Hello I was curious if there is any difference between the cycle life of a LiFePO4 that is regularly discharged to 80% vs lesser discharges, say 50% or 40%?
I have been looking at some 10c continuous 10ah headways. They claim 10c 100 amp continuous. But to get the max cycle life they can only be discharged at 1c, 10 amps.
I work less than 2 miles away and am bumping up my motor for 250 watts to 500 watts and have figured out the gearing to give me 20 mph on a 16 inch wheel. If I were to buy and build a 7s3p pack of headways pulling 30 amps would be 1c, which could handle my peak at 1c. As opposed to going 7s0p my peak would be 3c. Is the cycle life of 2000 w/80% dod the same if the depth of discharge less than 80% ? I wouldn't be discharging a 30 ah pack very much to go 2 miles. Would I still be limited to 2000 cycles? Or would shallower discharges give me more cycles? Softer discharge rates extend battery life that much I grasp. Would the increased cycles ( if any at all - due to shallower discharges ) when multiplied by the amount of energy used per charge be equal to the amount of energy for 2000 charges at 80% dod. Or is the cathode ( or some other component ) only good for a set amount of times regardless of DOD provided that the DOD never exceeds 80%?
Of course there are products out there like cycle anyalist that will let give you an approximate idea of how deep you are going into your batteries. I read somewhere that if ( hypothetically ) a commuter only has to charge his LiFePO4 batteries once a week ( at 80% DOD ) that the calander life of his battery will expire before the cycle life.
I haven't been able to find any info on this question only the 80% DOD never shallower because every1 is always discharging above 1c which makes 2000 cycles unobtainable anyway
ty - prolly take you wizards a whole commercial break to answer this , when you finally see it
update: I found a pdf for thundersky lifepo4's that showed 3000 cycles with 80% DOD and .5c charge and discharge and 5000 cycles with 70% DOD .5c charge and discharge. I'm guessing that the 3000 cycles at 80% DOD is from charging/discharging at .5c not 1c and that increases the cycles at 80% DOD from 2000 to 3000. A 50% jump in cycle life from halving the charge/discharge rate. And then the 5000 cycles is a combination of both halved discharge/charge rate and the 70% DOD. But 3000/5000 looks like a straight 40% improvement to me in terms of amount of cycle life. So 80% DOD at 1c 2000 cycles maybe 3000 cycles at 70% DOD. I'm going to keep looking for further verification and for other DOD's - 60%, 50%, 40%. heres a link to the pdf with the thundersky #'s
http://www.electricmotordepot.com/content/LiFeP04/ThunderSky/TS40Ah.pdf
I have been looking at some 10c continuous 10ah headways. They claim 10c 100 amp continuous. But to get the max cycle life they can only be discharged at 1c, 10 amps.
I work less than 2 miles away and am bumping up my motor for 250 watts to 500 watts and have figured out the gearing to give me 20 mph on a 16 inch wheel. If I were to buy and build a 7s3p pack of headways pulling 30 amps would be 1c, which could handle my peak at 1c. As opposed to going 7s0p my peak would be 3c. Is the cycle life of 2000 w/80% dod the same if the depth of discharge less than 80% ? I wouldn't be discharging a 30 ah pack very much to go 2 miles. Would I still be limited to 2000 cycles? Or would shallower discharges give me more cycles? Softer discharge rates extend battery life that much I grasp. Would the increased cycles ( if any at all - due to shallower discharges ) when multiplied by the amount of energy used per charge be equal to the amount of energy for 2000 charges at 80% dod. Or is the cathode ( or some other component ) only good for a set amount of times regardless of DOD provided that the DOD never exceeds 80%?
Of course there are products out there like cycle anyalist that will let give you an approximate idea of how deep you are going into your batteries. I read somewhere that if ( hypothetically ) a commuter only has to charge his LiFePO4 batteries once a week ( at 80% DOD ) that the calander life of his battery will expire before the cycle life.
I haven't been able to find any info on this question only the 80% DOD never shallower because every1 is always discharging above 1c which makes 2000 cycles unobtainable anyway
ty - prolly take you wizards a whole commercial break to answer this , when you finally see it
update: I found a pdf for thundersky lifepo4's that showed 3000 cycles with 80% DOD and .5c charge and discharge and 5000 cycles with 70% DOD .5c charge and discharge. I'm guessing that the 3000 cycles at 80% DOD is from charging/discharging at .5c not 1c and that increases the cycles at 80% DOD from 2000 to 3000. A 50% jump in cycle life from halving the charge/discharge rate. And then the 5000 cycles is a combination of both halved discharge/charge rate and the 70% DOD. But 3000/5000 looks like a straight 40% improvement to me in terms of amount of cycle life. So 80% DOD at 1c 2000 cycles maybe 3000 cycles at 70% DOD. I'm going to keep looking for further verification and for other DOD's - 60%, 50%, 40%. heres a link to the pdf with the thundersky #'s
http://www.electricmotordepot.com/content/LiFeP04/ThunderSky/TS40Ah.pdf
