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When I've been looking at batteries, especially those made in China, invariably I see a rate of Discharge listed with Units "C".I've seen it a few times. Here is a listing for LiFePO_{4} batteries on E-Bay....sorry, you cannot view external links. To see them, please REGISTER or LOGINWhich doesn't seem to make any sense either.If we take the last example, 54A discharge rate at 180Ah, gives a 100% discharge in 3-4 hours, which would be a little slow, but almost a livable rate.If this is the conversion factor (0.3C/Amp), dividing the rate for the first battery would give about 10 Amps, which would still give one about 30 hours for 100% depth of discharge.... which again is far too slow for many applications.If C stood for 100 amps, then for the first battery above, it would be about 3*100Amps/C, and one would get about a 100% depth of discharge in about an hour which wouldn't be bad.So, WHAT IS "C" (no, I'm not planning on accelerating my car to lightspeed).

I believe C is just the capacity in ampere-hours. In the first example they suggest charging it at 150 amps (which should take about two hours if it's fully discharged.)

Quote from: Geezer on 26/09/2011 07:12:26I believe C is just the capacity in ampere-hours. In the first example they suggest charging it at 150 amps (which should take about two hours if it's fully discharged.)Ahhh,That makes a little bit of sense. Except that current is always measured in Amps, not Amp Hours.And Capacity is measured in Amp Hours.But, it would mean that one could use similar specifications for multiple batteries, and it would make it easier to compare different batteries.

Quote from: Geezer on 26/09/2011 07:12:26I believe C is just the capacity in ampere-hours. In the first example they suggest charging it at 150 amps (which should take about two hours if it's fully discharged.)If you charge it at that rate it will probably blow up!The recommended charge current is 3A maximum, that's a charge time of 100hours. 300Ah/3=100

I think you are looking at the wrong kind of batteries for what you want. You need deep discharge batteries as used in submarines (bit big), electric vehicles etc.

No, it isn't. A 300 AH battery that took 4 days to charge would be about as much use as a chocolate teapot.

Quote from: MikeS on 26/09/2011 08:47:35Quote from: Geezer on 26/09/2011 07:12:26I believe C is just the capacity in ampere-hours. In the first example they suggest charging it at 150 amps (which should take about two hours if it's fully discharged.)If you charge it at that rate it will probably blow up!The recommended charge current is 3A maximum, that's a charge time of 100hours. 300Ah/3=100No, it isn't. A 300 AH battery that took 4 days to charge would be about as much use as a chocolate teapot.

Quote from: Geezer on 26/09/2011 09:09:08Quote from: MikeS on 26/09/2011 08:47:35Quote from: Geezer on 26/09/2011 07:12:26I believe C is just the capacity in ampere-hours. In the first example they suggest charging it at 150 amps (which should take about two hours if it's fully discharged.)If you charge it at that rate it will probably blow up!The recommended charge current is 3A maximum, that's a charge time of 100hours. 300Ah/3=100No, it isn't. A 300 AH battery that took 4 days to charge would be about as much use as a chocolate teapot.300 Ah battery cellsOperation voltage of cell is: 2,8 V - 4,0 VMax charge current: <= 3 CMax discharge current (constant): <= 3 CMax discharge current (impulse): <= 20 CStandard charge/discharge current (for long life time): <= 0,5 CCycle life (estimated):3000 charging cycles at 80% Depth Of Discharge5000 charging cycles at 70% Depth Of DischargeYes it is. If you want the longest life from this battery then 300Ah/0.5A = 600hours charge/discharge.This battery is not designed for a high charge discharge rate. From its slow charge/discharge rate one could probably deduce it is meant to be used as a float battery. It's just there as a backup in case of mains failure. You might think its about as much use as a chocolate teapot but it's a very long lasting chocolate teapot

Hmmm... Looking back at that ...sorry, you cannot view external links. To see them, please REGISTER or LOGINIt lists:Nominal Capacity: 180 Ah.Maximum recommended Discharge Current: 54A (Amps) (0.3C). Multiplying 0.3x180 = 54.So, I think Geezer is right that "C" stands for Capacity, or Capacity/h.

A 600 hour cycle time would make it practically useless. Have you ever heard of a battery with a 600 hour cycle time?"C" is capacity in ampere-hours. It does not directly relate to charge/discharge rates. That's why those parameters are quoted in terms of C.

