House batteries??

centerline · Mar 1, 2016

"traditional" wet cell 8D batteries?... are you referring to a true deep cycle or a typical starting battery? they make AGM in both types.... I have strong opinions against using the wrong battery in the wrong application, but its a personal preference if one wants to set their system up for charging AGM batteries.
AGM batteries are good batteries, but if charged in correctly or used in the wrong application, they soon become only another failed, yet more "expensive" battery that needs to be replaced again.

with the exception that there is only room for 1 8D battery to fit the space, myself, I would not choose an 8D battery when there are so many better options.
one should wonder why, even on land based solar arrays where they may be smallish ones, or massively large ones (in relation to what us boater use), why they dont use 8D batteries?... its because there are better batteries that will store more power, can have more charge/discharge cycles, be more cost effective over the entire life of the battery, for very little more money at the time of installation...

LeoLambert310 · Mar 1, 2016

check what your charger will handle as if you go AGM and it not able to charge it that's an extra cost again.

Don Lucas · Mar 2, 2016

eianm said:
AGM's are about twice the price and certainly last longer

Where did you get that?

By far the best bang for buck in batteries is 6V golf cart batteries. And if replacing 8Ds with them your back will also really thank you.

Maine Sail · Mar 2, 2016

eianm said:
AGM's are about twice the price and certainly last longer ,

Sure, in the marketing materials they might. There is no data I have seen that suggests AGM's last longer than a comparable duty flooded deep cycle battery and this certainly falls flat on its face in the marine market too.

In federally funded solar testing AGM batteries have proven to consistently yield the shortest cycle life performance and GEL and true deep cycle flooded batteries yield the longest.

Flooded deep cycle batteries are the most forgiving, most tolerant of abusive charging practices and generally outlast AGM in the marine market. If charged properly it is very, very tough to be GEL batteries for cycle life. I have multiple banks on cruising boats over year 12 and one at year 16 now. The key is charge properly!

All AGM batteries require:

The proper voltages for both float and absorption

Temperature compensated charging

Proper absorption cycle

Maximum charge rate for best longevity

Getting back 100% SOC after every discharge ASAP

AGM Batteries - Making the Choice (LINK)

eianm said:
Does anyone have any strong opinions re the choice between traditional wet cell 8D's as opposed to AGM's-

You could not pay me to install flooded 8D or 4D batteries on a cruising sailboat. With the exception of Rolls and Dyno battery none of the flooded 4D or 8D batteries are actually deep cycle products they are starting or dual purpose batteries and a waste of money for deep cycling applications. They also suffer from internally shorted cell failures at a considerably higher rate than any other battery I work with.. On a large sport fishing boat starting a couple of huge MAN's, Cummins or Cat's sure but not for deep cycling. "Useless as boobs on a bull" as they say..

eianm said:
with zero maintenance, but does anyone have any re world /reliable stats on this argument?
Maine Sail?????

Some AGM batteries are far from "zero maintenance". Lifelines for example require equalizing and all of them require the proper charging equipment and charging voltages and very few of them deal well with PSOC use.. 95% of boats out there are not correctly set up to properly care for or charge AGM batteries so a lot of additional expense may be necessary beyond just the batteries...

If you insist on AGM stick with the premium brands such as; Odyssey, Northstar, Lifeline and Firefly. If you stick with flooded batteries consider golf cart 6V (GC2 or T105's) or GC 12V batteries (Trojan T1275 etc.) not your typical group 24,27, 31, 4D or 8D.

jeepbluetj · Mar 2, 2016

(blatant post pad, as I have none)

What Maine Sail said.

GC6's. Don't need a crane to lift em. Last a long time. Cheap. Charge with any old charger. Yes, you need to stick water in them every now and then.

AGM's are great when you have the specific use case for them: need high charge rate, and you can always keep them fully charged. Flooded batts are more resistant to being abused, and 95% of boaters abuse their batteries*.

(*made up statistic)

centerline · Mar 2, 2016

jeepbluetj said:
Flooded batts are more resistant to being abused, and 95% of boaters abuse their batteries*.

(*made up statistic)

its actually closer to 99.95% of boaters that have batteries that are constantly being abused.

LeoLambert310 · Mar 2, 2016

I have 4 6 volt golf cart bat. over 6 years old with no problems just have to check the water level every month that takes 10 min. but then doing the normal checks every month on other items makes it a normal routine for safe boating.

seadaddler · Mar 2, 2016

I had 2-4-D's and only got 4 years out of them and switched to 4-6 volt T-105's and going
strong on 5 years and they don't need water every 4 to 6 months and do equalize often'
4- D's are so heavy and 4-6 volt so much better to store them on boat.
I keep my ref on 24/7 and let solar recharge the often and they get heavy work out.
Nick

centerline · Mar 5, 2016

it really all depends on your amp usage and how much abuse the batteries get during their life...

with moderate usage, the 4 6v batteries may be the best option for longevity, but if you are going to install 4 batteries, the T1275's will give many more amp hrs, and if you have high amp use, the 1275's would be the best...
because, when using 6v batts in series to make 12v, you are increasing the voltage but the amps remain the same as if it were only 1 battery (in a sense it IS only 1 single 12v battery that you constructed with wires, by hooking the correct number of cells together. each battery cell contains approx 2.2volts)... so it takes 4 6v batteries wired in series (which equals 2 12v batteries to get any gain in available amps... each time you add another set of the)

but with the 12v batts where they are already 12v, when you hook them together it adds the amps of one battery to the amps of the other battery, and so on with each battery added...

