SternWake
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- Nov 30, 2013
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My group 27 Northstar AGM has been an impressive battery so far.
It has about 465 Deep cycles on it over 38 months and several hundred shallow cycles and likely a few thousand engine starts. About 4 to 5 dozen of those Cycles are to well below 50%, as low as 25%.
It has been my ONLY battery since june of 2015. No dedicated house or engine starting battery, it is doing double duty. I use between 35 and 60Ah each night when I cycle it, and it has always easily started my engine the next morning/day.
My charging sources are 198 watts of MPPT solar, thickly cabled alternator, and 40amp adjustable voltage power supply, with a 25 amp'Smart' Schumacher kicker to add to the MEanwell's 40 amps. All but the Schumacher have adjustable voltage.
My previous judges of performance has been voltage held for Ah removed under X amount of load Watching my battery monitor frequently over many hundreds of dischrge cycles through many sets of batteries over the last decade.
Yet these parameters on this AGM, have remained nearly identical since the battery was new. The exception being after 5 or more PSOC( partial state of charge) cycles, or more than 5 cycles, even to full, without any high amp recharge applied( solar only).
When I noticed the performance sag, the remedy has always been a high amp recharge until truly full, then Voltage held for AH removed under X amount of load was back to 'New' levels and engine cranking gusto also returned to impressivly fast levels.
I have noticed that when depleted, the amps and time required to reach absorption voltage have been dropping as the battery ages. I also notice that when absorption voltage has been reached, the time it takes for amps to taper to 0.5% of capacity( 0.45 amps at 14.7v) has been increasing.
A few weeks ago I noticed the amps required had tapered to only about 45, to reach absorption voltage instantly, and this was a marked degradation in performance from 3 weeks before where it accepted 65 amps for ~20 minutes before attaining absorption voltage. And, I had to come to grips with a degraded battery.
But last night, I wanted a better yardstick of performance, so I drained the 90Ah battery to ~60Ah from full in 6 hours. At that average rate of discharge, the battery would be closer to 80AH, if it still has 90Ah total, which It simply cannot.
Anyway at ~60Ah from full, perhaps 33% charged, I turned on my inverter and powered 200 watt heater for a minute for a total load of 22 amps.
Voltage dropped to 11.5 under that 22 amp load at that level of battery depletion.
2 minutes after removing the inverter load, at 5.6 amps of load, voltage rebounded to 11.7v
2 minutes after that, under a 1.7 amp load voltage rebounded to 11.9v
2 minutes after that under a 0.3 amp load, voltage rebounded to 12.02v, and then I applied my charging sources.
Schumacher's 25 amps were first
Meanwells 40 amps were second.
battery temperature was 63F
Voltage quickly rose to 14.4v, but levelled off, then dropped to 13.9v over the next 5 minutes, then started climbing again at a constant 65 amps of charge current.
24 minutes later the schumacher started dropping amperage as battery voltage approached 14.7v, and then voltage sagged to 14.5v.
6 minutes later the battery hit 14.8v under 53 amps of charging source.
40 minutes after applying 65 amps initially, Amps had tapered to below 40, and I removed the schumacher with meanwell providing the 35.5 amps required to maintain absorption voltage
Battery temperature had risen from 63F to 77F and I decided to start reducing absorption voltage to 14.6v.
This required some babysitting as there is some voltage drop on my 8awg cabling from meanwell to battery, and the battery was still warming pretty rapidly despite the dropping amperage.
Amps had declined to 4.6 at 14.6v at the 2 hour mark and battery was well over 80F in sub 60F ambient temps and still warming.
I did not stay up/awake for the time required for amps to taper to [email protected], nor did I want to leave it at 14.6v while I slept, So I lowered voltage to 13.9v and went to bed.
3 hours later or so battery was accepting 0.1 amps at 13.9v and I goosed voltage to 14.7v again. It took 1.7 amps, and then dropped to 0.4a in the time it took to empty my bladder.
I lowered voltage back to 13.9v and slept for 3.5 more hours
Awoke to 0.1 amps at 13.9v and a voltage goosing to 14.7v again took 1 amp but that quickly tapered back to 0.1amp.
So this battery has earned my respect. A 90Ah battery with 465 deep cycles on it accepting 65 amps for 24 minutes is impressive. I'd like to know just how long it took amps to taper to 0.45a at absorption voltage, but when I first goosed voltage to 14.7v early morning during baldder emptying, it was basically full, and that was ~7.75 hours since I first appled 65 amps of charge current.
So this is acceptable too.
Anyway on this battery the High amp recharges have always been a 'reset' to performance, with much faster engine starting afterwards and a return to higher voltages held under normal overnight discharge as well as a decreased time at which absorption is required to be held before amps taper to 0.45.
