Community Forums

bg101 · 08-19-2008, 09:16 AM

I am a somewhat familiar with batteries – but am curious about the real differences between flooded lead acid, AGM and Gel batteries. I have heard mixed thoughts on each. Does anyone have any real experience using all 3, or 2 of these? I'm trying to understand if the maintenance free aspect of the AGM and Gel batteries are worth the extra cost over flooded. I have also heard different opinions regarding how well/deep the AGM and Gel batteries cycle compared to flooded. Any insight/experience would be great!

bg101 · 08-19-2008, 09:16 AM

I am a somewhat familiar with batteries – but am curious about the real differences between flooded lead acid, AGM and Gel batteries. I have heard mixed thoughts on each. Does anyone have any real experience using all 3, or 2 of these? I'm trying to understand if the maintenance free aspect of the AGM and Gel batteries are worth the extra cost over flooded. I have also heard different opinions regarding how well/deep the AGM and Gel batteries cycle compared to flooded. Any insight/experience would be great!

moldmkr · 08-19-2008, 10:54 AM

Welcome to the sight. There is a wealth on information here and I am sure some one will have some feed back. I would like to know the difference as well. Thanks for the question

GaryKD · 08-19-2008, 01:23 PM

Hi bg101,
I have used flooded and AGM. As an owner of a coach, I wanted to eliminate the water check one must do on the flooded cell batteries. I went from flooded to AGM and am please with the maintenance free environment AGM batteries provide.

RV Wizard · 08-20-2008, 12:15 AM

Here are some links that will give you the info:
http://www.usbattery.com/care.htm
http://www.dcbattery.com/faq.html#1
http://www.windsun.com/Batteries/Bat...ery%20Charging
http://www.rvsolarelectric.com/sources.htm
http://www.batteryfaq.org

racer0624 · 08-20-2008, 01:41 AM

Gary,
When plugged in with the charger on and batteries charged the voltage in our flooded cells run around 13.5V. Our new coach has AGM's and looks to be running around 12.8V which seems low to me. In your experience, are this voltages about normal?

RoadRohrers · 08-20-2008, 02:45 AM

Ditto to GaryKD. I went from the flooded acid to the Optima AGMs. I did it primarily from the maintenance standpoint. Once the LA gassed out and corrosion started it was a constant fight to keep things cleaned up. Just purchased new (used) motorhome. One of the terms is replacing the batteries (showing corrosion in only a year) with the AGMs. Service manager yesterday tried talking me out as he felt they AGMs did not warrant the cost. I will say there was, in my configuration, a little less power available for a slightly shorter period of time. That said, we go to bed when the sun sets and rises with the sun. Battery life was never an issue for us.

Think you will get over cost of the AGMs quickly, given their "install and forget" simplicity. This is just an opinion and does not constitue an endorsement or a statement of any fact. Just my opinion which may, and probably does differ with other posters.

GaryKD · 08-20-2008, 04:06 AM

Hi John,
My coach has an IOTA DS55 charger/converter. I have the same voltage reading (in float mode), 13.5V, for both the flooded cell and the AGMs.

That being said, I did have a problem with the original DS55. It would only work when the weather was cool. The bottom line is the voltage was around 12.6V when the weather was hot. The charger was not turning on its' fan. During the day the charger would overheat and shut off. The 12.6V reading was telling me the AGMs were fully charged. At night the charger would come back on.

If your lower voltage reading is during the day, determine if your charger is cutting out. It is easy to diagnose. Do you hear the charger fan running in the heat of the day? If not, put a hair dryer in the compartment the charger is in. Close the compartment door. In less than 5 minutes open the compartment door an listen for the fan. If your charger has a fan and it is not running, have a service center check the charger.

Cruzer · 08-20-2008, 06:50 AM

Gel Cells are pretty much history but AGMs are the hot ticket. I converted my last coach over to them and this coach also has them. As chassis batteries they really aren't worth the extra cost because the standard flooded batteries work fine.

But, as house batteries they are worth their weight in gold. AGM batteries have less internal resistance therefore they take a charge better and faster than flooded batteries. They're also a tad lighter in weight. Those are small benefits but the second biggest benefit to them is that they do not outgas hydrogen when charging. That means that you can put them virtually any place you want without fear of a battery explosion. Not having to add water is a big advantage over flooded if you have a tight spot where they are located.

the biggest benefit I've seen is that they actually give you more runtime than flooded batteries. You really should not draw a battery down below 50% or else the voltage gets too low and it damages both the battery and any items that you are running off of them (low voltage increases the amps run through them). Therefore a typoical 220 amp-hr battery will only let you use 110 amp-hrs safely. But an AGM battery has a different discharge profile. If you look at a graph of a flooded battery's voltage over time you'll see that the voltage drops off over a curve and reaches the minimum useable voltage at the 50% charge level. An AGM battery has a flatter curve and the voltage doesn't drop off as fast. That means you can use more of the battery's capacity (amp-hrs) before the voltage drops to that point. In my usage I'd estimate that the AGM batteries give you roughly 30% more runtime than flooded batteries of the same amp-hr rating. If you have a 4 battery system that's like getting one free battery that doesn't take up any space or cost you extra. To me that's the biggest benefit of AGMs.

Oh yeah, they also tend to last longer because they don't have to deal with any low water level issues and don't need equalizing to keep the electrolyte from stratifying.

The ONLY drawback is that they cost more.

Techie · 08-22-2008, 05:49 AM

We had flooded on our last rig andthe current rig; the house batteries had to be replaced (under warranty) and we had them upgraded to AGM.

Why? Mostly because the batteries are not on a slide-out rack and so checking the cell level was a pain. To make sure that we didn't develop a problem we would need to check the batteries every month.

Since our inverter/charger can be set to battery type it was a no brainer.

More expensive? You bet. But since we spend a lot of time in the desert as well as the snow (yes partially insane) it was worth it.