100 amp charging source vs 2 grp31 AGM
My friend plans on running an obscene stereo in his new box on wheels acquisition.
He wanted a dedicated power source for it able to power it for a respectable amount of time from battery power alone, and he wanted to make sure the batteries would live an adequate lifespan and be properly recharged.
Similar to Odyssey batteries, Northstar AGMs claim both cycleability and high CCA figures. No doubt a Lifeline AGM is better for maximum cycleability, but they are also pretty low on their CCA figures, and likely not ideal for the intended duty.
So My Friend on my recommendation gets two group 31 Northstar AGM batteries 100Ah each, 1150CCA.
I also had him order a 100 amp adjustable voltage Powermax boondocker.
When it arrived we paralleled the 31's(100 AH each) put a 10 amp load on them for 10 hours, and an hour after removing the load voltage had rebounded to 12.19V. Northstar claims 12.11 is 50%, so they did well.
When we turned on the '100 amp' powermax adjustable voltage model, it maxed out at 75 amps. 75 amps held for close to an hour before tapering began as 14.7v was approached at the battery terminals. It took close to 9.5 hours before it took less than 1 amp to hold 14.7v at 75F at which point the powermax was manually shut off.
All cabling used is 0 awg and about 4 feet of it, one way. Battery Parallel interconnect cables are 00 gauge, perhaps larger. 12 inches long.
2 days later the unparalleled batteries were still over 13.0v with nothing attached, and were stored in the coolest place available.
That was about 2 months ago. The were not touched again
Recently, a larger, 4 40 amp fuse 100 amp model arrived, about an inch longer than the previous '100 amp' model. It also had the highly coveted potentiometer for adjusting output voltage. One other 100 amp model arrived without this feature
So as I type, the batteries are again in parallel and powering a 10 amp load to end at 10 hours. 3 '50 watt' GE 12v lightbulbs registered 10.17 amps at 12.91v. Close enough. Registered 10.12a at 12.5v. The lesson, don't believe the wattage ratings on light bulbs.
The batteries were reading 12.92 and 12.91 volts when they were paralleled tonight. Initial amperage was 27 amps when dial was turned upto 14.8v It took about 40 minutes at 14.8v before amps dropped below 1, and then the 10 amp load was turned on about 62F. At 14.8v the three 50 watt bulbs drew 11.7 amps or so.
So true to the AGM claims, they did not self discharge very much.
So I am fairly confident this physically larger 100 amp power supply will do the full hundred and perhaps a smidge more. These batteries will love this much current.
I've owned a group 27 Northstar AGM for 15 months now, and am still impressed. It does not have many deep cycles on it, perhaps 3 dozen total, and I mostly use it for the engine starting battery, but it is rather impressive in its engine cranking violence. This ability is less impressive when it is shallowly discharged and recharged at lesser initial rates.
When it is deep cycled and hit with 40+ amps until absorption voltage is approached, the engine is cranked with all the gusto the slower recharge rates did not return.
So the load is to be removed at 7am, we will let the batteries sit for 90 minutes to 2 hours to see where battery voltage rebounds to.
Then we will fire up the new 100 amp powermax set to 14.75v, and hope for 100+ Amps. The powermax will be shut off when amps required to hold them at 14.7v fall below 1 amp.
Now if the shipping costs of returning the 75 amp unit are refunded, all will have been made right. Good thing this was not a time important purchase. Frankly, I'd be surprised if these batteries power the stereo within 6 months.
but My portion of this project, whenever it might occur, will to wire up these batteries to a dedicated 200 amp alternator, and relocating 2 ammeters and 2 voltmeters, and putting the potentiometer and powermax on/off switch on the dashboard.
One ammeter will measure alternator/powermax contribution, one ammeter will measure stereo draw.
Kind of fun spending other people's money. Not fun repeating the same things over and over as the information gains speed during skull transit from one ear to the other.
