DNAinaGoodWay wrote:So, it has to stay plugged in after 100% is reached to optimally balance, and for at least four hours?
Why is that? Does it draw small amounts of power occasionally during this process? I've never noticed it draw anything after 100%, but then, haven't ever looked for it.
Keep in mind that the behavior of '11-12 LEAFs is different than '13 LEAFs.
I don't think it's been determined that it needs to stay plugged in, but it does appear that on occasion if you leave a '11-12 plugged in on a 100% charge (no timers), it will top off the battery after 4-5 hours, presumably after some balancing has been done.
The '11-12 will cut off charging quickly on a 10% charge. Once power starts to taper from 3.3 kW, it will only charge for 15-30 more minutes - you won't see much time spent with the car pulling less than 1kW if at all.
The '13 LEAFs will sip electricity for a while after the pack is 100% - up to an hour has been reported. This appears to be much more effective at topping off/balancing the pack.
RegGuheert's trick of starting up climate control for an hour or more after a 100% charge simulates the behavior of the '13 on the '11-12 LEAFs, since the car will attempt to charge the battery as long as there is left over power after powering the HVAC.
This may be more effective than letting the car sit for a couple reasons:
1. Someone has said that the BMS doesn't actually remain active for all that long after the car shuts off (perhaps 30 minutes). Whether or not this is true is up for debate, but I haven't seen hard proof either way.
2. You can be certain that the BMS will be trying very hard during that hour the HVAC is running to keep the highest voltage cells from overcharging.
3. Less time spent at 100% charge is always better!
It would be very interesting to compare before/after LEAF Spy cell-pair plots after both techniques to see what kind of difference there is if any. I would give it a shot, but I'm still waiting for my pack to get down into the mid-60F temps to minimize the effects of high SOC/temp capacity loss - saw 6 TBs the other day!
Do you have results for 80% charge? I mainly charge to 80% so wonder what the level of balancing is. Thanks.
There won't be much to see, you will simply see it go from ~7 kW to 0 kW in a minute. Balancing will still be done if necessary - don't equate the tapering of the charge to balancing as they they are two separate functions.
The charge is tapered off to prevent cell-pairs from exceeding a maximum voltage. Cell-pairs are balanced by bleeding off the CPs with the highest voltage. The shunts can not bleed off voltage/energy from cells very quickly, so the car tapers off the charge and even pauses for a bit before topping off the pack a few times.
It would be great to get a chart as detailed as Rauv's (VERY nice plot!) for a '11-12, but the lower resolution charts I've seen taper off from ~3.8 kW to ~1 kW before shutting off. If the car comes back on to top off the pack (and I don't think this has been documented very well), it will happen hours later.