unbob
Hood River, OR
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Joined: 11/08/2004
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Greetings,
I'm a full-timer for the past 7 years. I started out with two 6-volt Concorde AGM batteries - and they're still going strong!
As far as charge-discharge cycles, I estimate the number somewhere over 1600. I charge with 200 watts of solar panels on my RV roof (120 + 80)
I'll be returning to Baja for the winter season and don't want my batteries to die while in Mexico. Yes, it's possible to find some type of "marine deep-cycle" battery - but who knows what quality or the source!? Also, might be difficult to find 6-volt. In any case, I don't want to go down that path and be forced to deal with that potential problem.
I'm thinking of purchasing two new AGM batteries before departing the USA and have them with me available in the event my current batteries die.
To any battery-guru out there - what would you do given this scenario? And do AGM batteries usually die a "sudden-death" or just start to take longer and longer to charge and begin to noticeably discharge faster?
Any and all comments and advice welcome!
Saludos, Rob
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Gadget Guy
Calgary
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Joined: 02/18/2007
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Just do a "Load Test" on the batteries to see in what condition they are in. When ever I buy a new battery I do a load test and record the result. That gives me a "base" for any subsequent test to see how the battery is functioning and gives me a very good idea of what I can expect from the battery for the next 6 months. It has become part of my twice a year battery maintenance.
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smkettner
Southern California
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Joined: 03/21/2005
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unbob wrote:I'm a full-timer for the past 7 years. I started out with two 6-volt Concorde AGM batteries - and they're still going strong!
That says it all to me. Run them as is.
Good chance you will get another three to five years out of them.
Unless you abuse them AGM tends to die a slow death and has a lower chance of a sudden shorted cell due to the construction.
2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675 watts solar
Send a PM if I missed something
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BFL13
Victoria, BC
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Joined: 02/15/2006
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If you get another set to be on standby, part of that would be arranging to keep them "maintained" while sitting. AFAIK in the heat they will need extra good care against self-discharge, etc.
Your solar might need an extra set of wires added, or instead hook up occasional paralleling new set with old set. (use jumper cables for a day every week or whatever the timing should be?)
You could also run both sets on some alternating schedule to keep the new ones active and not work the old ones as hard, so the old ones have a longer life.
2003 Chev 2500HD ExtCab, LB, 2WD, 6.0/4.10 Gas
2003 Komfort 26FS 5er (28.5 Ft-RK-10,000lb GVWR)
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unbob
Hood River, OR
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Joined: 11/08/2004
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Gadget Guy wrote:Just do a "Load Test" on the batteries to see in what condition they are in.
Sounds good. How do I perform a "Load Test"?
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Capt.Storm
Brockport NY.
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Joined: 04/18/2010
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In my old conversion van I had isolated yellow top optima battery that some say are not so good.
I use to run a cheap 12v fridge all night a lot with that thing.
It's about 6 years old now and it outlasted the reg starting battery in the van...both bought the same time.
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pianotuna
Regina, SK, Canada
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Joined: 12/18/2004
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Hi unbob,
Unfortunately most load tests are pretty useless for the type of load presented by an RV. They tend to indicate what sort of "motor starting" loads can be supported.
No one can predict the future--but with the 200 watts of solar the batteries probably have been returned to 100% state of charge on almost a daily basis.
I agree with smkettner--just use the batteries.
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
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mexbungalows
las peñas, michoacan, mexico
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Joined: 06/01/2007
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Connect a 2 gauge series wire to make available 12 volts. Put a constant current 200 amp discharge on the battery bank for 15 seconds. The voltage should not drop to less than 9.6 volts and the sag should be linear with no sudden slump.
Remove the 200 ampere load while noting voltage. Voltage should -not- stay at 10 volts very long without climbing toward 12 volts. The voltage should recover to above 12 volts within ten seconds after the load has been removed.
If you are a wild man with a volt meter, measure the voltage across each six volt battery during the test. Each battery should be quite close to exactly half the 12 volt voltage. Amperage stays the same so ignore measure it except for determining and maintaining that 200 amp loading.
Aren't valve regulated batteries fun to test? I cannot seem to be able to convince anyone out there to purchase an anp hour meter so AGM 101 will have to wait.
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wa8yxm
Wherever I happen to park
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Joined: 07/04/2006
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I keep reading where AGM's are long life.. About the only place I don't read that is on AGM manufacturer's web sites and in my own posts.
I have two AGM's.. I have two Golf Car Batteries (Six volt true deep cycle)
I have several assorted "Maintenance free"
I'll be replacing the AGM's with Maintenance free for about 1/3 the price
ONLY THE AGM's which are the newest batteries in the rig, (not counting flashlight batteries) need replacement.. The rest are going strong.
Nothin adds excitment like something that is none of your business
Kenwood TS-2000 housed in a 2005 Damon Intruder 377
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Dunebuster
Canton MI
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Joined: 11/03/2005
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First: Your long battery live is a product of good cycling and good temperatures (not too warm and not too cold) it is also good that solar chargig systems don't overcharge too much
Second: AGM's will last longer since the separator helps hold the plates together under better compression. (also tru for those cylindrical wound 12B batteries). Deep cycle/Maintenance Free batteries don't have that compression so as the battery wears out the plates start to disintegrate loosing both power (connectivity) and capacity (active material on the plates). The AGM battery holds the plates and active material in place so the failure comes later in live comparatively. This is very true in mobile trailers and in particular my 2 jetskis where I put in a pair of Dekka motorcycles batteries in 2000 and they are still running 10 years later despite only being used for maybe 200 hours of operation and poor self-discarge care by myself (I only charge them a couple times a winter)
Third: As batteries age the loose both power and capacity. Hooking up a pair of headlights (10A each) and a voltmeter and letting them run the battery down until you get to 10V can give you a good indicator of residual capacity. Since you are pulling roughly 20A,you can either measure voltage after 2 hours or measure voltage after 1 hour of discharge and keep a record of the results.. Admittedly you can only get good data if you do this if you start when the batteries are new but it is a decent way to measure where you are in battery life and capability..
Good luck
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