The powermax will have a spring wound timer, and I will do my best to have him understand how long to crank the timer. It would be nice to have a trigger to shut it off at 1 amp however long it takes. Oh well
He wanted a dedicated power source for it able to power it for a respectable amount of time from battery power alone, and he wanted to make sure the batteries would live an adequate lifespan and be properly recharged.
Similar to Odyssey batteries, Northstar AGMs claim both cycleability and high CCA figures. No doubt a Lifeline AGM is better for maximum cycleability, but they are also pretty low on their CCA figures, and likely not ideal for the intended duty.
So My Friend on my recommendation gets two group 31 Northstar AGM batteries 100Ah each, 1150CCA.
I also had him order a 100 amp adjustable voltage Powermax boondocker.
When it arrived we paralleled the 31's(100 AH each) put a 10 amp load on them for 10 hours, and an hour after removing the load voltage had rebounded to 12.19V. Northstar claims 12.11 is 50%, so they did well.
When we turned on the '100 amp' powermax adjustable voltage model, it maxed out at 75 amps. 75 amps held for close to an hour before tapering began as 14.7v was approached at the battery terminals. It took close to 9.5 hours before it took less than 1 amp to hold 14.7v at 75F at which point the powermax was manually shut off.
All cabling used is 0 awg and about 4 feet of it, one way. Battery Parallel interconnect cables are 00 gauge, perhaps larger. 12 inches long.
2 days later the unparalleled batteries were still over 13.0v with nothing attached, and were stored in the coolest place available.
That was about 2 months ago. The were not touched again
Recently, a larger, 4 40 amp fuse 100 amp model arrived, about an inch longer than the previous '100 amp' model. It also had the highly coveted potentiometer for adjusting output voltage. One other 100 amp model arrived without this feature
So as I type, the batteries are again in parallel and powering a 10 amp load to end at 10 hours. 3 '50 watt' GE 12v lightbulbs registered 10.17 amps at 12.91v. Close enough. Registered 10.12a at 12.5v. The lesson, don't believe the wattage ratings on light bulbs.
The batteries were reading 12.92 and 12.91 volts when they were paralleled tonight. Initial amperage was 27 amps when dial was turned upto 14.8v It took about 40 minutes at 14.8v before amps dropped below 1, and then the 10 amp load was turned on about 62F. At 14.8v the three 50 watt bulbs drew 11.7 amps or so.
So true to the AGM claims, they did not self discharge very much.
So I am fairly confident this physically larger 100 amp power supply will do the full hundred and perhaps a smidge more. These batteries will love this much current.
I've owned a group 27 Northstar AGM for 15 months now, and am still impressed. It does not have many deep cycles on it, perhaps 3 dozen total, and I mostly use it for the engine starting battery, but it is rather impressive in its engine cranking violence. This ability is less impressive when it is shallowly discharged and recharged at lesser initial rates.
When it is deep cycled and hit with 40+ amps until absorption voltage is approached, the engine is cranked with all the gusto the slower recharge rates did not return.
So the load is to be removed at 7am, we will let the batteries sit for 90 minutes to 2 hours to see where battery voltage rebounds to.
Then we will fire up the new 100 amp powermax set to 14.75v, and hope for 100+ Amps. The powermax will be shut off when amps required to hold them at 14.7v fall below 1 amp.
Now if the shipping costs of returning the 75 amp unit are refunded, all will have been made right. Good thing this was not a time important purchase. Frankly, I'd be surprised if these batteries power the stereo within 6 months.
but My portion of this project, whenever it might occur, will to wire up these batteries to a dedicated 200 amp alternator, and relocating 2 ammeters and 2 voltmeters, and putting the potentiometer and powermax on/off switch on the dashboard.
One ammeter will measure alternator/powermax contribution, one ammeter will measure stereo draw.
Kind of fun spending other people's money. Not fun repeating the same things over and over as the information gains speed during skull transit from one ear to the other.
The powermax will have a spring wound timer, and I will do my best to have him understand how long to crank the timer. It would be nice to have a trigger to shut it off at 1 amp however long it takes. Oh well
