New Batteries

[MarkD]

Academy - The Exide Golds used to be available thru boaters world. If you are referring to the Stowaways, these are available thru Sam's Club. They are both Group 31's.

I looked on the Boaters World website and couldnt find ANY deep cycle batteries. I know for a fact they have them however. Give the local store a call and they should be able to tell you what they have in stock. I do remember that I had to travel to a store nearer Long Island Sound to get the bigger sizes. Some local shops (away from the big water) sometimes wont carry them. They typically have group 24/27's....

Hope this helps.

 

[Alex D]

The other issue that keeps me away from Optimas and AGM is the fact that both, Optima and AGM have had their significant share of problems with early failure. Further when AGMs fail, they do on the spot from godd to no power. They do not "annouce" their failure like lead acid batteries

I believe AGMs can be load tested at the end of the season or prior to the start of boating and this will give you an indication of the likely remaining life. At least that is what my yard is saying. Tiara just switched back to flooded batteries because of the high cost without added life of AGMs. The value was not there. Many of their boats are sold in Florida and heat could be the culprit. I plan to stay with AGMs and test them because it is very difficult to get to my batteries. Having to check them monthly would be a real PITA.

BINGO! Having been a Corvette owner I remeber the debacle when they put AGMs in the '03 C5s. They would just up and die and leave people stranded sometimes far from home. No warning. One minute they work fine, the next they're bone dead.

 

[STIHLBOLTS]

You might want to try Battery Source instead of a west marine. Just bought a starter/deep cycle 31 for only 79.00. Lot's better price than $120.00. :smt009

 

[rondds]

academy
if you haul your boat for the winter, it doesnt pay to get the batts til you are ready to launch. you'll lose 4-6 mos on the warranty.

if you have sam's club in your area, that'd be the easiest place to get em (the stoaways).

 

[Dave M.]

BINGO! Having been a Corvette owner I remeber the debacle when they put AGMs in the '03 C5s. They would just up and die and leave people stranded sometimes far from home. No warning. One minute they work fine, the next they're bone dead.

I don't think comparing how they would work under the hood of a Corvette, if that is where they were, to use in a normal boat situation is meaningful. Almost no AGM can survive at 130 degrees, and I expect it would get hotter than that under the hood.

Doing a load test on an AGM battery certainly is possible, and can tell you about the condition of the battery. Doing more than one load test can tell you more. If you can put a relatively constant load on the battery that would discharge it in 6 to 18 hours, and you have a good voltmeter, you can test it yourself if you know or can measure the current draw. You just put the load on the battery, and take voltage measurements, record the voltage and time. Plot them on an x-y graph, and you get a nice curve. If you are able to hold current constant, then current times the time to discharge gives the amp-hrs.

A AGM battery will signal impending failure in three ways. First, the cell impedance of some cells will start to climb from their initial value. Actually, nearly all will climb, but some more than others. But since we don't have access to individual cells in our batteries, and we don't have impedance testers, we can't detect this.

Second, the float current will increase. You can check this with a clamp on ammeter such as I mentioned in a previous post. When it increases by a factor of 5 or 10 from new, then you should not stray far from shore.

Thirdly, when you load test them, they will give differing results depending on the discharge rate. So if you do a 4 hour discharge, they may come out at 50% of capacity, but if you do a 12 hour discharge, they may show 90% of capacity. This difference in % capacity remaining is your clue that the battery is failing, probably drying out. By this I mean that the plates are still good, the acid is still in the battery, and mat is good (although early version AGMs did have an issue with the mat not contacting the plate over time). The battery still has its capacity, you just can't get it out quickly. The culprit is the lack of water to let the process happen quickly enough.

That reminds me of a forth method to determine condition. Put the battery and a fairly quick load test, say 4 hour discharge rate. Record the voltage. When the battery voltage gets down to halfway between charged and discharged, remove the load for a minute. If the battery voltage stays about the same, you are seeing the real battery internal voltage and seeing its true capacity. But if the voltage pops back up to some substantially higher number, then you are seeing the effect of the cell drying out. IE, you are seeing the difference between the 4 hour and the 12 hour discharge rate. If it pops back up like that, you have problems, probably drying out.

Sometimes if the float current starts to climb too much, it can help to equalize the battery for 24 or 48 hours. IMHO, it is totally reasonable to get a clamp on ammeter and record this in your boat log. Don't equalize at a temp over 85 or so, try and equalize at around 75 degrees.

If you have the problem of a large difference between the fast and slow discharge tests, or the voltage popping back up in the middle of a load test when you remove the load, then the battery is dry. Obvious solution, add distilled water. Maybe 1/2 to 1 cc per amp hour battery capacity in each cell. This of course may be impossible, or all the reps may say it is impossible. But depending on cell construction, you may find a vent for each cell to relieve high pressure. It may be possible to remove the cover of the vent, and behind it there may be a screw in pressure relief seal that you can find a way to unscrew. You should have face and eye protection. If you get this far, take a syringe and use it to inject the distilled water into the battery. Even if the battery is laying on its side, so the opening is on the side of the battery, this is possible. There is no water sloshing around in an AGM, so none should come out. And it should be able to absorb what you put in. Whether or not all this is possible is totally dependent on the design of your particular battery. I have seen this add years of life to an otherwise dead AGM, on at least three different battery sets.

Wet cells are so much easier!

 

[LMBoat]

I'm a lead-acid guy too. My batteries are not bad to get to. They last 3-4 years, I don't have to change the charger out, etc. For me, the "old standby's" work great. I have good luck the Sears Marine Diehards. I can tell when mine are about to go and keep an eye out for a sale. I can usually get the Groug 27 for $70 bucks.