Battery choice

bheisser · 12-07-2016, 08:53 PM

Flooded deep cycle vs AGM deep cycle vs Gel deep cycle
can someone explain the difference.
cost is not really a major consideration

http://www.trojanbattery.com/markets/mr/12v/

**Bill** · 12-07-2016, 09:15 PM

Lead-acid batteries contain a number of lead plates, mounted parallel to each other and immersed in acid. The chemical interaction between the lead and the acid is what stores and releases electrical energy.

In terms of differences, a "deep cycle" battery can be discharged farther than a "motor-starting" battery, but has reduced ability to produce very high peak current. This is due to different internal construction. The lead plates in a motor-starting battery are many but thin, and they warp under deep discharge. The lead plates in a deep cycle battery are thicker, meaning stronger and less likely to warp.

In each of the three cases you mention, the lead plates are immersed in acid. In a flooded battery, the acid is a liquid with the viscosity of water. This is inexpensive construction, but the liquid can spill if the battery is turned on its side or upside down. In an AGM battery, the acid is absorbed into a porous glass mat that fills the spaces between the plates. Since the liquid is contained in the mat, it cannot spill. In a gel cell battery, a gelling agent is added to the liquid, again making it spillproof.

I'm not sure this is what you were looking for, but there it is. There is more detail on many web sites, such as

https://www.batterystuff.com/kb/arti...el-vs-agm.html

One of the best sources of info is Northern Arizona Wind and Sun, aka https://www.solar-electric.com. For example, see this set of articles

https://www.solar-electric.com/deep-...tery-faq.html/
You'll find, among other things, that these folks don't like (and won't sell) gel-cells.

Bill

BrucePerens · 12-07-2016, 09:55 PM

What converter you have is important. If you have the original converter, go with flooded, because it can handle overcharge the best. That converter may overcharge enough to boil off electrolyte.

If you have a four or three-stage charger, there's still the issue that AGM can be sensitive to overcharging and that it's temperature-dependent. 99% gas recovery doesn't mean you won't lose water, you will just lose it more slowly and you can't replace it.

My solar charger allows me to set the voltages and has a temperature probe. The one in my converter does not. This might be an issue if I had AGM and left the converter plugged in in storage. I have flooded batteries and allow the solar system to maintain them.

Padgett · 12-08-2016, 07:38 AM

For me, the closest match to my use was golf cart batteries so I have two GC2s in series. they just fit in the rear compartment width of my 2720SL next to the vent.

I have them on a little float charger when not in use. Just could not justify the price of AGMs but prefer.

stormpeakco · 12-08-2016, 07:45 AM

Quote:

Originally Posted by Bill

Lead-acid batteries contain a number of lead plates, mounted parallel to each other and immersed in acid. The chemical interaction between the lead and the acid is what stores and releases electrical energy.

In terms of differences, a "deep cycle" battery can be discharged farther than a "motor-starting" battery, but has reduced ability to produce very high peak current. This is due to different internal construction. The lead plates in a motor-starting battery are many but thin, and they warp under deep discharge. The lead plates in a deep cycle battery are thicker, meaning stronger and less likely to warp.

In each of the three cases you mention, the lead plates are immersed in acid. In a flooded battery, the acid is a liquid with the viscosity of water. This is inexpensive construction, but the liquid can spill if the battery is turned on its side or upside down. In an AGM battery, the acid is absorbed into a porous glass mat that fills the spaces between the plates. Since the liquid is contained in the mat, it cannot spill. In a gel cell battery, a gelling agent is added to the liquid, again making it spillproof.

I'm not sure this is what you were looking for, but there it is. There is more detail on many web sites, such as

https://www.batterystuff.com/kb/arti...el-vs-agm.html

One of the best sources of info is Northern Arizona Wind and Sun, aka https://www.solar-electric.com. For example, see this set of articles

https://www.solar-electric.com/deep-...tery-faq.html/
You'll find, among other things, that these folks don't like (and won't sell) gel-cells.

Bill

__________________________________
Thanks.

tentcamper · 12-08-2016, 12:43 PM

The first question, will you perform the maintenance required for a battery when the camper is in storage? Disconnect the battery, keep it charged or on a tender and from time-to-time check the voltage and water level. It sounds like a stupid questions, but most people don't do it, and are surprised when their battery needs to be replaced in 1 or 2 years.

Flooded batteries are very unforgiving if you let the charge drop below about 12V or the water level gets to low. AGM batteries do not need near the maintenance and do not self discharge near as quick. They do require you to disconnect the battery and 2 - 6 months give them a charge.

I'm under the impression with proper maintenance; flooded batteries you should get a life from 6 to 8 years. AGM batteries 7 to 9 years.

Cost: AGM batteries cost 70% to 150% more than flooded.

Will you be doing one or two batteries. You are the only one the can answer this. It will be determined by your needs: usage, type of camping, and if you have a method to recharge.

Two batteries. There are 2 schools of thoughts.

1) 2 - 6v batteries you can get a little more charge than 12v's. But if one fails in the field you SOL until you get a replacement.

2) 2 - 12v batteries, if one fails in the field you can disconnect the bad battery and limp along on other. There is a rare failure of a shorted cell that could downgrade the future charging capability of the other battery by discharging it far.

bheisser · 12-08-2016, 05:42 PM

tent camper
i will maintain the battery yes,, will i be meticulous,,,no.....
i will check the water,, disconnect when not being used,,,,
probably wont be charging it all winter...... if i leave it disconnected for 3-4 months is that going to ruin it?
1 battery,,,my wife doesn't want any part of boondocking,,,, i don't really care if i have to replace every 5 or every 8 years,, but i do want a quality battery that will perform if/when needed

tentcamper · 12-08-2016, 08:34 PM

Standard flooded batteries are said to have a self discharge rate of 5 to 15% rate. Temperature is going to greatly affect that rate. This is a time when colder is better. But once you drop below freezing, if the battery does not have a good charge it can freeze. Flooded batteries, you begin to damage once the charge drops below 50% charge, which is somewhere around 12.0 to 12.2 volts depending on temp and manufacture. The deeper the discharge is the more harm.

So if you start with a battery at 13V and let is sit for Nov until April, 5 months. At 5% you discharge by 25%, which is okay. At 15% you discharge by 75% you most likely permanently lost a large capacity of the battery. The second winter it's near tost. I think the rule of thumb is like 6 months you are damaging the battery. Hotter temps faster, cooler longer.

What you are saying about how you are going to maintain the battery. An AGM might sounds like your best choice.

AGM batteries are said to have a self discharge rate between 1 and 3% and never need to be watered. Also they are said to be able to be discharged to 80% with little damage.

I have no experience with AGM, but have done some research. If it was not for price, I think I would have one. Sams club seems to have the best deal. A G31 with about 225 amp RC for about $175. I buy flooded G31 batteries for around $100 and get 6-7 years of life, but I do the maintenance. Maybe the next will be AGM???

Padgett seems to have much experience AGM batteries, but I think he has flooded right now because of price. I would message him for his build.

Padgett · 12-08-2016, 08:50 PM

Sorta. All of my cars have AGMs and have bought two Sam's type 31 AGMs for two RVs but for the TM I went with 2 conventional GC2s ($160) rather than 2 AGM GC2s ($350) and maintain with a float charger (actually have floats on 4 of my 6 cars).

BTW Duracell AGMs at Sams are $25 off through Dec 24th.

tentcamper · 12-08-2016, 11:12 PM

Padgett, does sams put them on sale often or is this unique?