bogan
6th June 2013, 19:49
I've had a Shorai LFX12A2 for 2 years in my 647cc V-Twin Honda Bros. Skip to end if you just want the summary, the rest is just background details.
The size was below their recommended due to space constraints, but it has always turned it over just fine as I looked into the CCA ratings quite a bit before buying it.
Since it's been a while and the Shorai do not have internal balancing I decided it was time to do that, as it will likely prolong the battery life. After looking around I decided on an Imax B6 multipurpose balance charger developed for RC gear. At $23 which is around a quarter of what I could find the official charger for but with much more functions it was a no-brainer. Worth noting you still need to plug this into another battery or normal charger for a balance charge as it doesn't come with its own powerpack, though you can separate or integrated powerpack with them for not much extra too. Also, it needs a balance cable which didn't come with mine, but I had some correct plugs lying around so just made my own, simple 'patch' cable so left pin on one end goes to left on the other and so on.
I use my bike frequently, and there were only a few times when it went unused for over a week, usually during modifications. The longest was in the last couple of months and I put it on a normal charger once the voltage dropped below 13.2. That voltage drop was caused by testing the headlight and other electronics, not self discharge. The bike has the older style SCR rectifier. There has been no electrical problems throughout the time I've had the Shorai in there. What that translates to is somewhere between ideal and good conditions for the battery.
First up is a simple cell voltage check with no drain.
Cell voltage check, taken shortly after a ride so can be considered the in-use fully charged reading.
#1 3.60V
#2 3.57V
#3 3.63V
#4 3.60V
Total 14.40V
So at rest the voltages are reasonably well balanced, with the 0.03 possibly down to measurement errors. The total voltage is indicative of 100% capacity remaining too.
Next is the discharge check, which is discharging at a constant rate while observing the voltage, and recording the capacity.
After the first 1.5 amp-hours came out of the batteries (2.5hours in) I let it rest overnight and measured the cell voltage again.
#1 3.28V
#2 3.29V
#3 3.28V
#4 3.29V
Total 13.14V
Again they are very well balanced voltage-wise. The total voltage corresponds to 63% charge left from Shorai's figures. I did notice cell #1 had a lower voltage when discharging, suggesting a higher internal resistance.
Another quick 350mAhr taken out and then a storage balance, which set all cells to 3.3V
Then on to the balance charge main event!
2 hours in took 2 amp hours, at which point cell #1 hit the full charge voltage of 3.6V, the rest were down at 3.36V.
At this point the charger had to dissipate the energy to prevent #1 from overcharging, and the charge rate went way down.
Another 620mAhr went in during the next 5 hours.
Since the storage charge is a mid charge level balance, it doesn't do a brilliant job of balancing the levels of charge within the cells. The charger also had a discharge cutoff voltage set too low, so I couldn't do a proper bottom balance, so unfortunately I can't comment on each cells capacity after this time. However, with about 2ahr pulled out bringing it down to half capacity remaining from shorai's charts, overall I think it can't have lost much. Bottom balancing is of little use for a starter battery anyway, as the battery operates at only small levels of discharge.
So how is the top balance is the main question, well after 2 years one cell 'tops out' 620mAhr and 0.24V before the other 3. This might not sound like much, but its actually quite significant, were my bike putting out the to-spec 14.4V a 0.24V increase on one cell it would be 3.54 volts to 3 of the cells and 3.78 volts to one. That 3.78 volts is significantly above the recommended charging voltage of 3.6V, after which cell life is thought to degrade up to a voltage of around 4.1 when the damage is more immediately apparent. I'm not sure what the bike puts out, but the first reading of the battery was 14.4V so it has to be up there. So in all likelihood the cell balance has degraded enough that one cell is getting too much voltage, and further degrading the cell balance. A very good thing I caught it now, but would have been better to catch it sooner.
Summary:
After two years the cells have become unbalanced and capacity lifespan is likely reduced due to the imbalance. However, with more frequent balancing I still expect the lifespan to extend a few more years yet. Hard to say how long it took for the balance to start to go out of whack, but I'll plan to re-balance every 6 months with along with the 6 monthly oil change etc, and would recommend those who purchase any Lithium Iron starter battery (without internal balancing) to do a balance charge every 6 months also.
