dogman wrote:I agree Jeremy. ...
If you have a sucky cell in there in your new packs, paralelling it with the rest of the pile (step c) is not going to do it any good. If the previous break in cycling didn't wake it up, it's not going to. But of course, you do want em close before you hook up paralells.
I think Jeremy makes a good point about "LiPo hype" in the RC World, and, also, the fact that LiPo is stressed to near its limits with 3D flying, etc. Dogman's counter point of using LiPo on an eBike at lowered C rates with a typical 20amp controller compared to RC 'is' much lower stress on the LiPo battery to begin with. (Please note there are super-charged high-amp eBikes running on LiPo though.)
Going back to the "quick & dirty" method... IF someone does not have the money to invest in a good LiPo balance-charger and "bulk charges" instead w/o balancing -OR- one just wants to hurry-up and get going w/o fancy-charger, THEN STEP C is the "quick and dirty" way to go by paralleling all the batteries together w/o a balancer available. In effect, that is perhaps the only balance method without the LiPo balancer. Of course, sub-packs would need to be near matched voltage & capacity to connect together in parallel this way. Checking the sub-packs with a LiPo voltage meter after the "bulk charge" is cheap & quick-n-easy to do.
Lastly, I will "trump a point" by suggesting for many new to LiPo AND without having their eBike finished (can not install the LiPo-battery on the bike yet)... then, definately, don't wait to test and break-in your LiPo on the eBike. Go ahead and familarize yourself with your LiPo batteries and equipment off the eBike. Condition it and break it in with 5-10 cycles off the bike while you learn what you're doing and gaining experience too. Then, when your eBike is ready for the LiPo mounting and EV grins, you can ride with confidence the LiPo is up to the challenge too.
Another very good reason to check your sub-packs for several break-in charge-discharge cycles before building the final battery for installation is that these sub-packs are not (yet) in parallel configuration. Later, you will (probably) be paralleling these sub-packs to get a higher capacity battery, for example, combining three 5ah sub-packs to make one 15ah sub-pack in parallel. This will be your only chance to check each sub-pack before paralleling or connecting & final assembly. So do it now while it's still easy to do, rather than having to take apart the sub-packs later from their paralleled configuration if a problem is detected. Also, if you don't check now, then once the sub-packs are in parallel your voltage meters can't read the individual cells anymore. If a cell goes bad in parallel, then you can't isolate it individually. Better to be safe now than sorry later.
IF you want your LiPo to last for over a 1,000 cycles, then you're not wasting time or your LiPo's lifetime capacity by carefully charging & discharging during these inital learning & breakin cycles, imo. After all, it's U that is the smart charger anyways...