If you can find a noco 7200 its 12/24 for lead acid /agm and has repair mode that works ive had mine for a couple years and it was like 80 bucks when i bought it new !https://s3.amazonaws.com/rp-part-images/assets/0f27131c63403a7f2508f33d0a06905d.png
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Success at Repairing Military AGM Batteries?
- Thread starter G3isMe
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I have one of each. I put a battery on the Recover mode, and let it work for a few days. Then hit it with an internal resistance tester. Then my Carbon Pile tester. Its always better to KNOW, then to Trust/Think something is good. The carbon Pile tester is also a good way to load the battery, and draw/discharge it. Then I can recharge it again. Just to see (One more time) that what I have is a good battery. When I want to really discharge a battery, I use some DC lights. I found a string of them in the electrical junk container. Hook em up, close the garage, and come back in a day or so. The only bad thing about it is that they are party lights. All different colors. So it looks like a cat house at night, through the window.
- 16,662
- 23,800
- 113
- Location
- Burgkunstadt, Germany
It cost a lot mere here, but thats what I use. GREAT equipment.
Is this an attempt to disguise what your really doing in the "SHOP" in the we we hours ???? PIMP DADDY !!!!!
- 16,662
- 23,800
- 113
- Location
- Burgkunstadt, Germany
The girls said they were waiting on Uncle Chucky. Who am I to interrupt an old mans cultural evening?
Purely physical therapy for my back !! Purely medicinal !
- 16,662
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- Burgkunstadt, Germany
So the red head told me.
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- Greenback, TN
The easiest and in my opinion best load test for a battery is in the vehicle. Simply starting it. Start the vehicle while measuring voltage. Nothing to buy except a voltmeter, provides a quick load of the amperage needed to test the battery for typical use, and is usually a harder test than a connected load made with smallish wire and alligator clips. You can still use a modern battery tester to measure internal resistance.
A rejuvenated battery can show good voltage characteristics but not have much amperage capability. If you think about the plates, the surface areas are either active or not, and only a small active area is needed to show good voltage characteristics. Cycling the battery using a good load, then smart recharge, will repair more and more of the area until the battery has near full area active plates. It took almost 6 months to recover the last pair of Hawker Armasafe batteries. At their cost and long life they are definitely worth the effort!
The success seen at first is a great sign the batteries will recover. If they do fail the load test, don't give up, just keep repairing.
I also use NOCO chargers. The modern tester here is a Topdon BT200. It seems to be truthful. Anyone else using that model?
A rejuvenated battery can show good voltage characteristics but not have much amperage capability. If you think about the plates, the surface areas are either active or not, and only a small active area is needed to show good voltage characteristics. Cycling the battery using a good load, then smart recharge, will repair more and more of the area until the battery has near full area active plates. It took almost 6 months to recover the last pair of Hawker Armasafe batteries. At their cost and long life they are definitely worth the effort!
The success seen at first is a great sign the batteries will recover. If they do fail the load test, don't give up, just keep repairing.
I also use NOCO chargers. The modern tester here is a Topdon BT200. It seems to be truthful. Anyone else using that model?
If you want to quantify the capacity of a battery you need to build a discharge curve. This can be as simple as putting a 10 amp load on the battery and taking a voltage reading every 10 minutes. Some industrial chargers can do this automatically but we can't afford those.
In my experience batteries fail because the plates physically break apart. They either break apart and fall to the bottom of the battery and short out the cells or they break apart and simply reduce the surface area. In the first case the battery won't hold 12.6 volts and will have a cell that boils out when you charge it. In the second case the battery will charge very quickly and discharge very quickly. Neither case can be repaired with a charger.
In my experience batteries fail because the plates physically break apart. They either break apart and fall to the bottom of the battery and short out the cells or they break apart and simply reduce the surface area. In the first case the battery won't hold 12.6 volts and will have a cell that boils out when you charge it. In the second case the battery will charge very quickly and discharge very quickly. Neither case can be repaired with a charger.
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Without getting too technical, the smaller battery testers are also "real" and unlike the high current DC loading testers (the so called carbon-pile which the cheap DC testers are made with, it falls under the resistive loading category), are based on injecting an AC constant-current thru the battery and measure its impedance, which in theory it should reflect the internal resistance of the battery from which we could calculate the potential current capability, i.e at 12V a 1,000A battery would have 12milliOhms resistance, however a good test instrument would be also in the thousand$ range (some are over $10k), has a four wire measurement (two for current delivery and two for voltage measurements) and the cheap ones like in the picture above they are maybe in the 15-20% accuracy range, therefore a 1,000A battery could be off by as much as 150A-200A.
Also, in order to use the AC type tester, the battery SoC (State-of-Charge) should be at least in the 70-75% range, so when dealing with an unknown battery that would be another variable.
The high current DC loading testers also stress all the connections thermally to expose any potential hot spots.
The HMMWVs have that 1,000A-100mV shunt, which could be used to get a good idea about how much current the batteries are delivering at start, by connecting a DMM across it, in the 100mV range or next closest range above it (ideally a DMM with Peak/ Max function would work best as it would record and display the highest value, otherwise difficult to observe as the numbers are changing quickly during starting, plus the DMMs with Peak function have a faster acquisition time which can also capture the highest peak more accurately, where the lower integration time/ slower acquisition DMMs would show a lower Peak value as it takes longer to integrate the measurement that changes quickly).
Generally, the Peak functions caption sub-millisecond events in the hundreds of microseconds, while the Min/Max function alone runs at the sampling speed of the DMM, which is usually in the 3Hz range or about 3 times per second at 333mS intervals, which it could still be useful.
Another DMM with the Peak function (or use the same one and repeat the staring test, it would be close enough), but set for the Min measurement could be set to measure the battery voltage, which would record the lowest value it dropped to during starting.
If the 24V battery bank drops too much, then each battery should be measured separately to determine which one is the weakest link, since they are in series.
Just a few other ways to test batteries.
EDIT: Here are two DMMs that could do MIN/MAX, Fluke 77 IV and Klein MM420, which is in the $40-$50 range:
Also, in order to use the AC type tester, the battery SoC (State-of-Charge) should be at least in the 70-75% range, so when dealing with an unknown battery that would be another variable.
The high current DC loading testers also stress all the connections thermally to expose any potential hot spots.
The HMMWVs have that 1,000A-100mV shunt, which could be used to get a good idea about how much current the batteries are delivering at start, by connecting a DMM across it, in the 100mV range or next closest range above it (ideally a DMM with Peak/ Max function would work best as it would record and display the highest value, otherwise difficult to observe as the numbers are changing quickly during starting, plus the DMMs with Peak function have a faster acquisition time which can also capture the highest peak more accurately, where the lower integration time/ slower acquisition DMMs would show a lower Peak value as it takes longer to integrate the measurement that changes quickly).
Generally, the Peak functions caption sub-millisecond events in the hundreds of microseconds, while the Min/Max function alone runs at the sampling speed of the DMM, which is usually in the 3Hz range or about 3 times per second at 333mS intervals, which it could still be useful.
Another DMM with the Peak function (or use the same one and repeat the staring test, it would be close enough), but set for the Min measurement could be set to measure the battery voltage, which would record the lowest value it dropped to during starting.
If the 24V battery bank drops too much, then each battery should be measured separately to determine which one is the weakest link, since they are in series.
Just a few other ways to test batteries.
EDIT: Here are two DMMs that could do MIN/MAX, Fluke 77 IV and Klein MM420, which is in the $40-$50 range:
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