Preparing for camping

[MiniMag_Crazy_Greg]

I realize that the search function of CPF and CPF MP works well, but I can't find an answer for my questions. I am taking off for 4th of July and camping where there's no AC power, except from my 400watt DC/AC inverter in the truck and will be "off-the-grid" for close for 4 days, :rock: YEE-HAW!!!!!.

I have a AA/AAA charger (no-name brand fast ni-MH/Ni-Cad charger) that uses an AC/DC wall wart adapter and includes a cig. plug adapter, so charging my AA's isn't a problem. My other chargers are AC only, one I use for my UF 16340's 3.7v 880 mha (batteries and charger from DX), and the other is for my TF 18650 3.7v 2500 mah batteries. So, if push comes to shove, I can use my inverter to charge the 3.7v batteries in the car. BUT, I don't want to drain my truck battery, so here's my main question:

Can I charge my 3.7v Li-ion batteries if they're only PARTIALLY discharged to cut down on charging times? Right now, once protection cuts in, I read 2.7v on the cell, and then I charge it, bringing it back to 4.2v. The 16340's take close to 90 minutes, and the 18650 take close to 2 hours (if I charge one at a time).

Has anyone got any tips for off-the-grid charging of my Li-Ions? Thanks!!

EDIT:
18650 DX sku 6105
16340 DX sku 6672

 

[Vinniec5]

Will you be using the inverter with the truck running? or only when its off. That inverter will draw almost 30 amps if fully loaded and depending on the truck could blow the Alternator fuse while running and charging the battery check and see if and what size it is and carry a cpl spares just in case. Common dilemma on the Jeeps and Dodges for years its a hidden bolted-on fuse and when blown won't give you any hint it is until the battery drops under 10v and the check engine light comes on

 

[zipplet]

Li-Ion infact loves being partially discharged and then recharged - you get many many more cycles out of your batteries this way! It's one of the major benefits of it and why you can easily plug in your laptop/cellphone whenever you feel like it to charge it up (as they use Li-ion or Li-poly). There are infact lights out there that are explicitly pushed as being rechargeable whenever you feel like it even after only a short use (Inova T4 for example).

Regarding inverter use, yes as Vinniec5 says it will draw a crazy current fully loaded but if you are only running battery chargers the draw should be negligable (handful of amps) but you will want to run the engine atleast occasionally to avoid killing the lead acid battery.

 

[Closet_Flashaholic]

You probably won't like my answer, but whenever electronics are being powered from inverters, I always recommend using a "pure-sinewave" inverter. The chances are that yours is a "modified-sinewave" type. The pure-sinewave types are slightly more expensive (all else being equal).

Modified-sinewave inverters can cause a lot of problems for electronic devices. If the device does not have an external power cube (wall-wart) then it is more susceptible to problems. Problems range from excessive heat buildup in the device to excessive charging times to just having the charger not work at all.

If I had to charge 3.7v LiOn batteries, I would use a charger that can be powered directly from 12vdc. The one that I recommend is the Pila:

http://www.flashlightz.com/product.php?product=171829

I think the 12 cord is additional cost.

(BTW, link only provided as a reference, not an endorsement of the distributor, which I have no vested interest in).

 

[Oddjob]

Letting the protction circuit kick in all the time can drastically decrease the life of the cell. As ziplet said charge them frequently and they will last longer. I usually charge mine when they fall below 3.9V or so.

 

[bodhran]

I have a 10 cell smart charger with a car adapter that I bought for camping. Can I charge them without draining the car battery, or do I need to run the engine periodicaly? Sorry...that's in regards to eneloop AA's.