Best Replacement Battery

[dznf0g]

I burn diesel in my old mining lantern! (Or whatever is old an oily!)

[kejorg]

OK it has been a few years since I researched the AGM VS wet subject... however I will share what I did discover.

First off let me say that I have 2 198 AGM on a boat that sits for the most part in dry storage on a boat except for roughly 5 weeks out of the year (Lake Powell)...those batteries are maintained via 55watt solar panel and max 10 amp controller (actual charge from the panel is about 3.5 amps)... when in use the batter is charged by a high out put alternator and a multi stage regulator from the main engine... this boat is also set up to charge from shore power with a marine grade inverter/charger AGM capable.

I went with the AGM's 6 years ago and they are still running strong... the decision was a simple one for me... since these batteries do not gas and require no watering they were perfect for installation in a boat that is stored a lot in hot/cold dry weather... Additionally they will take as much charge as the system will deliver and they will recharge extremely quickly (they do not boil and gas). This boat has a primary load from a small frig and ice maker that run 24/7 I have run these batteries for 3 days without recharging.

Another consideration is how tough these batteries are when they get abused... consider that a wet cell batter will start to take damage at 10.5 volts that is roughly 15% of use from the typical bank... 85% of the battery charge should not ever be used if you want to preserve battery life... now in the real world be it Boats or RV's these batteries get abused few people realize the battery is draining off until some appliance along the load line stops working or starts to go dim at that point battery damage has occured and battery life is shortened, the more this happens the shorter the life is... so by nature we Boaters and RV folks abuse our batteries...an AGM has several advanatges... here is why ... the AGM will allow a much deeper discharge without doing damage so instead of using 15% of the battery like a wet battery AGM's will go well beyond 60% without harming the battery.

We have been posting about how long the batties last in terms of time when we should be talking about the cycles of the battery because it is not how long the battery is used but rather how much it is used(cycles)... that is what determines the life of a battery... a cycle being a discharge/charge.

There is a very good book out that deals with 12volts for end users like us... it was written by some blow boaters (sail boats) I think it is called "Living on 12 volts" it covers many of the subjects that folks like us are interested in... for example chosing one large bank or multiple banks? Well if the objective is to get the most value out of the battery then one larger bank would be the best choice simply becuase the battery is less likely to discharge as deeply as a smaller multi battery bank... I went away from isolated multipe battery banks for this reason alone one big battery is by far the better setup for my use..

My son and I both own AS we both run exactly the same system 1 single 198amh Deka AGM (125 lbs)with a 55w solar panel and 10amp controller... they are both mounted under beds/couches as close to the axels as possible ( they do not gas so they can be mounted anywhere)... additionally we will support the recharge with 3 stage charges powered (not charged) by Honda EU2000i when boondocking... the AGM's will also take charge from the TV and converters these chargers will not top off the AGM's... The solar panel/controller will.

The claims of 5-10X the life of wet batteries are not just hot air ... I replaced wet batteries every 2 years ... I am now on my 6th year... I have friends who keep their Houseboats in slips that are on 12 years with their AGM battery banks... the largest factor to long battery life is shallow discharges and proper cycling... AGM simply are more tolerant of our abuse.

Now the bad news the cost of the system in the AS was roughly 1K and I installed them... for me the cost was important but not as important as the function.

My son recently moved to Sun Valley Idaho he lived in his AS for 4 months while his home was being finished. His only recharge beyond the solar panel was a once a week trip to pumpout and take on water... while his electrical demands where low during most of this time there was 2 months that he ran heat at nights...

To sum this up... AGM's discharge deeper without damage, they recharge faster, they do not boil or gas, they will not corrode the terminals, they can be safely installed in living areas, They are not subject to damage from vibration... the best part there is no maintence except an occational wiping off the solar panel...

Everyone has to decide for themsleves for me I expect an ROI on the battery cost in 2 years and will be shocked if I do not get 10 years out of the AGM... the solar panel literally will last longer than I will.

FYI... AGM DEKA 198 AH approx. cost $450.00 ($2.27@AH) Wetcells roughly $160.00 ($ .80@ah) is a rough comparison but keep in mind that you can use the AH of an AGM much more effciently than a wet system due to the nature of how the two types cycle (15% vs 60%) ... said differently the ROI is far better than the wetties you do have to withstand the out of pocket... for me AGM is a clear winner in every aspect.

[kejorg]

BTW both gas and diesel smell (don't get me wrong I like it) but solar well let's just say that a lantern burning diesel at night in an As won't make it through a single game of strip poker... a solar powered AGM LED will get everyone naked you decide which is the happier ending.

[Aage]

Originally Posted by kejorg

BTW both gas and diesel smell (don't get me wrong I like it) but solar well let's just say that a lantern burning diesel at night in an As won't make it through a single game of strip poker... a solar powered AGM LED will get everyone naked you decide which is the happier ending.

Do you have any photos to back up this logic...?

[Mexray]

Kejorg....You've noted lot's of good info and experience with your battery systems...

However, I'm compelled to note that your 15% limit, on flooded cell battery discharge, to avoid damage is way off base...

In the past, many Manufacturers of batteries used to recommend avoiding discharges deeper than 50%, as a rule of thumb - in other words, it was a way to 'engineer' one's battery bank to include enough battery capacity for normal usage, and not have to routinely discharge below 50% for optimum overall battery life...

In reading US Battery's (an established long time mfg'r.) maintenance info, I find they now are using an 80% discharge number as their suggested discharge usage to enjoy long battery life...

The info is shown here: U.S. Battery - Care & Maint p.1 It's item # 8...

I would recommend anyone wishing to bone up on their battery systems, look on the web at several of the battery mfg sites for their in-depth information, specs, etc. - lots of great straight forward info!

Ray

[Dave Park]

You can discharge any deep cycle battery fairly deeply as long as it is constantly either charging or discharging, and not sitting in a discharged state - that's a recipe for sulfation.