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Old 03-03-2009, 09:51   #1
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Equalizing AGMs

Who here has tried equalizing AGMs? What voltage did you do it at and for how long?

Originally I was under the impression that you should never go over the manufacturers max voltage for AGMs but since then I've seen a couple of mentions of equalizing them.

The situation I'm in is that my house bank is pretty old and won't hold a charge - replacing the bank is the next step if I can't improve matters so I'm not sure what I have to lose by trying to equalize, provided they won't explode, melt etc.
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Old 03-03-2009, 11:06   #2
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Dave, a tech guy at Lifeline Batteries (AGM manufacturer), says to charge them fully first, and then apply a constant voltage of 15.5 VDC for eight hours. Equalizing will reduce the lifespan a bit, but will improve performance when they've lost some of their capacity.
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Old 03-03-2009, 11:19   #3
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And Trojan says that you should NOT equalize AGM or GEL batteries.

http://www.trojanbattery.com/Product...nglish_001.pdf
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Old 03-03-2009, 13:37   #4
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I think in my browsing I've read a lot more "dont do it" than "do it". However I figure that if I'm about to replace the batteries then I don't stand to lose much unless its dangerous.

Has anyone on this board actually done it?
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Old 03-03-2009, 14:53   #5
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This AGM equalization procedure used to be on the Lifeline website. I don't see it there now. But here is a copy:
Lifeline AGM Batteries Charging Procedure

Paul L
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Old 03-03-2009, 15:25   #6
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Tom, I have read here somewhere (I believe on this forum) that the capacity of the battery bank (AGM) can be, at least for the most part, restored by draining the bank down to about 11 volts and then fully charging. It may take several cycles to get the capacity up. They aren't fully restored but the procedure adds significant life to the batteries at times when the battery capacity has dropped prematurely due to improper charging.
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Old 04-03-2009, 06:57   #7
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Each AGM battery is different. You need to CALL your mfr. to see if ANY EQ is possible and if so, at what Volatage and for how long. Otherwise, don't attempt it.
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Old 04-03-2009, 13:44   #8
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Quote:
Originally Posted by camaraderie View Post
Each AGM battery is different. You need to CALL your mfr. to see if ANY EQ is possible and if so, at what Volatage and for how long. Otherwise, don't attempt it.
Don't because I'll break already broken batteries or don't because its dangerous?

I'll start with the discharging and recharging in a controlled manner idea to see if it helps. Calling the mfgs is a good idea - I think they are lifelines. Old, abused, lifelines.
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Old 05-03-2009, 10:44   #9
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Tom...if they are indeed Lifelines...you are in luck. Lifeline now call equalizing a conditioning charge which you should apply for 8 hours in a WELL ventilated space. The voltage used is dependent on ambient temperature as follows:
40 16.2
50 16.0
60 15.85
70 15.7
77 15.6
80 15.5
90 15.4
100 15.3
110 15.2
120 15.1
130 15.0
140 15.0
150 15.0
160 15.0
Over 160...shut it down!!
Note that you should bring the batteries to 100% charge before doing this. I've rounded off the voltages to the nearest tenth. Note the ventilation remarks!!
Do not do this with other AGM's unless you have confirmed SAFETY with the mfr.
Yes..AGM's can explode scattering a lot of nasty stuff if they get to overtemperature thermal runaway through overcharging!!
Suggest that even with Lifelines, you monitor temperature and do not permit the batteries to get over 160 degrees.
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Old 05-03-2009, 15:10   #10
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Temperature limit of charging

It is not advisable to equalize any lead-acid battery at or above 120 deg F. Even near that temperature it requires a voltage-limited constant-current charger with good line and load regulation specs.

Most "marine" chargers are not up to this task. I've been equalizing (bringing back from the dead) AGM and gel-cell batteries for 20 years and it can be done. Those batteries which will not recover will exhibit a wide temperature range from cell-to-cell...this is one good indicator as to whether or not one will be successful.
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Old 06-03-2009, 05:26   #11
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We have a Magnum charger/inverter and it has 2 agm settings. One for Lifeline batteries and the second for all other agm. Only the setting for Lifeline will allow us to equalize.

Barry
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Old 14-03-2009, 15:01   #12
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Quote:
Originally Posted by theonecalledtom View Post
Don't because I'll break already broken batteries or don't because its dangerous?

I'll start with the discharging and recharging in a controlled manner idea to see if it helps. Calling the mfgs is a good idea - I think they are lifelines. Old, abused, lifelines.
I am now looking at Lifelines.
Do you know how old yours are?
Or how much abuse (and still gave acceptable performance) they have taken?
Do you know which model or size they are?
Any other comments about the Lifelines?
How has the discharge recharge regime worked out (if you know yet)?

An comments would be appreciated.
Extemp.
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Old 14-03-2009, 15:05   #13
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Quote:
Originally Posted by Beach Cruiser View Post
We have a Magnum charger/inverter and it has 2 agm settings. One for Lifeline batteries and the second for all other agm. Only the setting for Lifeline will allow us to equalize.

Barry
A little off topic, but I see you have a Magnum charger/inverter.
Have you noticed much RFI?
Is it a true Sine Wave model?
Do you like it?
Any other comments about it?

Thanks,
Extemp.
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Old 14-03-2009, 15:25   #14
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I bought my 8D Lifelines in 2000, before we went cruising, and finally got rid of them in 2007, while in Venezuela. I would have replaced them with AGMs if they had been available there. I did 'equalize' them a few times according to directions I got from Lifeline. I used a Freedom 20 inverter/charger and set it to 'warm wet cell' to do the charge since that was closest to the voltage recommended by Lifeline (done after emails back/forth with the tech guy at Lifeline). I then monitored the process very closely, watching the amount of amps going in (very little) and the voltage. The batteries were fully charged when I did it. I shoul point out that I probably could have gotten a longer life out of them but I made several mistakes (undercharging) when they were new (I was using the wrong setting on my charge controller and didn't realize it).
HTH,
Larry
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Old 14-03-2009, 16:01   #15
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I have a MS-2012 pure sine wave unit. I am very happy so far, but I have only been using it for a few months. I have not noticed any RFI.

Right now we are in the Abacos and I am spending all my time at anchor. I charge mostly with solar and wind, but I have a Honda eu2000i generator that I use for running the water heater and occasionally charging. I really like the fact that I can change the amps the charger puts out. This allows me to control the load on the Honda.

The optional battery monitor is excellent.

Barry

Quote:
Originally Posted by Extemporaneous View Post
A little off topic, but I see you have a Magnum charger/inverter.
Have you noticed much RFI?
Is it a true Sine Wave model?
Do you like it?
Any other comments about it?

Thanks,
Extemp.
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