Cost Effectiveness AGM vs. Flooded Cell

[sailinglegend]

Here is another cost/Ah spreadsheet which also comes out in favour of AGMs being the cheapest. There are several pages to scroll through.

http://www.vonwentzel.net/Battery/04.Costs/index.ht

[topsideup]

I used a 0.40C for all the agm batts there for that was a variable that didn't change across the board regardless of bank size. I also used this figure because most of the reading that I have done state that 0.40C to 0.45C is safe parameters for most agm batts.

[Cotemar]

Originally Posted by topsideup

These were just some observations I had made and was curious if there were at all correct. My boat has 400 Watts of solar with a ts-60 charge controller. With my current setup I have to run my engine about 1 to 2 hours a day. My major problem is that I'm a bit of a techy and there for I use a lot of power, around 250 to 300 amps per day. I have 8 golf cart batts. on 2 separate banks with a total 860ah and a separate start bank. I was hoping that with agm batteries I wouldn't have to run my engine as much and my solar would be a bit more effective. Mabey thats just wishful thinking.

1) Running your boat engines to charge your house batteries is old school.
2) Get a small generator to charge house batteries.
3) Consider more Solar or a better controller

I am on the hook for months at a time and only use the boat motor to go from A to B if we have no wind. Solar powers everything. Our batteries are sealed lead calcium

[deckofficer]

From my experience with off grid homes, I have used the L16's, down to 6 volt golf cart batteries, and my last install was AGM. This was 18 years ago, the owner with the 6 volt golf cart batteries is on his 4th set, the L16 is on his second set, and the AGM is still on the same batteries. I'm glad you mentioned your bank size of 860 A/hr, how about 2 volt single cell AGMs? These are the batteries that have managed 18 years to date, and I have AGMs that are 17 years old.

SOLAR STAR VRLA AGM BATTERIES

Go with what Cotemar says, since China has entered the solar market, $1.13 per watt vs. the over $5 per watt I last paid for them.

If you decide on flooded, go with 2 volt cells and use hydrocaps. No more watering or explosive hydrogen build up in the bilge.

Back to AGM
2 volt, 700 a/hr
$1439.82 for six to be wired in series, and since your knowledgeable in battery care, look for at least a 15 year life.

Tom invites you to call him with your questions, below is how he feels about battery strings.......

The Solar Star Line of batteries have been made for and designed by The Solar Biz to meet the needs of our customers for good quality, high amp hour, 2 volt cells. Our Solar Star 2 Volt cells enable you to have a single, high quality, series connected string, of enough amp hours to provide decent autonomy. In the past in order to achieve a higher amp hour bank of batteries, most folks resorted to multiple parallel connected strings of smaller batteries. This design was an expensive compromise that resulted in a drastically reduced life of the battery bank. Parallel connected strings of the kind of batteries most folks buy are never impedance matched. This scenario makes equal charging quite difficult, resulting in bad cells in the string with the most resistance in a short amount of time, around 3.5 to 4.5 years. I think batteries are too expensive and too heavy, to have to replace in this short time period. There is not enough space here to answer all of the questions that the foregoing raises, so call Tom at 888-826-0939 and he will be happy to discuss this with you. Tom has 40 years experience with batteries in all sorts of situations, everything from Over the Road Trucks to remote off grid systems, heavy equipment, boats, RV's, aircraft, telecom, on grid back-up, computer network back up, commercial power back-up... the list goes on. If you have any questions about batteries Tom has probably designed and installed it... and, he talks alot!

[colemj]

A minor clarification: Hydrogen, being the lightest element known, cannot build up in a bilge. It will readily and easily escape any closed space (Helium, a heavier element, passes through balloons in a rather short time). Also, the concentration of hydrogen necessary for explosion is quite high. You would need a runaway boiling battery in an enclosed space with a source of ignition to cause an explosion.

To the OP: you will need quite the charging system to take advantage of a 860Ahr bank of AGM's. Your current charging setup will not take advantage of the higher charging rates. AGM's must be brought to full charge regularly (every day or two) in order to experience the longer lifetimes possible with these batteries. It does not sound like your current charging system is up to this task without long engine runs. You could possibly decrease the size of your bank using AGM's, but at 300Ahr/day usage, I would not do so.

Jentine: Equalizing, while sometimes necessary, is actually pretty bad for the battery if done often. Every overcharge causes oxidation of the plate and concurrent loss of function. Most flooded battery manufacturers recommend equalizing ONLY if necessary, as determined by specific gravity measurements. Maintaining charged batteries and bringing them back to charge regularly is far more effective at preventing sulfation. If batteries are brought back near full charge daily, equalization should rarely be necessary.

Mark

[gettinthere]

One change you should make is the 2 house bank setup. Go with one big one.
Deep discharging is hard on batteries. Having one large bank eases that issue somewhat. Then there's peukert, hard for me to explain but it applies here.
Buy Calders mechanical & electrical manual

[SeaKing]

Our boat came with two wet cell batteries, one each for the two main engines. The house bank was 8 gel cells. All 10 batteries were split between spaces under two beds. I switch all to AGM's as I did not want gasses under the beds. I was amazed when I finally discovered that long after the surveyor initally checked our boat. I thought that was a severe safety hazard have the two wet cells under the racks.

[topsideup]

Originally Posted by gettinthere

One change you should make is the 2 house bank setup. Go with one big one.
Deep discharging is hard on batteries. Having one large bank eases that issue somewhat. Then there's peukert, hard for me to explain but it applies here.
Buy Calders mechanical & electrical manual

I may of not been very clear with this and thus being my fault but I do have 2 house banks and 1 start bank. The 860ah is both of my house banks together. Sorry for the confusion.