Best type of battery?

[Hamin' X]

With all of the discussion on "Blue Water Sailing", I thought that the following battery comparison was very revealing.

Click Here To Read

This comparison is between Gell Cell and AGM Group 24 batteries. I found the number of cycles particularly interesting. The Gell Cell is the clear winner. I would not even consider Flooded Wet Cells for "Blue Water Sailing" for the obvious safety reasons.

[Moe]

That's true, however, gel cells take special charging, while AGMs can be charged with the same equipment as used for flooded cells, and that includes vehicle or outboard alternators. To get that life out of gel cells, you have to keep the charge voltage down (which takes longer to charge), especially at warmer temperatures. If you exceed it, the gel hardens and can develop cracks, which reduces the capacity. Gel cells are also more subject to thermal runaway if charged at higher than specified rates in a hot environment than are AGMs. I've used both, and prefer the AGMs.

[Hamin' X]

That's true, however, gel cells take special charging, while AGMs can be charged with the same equipment as used for flooded cells, and that includes vehicle or outboard alternators. To get that life out of gel cells, you have to keep the charge voltage down (which takes longer to charge), especially at warmer temperatures. If you exceed it, the gel hardens and can develop cracks, which reduces the capacity. Gel cells are also more subject to thermal runaway if charged at higher than specified rates in a hot environment than are AGMs. I've used both, and prefer the AGMs.

You are correct on the charging requirements, Moe. However, if one is planning on extended sailing, I would hope that your priorities would be to get the safest, longest lasting component available. Devices for Gel Cell charging from any source, are readily available. Click Here

I've never done any extended sailing, although I do make extended packing trips into remote wilderness areas, so my perspective may be skewed.
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[Moe]

Let me see if I understand this. Are you proposing to disconnect the outboard's alternator output from the heavy starting cable that runs to the battery, and run that alternator output to the power supply input of this box you link to above, so it can keep the outboard from overcharging the gel cells?

[Hamin' X]

No, if it were me, I would have a separate AGM starting battery. This could be a relatively small battery. I would then connect the Gel Cell Charger/isolator to the starting battery. The Gel Cells would be mounted under the V-berth and would only be used as house batteries and not starting. The starting battery, located at the rear would always be fully charged and ready for starting. This isolation scheme also, makes it easier to integrate solar and/or wind power.

[Moe]

That'll work. I like having a separate starting battery too.

[Hamin' X]

That'll work. I like having a separate starting battery too.

Like I said, safety first. Keep the starting rope handy, also.

[Hamin' X]

Geez, the more that I look into this matter, the more I have to look into it. Kinda like learning what it is you don't know about what you know about, so that you can know more about what you know about

Anyway, here is an excellent site with some great stuff on battery types, slanted toward the sailing crowd.

Click Here To See

Now I just have to figure out if this guy knows more about what I don't know about, than what I know about it.

[DLT]

Just my 2 cents, but all electronics fail at some point...

This goes double, if that's possible, for stuff like battery chargers...

So, you could easily find yourself out there in the middle of nowhere without any good way to charge your Gell batteries.

I agree that Gells may be better given some set of critera.

But, I like that fact that I have four batteries on board that can either start my motor or run my house stuff.

Right now, I have two AGMs. The other two are flooded-type: 1-the original battery that came with the boat, and 2-the battery my motor guy installed because #1 wasn't up to the task. They are all dual purpose.

I also have two separate battery chargers, one for each bank. I like that alot better than one dual circuit charger. If one fails, I have a backup - I just need to do some quick re-wiring to swap over...

If I were going on an expedition, I'd replace those flooded batteries with AGMs.

Call me crazy, but I like just about anything that's labelled "dual purpose". Yes, I know that, at least in this case, the dual purpose comes at a heavy price, as they are far from ideal for either purpose...

[Hamin' X]

There is a lot to be said for your point of view, DLT.

As I read the web site that I posted further, there are some things that the guy just doesn't know beans about. Like LED's (They are current driven devices,not voltage driven and the resistor is calculated for current limiting, not voltage dropping). However, he comes to the same conclusion as you on batteries, from a different angle. He also, chooses AGM's. I think that you are probably correct in your choice, although I would have all AGM's just incase the boat was knocked down or capsized. Also, the efficiency of the AGM's charging would outweigh the life of Gel Cells, especially when used in a solar system. Further research is, as usual, required.

[Moe]

I went with VRLA batteries in the Airstream because I got real tired of maintaining the flooded cells and the corrosive mist around aluminum. I went with AGMs for fast charging and reduced generator run time. I went with Lifelines for their reputation.

[Hamin' X]

Good, solid reasons. Some choices should not be price driven.

[Jack O'Brien]

Couple years ago, when I researched it well, I also chose LifeLine AGM batteries and have three of same age and size. Two in parallel serve as combination house & starting. They are position '1" on the switch which is always set on '1" or "off". The third is never used and is kept charged via a Combiner 50. The switch would allow using it if needed. The battery is in the bow and if I ever get my windlass installed it will be a close power source for it.

[maddmike]

Add my vote for Lifeline AGM's, a smart charger, and digital voltage/amp readout. I have seen far to many Gel 'folks' stuck in places waiting 3 weeks for their 'overnight' DHL parts package to clear local customs. As a side note, all the aircraft we used in the arctic & antarctic used some type of AGM batts., not sure of the actual stats. but seems I recall 'shock impact' was one reason.

[Lake Hopper]

I use three Optima marine blue top deep cycle dual purpose batteries in my boat and also in my RV. I have found in the last ten years that they answer all concerns. Fast charging, up to 100 amps. No special charger required. Maintains charge for up to a year when not being used. Comes back to full charge even when fully discharged for weeks. Mount in any position, no gas, no corrosion. Plenty adequate for starting the Merc 50 and power tilt. Two are hous batteries and take care of all needs plus some. Charged by engine use, maintained by solar cell off the grid. I have them connected by three switches and one combiner for ultimate isolation and charging of all batteries.

All my cars and trucks have the Optima Yellow tops, too. Starts in -25 degree cold! They have saved me a lot of time, work and money over the years. No maintenace!

I buy them online at: http://www.remybattery.com/350/shopdisp ... +Batteries for that is the best deal I can find.