I figured after 2 conditioning charges, it might get over 85%, but I never would have thought that after just one round it would get over 90%. Now I really want to put it back into service and see how much life it has left. I doubt I’ll do it, but it has me wondering.
I’ll do my best to put Concord’s recommendations in simple English that doesn’t have all the fancy words, warnings, and attorney modifications. This information comes from Concorde’s “RG SERIES MAIN AIRCRAFT BATTERY COMPONENT MAINTENANCE MANUAL.”
They describe three different charging protocols
- Constant Potential Charge
- Conditioning Charge
- Deep Discharge Recovery
- Constant Potential Charge: Better understood as a constant voltage charge. This is the preferred charging protocol Concorde recommends. The battery is charged at 14.125 volts (or 28.25 volts for 24 volt batteries) and charged until the amp draw falls below 5% the C1 rating, and the charging continues for an additional minimum of 4 hours.
My RG-35AXC battery has a C1 rating (found printed on the front of the battery or Concorde’s website) of 33 amps. So for this charging protocol, I charge at 14.125 volts until the amp draw gets to 1.65 amps and then I charge for at least 4 more hours.
- Conditioning charge. This charging protocol is called for when the battery fails a capacity test. The battery is charged at a constant amperage for 16 hours. Per the manual, the charger needs to be able to provide at least 34 volts for 24 volt batteries and 17 volts for 12 volt batteries. It needs to be able to provide an amperage of 10% C1.
In my case, the voltage got over 17 volts, but never over 18 volts. My C1 of 33 amps required a constant amperage 3.3 amps. The 16 hours does not need to be constant (8 hours x 2 days is fine). The battery should rest for 8 hours and then undergo a capacity test.
- Deep discharge recovery protocol. This is done any time the resting battery voltage is below 10 volts (or 20 volts for a 24 volt battery). I can only see this being used if a master switch is left on and the battery is fully depleted or in an alternator failure situation. This battery charging protocol is similar to the conditioning charge in that a constant amperage charge is done. You still charge at 10% C1 amperage, but instead of charging for a fixed 16 hours, the battery is charged until it reaches 15.5 volts (31 volts for 24 volt batteries) and then it is charged for an additional fixed 4 hours. This charging protocol should not be interrupted.
My experience, data, and results:
I bought a Matix MPS-3206 power from Amazon for $79. This power supply can charge at constant amperage / current. It was unclear to me how to get it to charge in constant current mode vs constant voltage mode. At some point I set the voltage to 14.125 volts (required for the constant potential / voltage protocol) which caused a problem later. When I actually hooked the battery up and set the constant current to 3.3 amps the power supply automatically went to constant current (amperage) mode. I started my 16 hour timer and thought life was good.
My problem came when the battery reached 14.125 volts. I wasn’t there to witness it, but the MPS-3206 automatically switched from constant current mode sending 3.3 amps to the battery to constant voltage mode and held 14.125 volts and started lowering the amperage sent to the battery. Once I realized this, I changed the voltage to 18 volts (Concorde recommended at least 17, so I went 18). I’m glad I did, as the battery took over 17 volts. If I had set the voltage on the MPS-3206 to 17 volts (as Concorde recommends) it would have switched to constant voltage at 17 and not sent 3.3 amps to the battery for a number of hours.
I don’t know if my battery was an anomaly as it required more than more than the 17 volts recommended. This is not an issue for a 12 volt battery with the MPS-3206 power supply, but for a 24 volt battery it would probably be an issue. I would not use the MPS-3206 for a 24 volt battery as it has a maximum of 32 volts available. I bought the MPS thinking it would work in the future for a 24 volt battery as 32 volts is close to 34 volts. After this experience, I would not use it. When I cross that bridge, I’ll buy a constant current power supply that can put out at least 36 volts even though Concorde only recommends at least 34 volts.
I checked the battery’s temperature with a FLIR i7 infrared camera and recorded the highest temperature. It was interesting to note over the 16 hours how the hottest spot in the battery moved. To me that indicated that “repair” to the battery was occurring once a damaged area was “fixed” the constant current found another damaged area to work on (that’s just my theory, so if I’m wrong, please educate me). Concorde recommends to pause charging anytime the battery artery gets above 130° F. I never got close to this.
I randomly checked voltage, amperage, and temperature. At 7:15 PM (19:15) the capacity test was 59.7% and after resting a short while, the battery had 11.7 volts.
I started the conditioning charge procedure / protocol.
Time. Volts. Amps. Temp °F
19:20. 12.39. 3.3. 80.2
20:30. 12.77. 3.3. 80.2
21:19. 12.95 3.3. 79.7
00:24. 13.59. 3.3. 79.2
Off to sleep…
05:45. 14.12. 0.11. NR (not recorded). Max voltage changed to 18 volts
08:45. 16.6. 3.3. NR
09:07. 17.05. 3.3. NR
10:04. 17.33. 3.3. NR
10:50. 17.46. 3.3. 82.8
13:37. 17.52. 3.3. 90.0
Paused charging between 13:37 and 16:18
16:18. 17.55. 3.3. NR
17:16. 17.48. 3.3. 92.3
18.49. 17.29. 3.3. 101
At 19:50 the resting voltage was 13.09
I let the battery rest a few day and the voltage was recorded 13.09v, 13.02v, 12.99v, 12.98v
I did a capacity test and it took 55 minutes to get to 10 volts and tested positive at 94.0%.
Side note: I have a hypothesis that once the battery maximum voltage started to go down and the battery temperature started to climb I had reached the point that any fixable damage was complete and I was now causing damage to the battery. Concorde doesn’t mention this in their manual, so it’s just my hypothesis for now. If anyone has any thoughts or comments, please share.
After the capacity test resulting in 94%, I needed to do the constant potential / voltage charge procedure. I’m not sure the MPS-3206 is the right charger / power supply for this. If anyone is still reading this and can comment, please do. The next couple paragraphs explain why I don’t believe it’s optimal.
The manual states that the charger / power supply should be set at a constant voltage (14.125) and the highest output possible as the Concorde battery can handle 8XC1. What is the “8XC1”? For me that is 8x33 = 264? What are the units there? 8 x 33 amps = 264 amps??
I set the MPS-3206 to the max current 6.1 amps and set the voltage to 14.125. It charged in constant current mode until it reached 14.125 volts and then stayed there until I discontinued charging. I couldn’t figure out how to force the MPS-3206 to charge at 14.125 volts unless I turned the current way down (to less than 1 amp). I think a different power supply / charger is needed to follow Concorde’s recommendations for a constant potential / voltage charge procedure.
So there it is… probably not too many still reading, but now it’s documented for me. I’m open to any comments and would be happy to answer any questions. I was very surprised to see the results!
Best
