Group 27 AGM mid life performance report
My 90AH Northstar AGM battery is now 38 months old, and has accumulated ~465 deep cycles. When I cycle it, generally I consume 35 to 65AH nightly, average about low 40's Since June of 2015 it ...
Forum Discussion
Well comparing the Northstar and UPG AGMS is more like comparing tangelos and oranges. Not sure which is which.
Lifeline touts thick plates and long cycle life, while Odyssey and Northstar tout thin plates and high CCA figures, with the ability to deep cycle.
They are reported to perform better than the lifeline in PSOC duty than lifeline, at least according to a test done by practical sailor magazine.
One reason I initiated this 65 amp from ~33%, is a week 10 days ago, or so, After a prolonged period with no Cycling, just plugged in and temperature compensted floating, then a deep cycle(55Ah from full), then a high amp(alternator) recharge, it did not accept many amps before reaching and staying at absorption voltage, and then amps took forever to taper to 0.4. The alternator is thickly cabled and was not the limiting factor. 50 amps tapered to mid 40's before I took off the parking brake, and I was very disappointed at noticing the performance loss, and wondered about the prolonged period of floating. There were some very shallow cycles, 5 to 7AH, and i did not crank voltage upto 14.7, but just it fill at 13.7 from 5 to 7Ah from full, then float all night long.
Something about the floating for so long with very shallow short duration cycles and no 14.7v afterwards, did not jive with the battery at this age when I asked it to wake back up and goto work in the salt mines with deep overnight cycles again.
So the 65 amp from ~33% SOC was a deliberate test, hopeful to see similar results as the previous time I unloaded both charging sources on it when well depleted, and in that regard, it was a success, and the 80 to 100%, while not as fast as when newer is improved over the super lethargic 80-100 after the prolonged float session.
Then there is Odyssey's 'reconditioning' procedure which basically says drop voltage to the 10 range under a load like vehicle headlights, then apply 40% of the 10 hour rate until 14.7 then hold until amps taper to zero, and repeat one more time to return to maximum possible remaining capacity. A 100% discharge followed by a high amp Full 100% recharge until amps taper near zero, however long that takes. Twice.
http://www.odysseybattery.com/documents/ODYSSEY_Battery_Reconditioning_Charge_Procedure.pdf
This is apparently what the carbon foam Firefly AGM also recommends, but they failed to recommend a rate at which to discharge. It appears I might get a chance to perform that reconditioning on an abused, but relatively young ( 8 months old) Firefly next week. It is owned by a Newb, and It was deliberately drawn to 10.5v, and much much lower, but under a very light load over many days, and is solar only recharged, and has leaked from the vents and acted wacky for a few days afterwards, but now is apparently back to 'normal.'
I hope the Firefly outperforms my Northstar, and it certainly should being rated for 20more AH capacity. Would love a 77F water bath and a load which remained constant over a voltage range of 13 to 10.5v to perform a true accurate capacity test, but will have to judge and estimate capacity and performance.
Northstar's documentation and recommendations leaves a lot to be desired, and I have usually followed Odyssey's documentation and recommendations, even using 14.7 instead of 14.46 Vabs.
As for the heat build up, well way back when, when i swapped the screw31 with the northstar in location, well the exhaust pipe is about 22 inches away, and I wrapped the battery in reflectix to reflect radiated heat. I Should have instead made a reflective barrier instead of wrapping the batery in reflectix.
The battery temp sensor is on the side of the battery casing, in the middle of a cell, and prolonged driving has it read abnormally high temps behind 2 layers of reflectix, but this drops quickly once I stop moving and engine off. Still the battery is bathed in engine heat almost as if it is in the engine bay.
But some of the temperature rise during high amp recharging has to be attributed to the battery being effectively insulated on 5 of the six sides.
I've been meaning to unwrap it and make a heat shield barrier instead, but the 67LB Northstar is a wrist breaker and very difficult to lift out and drop back into place, and I no longer have another battery to switch all loads to while performing such a task. Not impossible to work around, but I do lack gumption more often than I care to admit.
