New batteries

Anchor Management

Anchor Management

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Going to replace my 8D batteries this year. Was thinking about AGM but they are about twice the price. Roughly $600 vs. $300. What's the real advantage of this?
 
Honestly I ve yet to experience AGMs lasting any longer than lead acids...

The only real benefits is that you don't have to add water to them so if your batteries are hard to reach as is often the case on many production bias, it s worth depending extra and not have to break your back. If you switch to AGMs don't forget to set your charger for AGMs
 
I have used AGMs for years. I have had very good luck with them, usually lasting 6 years compared to 3 for standard batteries. According to many it is the cheapest battery you can buy because it is able to stand more cycles, thus the per cycle cost is lower. I just like I don't have all the maintenance headaches or have to worry about acid spills. I have 3 in my boat, 1 in each Waverunner, 2 in my diesel truck and even one in my airplane. All give very good and very long service. I first found out about them when I saw them installed in a boat operated by the Navy SEALS. They like them because a round can go right through them and they keep working. I don't expect to take any fire, but it is a testament to the capability of the battery.
 
I am going into my 7th season with 2x4D Insterstate batteries, no weakness in sight. Runs everything plus the bow thruster all day. Add some distilled water as needed. At $220 each I will replace them when they die.
 
quote:
Originally posted by Anchor Management

Going to replace my 8D batteries this year. Was thinking about AGM but they are about twice the price. Roughly $600 vs. $300. What's the real advantage of this?

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Advantages are usually said to be reduced maintenances (mostly: none), reduced off-gassing, faster charge acceptance rate (potentially useful if you anchor out a lot), in some cases more cranking amps (e.g., Odyssey), and in many cases more cycles and/or longer overall lifespan. Latter depends on whether you follow the manufacturer's charging recommendations.

Disadvantages are price, and they're somewhat easy to murder if you don't follow the manufacturer's charging recommendations.

FWIW, our oldest AGM bank is just now entering it's 12th season... due for replacement sometime this Summer when I get a round tuit.

-Chris
 
If you anchor out frequently there are two weaknesses with AGM batteries; they need to be brought to full charge after every discharge and they cannot be equalized (except Lifeline brand). Both of these points are documented in research by Practical Sailor magazine and my own experience where I only got a year out of an AGM bank (I replaced with flooded batteries and got 4 years). True, they can take a bullet and not spill as they were designed for military applications. They can also be mounted at nearly any angle (except upside down I believe). IMO the best value is still flooded batteries.
 
Never saw the need for anything but wetcells. 3 or 4 years and done. Never had to worry if I was stretching the life of batteries or running on borrowed time.
 
Thanks guys. For me, most important is value. If I'm going to pay roughly twice as much, I want to get roughly twice as long out of the battery. Hate having to remember adding water but they are easily accessible.
 
If you are going with wet cells, do yourself a favor a buy/install a battery watering system. Costs money up front but takes the hassle out of battery maint.

Wet cells go south when they are low on water. If you keep the topped off they last.

I installed on both banks of 8d's (24volt=(8Dx2)x2). Very easy to water the batteries now.

http://www.batterywatering.com/

I installed on all of my battery powered equipment in my warehouses and it really saves time and money in the long run.
 
All this talk about sensitivity and care of AGMs is based upon the old technology. How is it that Johnson Controls AGM batteries are in my diesel truck with no fancy charging, equalizing etc? The last set lasted 6 years.
 
quote:
Originally posted by GeeBee

All this talk about sensitivity and care of AGMs is based upon the old technology. How is it that Johnson Controls AGM batteries are in my diesel truck with no fancy charging, equalizing etc? The last set lasted 6 years.

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Charging hasn't been a big deal. Reading suggests AGMs last longest when fully charged after each (or pretty soon after each) cycle. That's not particularly difficult for us.

In an automotive application, the battery would almost always be left in a fully-charged state after each use... and AGMs don't self-discharge much.

Ours are Odyssey, one of the two brands Practical Sailor recommended at the time. (The other was Lifeline. A couple other good brands exist, but apparently you get what you pay for when it comes to the rest.)

-Chris
 
Though too tall for most installations forklift batteries have good longevity. Mine are going on their fifteenth (15) year!

Ronbo
 
We used AGMs in our house bank which was composed of 2 8Ds in parallel. They never lasted more than 4 years. They were maintained at float with temperature compensation and always charged after a discharge. We went back to Sams Club 8Ds for cranking, and NAPA wet cells for the house bank.
They were a waste of cash but easy to maintain. Our wet cells from Sams lasted just as long.
 
I add a little distilled water to my old style 8D batteries once a season and have been getting 6 or 7 seasons out of them. Never seemed worth it to me to pay double or more for other types.
 
I have never gotten more the 4 years and have gotten less.
Two of my batteries are very hard to get to both to maintain and replace!
 
Plus 1 on the distilled water. We keep a jug on the boat.
 
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