Batteries......AGM vs. Conventional flooded cell

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mikeylikesit

mikeylikesit

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So, after spending a bit of time learning about Batteries, and their RV specific applications.....

http://www.rvforum.net/miscfiles/Choosing_right_battery.pdf  and  http://www.vonwentzel.net/Battery/00.Glossary/

among others,......

I'm a bit torn as to which way to go.  I like the idea of a longer lasting battery with less maintenance, so I'm leaning towards the AGM type.  However, I'm replacing conventional deep cycle 6v batteries in a 21year old Coach, which was obviously designed (charging system) for conventional batteries....

As a Facility Maintenance Engineer, I am a big time proponent of the "it works, don't fix it" philosophy.  Hence, my dilemma.

I guess the question is, Has anybody with an older class A replaced the coach batteries with AGM type, and wished they didn't?  If so, why?

Thanks in advance......man, I sure have alot to learn about my RV, and appreciate the collective knowledge that this forum makes available!
 
Being your coach is 21 years old, it could probably benefit from a converter upgrade, so if "money is no object", go with the AGM's and an up graded converter. Try here for a new converter:

http://www.bestconverter.com/
 
Right now your best choice might be to buy the less expensive flooded, cell 6v golf cart batteries and put the extra money into a better converter.charger. You 21 year-old original is most likely a battery killer. What make and model charger is it?

For 6v GC2 type batteries, the AGM vs flooded cell choice mostly boils down (pun intended!) to whether you are faithful about battery maintenance or not. If you tend to be lax, the AGM can actually save you money in the long run. However, if you have a quality 3-stage charger and don't forget to check the electrolyte level in the cells occasionally, flooded cell GC2 (golf car) batteries are hard to beat in terms of price/performance.

With a modern multi-stage charger I would not be too concerned about the charge profile difference for flooded vs AGM either. Smart chargers may not get the optimum performance that a lab can achieve with a finely tuned charging profile, but the many variables in real life usage pretty much over-shadow that anyway.
 
I keep reading about the advantages of AGM's but in researching and checking the battery manufacturer's web sites and specifications I fail to find any advantage other than
1: Mount in any position (no "this side up" sticker)
2: Low venting, can be placed INSIDE
3: Maintenance free (low maintenance)

Longer life.. Specifications sheets do not confirm
Higher capacity: Likewise
Faster Recharge.. LIFELINE only, others do not confirm
HIGHER COST:  All confirm that.
 
John, another advantage seldom mentioned is fewer pieces of ruined clothing.  Every time Jerry got within ten feet of the old wet batteries he ended up with a hole in something - even though wearing a work coat or work apron.  :'( I don't think he's ruined any clothing since we made the change to AGM batteries!  ;D I love the AGMs!

ArdraF
 
ArdraF said:
John, another advantage seldom mentioned is fewer pieces of ruined clothing.  Every time Jerry got within ten feet of the old wet batteries he ended up with a hole in something - even though wearing a work coat or work apron.  :'( I don't think he's ruined any clothing since we made the change to AGM batteries!  ;D I love the AGMs!

ArdraF
Click to expand...

All he needed was polyester clothing. Acid loves to eat cotton, but leaves polyester alone.
 
The battery acid did the same thing back when polyester pants were popular.  You know how oil leaps five feet to reach someone's clothing?  Battery acid does the same thing - to the same person!  ;)

ArdraF
 
Pool acid is worse.  And pool chlorine is worse than that. 

But nothing comes close to BBQ sauce!
 
Longer life.. Specifications sheets do not confirm
Higher capacity: Likewise
Faster Recharge.. LIFELINE only, others do not confirm
HIGHER COST:  All confirm that.
Click to expand...

I think John is mostly right about the advantages of AGMs.  They are longer lived than some battery types, but have no life advantage over rugged deep cycles, e.g. golf car batteries. However, AGMs do provide more deep charging cycles than automotive starting batteries or Marine/RV so-called deep cycles.  Furthermore, amp-hour capacity is almost always slightly less than a flooded cell of the same physical size. As for charging rates, it's still a lead-acid chemistry and that pretty much dictates the optimum and max charging rates.  AGMs probably handle single-stage chargers better than flooded cells, primarily because they tolerate near-boiling rates better, but with a decent 3-stage charer there will be no material difference in charge time.


The lack of an acid film on the batteries and nearby surfaces is indeed a real plus and a significant part of the reduced maintenance effect. No corroded connections or surfaces. Not to mention the potential for ruined clothes!
 
thanks for the input, folks!  :))

I went with the conventional flooded cells.  Could not justify the expense of the AGM's.

Gary, the converter was replaced in 2008........fortunately the previous owner kept a very good maintenance log,, however, I can't find the darn thing!  I'll trace the battery cables out tonight to find the converter.......but I am liking your suggestion that I get a good, modern one. :)
 
8Muddypaws said:
Pool acid is worse.  And pool chlorine is worse than that. 

But nothing comes close to BBQ sauce!
Click to expand...

I used to work with maintenance folks way back in the day at the papermill.... I think the worst substance know to man kind in this regard is never sieze (or anti seixe) thread lubricant.  That stuff...man, get a small drop on you and before you blink it'll be on every piece of clothing you're wearing + your car's upholstery!
 
By 2008 many of even the lower priced models included 3-stage charging, so you might be OK. Find that converter/charger and ID it!  It may be integrated with the AC/DC load center or may be a standalone (aka deck mount) converter/charger.  Odds are the original in a 21 yo coach was an integrated unit, but the replacement may have added a deck mount adjacent to it and disconnected the internal charger.
 
You know I never considered the Ruined clothing.. But then I have never ruined clothing handling batteries... (Of course I like to let OTHER people handle the batteries any more)
 
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