Battery Question - What is best

[Chip Hindes]

The AGM is less expensive and more compact than the combination of a Wet Cell battery and the proper mounting box even without accomodating overboard venting.

Yes, and a Mercedes is cheaper than a gold plated Chevy. I personally see no necessity to mount a flooded cell battery in a box or to provide venting. The amount of hydrogen vented by a properly charged battery is miniscule and dissapates immediately. Even if I did, unless the AGM or gel batteries you buy are way cheaper or the battery boxes way more expensive than what I have seen, the numbers don't add up as you say they do. Plus, you're still ignoring the charger issue when it comes to cost.

I use AGM batteries in my car, they are sold for automotive use, they must be able to accept wet cell charging.

Your conclusion doesn't follow, and it's simply not true according to those who seem to know more about it than you. I don't claim to be an expert. I'm quoting others whom I believe have no particular reason to make things up.

I used AGM batteries exclusively in my Mac26X with excellent results. Charging for the starting AGM was from the Suzuki DF50. Charging for the house AGM was using a three stage regulated charger whch had battery charging smarts in it. This charger could charge 30Amps rate. The charger was selected as a regulted type that could be used to operate the house loads even without a battery, it was a type used often in the solar house power world. This charger was not AGM specific, but worked very well. There is a 70Amp model which I would select if I had it to do over. The charger will not overcharge the battery, that is a standard feature on most battery chargers. If there is no built in overcharge protection the charger should not be left un-attended.

We don't really know whether you've been doing things right or have just been lucky. I'll give you the benefit of the doubt. The manual for my charger says it's to be used for flooded cell batteries only. If you're saying I should ignore what's in the manual based on your experience, no thanks.

Honestly, I was waffling as to whether my next set of batteries would be AGM or gel, until I found out I'd need an expensive new charger as well.

You cannot charge AGMs over 14.2V since that would take an enormous amount of current to overcome (pull a voltage drop accross) the low internal resistance. Instead the charging voltage will be limited by the AGM battery. I call this inherently safe charging.

You can call it whatever you like, that doesn't make it so. Your statements conflict with those from West Marine.

It would take a huge overcharge to force gasses out of an AGM battery. Remember that the AGM has space right next to the lead plates to retain all the gasses normally going into and out of solution. Also remember that the AGM battery will not heat up much at all when charging. AGM is much safer to have on a boat since the accumulation of hydrogen gas from wet cell batteries in the enclosed bilge or cabin might present an explosion hazard.

Ditto.

When there was a power blackout in my area, I used one AGM battery to power the VCR/DVD and TV for the kids in the house. They could watch a movie or two, then I would switch it over to just TV and catch the news while also running the aquarium life support for the fish. After a long night the AGM would be down to around 11V. Next morning I would carry the 70lb. AGM to work and charge it while I worked. Try carrying a wet cell battery to and from work under your arm for a week and see how many of your clothes get acid holes.

Why would I want to try such a thing, and what possible relevence does this have to use in a Mac? I don't intend to take the batteries out of my boat until I have to replace them. With reasonable care, I'm not worried about acid burns or damage to my clothing.

How about this reason to use an AGM in the Mac26X: Do you want to store stuff in the bilge storage provided in the Mac26X? If you do and you have a bucket of acid evaporating/outgassing down there with your stuff, be prepared for acid fume damage.

You're just making stuff up to test me, right? I've had not one but two buckets of acid in my bilge evaporating and outgassing for four years, and have yet to notice acid fume damage. An occasional splash with salt water, now that I'm concerned about.

How about when you do battery maintenance and knock off that crusty stuff on the wet cell terminals, or overfill it, or have acid spill out when the boat is healed over then end up washing down your bilge with baking soda to neutralize the acidy mess?

Four years, haven't had any of this happen yet. I've had the rail in the water to the point water is coming into the cockpit, but no battery acid spilled. I haven't rolled the boat completely yet, and I don't intend to.

