Not Cheap 6Volt Lantern Made Rechargeable (Li-Ion)

As an alternative/adjunct/compliment to bmccue1964's post, here is a Li-Ion mod I've done to a 6V lantern. These days I have a preference for Li-Ion when it comes to rechargeable cells. Superior charge retention and low temperature perfomance compared to Nicad/Nimh. And even though it's been years since I've used SLA, I still recall how quickly they perish when discharged too deeply.

The host lantern is a Ray-O-Vac model. $9.99 and $8.99 at Home Depot and Walmart in my area. I was intrigued by it's 4 D-cell adapter; that was why I selected this model.

(In another thread, it was correctly noted that this adapter is available from www.digikey.com - for only $2.70 apiece. I don't know if Digikey has a minimum order requirement. Their part number for this item is BA4D-S-ND).

The Li-Ion pack is a Canon BP-945. 7.2v at 5500mah; replacement packs can be found on eBay for approx. $35. Often times less if you are patient. I got both of mine for $22 each.

The 7.2v pack is too hot (8.4v) out of the charger for most 6v bulbs. I've selected a KPR-118 bulb from Radio Shack, 7.2v @ 600ma. I've had up to 9 1/2 hours of run time per charge. Yes, then beam is full of artifacts. But this is meant to be a 'You better be working even after sitting in the trunk of the car for a full year unattended' light as opposed to a 'Let me impress the neighbors by taking down a 747 Jumbo Jet with my 50 million cp' light.

Biggest downside is charging the pack. There only seems to be quick chargers for 7.2v 1850mah packs. Expect to spend anywhere from 8 to 9 hours to get one of these puppies topped off.

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

Contrary to popular belief, li ion rechargeables are NOT like lithium primary cells which hold their charge for years and years with no loss. Li ions do have some self discharge. Not as much as NiMH, but some. That camcorder pack will probably lose half its charge over 6 months or so. NiMH would lose pretty much its whole charge in that long.

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

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Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

Good idea!

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

[ QUOTE ]
paulr said:
Contrary to popular belief, li ion rechargeables are NOT like lithium primary cells which hold their charge for years and years with no loss. Li ions do have some self discharge. Not as much as NiMH, but some. That camcorder pack will probably lose half its charge over 6 months or so. NiMH would lose pretty much its whole charge in that long.

[/ QUOTE ]

I certainly did not mean to imply that primary and rechageable lithium cells had the same storage characteristics! The self-discharge rate for Li-Ion cells is given as 4 to 5% the first month and 1 to 2% thereafter. So the theorectical worse case lost for one year is 27%. 73% remaining capacity after one year is not too bad, in my opinion.

Anyway, to Hell with theory. I've got two additional packs I'm charging now. Will toss them into the trunk of my automobile on New Years Eve. Will pull one out on June 30th to test it and the other one next New Year's Eve. Real-world testing baby /ubbthreads/images/graemlins/thumbsup.gif.

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

[ QUOTE ]
I certainly did not mean to imply that primary and rechageable lithium cells had the same storage charactistics!

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EvilLithiumMan, you didn't. It was clear you were talking about rechargeables.

Clever idea and well executed with a good description and photos. Kudos /ubbthreads/images/graemlins/thumbsup.gif

BC

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

Nicely Done ELM! You are truly lving up to your name /ubbthreads/images/graemlins/wink.gif

Wilkey

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

I don't get it. Why not just use non-rechargeables if you are going to let it sit for a year? From the website below, it seems the rechargeable lithiums degrade over time and with heat, so a year or 2 in the car, with the hot sun in the summer, and that's it. If you use the light daily, then it makes sense. Anyway, I'm not trying to be rude, I'm just confused.


from
http://www.powerpulse.net/powerpulse/archive/aa_103000c5.stm

The lithium-ion has found a strong market niche with portable devices demanding small form factors. The most popular uses are cellular phones and notebook computers. Because of the aging aspect, the lithium-ion is most suitable for applications with a hectic user pattern. Where the lithium-ion falls short is on high-current applications and operations that regularly need a full discharge. Typical applications for which the lithium-ion is less suited are power tools, heart defibrillators and mobile radios for public safety.

Another field where the lithium-ion has proven less favorable is in applications that require occasional battery use. On a laptop that is mostly powered by ac, for example, the lithium-ion battery ages in time and the full benefit of the battery cannot be realized. For these applications, other battery chemistries may serve better. High heat levels inside some laptops also cause the lithium-ion to fail prematurely. However, field tests have revealed that the lithium-ion is less affected by heat than the NiMH.

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

OK, I guess I've got some ideas for my next project, a "Not So Cheap Rechargeable light!".

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

[ QUOTE ]
cheesehead said:
I don't get it. Why not just use non-rechargeables if you are going to let it sit for a year?



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That's a fair question. I am only doing this experiment to satisfy my own personal curiosity of Li-Ion storage.

You are correct that using primary cells would be a better choice if my only objective was to have a flashlight do nothing but sit around unused for a year. As a matter of fact, if I were to make my own 'survival' light, it would be powered by primary lithium cells which have excellent non-use storage characteristics.


As a final 'admission', I do have to admit to carrying a grudge against alkaline cells. 20 years ago when I owned a Dodge van, I put together 'spare parts toolkit' of sorts. Belts, hoses, fuel filter - items of that nature. One of those items was a new three D cell Maglite, complete with either Energizer or Duracell 'Guaranteed Leakproof' cells. Two years after assembling this 'kit', I was rummaging through it and pulled out the Maglite and turned it on. Nothing, it was dead. I was horrified (and pissed) when I removed the tailcap. The cells had completely decomposed into a grayish mess. They were so swollen, they could not even be removed, I threw that expensive Maglite into the trash.

'Guaranteed Leakproof' indeed! Even though major cell manufacters still support their products with a 'Will replace of repair your equipment ...' policy, they are prevented in this country from using such deceptive claims by the FTC. At least I haven't seen that phrase used in a long time. And I think this site is saying that as well, but I honestly haven't read it word-for-word.

http://www.arentfox.com/quickGuide/businessLines/advert/advertisingLaw/adLawLawsRegs/trr/battery.html

Re: Not Cheap 6Volt Lantern Made Rechargeable (Li-

ELM,

Ah, I knew there was more to the story. Thanks for replying. Real world testing is the best way to go. