AGM battery experiences

[Jim Walsh]

Looking for your views/experiences with 12 volt AGM batteries. I'd like to hear the good and bad. Name names please.
I currently have two flooded group 27's with a standard off/1/2/both battery switch which have served me well.

[moctrams]

I have two banks of Exide Orbital AGM batteries. They are rated at 935 Cranking amps with 100 minutes reserve capacity. Each bank has two batteries in parallel and connected to the Main Battery Switch, positions 1 and 2. I keep them topped of even in winter using two 100 watts solar panels mounted above my bimini. One bank is in the stbd. Cockpit locker and the other in the v-berth to the rear of holding tank. Hope that helps.

[Klem]

Hi Jim,

I have used the Sears Diehard Platinum batteries in the past and had good service from them. If I remember right, they are rebranded Odyssey batteries which are good AGM's. They lasted at least as long as any other batteries I have had and I would think that they had better performance although I didn't actually keep good logs.

I am curious why you are considering switching to AGM's? They definitely have some advantages but they also have some big disadvantages. The good parts are the higher capacity, higher charge rates, very low discharge rates and ability to be mounted in any orientation. The disadvantages all seem to be related to how easy it is to ruin a very expensive bank. There are definitely people who benefit from AGM's but I know of multiple people who have switched to them simply because they are "better" only to discover that they didn't need the small amount of extra capacity and they ended up being more expensive.

I too am curious to see other people's responses.

[Jim Walsh]

I tend to install my flooded batteries on their shelf in the spring and only check the electrolyte levels once in the summer since they are a pain to access. The battery shelf on the CD31 is in the port cockpit locker against the side of the hull. Perfectly secure but access was an afterthought. I know they can be relocated but I'd prefer to upgrade to AGM's and keep them where they are. Capacity for me is no big issue. Some people exhibit a reticence to run the diesel to top off the batteries every couple days or so, but I don't mind at all. I don't have a reefer to worry about so I use very little energy other than those times my radar is active.

[Russell]

I tend to install my flooded batteries on their shelf in the spring and only check the electrolyte levels once in the summer since they are a pain to access. The battery shelf on the CD31 is in the port cockpit locker against the side of the hull. Perfectly secure but access was an afterthought. I know they can be relocated but I'd prefer to upgrade to AGM's and keep them where they are. Capacity for me is no big issue. Some people exhibit a reticence to run the diesel to top off the batteries every couple days or so, but I don't mind at all. I don't have a reefer to worry about so I use very little energy other than those times my radar is active.

A battery watering system can solve the access issue as well.

[Neil Gordon]

I don't have a reefer to worry about so I use very little energy other than those times my radar is active.

Having kept my on board systems simple, I use very little energy, as well. Two batteries and a 1/2/both/off switch has worked well.

Just a few added comments:

My MD7A and now my Beta 14 are fairly small and don't require serious starting cranking power to get them going.

I use both batteries for starting and let them both charge as long as the motor is running. From there, I use #1 in the odd months and #2 in the even months. That way (i) I don't need to remember the day of the month, and (ii) I don't discharge one, then the other, and back and forth, if for whatever reason I don't run the engine for a while.

It's worked for me for 19 years.

[Bill Goldsmith]

I have two Lifeline 31 AGM batteries for my house bank and one Lifeline 27 AGM as my starting battery. I may be a *little* OCD about my electrical system, but I disentangled my starting battery from the main switch years ago and never looked back. I installed a separate Blue Sea on/off switch for the starting battery, and separate on/off witches for each house battery. My panel also has an emergency "all" switch that combines all three in a pinch.

Most of the time I run both house batteries ON at the same time (which parallels them), but if I see a problem developing in one battery I can isolate it from the loads by turning it OFF. I charge the two house batteries together using a smart regulator and a Xantrex Pathmaker battery combiner. The starting battery is charged using a Balmar Digital Duo-Charge.

This sounds like a complicated and expensive setup, but it actually simplifies my life immeasurably. The charging path is independent of the battery load switches--when the engine is running or the shore power charger is on, the batteries charge automatically even if their switches are in the off position.

I installed this system in 2003/2004, and only replaced the batteries in 2013. I figure 9 or 10 years out of the original Lifelines was a good track record, and was achievable because I followed MFG recommendations using a smart regulator for the identical house batteries, and a separate smart regulator for the starting battery which is a different size.

My starting battery never dips below 13 volts. The cabin lights never dim when I start the engine. I have never had to use the emergency switch. The only failure I have had was a failure of the main smart regulator (a Balmar MaxCharge) which, sadly, was out of warranty, and the company was not interested in standing behind it as many companies do. I replaced it.