The size was below their recommended due to space constraints, but it has always turned it over just fine as I looked into the CCA ratings quite a bit before buying it.
Since it's been a while and the Shorai do not have internal balancing I decided it was time to do that, as it will likely prolong the battery life. After looking around I decided on an Imax B6 multipurpose balance charger developed for RC gear. At $23 which is around a quarter of what I could find the official charger for but with much more functions it was a no-brainer. Worth noting you still need to plug this into another battery or normal charger for a balance charge as it doesn't come with its own powerpack, though you can separate or integrated powerpack with them for not much extra too. Also, it needs a balance cable which didn't come with mine, but I had some correct plugs lying around so just made my own, simple 'patch' cable so left pin on one end goes to left on the other and so on.
I use my bike frequently, and there were only a few times when it went unused for over a week, usually during modifications. The longest was in the last couple of months and I put it on a normal charger once the voltage dropped below 13.2. That voltage drop was caused by testing the headlight and other electronics, not self discharge. The bike has the older style SCR rectifier. There has been no electrical problems throughout the time I've had the Shorai in there. What that translates to is somewhere between ideal and good conditions for the battery.
First up is a simple cell voltage check with no drain.
Cell voltage check, taken shortly after a ride so can be considered the in-use fully charged reading.
#1 3.60V
#2 3.57V
#3 3.63V
#4 3.60V
Total 14.40V
So at rest the voltages are reasonably well balanced, with the 0.03 possibly down to measurement errors. The total voltage is indicative of 100% capacity remaining too.
Next is the discharge check, which is discharging at a constant rate while observing the voltage, and recording the capacity.
After the first 1.5 amp-hours came out of the batteries (2.5hours in) I let it rest overnight and measured the cell voltage again.
#1 3.28V
#2 3.29V
#3 3.28V
#4 3.29V
Total 13.14V
Again they are very well balanced voltage-wise. The total voltage corresponds to 63% charge left from Shorai's figures. I did notice cell #1 had a lower voltage when discharging, suggesting a higher internal resistance.
Another quick 350mAhr taken out and then a storage balance, which set all cells to 3.3V
Then on to the balance charge main event!
2 hours in took 2 amp hours, at which point cell #1 hit the full charge voltage of 3.6V, the rest were down at 3.36V.
At this point the charger had to dissipate the energy to prevent #1 from overcharging, and the charge rate went way down.
Another 620mAhr went in during the next 5 hours.
Since the storage charge is a mid charge level balance, it doesn't do a brilliant job of balancing the levels of charge within the cells. The charger also had a discharge cutoff voltage set too low, so I couldn't do a proper bottom balance, so unfortunately I can't comment on each cells capacity after this time. However, with about 2ahr pulled out bringing it down to half capacity remaining from shorai's charts, overall I think it can't have lost much. Bottom balancing is of little use for a starter battery anyway, as the battery operates at only small levels of discharge.
So how is the top balance is the main question, well after 2 years one cell 'tops out' 620mAhr and 0.24V before the other 3. This might not sound like much, but its actually quite significant, were my bike putting out the to-spec 14.4V a 0.24V increase on one cell it would be 3.54 volts to 3 of the cells and 3.78 volts to one. That 3.78 volts is significantly above the recommended charging voltage of 3.6V, after which cell life is thought to degrade up to a voltage of around 4.1 when the damage is more immediately apparent. I'm not sure what the bike puts out, but the first reading of the battery was 14.4V so it has to be up there. So in all likelihood the cell balance has degraded enough that one cell is getting too much voltage, and further degrading the cell balance. A very good thing I caught it now, but would have been better to catch it sooner.
Summary:
After two years the cells have become unbalanced and capacity lifespan is likely reduced due to the imbalance. However, with more frequent balancing I still expect the lifespan to extend a few more years yet. Hard to say how long it took for the balance to start to go out of whack, but I'll plan to re-balance every 6 months with along with the 6 monthly oil change etc, and would recommend those who purchase any Lithium Iron starter battery (without internal balancing) to do a balance charge every 6 months also.