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Quent,
Which AGM batteries do you have? I need to replace all
of my 3-year-old West Marine AGM’s. They pretty much
gave up the ghost 6 months ago down islands, won’t hold
a charge – after just 2½ years! I sure won’t be buying
more of those, so I could use some feedback regarding
brands and sources. I prefer AGM’s because they’re
going to live beneath my bunk in the aft cabin, and
it’s one less thing to maintain. However, I could
modify that space to accommodate lead-acid batteries if
I were convinced that’s the way to go.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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Tor,
I think you will find that WM is the most expensive source for batteries.
They sell primarily Dekas, which is a good brand, but available through
other outlets at a much lower price. If you decide to go with flooded 6v,
Allen’s Auto Electric in GCS (across rte 17 from St. Brendan’s Isle) sells
a lot of Trojan T105s for golf carts. They had the best price I could find
($100) in the JAX area for T105s. I have a dock mate who claims he can get
T105s for $50, but then he’s a heavy drinker.
I’ve used WM 6v batteries in the past, but (like you) I had both house
banks fail on me this winter. One bank purchased from WM just before
leaving for the Bahamas. I had to purchase 2 batteries in Marsh Harbor
($$$$). I thought I might get a better deal in GTC or MOW given everyone
on those islands drives a golf cart. Turns out most pf the golf carts in
the Bahamas run on gasoline. Electricity is too expensive and unreliable
to use for charging.
The good thing about WM is that they do stand behind their products. They
gave me a full refund on my purchase when I got back to the states. The
refund on two WM Dekas covered the cost of four T105s.Regards,
John Stevenson
http://www.svsarah.com
Sarah’s BlogOn Mon, Jun 30, 2014 at 9:01 AM, Silverheels via maillist <
> wrote:Quote:Quent,Which AGM batteries do you have? I need to replace all
of my 3-year-old West Marine AGM’s. They pretty much
gave up the ghost 6 months ago down islands, won’t hold
a charge – after just 2½ years! I sure won’t be buying
more of those, so I could use some feedback regarding
brands and sources. I prefer AGM’s because they’re
going to live beneath my bunk in the aft cabin, and
it’s one less thing to maintain. However, I could
modify that space to accommodate lead-acid batteries if
I were convinced that’s the way to go.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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AGM batteries have several advantages VS flooded batteries, but beware when using AGM batteries with a smart-charger. They don’t like the 14.4V quick-charge setting that flooded batteries tolerate. While they will take it for short periods of time, they can be damaged if you overcharge them. This can happen if you start and stop your engine several times during a day thereby repeating the quick charge cycle in your smart-charger. I had a pair of AGM batteries on my boat for two years but they got cooked by my smart-charger.
http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm
I have four 6v golf-cart batteries on my boat that I bought at Sams about 6 years ago. They are still going strong. I top-off the electrolyte with distilled water and avoid running them down below 12.0V under a moderate load.
Rich
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Thanks, John. I didn’t pay West Marine prices for my
batteries since I have a (discounted) Port Supply
account, but it seems their AGM’s only carry an
18-month warranty. I guess they know they’re not going
to last. And anyway, as you point out, a warranty
doesn’t do much good when you’re down islands.If I decide to go with lead-acid, they will almost
certainly be 6V golf cart batteries, in which case I’ll
definitely check out Allen’s Auto Electric. I’d like to
learn more about available AGM’s first, though, and
make a price-vs-value determination. Also need to
measure to see what’ll fit in the locker I built to
accommodate the WM AGM’s.Tor
Silverheels, P-424 #17
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Rich,
Very interesting info about AGM’s and smart chargers. Is that always the case, regardless of charger brand or settings? I’ll double check my Xantrex smart-charger, but I know I set it for AGM’s. Just assumed that made them compatible.
I’ll read that article shortly. Thanks!
Tor
Silverheels, P-424 #17
http://www.silverheels.us
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Hi Tor
Our most recent batteries are Sam’s Club AGM GC, six in total. I understand these to be Deka batteries, identical to Deka labeled but a good bit cheaper. We replaced a set of eight Interstate wet gc batteries that we got in Vero Beach in 2009. The agms spent the winter on the charger so I don’t really know how good they are. I think the six AGMs should have the acceptance rate of eight wet cells.
We also installed 3 size 31 Sam’s Club AGMs in the van, and i’m very happy with them. They seem to hold voltage under load very well, and charge quickly.
AGMs are different than gell cell batteries that are said to be charge voltage sensitive. Everything I’ve read suggests that agm perimeters are similar to wet cell batteries, but time will tell.
One caution I’ve heard about AGMs is that if you run them down, they have a high acceptance rate, meaning that they will max your alternator longer than similar wet cells. So if you anchor out and deplete your batteries, run your engine a bit faster so that the alternator fan can pull more air past the diodes.