according to my calculations, at a 20hr rate the 4 1275 batts will give you 600amps
whereas the 4 105 batts will give 450amps... this is as advertised by Trojan.

if the amp hrs of all batteries were the same, no matter the voltage, it would take 4 6v batteries to equal the amps of 2 12v batts...

to more accurately answer your question as to which would be the best for you, we would need to know how many amps you draw, and how fast you draw them, and your charging habits you use to make sure the batts are always recharged in a timely manner.... and not so much what you think these are, but what they actually are, which is most often very different

Maine Sail · Mar 5, 2016

eianm said:
Guys- i have one more question- when it comes to life expectancy and overall capacity- is it better to go with 4 x 6v Trojan T105's or 4 x 12v T1275's? if i understand correctly- going with T1275's I would end up with 664Ah capacity and if i go T105's i will have 500Ah @12v- am I correct? If so , wouldn't i be better to go to the T1275's?

Four T1275's is 600Ah = $780.00 - $1.30 per Ah
Three T1275's is 450Ah = $585.00 - $1.30 per Ah
Four T105's is 450Ah = $524.00 = $1.16 per Ah

The T1275 is essentially a 12V version of the T105 but they are more expensive per Ah. A T105 can be had for about $131.00 and you'd need two at a minimum for 225Ah's. This makes the T105 about $1.16 per Ah. The T1275 is a 12V battery so you'd only need one, at a bare minimum, and they run about $195.00. This makes the T1275 $1.30 per Ah. Both batteries have the identical factory cycle life specs. Generally 12V GC batteries are more costly per Ah but you can get away with three vs. four, if space is an issue.

Sailgunner · Mar 5, 2016

Maine Sail said:
Four T1275's is 600Ah = $780.00 - $1.30 per Ah
Three T1275's is 450Ah = $585.00 - $1.30 per Ah
Four T105's is 450Ah = $524.00 = $1.16 per Ah

The T1275 is essentially a 12V version of the T105 but they are more expensive per Ah. A T105 can be had for about $131.00 and you'd need two at a minimum for 225Ah's. This makes the T105 about $1.16 per Ah. The T1275 is a 12V battery so you'd only need one, at a bare minimum, and they run about $195.00. This makes the T1275 $1.30 per Ah. Both batteries have the identical factory cycle life specs. Generally 12V GC batteries are more costly per Ah but you can get away with three vs. four, if space is an issue.

Very nice analysis Main Sail

Joe A · Mar 5, 2016

I like the T105 solution because there are less cells. Three T1275s is a total of 18 cells. Four T105s is a total of 12 cells. Doesn't 33% less cells = 33% less chance of failure due to one bad cell? Is this a valid advantage?

centerline · Mar 5, 2016

Joe A said:
I like the T105 solution because there are less cells. Three T1275s is a total of 18 cells. Four T105s is a total of 12 cells. Doesn't 33% less cells = 33% less chance of failure due to one bad cell? Is this a valid advantage?

not really so much..... and in my opinion, in the case you describe I think the 12v batts give the advantage, if you are on a cruise and dont have immediate access for a replacement.
when 1 cell goes bad in one of the 12 volt batteries, you can drop it out and still have 3 good batts providing 450amps, but with the 6v batteries, when 1 cell goes, you lose 2 batteries, and are down to operating on the remaining two, which are providing only 225amps.......
if a person only has 2 6v batts (in parallel) in the bank, if he loses 1 cell in 1 battery, his entire bank is bad....

and because of this, it is my opinion that if a person only has room for 2 batteries per bank, a good choice would be the 12volt, rather than the 6 volt.... but this problem is kind of a non-issue for local/brown water boats that are always close to replacement batteries.

what is more of an issue is, knowing what conditions the batteries are in, all the time, so you can catch a problem early, and, buying good batteries with good warranties, and filing the paperwork where you can find it if you need it...

dakno · Mar 7, 2016

Something I haven't seen in this thread is , the labor of watering on a regular basis ( removing panels ,covers, access to cells ) as your charger is always cooking the batteries, gassing /venting and the danger of explosions in the cabin. AGM's are expensive, less forgiving than lead acid but you install and maintain charge and that is 90% of your maintaince. You will sleep better when you hear that charger spool up.

Don Lucas · Mar 8, 2016

People will always find ways to justify spending money I guess.

Maine Sail · Mar 8, 2016

dakno said:
Something I haven't seen in this thread is , the labor of watering on a regular basis ( removing panels ,covers, access to cells ) as your charger is always cooking the batteries,

If your charger is "cooking" the batteries you need a new charger.. If you are concerned about frequency of watering Water-Miser caps run about $3.40 each..

dakno said:
gassing /venting and the danger of explosions in the cabin.

The ABYC standards for the venting of battery banks are no different for AGM or GEL than they are for flooded batteries. All banks need proper ventilation.

dakno said:
AGM's are expensive, less forgiving than lead acid but you install and maintain charge and that is 90% of your maintaince.

Keep in mind that for Lifeline AGM batteries that are regularly PSOC cycled equilizing "conditioning" for 4-8 hours is required for the best longevity. This is a time consuming and tedious process that you should be there for to monitor battery temps. I think the longest battery watering I have done took 35 minutes.

dakno said:
You will sleep better when you hear that charger spool up.

Provided your charger has the proper voltage settings for your particular AGM batteries, and it has temp compensation, this may be true for some. Feed AGM's the wrong voltages, and the vast majority of "dip-switch" chargers miss the mark, don't temp compensate, then every time the charger fires up you may be over charging or under charging them. VRLA batteries are much less tolerant of poor charging practices than flooded batteries...