So the bottom line is: Going to AGMs can simplify your life. No water to worry about. They last a long time if treated properly. If applicable, in the winter they can be left in place. They are pricey, and the necessary smart regulators are pricey. And if you add a separate starting battery on a separate circuit as I did, it can be more pricey with the extra battery and all the extra switching and wires. But I do like the peace of mind and redundancy my system provides.

[Jim Walsh]

Bill, were you originally equipped with three batteries or was adding the third battery part of your upgrade?

[Bill Goldsmith]

Jim,

I added it. I installed a level shelf in the storage space under the navigator's seat (the forward portion of the quarter berth). I am not sure where you would locate a third battery in a 31 but I am sure there are options.

Bill

[Klem]

I tend to install my flooded batteries on their shelf in the spring and only check the electrolyte levels once in the summer since they are a pain to access. The battery shelf on the CD31 is in the port cockpit locker against the side of the hull. Perfectly secure but access was an afterthought. I know they can be relocated but I'd prefer to upgrade to AGM's and keep them where they are. Capacity for me is no big issue. Some people exhibit a reticence to run the diesel to top off the batteries every couple days or so, but I don't mind at all. I don't have a reefer to worry about so I use very little energy other than those times my radar is active.

Hi Jim,

This certainly makes sense. Our batteries are fairly easy to access so I luckily don't have to worry about this. As Russell pointed out, it may be worth looking into whether a battery watering system would be worthwhile. Luckily your loads are small enough making the battery cost difference relatively small. Other good resources on the subject are member Maine Sail (his website as well as his postings across many different forums) and morganscloud.com which discusses battery technology and AGM's specifically.

[Jim Davis]

While it doesn't make access any better it does make filling easier. I bought a sink supply tube and slipped vinyl hose over the end. I use about six feet of hose. To use I sit a gallon jug of distilled water above, but near the batteries, drop the supply tube in the jug and lead the hose to the batteries. I start the siphon by sucking on the hose and control flow with a finger tip. This lets me fill in cramped space with little overhead clearance. My batteries don't have to be moved, it is just all the miscellaneous equipment and crap that has to be moved to let me get down in the cockpit lockers.

http://www.lowes.com/pd_24958-104-88100 ... facetInfo=

[Maine Sail]

I have lots of experience with AGM batteries and they can be great but you really can't just treat them as a drop-in replacement for flooded batteries, if you want your money's worth.

AGM Batteries - Making The Choice: http://forums.sbo.sailboatowners.com/sh ... post770726

[jen1722terry]

Hi Jim, and sorry to be so late responding. We got back from the Nova Scotia House on New Years, but have been so busy there was no time to do all the CD stuff we so enjoy.

Anyhow, on the AGM batteries:

You may recall that Jenn and I bought Don Sadler's 31 in 2013. Don was a retired USN Master Chief and made a few major changes to the electrical system, specifically: all new AGM batteries, a 160 W solar panel with controller and battery temp gauge and all new engine wiring.

Don lived close to an Interstate plant or distributor in Pennsylvania and was able to get two G-31s cheap. He built a rack under the cockpit sole, behind the engine for the batteries, saying he wanted to get the weight lower. This also moved the weight a bit aft, adding to the "squat" our boat has from the weight of davits and dinghy, plus the old, heavy water heater. It's very difficult to get to these batteries to check them, so I'm glad they're AGMs. They were installed in 2010 and are still strong. With the big solar panel and no refer, we never worry about power (though we may get a 72 watt dehumidifier).

Anyhow, the two 31s are the house bank wired to the 2 position on the battery switch. I believe he installed the temp guage to monitor the temp of the house bank. Why? I'm still not sure. He also installed a blower fan on the engine vent hose set to run all the time, again, per Don, to keep the batteries from overheating. I discussed this with our surveyor and two mechanics, and they all agreed that the fan was not needed. The solar intake/outlet fan on the vent hose were more than adequate. So I rewired the blower fan to a switch on the dash. I now just use the fan prior to starting like most folks.

Don replaced the starting battery with a GR. 24 Deka AGM in 2012, wired to position 1 the battery switch. It has not be a problem, though we've yet to have starting problems where we would do excess cranking. We usually have the switch set to "All" for starting and when running for charging (engine or solar). Engine off, postion 2.

All in all, the 3 AGMs have been great. Lots of power and zero maintenance, so far.

If you'd like to email Don to get his thoughts on his installation, send me a PM and I'll share his email.

That's all for now. Spring is just around the corner. I'm getting thumb surgery in a few weeks (too many painted old boats and houses) and we're hoping I'll be fit for June launching in Nova Scotia.

You stay warm down there in CT

Jenn and Terry