AGM Batteries vs Wet Cell

[johneri1]

P.M. = private message; you sent me a private message which I think (but am not sure) I answered. . . .

[Stenn]

Oh, OK, I get it. Yep, I got your answer.

I figured it should be private, since it was an "Off Topic" "Hi, how are ya" message from one Newport sailer to another....didn't figure we should be filling up this AGM battery thread with those kinds of posts....

Stenn

[johneri1]

Okay good, Stenn, and I'm sure you're right.

[markpj23]

I was asked in another thread why I went the wet-cell Trojan T-105 route when I replaced my house batteries.

For me it has to do with the existing charging system, lack of time at the moment to completely rework the house banks to what I feel would be a better arrangement, and the need to get replacement batteries quickly.

I did not do extensive technical research as others here have. Easiest approach for me was to replace what I had with like units.

[Pelagic]

Hi Mark, Good idea to keep this thread going

To recap:

I am replacing my large house bank and have looked at the:

Trojan J185H x 6 for 600AH @ 24v which can sit in a mid-ship deep well forward of the water tank,

FullRiver FR8D x 6 which replace the existing Yuasa FLA 8D’s that are situated under the dinning table, a bit closer to the charger and distribution point.

I wondered what the battery Gurus opinions might be about which is a better choice for a live aboard?

[Stenn]

Originally Posted by markpj23

I was asked in another thread why I went the wet-cell Trojan T-105 route when I replaced my house batteries.

For me it has to do with the existing charging system, lack of time at the moment to completely rework the house banks to what I feel would be a better arrangement, and the need to get replacement batteries quickly.

I did not do extensive technical research as others here have. Easiest approach for me was to replace what I had with like units.

I don't get the appeal of these T-105's.....sure they're made to be deep-discharged.... hooking 2 in series to get 12 volts means lots of lead.. and lots of capacity....

..but they're only about $10 cheaper than the MK 8A24's AGM's I bought, and the T-105's being only 6 volts.....you have to multiply cost by 2 for every T-105 installation, at least.....multiples of 2.....wow !

In my setup, with 2 12 volt MK AGM's going through a 2-position battery switch, I'd need 4 T-105's to have two 12 volt banks, and by the standards I hear being talking about on this board, that would be a minimalist installation.

It must be really nice to own a boat so big that there'd be room for all those T-105's.

One question......If I have my existing battery bank, and 2-position battery switch, on the starboard side of my cabin, fairly close to the hatchway,.....and I want to install two more 12v's on the port side, but back in the engine compartment, to balance the boat....how long is OK for battery cables to be if I want to run them both back to tie into the existing battery switch?

Thanks,
Stenn

[Landshark]

A few comments on this string about AGMs. First, let me address the statement, “As a cruising boat it is impossible to charge batteries to 100% every time a charge is applied.” Well then something is seriously wrong with your DC plan. A smart cruising strategy is to have a number of charging sources so that when one is inadequate another can be brought on-line. There’s no way around it, but burning diesel in the main or genset is a good way to make electricity. Solar panels and wind generators as secondary charging systems, not something to be relied on as the primary charging system.

AGMs do need a 100% recharge. But they can be discharged further, and incur more discharge/recharge cycles than can wet-cells. And a really big plus is that they can absorb just about all the amperes a DC charger can generate. Consequently, AGM charging time is incredibly short compared to wet cells. So, if AGMs fail because there not receiving adequate recharge it’s not the batteries fault.

As with any technology there are compromises. What one gets with AGM batteries is more duty cycles, deeper duty cycles, short charge intervals, no maintenance, no acid spills, no hydrogen gas, and no corrosion of nearby metal and cables. All AGMs ask in return is a full recharge. Seems like a good trade-off to me. All one needs to have is an adequate recharging system.

[Therapy]

I understand charging to some extent but what I am not exactly sure of is that last bit of the float charge, taking a long time (relatively) at low currents.

Now if all was being done while one was asleep and only a bulb or two were on then I see it as easy (relatively).

I guess I don't know how to fully charge a battery while it is being used, unless it is as simple as put more to it than it is putting out. If one had a bunch of solar and wind and low usage then the battery could theoretically never discharge at all???

[Janny]

Has anyone heard of 'Energy 1' AGM from NorthStar or had experience with them? That's what we think we're going to do.

[Pelagic]

When I read the AGM Charging instructions for FullRiver they tell you that getting a good 3 stage charger and setting it properly to the ambient temp is critical. That “equalization” is not required on a routine basis if you have been cruising and not charging properly. (They recommend you just cycle the battery and fully recharge to equalize.
Because of construction they state that sulfation is relatively minor but that irregular cell development occurs and that is when they recommend equalization.
The procedure is to bring the batteries slightly past gassing 15 to 15.5 volts (for 12 volts) using 6 amps for 3 to 12 hours and STOP if batteries get very warm.
Most of the problems they observe is from incorrect settings for ambient temp.

[GordMay]

Professional BoatBuilder magazine (Issue 111 - February/March 2008) has an interesting article by Nigel Calder about new battery technologies, entitled: “BREAKTHROUGH” (begins page 104)

Goto: Professional BoatBuilder - February/March 2008

[sluissa]

I'm new to the whole battery and DC electrics thing. I can handle one battery, but when you start hooking them up in series I get a bit confused. If, for example, you hook two 6v 100ah batteries in series, do you get the equivilant of 1 12v 200ah? or 1 12v 100ah?

[slomotion]

1 12v 100ah

In parallel they would give you 200ah at 6v.

[Pelagic]

Very Interesting article Gord and encouraging for future installations. I think the present charging systems will not tolerate that kind of high demand and the DC monitoring equipment will need to be re-calibrated.

Will be nice when someone can offer a complete package and recharge of 600Ah @ 24v from 50% to 100% can be done in 1 hour.

[camaraderie]

Wow Gord...that is a fantastic link! For the first 2 pages as Calder was saying everything I've been saying on this thread like a good disciple! Then he starts talking about the new technology and it looks like everything will shortly change...all to the good!