, causing the compressor to run 24/7 without cycling. Still, 3 AGM's should do better than your results.
 
Jun 4, 2011
26
Hunter 31 Panama City
Discovered what was at the root if my battery issue. Pulled the batteries out for testing and 2 of the 3 were cracked open!

Unsure if the cause, more research to do on that.

Now the decision to he made relates to the two remaining batteries which are the same type and age of the two damaged batteries. While they are in working order, it is my belief that the right plan is to replace all the batteries.

Atleast the problem is diagnosed! (except for what caused the batteries to crack)
 

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Mar 3, 2003
690
Hunter 356 Grand Rivers
I have 2 4D lifeline house batteries and 1 Group 24 lifeline starting battery. I installed these batteries in the spring of 05. I am on my 7th season with them and am beginning to experience some issues with the house bank. The batteries seem to be limiting the voltage to about 13.25 instead of the usual 14 to 14.5. I think I will have to replace this season, and certainly by next spring. Since putting on these batteries I have been on the boat a total of 434 days. The three batteries cosst around $750 in 05. Going to be much more this time.
 
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