Batteries lasting only 2 years - AGM any better?

[Joe500]

My battery bank consists of two group 31 flooded batteries for bank 1 and one group 24 starting battery on bank 2. They are charged by the engine alternator and a 100 Watt solar panel with Victron Blue Solar MPPT charge controller. My boat normally sits on a mooring during the season, though starting this year it will be at a dock.

We replaced the batteries in 2013. In October 2015, with the colder temperature, we could not start the engine. We would just hear the solenoid clicking away. New batteries seemed to solve the problem in May 2016. Now, in May 2018 on the first starting attempt, all we get is the solenoid clicking with no rotation. I assume it's the batteries again (though voltage only falls to 12.4 when I rotate the key). If it is indeed the batteries, why are my batteries lasting only two years?

One thing I should mention is that I leave the batteries in the boat in the Connecticut winter when the boat gets hauled out, and I let them get charged by the solar panel. I don't take them out because sometimes we do work in the boat in the winter and need some power, because they are heavy to haul up and down the ladder, and because I don't have a good garage to store and charge them. The solar panel works well, though there was an entire month when the solar panel got disconnected and there was no charging.

When I replaced the batteries in 2016, I also installed a Victron battery monitor so I could monitor amperage, charge, etc. I'm careful not to discharge the batteries too deeply.

Is two years normal? If I got an AGM battery, would it last longer given this setup? Should I get the optima brand AGMs? My understanding is those handle a variety of charging profiles and so I wouldn't have to get a new alternator. My boat is from 1987 so I don't even know if I could get an alternator for AGM batteries for it.

Any thoughts or suggestions would be appreciated.

Joe

[Lepke]

I use flooded batteries for both starting and in house banks. They usually last 8-10 years. I use Dyno batteries, one of the best brands made in the US.
If you allow the water to boil off or if the battery freezes, it will limit the life. I live aboard and some winters I get near zero. But I'm in the water and my bilge and engine room stays just above freezing. Coldest I've measured is 34°.
If freezing is the problem and you have power to the boat there is a temperature plug available that comes on at 35° and off at 45°. It can handle 1500 watts, enough for a heater or heat lamp.
The Thermocube comes in other heat ranges for things like AC. Less than $20 on ebay.

[Joe500]

Wow, 8-10 years, that's great. My batteries are interstate brand, I get them from the local marine shop. The boat gets hauled out for the winter in Connecticut. I didn't know about the permacube, that's neat. Unfortunately, permanent power connections are not allowed in the winter in the marina. I imagine temperatures can get as low as 10F at night, but the batteries stay charged and therefore my understanding was that they would not freeze.

[travellerw]

I get the feeling that you are not getting true deep cycle batteries from your local marine shop. I know interstate is a great brand, but maybe they have some "duel use" batteries that you are getting.

2 years is not typical for lead acid batteries that are lightly used like that. We have standard golf cart batteries and have 2.5 years on them (full time live aboard). Our batteries have over 700 cycles on them.

AGM batteries are great, but I think they might be overkill for you. Maybe have a go at 6V golf cart batteries. Cheap and cheerfull (SAMS club or Costco).

[Sailmonkey]

We’re on our 8th year with 4 golf cart batts for the house and a group 24 start battery.

I’m wondering, during the season, how low do you cycle the batteries? And how throughly are they charged?

[Jim Cate]

And how throughly are they charged?

Critical question!

AGM batts like to be FULLY charged on a regular basis. Many solar regulators do not actually do this. See Manesail's writings on this subject... might explain lot for you, and likely lead you away from AGMs.

Jim

[44'cruisingcat]

If the volts are only dropping to 12.4 when you try to engage the starter, I'd suggest the problem may not be the batteries.

Check all the connections between the batteries and the starter, also make sure the negative side is clean and well connected to the engine block.

The starter relay contacts may be dirty too.

[Neptune's Gear]

First, batteries don't die, they are murdered! You MUST charge them correctly, as per the PDS for that exact make and model.
Next is that this issue sounds like a stuffed solenoid, or excessive voltage drop at the starter solenoid. Check the cabling - how old is it, does it have quality crimps and terminals?
My last set of batts was VRLA, and lasted 14years, incl 3 years liveaboard around the world. Look after them and they will look after you.

[Pete7]

In addition to Neptunes excellent suggestions, how are these batteries wired up? Does the solar panel only charge the house bank or house and engine start, if so how?

We have an almost identical system, 2 x 110 AH FLA and a separate small engine battery. The 150w solar panel charges the house and when that is full a VSR trips in at 12.8v and charges the engine battery. House bank are Varta Hobbies, nothing special and now 7 years old.

Pete

[ranger58sb]

Originally Posted by Joe500

Is two years normal? If I got an AGM battery, would it last longer given this setup? Should I get the optima brand AGMs? My understanding is those handle a variety of charging profiles and so I wouldn't have to get a new alternator. My boat is from 1987 so I don't even know if I could get an alternator for AGM batteries for it.

Not normal; something you're doing is killing your batteries prematurely.

And most AGMs would apparently be worse, since they need to be fully recharged relatively often. Firefly Carbon Foam AGMs might be an exception to that, at even more expense.

Probably better to work out how you're killing your flooded batteries before making any other changes...

-Chris

[roland stockham]

Interstate are good batteries. AGM's will do worse. This is not a battery problem it is a charging one. For some reason your system is not keeping the batteries charged. If a battery stays flat for more than a few days it will severely shorten it's life. Also I they are not fully charged about once per month they will die more slowly due to sulfation. I would suspect it is the second problem that you have. Likely you are only getting to 90-95% charge. That means you will loose about 5% of your battery capacity per month. I would suggest the ideal is to plug into a dock supply or run a small geny for a day once per month. After charging normally I like batteries need to be kept at 14.5-14.8v for 4-6hr once per month to avoid this. When really full charge FLA's should be accepting less than 3% of capacity at 14.8v (i.e. 3a per 100 amp/hr).

[ArmyDaveNY]

How are your batteries mounted? If they are fore and aft, that could be a big issue. They should be positioned athwart ships. If they are fore and aft, the plates may be exposed to air and that could be an issue.

This is a great read on how to properly situate your batteries.
Installation & Orientation of Flooded Batteries Photo Gallery by Compass Marine How To at pbase.com

As the others have said, check the entire system. Also, if possible get deep batteries such as gold cart batteries. This will allow the internal plates to remain in the electrolyte even when heeling.

[Caliber40]

What was the voltage before you keyed the switch? A fully charged battery is 12.8 V and 12.4 represents approx a 50% charge. On a regular basis how often do the batteries go below 12.3V ? If often how low do you let them drop to that level.

Very possible you have a starter/solenoid issue. Some boats have too small of a connector wire from the ignition switch to the solenoid causing below satisfactory drop in voltage. I dont remember what engine you have but Yanmars are notorious for this.

If you are starting with a 12.8V battery and getting "clicking" I'm betting it's not the battery.

Good luck

[01kiwijohn]

I have a similar set up and get about the same life as you do. We live aboard for about 5-6 months per year. Gels and AGM may be better but, we travel into some more remote areas and figure that simpler is better for us. I can get a replacement lead acid battery almost anywhere. May not be an ideal replacement, but will work.

[RSB333]

As mentioned already, it appears that the batteries might not be the problem. Check the voltage before trying the starter. If they appear at or near fully charged, then it's likely there is a voltage drop in the starter circuit. I had this problem, and foolishly replaced the starter - to no avail. When I replaced the wire from the key to the solenoid with AWG 10, the problem went away. My single group 31 FLA starting battery is two years old and going strong.
rsb