I was surprised at the temp rise even as amps were dropping quickly in relatively cool ambient temperatures. The battery temp sensor has been an eye opener. I think high amp charging while moving or in high ambient temps or both, will have me extra glad I can regulate voltage by spinning a dial on my dashboard.
Lifeline touts thick plates and long cycle life, while Odyssey and Northstar tout thin plates and high CCA figures, with the ability to deep cycle.
They are reported to perform better than the lifeline in PSOC duty than lifeline, at least according to a test done by practical sailor magazine.
One reason I initiated this 65 amp from ~33%, is a week 10 days ago, or so, After a prolonged period with no Cycling, just plugged in and temperature compensted floating, then a deep cycle(55Ah from full), then a high amp(alternator) recharge, it did not accept many amps before reaching and staying at absorption voltage, and then amps took forever to taper to 0.4. The alternator is thickly cabled and was not the limiting factor. 50 amps tapered to mid 40's before I took off the parking brake, and I was very disappointed at noticing the performance loss, and wondered about the prolonged period of floating. There were some very shallow cycles, 5 to 7AH, and i did not crank voltage upto 14.7, but just it fill at 13.7 from 5 to 7Ah from full, then float all night long.
Something about the floating for so long with very shallow short duration cycles and no 14.7v afterwards, did not jive with the battery at this age when I asked it to wake back up and goto work in the salt mines with deep overnight cycles again.
So the 65 amp from ~33% SOC was a deliberate test, hopeful to see similar results as the previous time I unloaded both charging sources on it when well depleted, and in that regard, it was a success, and the 80 to 100%, while not as fast as when newer is improved over the super lethargic 80-100 after the prolonged float session.
Then there is Odyssey's 'reconditioning' procedure which basically says drop voltage to the 10 range under a load like vehicle headlights, then apply 40% of the 10 hour rate until 14.7 then hold until amps taper to zero, and repeat one more time to return to maximum possible remaining capacity. A 100% discharge followed by a high amp Full 100% recharge until amps taper near zero, however long that takes. Twice.
http://www.odysseybattery.com/documents/ODYSSEY_Battery_Reconditioning_Charge_Procedure.pdf
This is apparently what the carbon foam Firefly AGM also recommends, but they failed to recommend a rate at which to discharge. It appears I might get a chance to perform that reconditioning on an abused, but relatively young ( 8 months old) Firefly next week. It is owned by a Newb, and It was deliberately drawn to 10.5v, and much much lower, but under a very light load over many days, and is solar only recharged, and has leaked from the vents and acted wacky for a few days afterwards, but now is apparently back to 'normal.'
I hope the Firefly outperforms my Northstar, and it certainly should being rated for 20more AH capacity. Would love a 77F water bath and a load which remained constant over a voltage range of 13 to 10.5v to perform a true accurate capacity test, but will have to judge and estimate capacity and performance.
Northstar's documentation and recommendations leaves a lot to be desired, and I have usually followed Odyssey's documentation and recommendations, even using 14.7 instead of 14.46 Vabs.
As for the heat build up, well way back when, when i swapped the screw31 with the northstar in location, well the exhaust pipe is about 22 inches away, and I wrapped the battery in reflectix to reflect radiated heat. I Should have instead made a reflective barrier instead of wrapping the batery in reflectix.
The battery temp sensor is on the side of the battery casing, in the middle of a cell, and prolonged driving has it read abnormally high temps behind 2 layers of reflectix, but this drops quickly once I stop moving and engine off. Still the battery is bathed in engine heat almost as if it is in the engine bay.
But some of the temperature rise during high amp recharging has to be attributed to the battery being effectively insulated on 5 of the six sides.
I've been meaning to unwrap it and make a heat shield barrier instead, but the 67LB Northstar is a wrist breaker and very difficult to lift out and drop back into place, and I no longer have another battery to switch all loads to while performing such a task. Not impossible to work around, but I do lack gumption more often than I care to admit.
I was surprised at the temp rise even as amps were dropping quickly in relatively cool ambient temperatures. The battery temp sensor has been an eye opener. I think high amp charging while moving or in high ambient temps or both, will have me extra glad I can regulate voltage by spinning a dial on my dashboard.
