After about 6 months running LiPo on my commuter setup, I’ve just replaced a pack which copped the brunt of my noob mistakes. So I thought I’d share my experience, in case it is useful for others trying to decide which chemistry to use.
Running 12S Zippy packs, my commute uses 2Ah out of the (alleged) 4Ah capacity. This is based on charging to 4.15v, at the end of the trip the voltage was about 3.8v. My 30A controller means the packs are seeing peaks of 7C, compared with the (again, alleged) 20C rating of the Zippy's.
Towards the end of the commute, I noticed acceleration wasn’t as good. Not enough to be a problem, but I’m glad I oversized my batteries and I really wonder if pushing 20C Zippys to even 75% capacity regularly would be a good idea. Next time my LiPos need replacing (hopefully not for a long time, now that I know how to treat them better), I’ll probably try 30C or Turnigy cells to see if they perform better.
The death of a pack in about 6 months may be partly due to me leaving the cells constantly charged to 4.15 volts (ie putting them on the charger straight after a ride, so they’re ready to ride at a moment’s notice). But I think the main factor was that they were accidentally deep discharged a couple of times, which resulted in very unbalanced cells. The most recent time, it sent a cell puffy and way below the 2.7 volts “golden rule”, so that pack has now been replaced.
As for the “new” packs, one of them has actually been in storage for over 6 months as a spare (never used). A cell in this pack initially wouldn’t charge past 4.05v, causing the iCharger to work overtime trying to bleed off voltage from the other cells. Luckily, after a few shallow cycles, this cell has come good and is now fully charging.
I must admit, using LiPo is a lot of work for a commuter bike! Buying a prebuilt LiFePo4 pack and charger would be more practical: no DIY series/parrallel connections, a charger which you just plug in and turn on without needing to know what it’s doing, not needing to devote your life to monitoring cell voltages, the battery is happy to be charged the night before and, of course, less risk of burning your house down if something goes wrong. It’s much more “plug and play”. Having said that, I love how discreet and lightweight my LiPo setup is, so I’m happy to live with these downsides.
In about 6 months, I’ll report back on how the new Zippy packs are lasting, now that I’m treating them better.
I look forward to any questions/comments you may have.
Simon
Running 12S Zippy packs, my commute uses 2Ah out of the (alleged) 4Ah capacity. This is based on charging to 4.15v, at the end of the trip the voltage was about 3.8v. My 30A controller means the packs are seeing peaks of 7C, compared with the (again, alleged) 20C rating of the Zippy's.
Towards the end of the commute, I noticed acceleration wasn’t as good. Not enough to be a problem, but I’m glad I oversized my batteries and I really wonder if pushing 20C Zippys to even 75% capacity regularly would be a good idea. Next time my LiPos need replacing (hopefully not for a long time, now that I know how to treat them better), I’ll probably try 30C or Turnigy cells to see if they perform better.
The death of a pack in about 6 months may be partly due to me leaving the cells constantly charged to 4.15 volts (ie putting them on the charger straight after a ride, so they’re ready to ride at a moment’s notice). But I think the main factor was that they were accidentally deep discharged a couple of times, which resulted in very unbalanced cells. The most recent time, it sent a cell puffy and way below the 2.7 volts “golden rule”, so that pack has now been replaced.
As for the “new” packs, one of them has actually been in storage for over 6 months as a spare (never used). A cell in this pack initially wouldn’t charge past 4.05v, causing the iCharger to work overtime trying to bleed off voltage from the other cells. Luckily, after a few shallow cycles, this cell has come good and is now fully charging.
I must admit, using LiPo is a lot of work for a commuter bike! Buying a prebuilt LiFePo4 pack and charger would be more practical: no DIY series/parrallel connections, a charger which you just plug in and turn on without needing to know what it’s doing, not needing to devote your life to monitoring cell voltages, the battery is happy to be charged the night before and, of course, less risk of burning your house down if something goes wrong. It’s much more “plug and play”. Having said that, I love how discreet and lightweight my LiPo setup is, so I’m happy to live with these downsides.
In about 6 months, I’ll report back on how the new Zippy packs are lasting, now that I’m treating them better.
I look forward to any questions/comments you may have.
Simon