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Old 06-14-2019, 04:53 PM
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Originally Posted by jamesrxx951 View Post
the original thought was you could not check an A123 but these cell checkers and cellpro chargers seem to be really accurate.
The cell checkers measure voltage. I don't believe anyone said they didn't or couldn't do that. Of course they can. It's just that on A123's, measuring voltage isn't particularly useful.

On LiPo's, LiIon, NiMh, and NiCd reading the voltage can actually be important. It's useful for the last 3 chemistries when measured under load using a loaded tested (like the ones from Fromeco)

On LiPo's, for example, the % capacity remaining is generally approximated by the % that the measured voltage is between 3.7 and 4.2 volts. It's not 100% accurate but gives a decent idea of what's left. One can also tell if the cells are balanced.

I must be missing your point, James. My apologies. Can you explain what you believe you are getting from measuring the voltage of A123's if not some indication of battery condition or the remaining capacity?
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Old 06-14-2019, 05:39 PM
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Originally Posted by RCAddiction View Post
A 123 batteries are very "stiff", in battery terms, so applying a 1amp load to them doesn't drop the voltage much. But the bigger deal as Jack alluded to above, is that unlike Lipo or LiIon or NiMh or NiCd, or even lead acid, the discharge curve is very flat. So you can't tell how much battery is left by measuring the voltage, even under load. A123's stay at a nearly flat voltage until they are very nearly exhausted. Then the voltage drops off a cliff rapidly.

Using A123's means that you recharge after a flight or 2 to see how much you use per flight. I use 300 - 400 mah per flight out of each of 2 packs as an example. That means, for me, 4 flights uses maybe half the battery capacity of a 2500mah.

And over the course of using them, I occasionally check the battery capacity with a full charge/discharge cycle at 1/10 to 1/5 of the rating. So I do a discharge at 250-500 mah over 5-10 hrs to establish a baseline for when the batteries are new and simply keep track. A123's, at least the genuine ones, have an amazingly long life if not over charged or discharged.


That's the same amount of flights I get out of my single a123, 2500 mah,running 5, 7955's and a ignition.Then it takes about 3-4 mins. to recharge. They are bullet proof,super easy to take care of and they last a long time.
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Old 06-14-2019, 06:11 PM
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Originally Posted by RCAddiction View Post
The cell checkers measure voltage. I don't believe anyone said they didn't or couldn't do that. Of course they can. It's just that on A123's, measuring voltage isn't particularly useful.

On LiPo's, LiIon, NiMh, and NiCd reading the voltage can actually be important. It's useful for the last 3 chemistries when measured under load using a loaded tested (like the ones from Fromeco)

On LiPo's, for example, the % capacity remaining is generally approximated by the % that the measured voltage is between 3.7 and 4.2 volts. It's not 100% accurate but gives a decent idea of what's left. One can also tell if the cells are balanced.

I must be missing your point, James. My apologies. Can you explain what you believe you are getting from measuring the voltage of A123's if not some indication of battery condition or the remaining capacity?
I believe people get hung up on the 6.6v of an A123. While it will drop slightly under load, it maintains that voltage. But once you start measuring past the 10th of a volt, you can actually get an idea on the state of charge of a battery. How do you think our chargers know to start slowing down the rate of charge when a battery is starting to top off?
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Old 06-14-2019, 08:06 PM
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How do you think our chargers know to start slowing down the rate of charge when a battery is starting to top off?
The charge protocol for an A123 is here:
http://liionbms.com/pdf/a123/charging.pdf

Termination of the charge occurs when the cutoff current (50ma) is reached while holding a constant voltage of 3.60V per cell. Charge doesn't terminate at a "peak" voltage like a NiMH or NiCd battery. When the battery essentially won't take any more current at a given voltage, it's done charging.

From the above A123 Systems battery management specification:

Recommended charge method: CC-CV
The cell should be charged at the recommended charge current until the normal charge voltage is reached. Apply a constant voltage hold at the recommended charge voltage until the cut-off current for CV hold is reached (or 30 minutes, whichever comes first). The cell will be charged to 100% state of charge (SOC).
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Old 06-14-2019, 08:12 PM
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That's the same amount of flights I get out of my single a123, 2500 mah,running 5, 7955's and a ignition.Then it takes about 3-4 mins. to recharge. They are bullet proof,super easy to take care of and they last a long time.

Even the 2300's can handle 60A discharge rate as well as up to 10A charge rate. Of course that assumes that one's cables, switches and connectors are up to it!
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Old 06-14-2019, 08:25 PM
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I use a Hypersonic charger that does nothing else but a123's,at a 10 amp rate.Simple and easy to use, no switch's no bottons. I just connect direct to battery and it is done in just a few minutes,been using it for years.
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