Every other flooded marine battery I have employed previously( group 27 and 31), the performance drop off, as to how I judge it, voltage held for Ah removed under the load at the time of reading, was in a steady decline with a steep drop at the end which signalled time to replace.
But this AGM is playing by a different rulebook as after a high amp recharge' reset', the voltage held for AH removed and the load at that time, remains very near where it was when new.
The only way I can discern that this battery is aging, is because the amps required to attain absorption voltage are less than when new, and the time it takes amps to taper to 0.5% of capacity at absorption voltage, takes longer.
Odyssey has a reconditioning/ capacity restoration procedure which says to load battery with ~15 amps or more until voltage drops to 10 volts or so then apply a large charging source until 14.7 and hold 14.7v until amps taper to near Zero.
Lifeline's conditioning procedure is to attain 15.5v for 8 hours after a normal 'full' charge.
No other AGM that i know of lists any reconditioning procedure.
My test last night, I used 11.5v instead of 10.5v, but that is as close as I have come to either method designed to restore lost capacity.
The high amp recharge is key with this battery, and the hold absorption voltage until amps taper to 0.5% of capacity. It does not have to happen every single recharge, and it would be a bad battery if it were required each and every time, but when i see the warning signs that the battery is getting a bit pertrubed, It is nice that a high amp recharge to truly full has been resetting it to 'like new' capacity and performance.
So While this battery ius by far the most expensive i have ever used, It will likely also provide the best cycles per dollar ratio when all is said and done.
But to be fair to my previous flooded marine batteries of yesteryear, I could not recharge them nearly as precisely to extract the most from them.
When the previous Flooded batteries started obviously declining, nothing I did seemed to ever reset them, and the decline continued despite efforts to stop or perhaps reverse them, but this high$$ AGM battery, when I notice performance loss, I know that a deeper discharge followed quickly by a high amp recharge will most likely reset it to 'impressive' status once again.
At 465 Deep cycles, it can't be just like new. Some degree of capacity loss has to have occurred. I could not really perform a truly accurate 20 hour capacity test to know for sure, and do not want to intentionally drain a battery to 10.5v just for the test.
My point is is that voltge held under X amount of load, for a certain # of Ah removed cannot be used to judge this high$$ agm battery, as after the high amp recharge to full, these numbers are so far, just like when new.
It has about 465 Deep cycles on it over 38 months and several hundred shallow cycles and likely a few thousand engine starts. About 4 to 5 dozen of those Cycles are to well below 50%, as low as 25%.
It has been my ONLY battery since june of 2015. No dedicated house or engine starting battery, it is doing double duty. I use between 35 and 60Ah each night when I cycle it, and it has always easily started my engine the next morning/day.
My charging sources are 198 watts of MPPT solar, thickly cabled alternator, and 40amp adjustable voltage power supply, with a 25 amp'Smart' Schumacher kicker to add to the MEanwell's 40 amps. All but the Schumacher have adjustable voltage.
My previous judges of performance has been voltage held for Ah removed under X amount of load Watching my battery monitor frequently over many hundreds of dischrge cycles through many sets of batteries over the last decade.
Yet these parameters on this AGM, have remained nearly identical since the battery was new. The exception being after 5 or more PSOC( partial state of charge) cycles, or more than 5 cycles, even to full, without any high amp recharge applied( solar only).
When I noticed the performance sag, the remedy has always been a high amp recharge until truly full, then Voltage held for AH removed under X amount of load was back to 'New' levels and engine cranking gusto also returned to impressivly fast levels.
I have noticed that when depleted, the amps and time required to reach absorption voltage have been dropping as the battery ages. I also notice that when absorption voltage has been reached, the time it takes for amps to taper to 0.5% of capacity( 0.45 amps at 14.7v) has been increasing.
A few weeks ago I noticed the amps required had tapered to only about 45, to reach absorption voltage instantly, and this was a marked degradation in performance from 3 weeks before where it accepted 65 amps for ~20 minutes before attaining absorption voltage. And, I had to come to grips with a degraded battery.
But last night, I wanted a better yardstick of performance, so I drained the 90Ah battery to ~60Ah from full in 6 hours. At that average rate of discharge, the battery would be closer to 80AH, if it still has 90Ah total, which It simply cannot.
Anyway at ~60Ah from full, perhaps 33% charged, I turned on my inverter and powered 200 watt heater for a minute for a total load of 22 amps.
Voltage dropped to 11.5 under that 22 amp load at that level of battery depletion.
