Batteries.....

[Baker]

Well, I have a Mainship Pilot 30.* the way they did the electrical system will make the gurus freak a little.* My whole boat...house...starting....windlass....bow thruster is run off of 2 group 31s(I think....they could be 27s).* Yep, the whole shabang off of those 2 measly little batteries.* I am under the impression that these are the OEM batteries so they have survived over 3 years but they are starting to cook off some water now so I don't reckon they have much longer to live.

I am not gonna re-engineer the whole system.* My question is what kind of batteries would work best under these abusive conditions.* I have thought about using a sealed battery(AGM) to cut down on maintenance but those things are bucks.* The originals have served pretty well and still are....that would be the cheapest way to go especially to get another 4 years out of them.*

Note: I have 2 6 volt Trojans in a seperate bank for the inverter.* If I changed the type of battery in the above question I would have to change the type of battery for the inverter as there is only one charger and it needs to be set on a particular type of battery to charge.

 

[Keith]

Ideally, all batteries should be the same type, and the same age. I LOVE my AGM batteries. No maintenance and they recharge very fast. The key is to have a good three stage "smart" charger, and never discharge them below 50%. I have a Newmar: http://www.newmarpower.com/Phase_Three/Phase_Three.html

Another thing I swear by is a pulse type desulfator. I use the BatteryMINDer on this page:
http://www.batterystuff.com/battery-restoration/12-volt/
I just move it back and forth between the two banks every 2-3 months, and even put it on my car battery occasionally. There are several choices on that page that you can pick from.

-- Edited by Keith at 05:02, 2007-10-06

 

[RCook]

Our house batteries are East Penn Deka AGM, and starters are Optima.* They just finished their seventh season, some 2400 engine hours and hundreds of nights at anchor.* Both banks still seem like new, as far as I can tell with help of the Link monitor.


We use a Balmar Maxcharge 612 regulator, set to "Optima" charge profile, which is very close to what's recommended for the Deka AGM's.* The traditional flooded battery profile would work, but the Optima one is a bit better.*

For shore power charging we use a Freedom 10 inverter/charger, set to "AGM".* The house bank is plugged in all winter.

The Deka's are what West Marine sells, but I got mine for far less at a local battery supplier.* I would highly recommend both the Deka's and the Optima's.

 

[Baker]

I am a huge fan of Optima batteries. I know they are not cheap. They never really talk about the technology they use....or they don't really give it a name. Anyway, do they make a true marine deep cycle battery. I know they make starting batteries and I know they make a "combined use" battery. But I have never really found a true deep cycle. I actually saw a rack at Sam's for Optima deep cycle batteries but that particular rack was empty.

Another question....It seems that a couple of people have mentioned that AGM and flooded batteries have the same charge profile. Would it be safe in this situation to put AGM(or Optimas) for the multipurpose house,etc. bank and keep the flooded 6 volts on the same charger???

 

[RCook]

Optima makes "dual purpose" batteries, with greater AH capacity than their pure starter batteries, in both blue top ("marine"), and yellow top (larger size dual purpose), but neither is very much of a deep cycle battery.* Other AGM's offer*greater AH capacity per dollar, or per pound.*

BTW, just to keep things confusing, the blue tops come in both starting and dual purpose versions.* Red tops are*starting only, just like the blue starting ones except for the terminal type.

Optima specs:

http://www.optimabatteries.com/optima_edge/technical_specs.php

I don't think I'd be charging the AGM bank and the flooded bank (or any other dissimilar banks, for that matter) at the same time with*one charger, unless it has two separately regulated charging circuits.* If you can charge them separately I think it would be OK.

I'm not certain I have this right, but my research a few years ago suggested that*Concorde Lifeline*recommended charging voltages were rather more different from flooded (lower voltages, as I recall) than my Deka's.* Before selecting an AGM, I'd want to know just what voltages they recommend.


-- Edited by RCook at 11:29, 2007-10-06

-- Edited by RCook at 11:30, 2007-10-06

 

[Elnav]

The short answer is,* AGM**only tolerate a lower float voltage than flooded batteries. The higher float value for Wet or flooded would cause out gassing in a sealed cell and thus detroy it.

If you turn off the charger as soon as you get into the float stage* it makes no difference.

 

[Elnav]

R Cook wrote:
I'm not certain I have this right, but my research a few years ago suggested that*Concorde Lifeline*recommended charging voltages were rather more different from flooded (lower voltages, as I recall) than my Deka's.* Before selecting an AGM, I'd want to know just what voltages they recommend.



REPLY
the longer answer is yes voltages do differ as recommended by the variious manufacturers.* While still employed by Xantrex I began a review and update of the charge table data *used in* their charger algorithms.
Each manufacture has a slightly different set of numbers based on a host of variables including* plate thickness, electrolyte temp internal battery construction* and even*lead oxide formulation.

Unfortunately, real world use of a battery seldom conforms to the theoretical laboratory test procedure.* Charging takes *place simultaneously with* discharge to connected loads. Charge current varies as a result. *so does ambient temperature. Which afect boil point of electrolyte.
Worst of all, lead sulfate remaining from previous discharge cycles tends to inhibit free and even charging of all plates equally.

The bottom line being that* except for the end stage of float,* it makes only a small difference between* flooded and AGM* as far as bulk charging* and absorption stages are concerned.* The real killer of bateries is oftne that extended period of staying dockside and the charger connected and no loads connected to the battery.
Continued float stage on a fully charged battery is what causes over charging and electrolyte boil* off. The recommended float voltag efor AGM is 13.8 at 70F* but drops as battery temp rises. Considering* thi scan rise to as muhc as 120F* it measn maximum float voltage may have to be down to 13.1V

The best chargers shut themselves off after about 12 hours. They do not come back on until the voltage drops below 12.2V or therabouts or a lenghty period of time has elapsed.* The venerable TC40+ from Statpower days* recycled every 21 days. This charger is still among the best products on the market.*
Unfortunately many cruising boats now have such large battery banks, *they need a 100* or even 200 amp charger to supply the theoretical max bulk charge.
Arild

 

[Baker]

Okay, so what about getting AGMs and setting the charger to charge AGM while still having the flooded 6 volts for the inverter???

 

[Arild]

That wil lresult in your flooded batteries not geting 100% fully charged if you only charge from shore charger set for AGM.
If yo ustil charge them from your rngine driven alterantor which is stil set for Flooded, then you would probably pick up the remainign charge that way.

One godo way to overcome the possibel under charge situation is to do an equalize charger every couple of months.
Originally AGM battery manufactures said to NEVER equalize AGM batteries. Then later on they reluctantly admit4ed that ashort equalization charge once a year or so could be a good thng. The reason being AGM batteries also accumulate sulfate and without a full charge to 14.2V they never get al of the lead sulfate reversed.
Another solution for when your engine driven alternator is charging for long periods of time is to insert a diode in seris with the AGM. The silicon diode drops th evoltag eby 0.7V from 14.2 to give you 13.5 which is right in the ball park. Just make suer the diode is rated for the ful charge current.

 

[Phil Fill]

We have had many discussions about batteries on you know the other site and I have looked at changing over the years.* However the regular flood batteries are the cheapest way to go in the long run especially if you are not going to spend big bucks and constantly maintain/check them.* We have three

deep cycle house and three

starting batteries divided up into 3 banks.* The main point is to use deep cycle for house and start for the engines, and not mix with different kind of batteries.*

*
The our cheep flood, 125 bucks/each, have lasted for 7 years, and we draw from the house bank every day. *I mean why spent thousand to charge a coupe of hundred bucks of batteries.* I just dont get it?**

**