Having the dangers of a vented to the cabin bucket of acid in a Mac26X is not warranted when for a few dollars more (40% more usually) you can be far safer.

Which battery would you rather sleep nest to? A leaky bucket of acid wet cell? Or a nice clean can be mounted on its side and shipped UPS AGM battery?

Every price I've seen, the AGM and gels are nearly 100% more.

Nearly everything connected with boating is dangerous to some degree. I've been living with this particular level of dangerousness for four years, I haven't lost any sleep, and I will probably do it for many more.

I'm 54 years old, I have been buying batteries since I was 18, and although I admit there is some convenience involved, I have yet to hit the necessity to have a battery shipped. Stores in my area have batteries. Go to the store, buy a battery. Not too tough.

The idea that you might mount a battery on its side is interesting but irrelevant.

I figure the AGM is worth a lot more than the slight extra cost...

You and some others think it's worth it. I and some others don't. You can consider us misguided if you want. The feeling is mutual. We all look at the same set of "facts," some of dubious validity, and a whole lot of opinion, and come to different conclusions.

Not surprising. None of us can be "proven" right or wrong in our conclusions, and either position is valid. This doesn't have to be a debate in which we pick opposing positions and can't concede any of the points of the other guy.

[Robert]

Chip, you have not found anything good about a wet cell battery other than you have been buying them for 36 years.
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West Marine is hardly a battery expert, they just want to sell what they stock. I am no battery expert either, but from battery web pages and from Batteries Plus people and from my personal experience AGMs are a far better value than wet cells.
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I don't like corrosion. I put stainless calipers on the trailer at extra cost, the initial cost was more but not having to replace them often makes them less expensive in the long run.
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There was a previous post in this thread explaining battery acid damage does happen.
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Maybe some people like you do all your maintenance on time and get lucky and don't have problems for years.
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AGMs make life easier with less maintenance, no worries about leaks or fumes etc... For the small amount extra they cost divided by the number of years of use and freedom from worries AGMs are an excellent value.
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I use AGMs in the cars because I have had rusted battery boxes and corroded terminals before, I choose not to have those problems, AGMs are a way to avoid those problems.
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The wet cell battery is easy and cheap to replace, but the collateral damage they may cause might be much more difficult and expensive to repair.
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I wish you continued luck with your wet cells. Please don't tell people that AGMs are bad, as you and I have pointed out there are no downsides to AGMs other than initial cost.
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Note: Gell Cells are an entirely different issue I have no experiece with, they are not AGMs.
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AGMs are tried and true already, they have been around a long time.

[Duane Dunn, Allegro]

AGM's are in almost all cases superior to wet cells. But you do have to watch your charging regeim. They will be happier with a lower charging voltage than a wet cell just like a gell cell is. They and Gel cells are Valve Regulated (VRLA). They hold the gases internally up to a point, but then the valve kicks in and relieves the pressure rather than let the case pop. It is a one way street. Once you have lost some of the gas, which has been boiled out of the water content it is gone. You can't replace it in these sealed batteries. They CAN be boiled dry just like a gel cell can. Don't ever use a equalization charge on either.

I also agree with Chip that we gain nothing by the AGM's ability to accept a higher charge rate. Our dinky outboard electrical systems can't even come close to the limit of a wet cell, yet alone a AGM, and my wimpy 5 amp shore charger certainly doesn't max anything out.

I think this is a case again of us getting to hung up on what can be done to these boats, rather than what is appropriate for the boats. MacGregor has built a very simple boat, simple in design, simple in construction, simple in rigging, a perfect example of the KISS approach. I think it's silly to install an electrical system fit for a round the world yacht in a Mac. Why do I a need a battery that can accept tons of amps in a very short time when my average daily usage is less than 10 amp hours. And I have a lot of electrical toys not to mention 3 kids on board. I've kept close track the last two trips and have never used more than 8ah in a day. It's true that we may motor more than many of you, but I think most will find that if they take an honest look at how they use the boat even if you sail alot your electrical demands are quite low.