2 minutes after removing the inverter load, at 5.6 amps of load, voltage rebounded to 11.7v
2 minutes after that, under a 1.7 amp load voltage rebounded to 11.9v
2 minutes after that under a 0.3 amp load, voltage rebounded to 12.02v, and then I applied my charging sources.
Schumacher's 25 amps were first
Meanwells 40 amps were second.
battery temperature was 63F
Voltage quickly rose to 14.4v, but levelled off, then dropped to 13.9v over the next 5 minutes, then started climbing again at a constant 65 amps of charge current.
24 minutes later the schumacher started dropping amperage as battery voltage approached 14.7v, and then voltage sagged to 14.5v.
6 minutes later the battery hit 14.8v under 53 amps of charging source.
40 minutes after applying 65 amps initially, Amps had tapered to below 40, and I removed the schumacher with meanwell providing the 35.5 amps required to maintain absorption voltage
Battery temperature had risen from 63F to 77F and I decided to start reducing absorption voltage to 14.6v.
This required some babysitting as there is some voltage drop on my 8awg cabling from meanwell to battery, and the battery was still warming pretty rapidly despite the dropping amperage.
Amps had declined to 4.6 at 14.6v at the 2 hour mark and battery was well over 80F in sub 60F ambient temps and still warming.
I did not stay up/awake for the time required for amps to taper to [email protected], nor did I want to leave it at 14.6v while I slept, So I lowered voltage to 13.9v and went to bed.
3 hours later or so battery was accepting 0.1 amps at 13.9v and I goosed voltage to 14.7v again. It took 1.7 amps, and then dropped to 0.4a in the time it took to empty my bladder.
I lowered voltage back to 13.9v and slept for 3.5 more hours
Awoke to 0.1 amps at 13.9v and a voltage goosing to 14.7v again took 1 amp but that quickly tapered back to 0.1amp.
So this battery has earned my respect. A 90Ah battery with 465 deep cycles on it accepting 65 amps for 24 minutes is impressive. I'd like to know just how long it took amps to taper to 0.45a at absorption voltage, but when I first goosed voltage to 14.7v early morning during baldder emptying, it was basically full, and that was ~7.75 hours since I first appled 65 amps of charge current.
So this is acceptable too.
Anyway on this battery the High amp recharges have always been a 'reset' to performance, with much faster engine starting afterwards and a return to higher voltages held under normal overnight discharge as well as a decreased time at which absorption is required to be held before amps taper to 0.45.
Every other flooded marine battery I have employed previously( group 27 and 31), the performance drop off, as to how I judge it, voltage held for Ah removed under the load at the time of reading, was in a steady decline with a steep drop at the end which signalled time to replace.
But this AGM is playing by a different rulebook as after a high amp recharge' reset', the voltage held for AH removed and the load at that time, remains very near where it was when new.
The only way I can discern that this battery is aging, is because the amps required to attain absorption voltage are less than when new, and the time it takes amps to taper to 0.5% of capacity at absorption voltage, takes longer.
Odyssey has a reconditioning/ capacity restoration procedure which says to load battery with ~15 amps or more until voltage drops to 10 volts or so then apply a large charging source until 14.7 and hold 14.7v until amps taper to near Zero.
Lifeline's conditioning procedure is to attain 15.5v for 8 hours after a normal 'full' charge.
No other AGM that i know of lists any reconditioning procedure.
My test last night, I used 11.5v instead of 10.5v, but that is as close as I have come to either method designed to restore lost capacity.
The high amp recharge is key with this battery, and the hold absorption voltage until amps taper to 0.5% of capacity. It does not have to happen every single recharge, and it would be a bad battery if it were required each and every time, but when i see the warning signs that the battery is getting a bit pertrubed, It is nice that a high amp recharge to truly full has been resetting it to 'like new' capacity and performance.
So While this battery ius by far the most expensive i have ever used, It will likely also provide the best cycles per dollar ratio when all is said and done.
But to be fair to my previous flooded marine batteries of yesteryear, I could not recharge them nearly as precisely to extract the most from them.
When the previous Flooded batteries started obviously declining, nothing I did seemed to ever reset them, and the decline continued despite efforts to stop or perhaps reverse them, but this high$$ AGM battery, when I notice performance loss, I know that a deeper discharge followed quickly by a high amp recharge will most likely reset it to 'impressive' status once again.
At 465 Deep cycles, it can't be just like new. Some degree of capacity loss has to have occurred. I could not really perform a truly accurate 20 hour capacity test to know for sure, and do not want to intentionally drain a battery to 10.5v just for the test.
My point is is that voltge held under X amount of load, for a certain # of Ah removed cannot be used to judge this high$$ agm battery, as after the high amp recharge to full, these numbers are so far, just like when new.
