I fear I am beginning to have a bit of a issue with the battery in my solo2. I had not yet discovered all this forum and the great info in it, specifically that about the initial overcharge, and I let my unit charge over night one time aswell. The first full charge lasted great, I felt it was right where it was supposed to be. However each charge since then has seemed to provide less and less run time. I now try to charge it before it gets to 25% and charge it up to 85-90%. I will have to do some tests today/through the week and see how much run time I get, but I feel it has significantly dropped. Hopefully Im just using it more than I realize or something.
As you suggest, there's a huge factor in there.....the owner and how he vapes? I ran into this several years back with the original Solo. I discovered things like the scale is rigged, the first step of 7 on the 'battery meter' was twice as large (capacity wise) as the rest of the steps. There the voltage across a single 18650 (of the two) drops almost exactly a step per LED after that. That is the lights represent 4.0, 3.9, 3.8, 3.7, 3.6, 3.5 and 3.4 Volts or more as they light. So, even below the last step there is still some protective margin before the protective stop.
Solo II seem similar, only with less steps? That will take some more measurements to confirm, but for now I'm comfortable with that estimate.
I finally decided to remove the human element, I ran a series of 'open top, no stem, full blast (heat) runs back to back. You get close to 50 this way IIRC, but it's very repeatable after the human factor is removed. Fears of 'early aging' disappeared after that.
I have an additional tool in this, I have an 'integrating charging current' rig that measures the total charge replaced in the pack directly in mAh which I started using a few years back. It took a very long time for my original Solo to finally start losing capacity, I'm about to rebuild that pack after four or five years of at least 'once a day' on average use. No doubt more.
A defective 18650 is always possible, of course, but I suspect it's not a real degradation in t he pack this soon.
@dynospec - According to Arizer their devices have built-in protections so you cannot over-charge the battery and it cannot drain too far.
I know it is good to be careful with batteries but you won't realize the full potential of the battery if you don't use the full potential.
Of course they do. But maximum sessions per charge is only one way to rate batteries? Also a factor there for real customers is battery lifetime? How soon do I need to replace the pack?
So, if I told you you could set the upper charge limit as close to 4.25 Volts worst case and add a few more sessions per charge (always a Sales advantage on it's face?) what do you think the Sales types at Arizer would vote for? Then, if I told you
that practice kills the battery off sooner so the
customers will have to buy a new vape or replacement battery sooner? I bet that would please them too, wouldn't you?
My advice about 'sound battery management' is based on this idea:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
Please pay special attention to the stuff around figure 4. Following my advice (and practice) of stopping a session or two early (at closer to 4.0 Volts) MORE THAN DOUBLES THE LIFESPAN OF THE BATTERY PACK. IMO enjoying Solo for more years is really the best way "realize the full potential of the battery", that is by using it for a LOT longer before replacement.
Each guy gets to make his own call here, but IMO advice should also come with the 'downside'? The downside of the advice to 'ignore other advice, run it hard and enjoy it' is it will cost you in early battery replacement.
Running the pack 'into the mud' as risks as well. The cells are in series, you can't charge one without also charging the other. Over time this means the weaker one will never again get fully charged (since the stronger one will reach full first), the pack was carefully 'balanced' when built (I match to about 10mAh, the two 18650s I'm going to use are 8mAh different) but this degrades over time and the balance gets worse and worse. Deep discharges beat up the weaker cell early to protect the stronger one in an ironic way?
FWIW, I feel so strongly about this I built a 'Gadget' to automatically stop charging early. One version looks like this:
The charger plugs in upper left, the button starts the cycle putting power out the cable to the Solo by turning on the transistor upper right. The 'shunt' resistors near the transistor monitor the charge current and automatically cut the charge when the drop set by the blue adjustment has been reached (currently set for 85% of full IIRC). My first Solo (which didn't get 'the treatment' from the start) has finally dropped to 5 or 6 sessions per charge. When I strip the pack I'll measure the remaining capacity but I'm confident it's not 2200mAh any more.
Bottom line, if you're careful the battery can last a LOT longer? Some of us consider that getting 'full potential' for your battery dollar.
Your call, of course. It's yours to use as you see fit. Arizer will be happy to take your money for a new pack when you're ready. And they're glad to give you advice to make that as soon as possible.........
For myself, I'll continue to give the advice I do. Overcharge (before any use at all, or don't bother....) the first time only. Don't push the bottom end too much, recharge before it 'hits bottom' and stop charging early (at 80 or 90%) when you can. Every time you do so (stop 10% early) you get 'a free cycle' on battery life.
OF