msiminoff wrote:
Hi Jeff,
It's awesome that Sears was happy to replace the batteries for you under warranty. I often recommend the DieHard Platinums for exactly that reason (plus the nationwide availability).
However those EnerSys batteries are very hard to kill (I have been abusing mine for a long time!)... and based on the description you provided I suspect that root cause of the issue is related to the charging, and not the batteries themselves. In other words; I think that the batteries were simply discharged, not defective. For starters, your charger (and solar panel/controller) are small considering your 200Ah of AGM's. At the voltage you stated (13.2) the batteries would never have reached 100% SOC. They should have been absorption charged at 14.7V and should have been float charged at 13.6. In addition if they had been fully charged and then disconnected when you parked the TC for the winter those AGM's would have a storage life of more than 2 years.
The test that Sears conducted is so far outside of EnerSys's charge & testing protocol that it's laughable... and a 4 minute charge (regardless of current) is followed by a high current discharge is meaningless.
EnerSys has specific guidelines for charging deeply discharged batteries and states that a group 31 battery should be charged at 5A for 24 hours and the voltage should be allowed to rise to as much as 18.0V (the Boondocker can't do that)... then the batteries should have been removed from the charger for 18 hours before capacity testing.
Anyway, now that you have fresh batteries I suggest that you download the TECHNICAL MANUAL from EnerSys and review the information in the charging section. If you are hoping to get many years of service and high capacity from the Platinums, you may also want to consider a larger and more configurable battery charger and solar controller.
Cheers,
-Mark
Hi Mark,
I'll read through the manual.
I read the manual and it states to use a charging power supply capable of up to 18 volts but not to actually charge at that voltage. They imply to use an absorption charge at 14.7-15 volts, then let it drop to 13.6 volts, then to a float of 13.2 volts.
When I took the batteries in to SEARS, they had been charging for a while since the PNW Rally and the solar took them up to 14.6 volts each day at low current. I removed them and placed them in my truck where they sat a couple days. They measured 13.7 volts each a couple hours after removal. I did not measure the voltage again before testing and replacement at SEARS.
I read a bit about Lifeline and they recommended desulphation or restoration from deep discharge charging at 15.5 volts for 8 hours per battery. I did that and it seemed to help but the batteries still only lasted a couple hours before suddenly dropping to 10.2 volts. It seems to me that that is about the voltage of one bad cell in each battery giving out.
All my reading on AGM batteries so far suggests 14.6-14.8 volts absorption, 13.6 acceptance, and 13.2 float charging. I don't know that they require an infrequent equalization charge. When the TC is on the truck, I have 4 AWG wire directly from the alternator to the TC batteries usually charging between 13.2 and 13.8 volts but have measured 15.2 volts for a few minutes. The 45 amp boondocker is supposed to sense what the batteries need and apply that voltage. Since they had 12.9 volts off the shelf when I installed them today, the 13.2 volts the Boondocker applied seems correct to me. The solar panel and controller will apply up to 14.6 volts at up to 3.6 amps tomorrow. That should bring the batteries up to full by most standards I've read thus far. Applying a battery warmer blanket for optimal battery temperature and remote temperature sensors on the batteries would be the next step for accuracy in charging.
We'll see what happens.
J
