AGM Battery - Two Holes in Case

[four winds]

Been reading all the electrical threads with interest. Planning upgrades to my setup.

Yesterday I noticed the Guest 5/5 dual battery charger was not in float even though I've been at the dock for weeks. Not using much DC so I was suspicious. Checking the analog volt meter next to my DC breaker panel showed one battery to be a volt less than the other.

Knowing something was amiss, I grabbed a flashlight and found one battery to be warm and the other cold. Further inspection showed the two melted spots pictured below.

Looks like it melted from the inside out. Looks like it could be the location of the connection lugs for that cell. Does that make sense? Did a cell short out?

Batteries are Sea Volt from West Marine, group 31 105 amp hour each. Date code wasn't punched out, but the case sticker says A7 on both, so could have been made in Jan'07, I'm guessing.

The batteries are in a wooden case with a plastic lid. Notice the proximity to the nylon strap. The strap was stuck to one of the holes where it protrudes the most. I can't believe that had anything to do with it.

From my reading here, everything is wrong with my setup. I recently upgraded to a 80 amp Hitachi, but:

-it's internally regulated
-the charge wire still goes to the starter.
-2 AGM batteries with a Guest 5/5 charger made for flooded or gel (just read this last night) and only 10 amps.
-batteries on a 1-all-2-off Perko switch, 2 banks of 1 battery each, no start battery or echo charge.

I've started making a wiring diagram for the boat and intend to make some changes as funds permit.

For now I've isolated the bad battery and will use only one. I have a spare battery for the dink trolling motor that's good to go. So I can still go for a sail overnight and have a backup start battery. Obviously need to get things better sorted out before my next extended trip, not sure when that will be.

Any advice or discussion of how best to upgrade my system would be appreciated. With the caveat that I can't throw huge sums of wallet shrapnel at the issue immediately, but over time can get there.

[btrayfors]

Yep, A7 is very likely Jan 2007. And, these date codes on the WM (East Penn) batteries are sometimes the date they left the warehouse, not the date of manufacture. I just came across a whole bunch of bad AGMs in a local WM and called East Penn to try to get some further info.

In any case five years is about it for AGMs. I think in your case I'd:

1. Replace both batteries;

2. Use flooded not AGMs....cheaper, more tolerant, best bang for the buck. Also, they won't over-tax your Hitachi alternator;

3. If you can squeeze in two golf cart batteries for the house bank, that would be an improvement.

4. Get a new battery charger. Best bang for the buck, IMHO, are the Iotas...I'd get a DLS-45/IQ4 or DLS-55/IQ4 for your setup. Not very expensive and very capable. Or, if you're really feeling flush and would like to spend $400-500 on a battery charger, one of the new Sterling/ProMariner Ultras would do the trick.

5. Move the alternator output to the house batteries, with a 100-amp ANL fuse located near the batteries.

6. The start battery could be just a group 27 or 31 12V starting battery (NOT a dual-purpose or deep-cycle). An EchoCharge could take care of the maintenance automatically.

Bill

[four winds]

Thanks Bill, your advice is right along the lines I was expecting.

I've had shorted cells before in cars, but never a hole in the case. I'm guessing the battery is merely succumbing to old age.

I figured on the need to replace both batteries. I like the idea of AGMs but I'm just not set up to properly maintain them. I'll start researching flooded batteries. And look into the chargers you mention.

Of particular note, you did not advise to go to an external regulator which suits me just fine.

I need to do this in stages, so my initial thoughts are;

First, install two new batteries paralleled as a house bank 1. Put the existing dink battery in as starter bank 2. (usually row the little boat) Leave the charge wire on the starter for now. Use the dink battery on bank 2 to start the engine and motor out.

My Perko switch allows make before break, so if motoring for longer time I can switch to the house bank 1 to charge while underway and use at anchor for the overnighters.

Second, install an Echo Charger and move the charge wire to the house bank 1, charging the start battery through the Echo.

Third, install a new shore power charger. I wonder if this is needed if I switch to flooded, though it's pretty small at only 5 amps for each battery. It is supposed to keep the batteries balanced with dual outputs. It's not a particularly robust looking device, but works. I also have one of the typical Schumacher Ship 'n Shore 15 amp chargers as a backup.

[four winds]

Well, looks like more than $600 to replace with the same batteries, and over $800 for equivalent gels. Not going down either of those paths.

The venerable Trojan T-105 6 volts would be around $300 for a pair with an extra 20 Ahr capacity over the current pair of AGMs. And I'm hardly 20 miles from a warehouse location.

There is a new model 105, the T-105-RE. (Renewable Energy) It weighs a few pounds more than the T-105 and the data sheet says it has heavier construction in some details.

I'm thinking these would serve me well, though open to opinions of others.

[cal40john]

There's nothing wrong with your system as described. Nothing that would have caused a cell to short. But there are better ways to do it as you've seen in the discussions for making your batteries last longer and take less time to charge.

John

[mitiempo]

I agree with Bill's recommendations. You could save money though and buy the Duracell brand golf cart batteries from Sam's Club. They are made by Deka/East
Penn and are good batteries. They are sold at Sam's for about half what West Marine sell them for. About 170 for the pair at Sam's I think.

[sailcruiser]

I have read good things about both Sam's and Costco 6v batteries. I will likely buy from Costco since I'm not a member of SAMs. MaineSail did an interesting writeup on Walmart batteries too. If you don't need a huge shore power charger less is more. I just replaced my charger with a 15 amp from Victron. Iota was my second choice. Otherwise you seem to be on a good path. I'm in a similar mode with my boat. SC

[four winds]

I was surfing the Sam's Club site but couldn't locate the battery section.

I will look further and check Costco.

Thanks for the input everyone. I need to spend my pennies wisely.

[sailcruiser]

I do understand that sentiment. I've linked the posti referred to below from this forum's sister site. MaineSail is a marine electrician.
http://forums.sbo.sailboatowners.com...d.php?t=132350

If you poke around a little more you'll find the Walmart post as well. Good luck! SC

[four winds]

I'm reading a thread from last year with good discussion as well.

But it's late and I'm too tired to concentrate, so calling it a day.

http://www.cruisersforum.com/forums/...ies-46671.html

[Kettlewell]

As far as I'm concerned everyone should read this thread by MaineSail before they redo their batteries and battery switches.