Quent -
Hi Tor,
We installed Lifeline AGMs, five of the group 31 105 AH size, when we
blatantly copied your setup. We are now on the fifth season with them
and they appear to be going strong. Lifeline were the first developers
of AGMs and they seem to do them right. The trick is to buy them from a
non-marine source such as the solar power suppliers for off the grid
folks. Yes I know that you still pay a premium for them but I feel that
the convenience and longevity make up for it.On another note, Quent is correct regarding the high acceptance rate of
AGMs. We have a friend who discharged his bank past 50% and when he ran
his engine to recharge, fried his alternator because he hadn’t set an
amp limit on his regulator.On 6/30/14, 4:28 PM, quent via maillist wrote:
Hi Tor
Our most recent batteries are Sam’s Club AGM GC, six in total. I understand these to be Deka batteries, identical to Deka labeled but a good bit cheaper. We replaced a set of eight Interstate wet gc batteries that we got in Vero Beach in 2009. The agms spent the winter on the charger so I don’t really know how good they are. I think the six AGMs should have the acceptance rate of eight wet cells.
We also installed 3 size 31 Sam’s Club AGMs in the van, and i’m very happy with them. They seem to hold voltage under load very well, and charge quickly.
AGMs are different than gell cell batteries that are said to be charge voltage sensitive. Everything I’ve read suggests that agm perimeters are similar to wet cell batteries, but time will tell.
One caution I’ve heard about AGMs is that if you run them down, they have a high acceptance rate, meaning that they will max your alternator longer than similar wet cells. So if you anchor out and deplete your batteries, run your engine a bit faster so that the alternator fan can pull more air past the diodes.
Quent_______________________________________________
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Another issue with AGMs, not only are the voltage sensitive but I believe they are less tolerant of abuse in general. AGM specs I have seen say they should be fully charged on a regular basis or they may die and early death. If you are on shore power regularly, have extra solar capacity or some other way to top off the batteries on a regular basis OK. But off the grid and charging to 80-90% AGMs may not be the best option.
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Hi Dave
Some voltage regulators monitor alternator temperature and reduce charge rate if the alternator overheats. Seems like a good idea.
The perfect storm of fried diodes is the combination of the depleted agm batteries, engine running at slow idle, then running the anchor windlass. Under these circumstances, the alternator can fail pretty quickly. Running at fast idle produces more power, and helps cool the alternator.
Quent -
Great info. Thanks. I’ll check out Lifeline’s AGMs.
Tor
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I have good charging capabilities away from the dock;
wind, solar, big alternator with smart regulator, and a
Honda generator to power a big battery charger, also
with smart regulator. For all that, I may not have
topped off my AGM’s as often as they might have liked.
I suspect part of my problem with them stems from
packing them sardine-fashion into a tight, closed
locker. I believe they’re getting hot in there, and I
know AGM’s resent heat. I’m installing a vent grill and
maybe a little computer fan to alleviate that
situation.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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I didn’t know that about alternators. Glad I do now. As
it is, I habitually idle my engine at about 1100 RPM,
to better charge the batteries, including the windlass
battery up forward. I’ve been doing that because I felt
the alternator was putting out the most amps for the
revs at around that RPM. Seems like maybe I got lucky
and also spared its diodes.That said, I generally charge batteries via the solar
panel and wind generator, and by powering the battery
charger with a Honda generator. I only run the engine
to propel the boat when I can’t (or am too lazy to)
sail.Tor
Silverheels, P-424 #17
http://www.silverheels.us
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You can’t put a smart regulator on just any alternator. Even though an alternator might be rated at 80A, most alternators will overheat if subjected to their max output for extended periods of time. Balmar specifically makes their alternators to take this kind of punishment but if you have a stock alternator that came with your engine, adapting it to a smart charger may damage your alternator. Some smart regulators have adjustments that can limit the output to less than the full current capability of your alternator, e.g. reducing the max charge output from 80A to 50A. This prevents a less robust alternator from getting fried, but increases the amount of time needed to charge.
Balmar isn’t the only alternator that can take high charge rates for extended periods of time. There are industrial alternators out there that are much less expensive and can take this kind of punishment. Mounting them can be tricky however since off-the-shelf brackets may not be available for your engine. A good alternator shop can probably match an industrial alternator to your engine if you bring in your bracket and alternator for reference.
Rich
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I agree with Rich. Most stock alternators are designed only to recharge the power used to start, then to power accessories. They aren’t meant to recharge depleted batteries on a cruising boat.
Several options come to mind. An externally regulated Balmar or other “marine” alternator that is loaded below its “hot” rating, a really robust commercial, preferably large frame alternator, or one of the above with the diodes relocated to a cooler location. Or in our situation, just use two alternators driven by the same regulator. Electrically, the regulator sees the pair as one big alternator.
We also have a dc genset with remotely mounted diodes and a 160 amp alternator. Now has lots of holes in the case where the diodes were for cooling air. Seems to work well, but we’ve never really tested it hard.
If anyone is interested, I’ve got a couple big alternators, max 200 amps, happy all day at 160 amps, large frame, sitting in the garage.
Quent -
Rich,
I used a good alternator shop. They guy marinized a
common truck alternator – 105 amps, I believe; I’d have
to look to remember which make/model – disconnected the
internal regulator, and recommended the smart regulator
I have. This was about 6 years ago and all is well, so
I guess he got it right.Tor
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