Does leaving batteries peaked really harm them?
 

I've read that but I have always charged mine after using so they are ready for the next time. I tried leaving them at about 50% for storage but I have limited opportunity for drive time and very handy to have the batteries precharged. I found that I wouldn't even bother with it if they were not charged due to time shortages.

I was wondering the same thing as I use 18650 lips for flashlights and electronic cig mods and keep about 10 charged at all times and haven't noticed any changes.

No real damage from that.... Honestly if you store in lower temp it does more good than discharging to a "store level". iMO its good practice to not leave packs peaked if you don't plan on using them the next day... but most agree if you are going to not use the pack for a month discharge it to store level as a max length.

I always for years have pre-charged packs the night prior to racing with no ill effect on cycles or the pack.

Now some crazy 17.5t racers will want to do different things right before a race to get the packs to ideal temps with maximum voltage but that is another game all together.

What is "next time"? Next day, a week, 2 weeks or longer?

Leaving them fully charged is not ideal, puffing will be the result and they will be ruined. Is it that you have to wait hours for all your lipos to charge? Do you have a good charger, something that can charge your lipo's over 1C?

Like 8ight-E does, I charge mine up the night before. If in a rush, I'll do a 2 or 3C charge and in 1-2 hours, I'll have my batteries ready to go.

I think you'll find any poofing is more from temps being too high (ambient) where you store it vs a full charge. I've left packs charged in error for months w/o issue in the past. Now if you leave a pack peaked or not in a vehicle or anywhere temps soar it will poof. Often after a pack poof's some a charge will relax it funny enough,, but again mostly temp related. I don't advise that even if I have done it myself :P and of course there are different levels of poofing.. if the hard case pops off the pack I so big, you may not want to mess with it.. lol. The most common issue is if you don't have tight plugs and you have some shorting going on (arcing) it will also generate heat and often you get a poofed pack if the plugs don't de-solder themselves.

I've left 3 batteries peaked at 8.4v and all 3 puffed. Even 1 day fully charged puffed em.

Now I make sure to always discharge down to 3.7 when the night is over. I invested in a decent charger so I could charge quickly and also discharge.

Charging just before use is better for the lipo, helps keep IR down for good punch and slows the capacity loss. I charged ahead of time, sometimes the night before but frequently before leaving for the track, for years too but once I switched to charging just in time the IR stays low and capacity holds up much better and for far longer.

Besides high powered charging to reduce charge time there are a couple possibilities to consider. Use a storage voltage on the high side of the various recommendations, around 3.85V/cell. Then either use a fast charge mode or manually stop the first charge as the amps tail off to a slow charge. I've even went out for a few warm up laps without charging past storage, with another pack on charge (easier with some classes/uses than others of course).

On my packs I can tell a diff if they were charged the Night before they feel real flat then the next charge they back with there punch.