Quote from: MikeS on 26/09/2011 09:34:27Quote from: Geezer on 26/09/2011 09:09:08Quote from: MikeS on 26/09/2011 08:47:35Quote from: Geezer on 26/09/2011 07:12:26I believe C is just the capacity in ampere-hours. In the first example they suggest charging it at 150 amps (which should take about two hours if it's fully discharged.)If you charge it at that rate it will probably blow up!The recommended charge current is 3A maximum, that's a charge time of 100hours. 300Ah/3=100No, it isn't. A 300 AH battery that took 4 days to charge would be about as much use as a chocolate teapot.300 Ah battery cellsOperation voltage of cell is: 2,8 V - 4,0 VMax charge current: <= 3 CMax discharge current (constant): <= 3 CMax discharge current (impulse): <= 20 CStandard charge/discharge current (for long life time): <= 0,5 CCycle life (estimated):3000 charging cycles at 80% Depth Of Discharge5000 charging cycles at 70% Depth Of DischargeYes it is. If you want the longest life from this battery then 300Ah/0.5A = 600hours charge/discharge.This battery is not designed for a high charge discharge rate. From its slow charge/discharge rate one could probably deduce it is meant to be used as a float battery. It's just there as a backup in case of mains failure. You might think its about as much use as a chocolate teapot but it's a very long lasting chocolate teapotMike, this type of battery is intended for rather rapid charge/discharge rates. A 600 hour cycle time would make it practically useless. Have you ever heard of a battery with a 600 hour cycle time?"C" is capacity in ampere-hours. It does not directly relate to charge/discharge rates. That's why those parameters are quoted in terms of C.

Quote from: CliffordK on 26/09/2011 09:24:29Hmmm... Looking back at that ...sorry, you cannot view external links. To see them, please REGISTER or LOGINIt lists:Nominal Capacity: 180 Ah.Maximum recommended Discharge Current: 54A (Amps) (0.3C). Multiplying 0.3x180 = 54.So, I think Geezer is right that "C" stands for Capacity, or Capacity/h.Not so.Going back to the original example if C stands for charge/discharge capacity and it is 0.3 then it follows thatfrom the above figures"Max discharge current (constant): <= 3 CMax discharge current (impulse): <= 20 CStandard charge/discharge current (for long life time): <= 0,5 C"Max. discharge current is 300Ah x 0.3 = 100AMax discharge current (impulse) is 300Ah x 20 = 6000AStandard charge/discharge current (for long life time) is 300Ah x 0.5A = 150AThe standard charge/discharge current is higher than the max. discharge current. See the problem?

Quote from: CliffordK on 26/09/2011 09:24:29Hmmm... Looking back at that ...sorry, you cannot view external links. To see them, please REGISTER or LOGIN was 180 AH.Recommend Charging-Discharging Current (0.3C,A) 54 AmpsMaximum short-tine Discharging Current (period≤10s,A) 1000 AmpsSo, it was a little more than half the capacity of the Winston Battery, but less impressive specs. If I get an EV, I should get a better idea of the actual amp usage, both short term (acceleration) and long term (normal driving), but ether battery is likely close, especially if one incorporates an active cooling system.The biggest problem is getting an acceptable price. Tesla lists their battery pack as being worth $36,000. While I don't intend to spend that much, it would not be hard to spend $10K on a lithium battery pack. And, abuse it too much and it becomes worthless.

Hmmm... Looking back at that ...sorry, you cannot view external links. To see them, please REGISTER or LOGIN was 180 AH.Recommend Charging-Discharging Current (0.3C,A) 54 AmpsMaximum short-tine Discharging Current (period≤10s,A) 1000 AmpsSo, it was a little more than half the capacity of the Winston Battery, but less impressive specs. If I get an EV, I should get a better idea of the actual amp usage, both short term (acceleration) and long term (normal driving), but ether battery is likely close, especially if one incorporates an active cooling system.The biggest problem is getting an acceptable price. Tesla lists their battery pack as being worth $36,000. While I don't intend to spend that much, it would not be hard to spend $10K on a lithium battery pack. And, abuse it too much and it becomes worthless.

300Ah x 3C = 900A charge in 1/3 hour. That's one impressive battery, no wonder the price.

I believe C is just the capacity in ampere-hours...