Here is a small video I put together about charging my Buddipole 4S2P A123 Battery Pack
Buddipole 4S2P Battery CellPro 10S - YouTube
Buddipole 4S2P Battery CellPro 10S - YouTube
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Buddipole Cellpro 10S Portable Power Charging
- Thread starter Happy_Hamer
- Start date
i charge my r/c lipos alot and this is a good read about the internal resistance .enjoy!
its best if each cell reads near the same .i see you have a low and hi resistance cell there .
INTERNAL RESISTANCE
Another rating??? Yep, the first 3 are industry standards and as was mentioned with that last one (C discharge ratings), is used by the manufacturers to market their product or justify a higher price and realistically can't be verified, but they are still a good general guide line when choosing a pack.
Internal resistance to the rescue! This one is verifiable and one of the best ways to monitor your RC LiPo batteries condition. Most decent higher capacity and higher discharge rated LiPo cells will have roughly 2 to 6 milliohms (0.002 to 0.006 ohms) of internal resistance when brand new. To calculate the total internal resistance of a series wired pack, you would then add these numbers together so a 4S pack with each cell having 4 milliohms of resistance will show a total internal resistance of about 16 milliohms (0.016 ohms).
As I mentioned, as packs age, the internal resistance goes up and the warmer they run. Lower discharge rated packs and small capacity packs will generally have higher internal resistance readings. It is not unusual to measure internal resistance numbers in the region of 200 milliohms on smaller 100 to 200 mAh micro park flyer LiPo packs when they are brand new for example.
So the best way to use internal resistance (if your charger supports this very useful function) is to take an IR reading of your LiPo/s when it/they are brand new. I will then write that number (or the IR of all the cells in the pack) somewhere on the pack with a permanent marker so I will always have a brand new IR base reference for that particular battery. As the packs age, I can simply reference how the resistance is increasing or if one cell for some reason is getting bad.
How do you measure internal resistance? This is where good computerized chargers come into play. The good ones that support this feature with built in balance boards will check the "IR" of each cell as well as the entire pack. Pictured above I am taking the IR reading of each cell in this new 6S Turnigy LiPo. It is hard to make out in the photo, but the IR of cells 1-6 are 2,2,1,1,1,2 milliohms each giving a total IR for the entire pack of 9 milliohms - pretty respectable!
Internal resistance really opens up a huge and complex topic of how to accurately calculate voltage drop in the pack and the total amount of watts being expended in the form of heat within the pack. I am not going to get into those calculations here for the simple reason I am not qualified enough to explain them.
its best if each cell reads near the same .i see you have a low and hi resistance cell there .
INTERNAL RESISTANCE
Another rating??? Yep, the first 3 are industry standards and as was mentioned with that last one (C discharge ratings), is used by the manufacturers to market their product or justify a higher price and realistically can't be verified, but they are still a good general guide line when choosing a pack.
Internal resistance to the rescue! This one is verifiable and one of the best ways to monitor your RC LiPo batteries condition. Most decent higher capacity and higher discharge rated LiPo cells will have roughly 2 to 6 milliohms (0.002 to 0.006 ohms) of internal resistance when brand new. To calculate the total internal resistance of a series wired pack, you would then add these numbers together so a 4S pack with each cell having 4 milliohms of resistance will show a total internal resistance of about 16 milliohms (0.016 ohms).
As I mentioned, as packs age, the internal resistance goes up and the warmer they run. Lower discharge rated packs and small capacity packs will generally have higher internal resistance readings. It is not unusual to measure internal resistance numbers in the region of 200 milliohms on smaller 100 to 200 mAh micro park flyer LiPo packs when they are brand new for example.
So the best way to use internal resistance (if your charger supports this very useful function) is to take an IR reading of your LiPo/s when it/they are brand new. I will then write that number (or the IR of all the cells in the pack) somewhere on the pack with a permanent marker so I will always have a brand new IR base reference for that particular battery. As the packs age, I can simply reference how the resistance is increasing or if one cell for some reason is getting bad.
Internal resistance really opens up a huge and complex topic of how to accurately calculate voltage drop in the pack and the total amount of watts being expended in the form of heat within the pack. I am not going to get into those calculations here for the simple reason I am not qualified enough to explain them.