[Chip Hindes]

Chip, you have not found anything good about a wet cell battery other than you have been buying them for 36 years.

Cheap=good. There you go; words of one syllable.

That's not all I said, but why reiterate again the exact same arguments; you'll just ignore tham again.

Other than your warnings of dire consequences which for me remain theoretical, I haven't found anything bad about them either.

Cheap, and not so bad, versus expensive and not much better.

When you question to neutrality of West Marine on the matter, you neglect to note that they sell all three types of batteries. Being a crass, commercial retail operation, they stand to make way more profit on the way higher prices of the gel and AGMs, so why wouldn't they push those?

[Robert]

The subject of this thread is:
What Batery is Best? Answer = AGM.
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I think all will agree that the AGM is better than wet cell, even Chip:

Cheap, and not so bad, versus expensive and not much better.

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For me, peace of mind knowing there will be no mess is worth the expense.
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For those worried about weight, AGMs weigh a little less for a given capacity and AGMs have much more cranking amps than wet cell due to low internal resistance.
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For those who park their boat for months at a time, the AGM will not self discharge nearly as fast as wet cell, so when you get back to the boat, you can still start the motor.
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One downside of AGMs - if you manage to overcharge so much that it actually opens the relief valve, you cannot replace the lost volume. But this is very hard to do on a battery that barely heats up at all while charging as opposed to wet cell which can boil when charging.
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So after all this discussion, AGM is best, if you don't mind spending a little more on the initial cost.

[mgg4]

Ok. Given that we have (tentative) agreement that AGM is better than wet-cell (though there may still be debate on that issue), how does AGM stack up against the Gel Cell?

I'm leaning towards AGM for my new setup, but I want to give all three major battery configurations a good once (or twice) over before I make my purchase.

So, anyone out there want to wade into the fray?

--Mark

[Mark Prouty]

The Amp Hour rating tells you how much amperage is available when discharged evenly over a 20 hour period.

I have two batteries with different amp hour rating.

Can I connect them in parallel without negative impact?



What is group type? eg: group 24 or group 27.

These batteries are different ages. I wondering what impact age really has. Will a new battery connected to an older battery drawn down to the level of the older battery and therefore wont last as long a significant enough factor not to do this.

Should I just drop the 60 bucks and buy another new battery?

http://rk-enterprises.home.att.net/conn ... teries.htm

[mike]

Ok. Given that we have (tentative) agreement that AGM is better than wet-cell (though there may still be debate on that issue), how does AGM stack up against the Gel Cell?

I'm leaning towards AGM for my new setup, but I want to give all three major battery configurations a good once (or twice) over before I make my purchase.

One thing's certain... although there may be some disagreement back and forth as to whether a standard (intended for flooded batteries) charging setup can be used for AGMs, I think it's a certainty that gels need special treatment (special charging voltage, whether it be from a shore power charger, or the motor).

--Mike

[Paul S]

The Amp Hour rating tells you how much amperage is available when discharged evenly over a 20 hour period.

I have two batteries with different amp hour rating.

Can I connect them in parallel without negative impact?

What is group type? eg: group 24 or group 27.

These batteries are different ages. I wondering what impact age really has. Will a new battery connected to an older battery drawn down to the level of the older battery and therefore wont last as long a significant enough factor not to do this.

Should I just drop the 60 bucks and buy another new battery?

http://rk-enterprises.home.att.net/conn ... teries.htm

I wouldn't connect them unless it was an emergency (starter battery died)
Different age..different size..different rating.. all not good.

Batteries are pretty cheap, I would (and did) just get new ones. The factory micky mouse battery is in my basement now powering my backup sump pump. It never saw the water.

You could put a switch between them as an emergency parallel..But I wouldn't connect them full time in this case.

My setup is 2 batteries (each with an on/off switch) exact same size and age, and a parallel switch 'just in case'.

With boat shows coming up, you might get a decent deal at the show (I got 1/3 off mine).

Group 27 is larger and, depending on brand, more power than a 24. I have 2 27s.


Paul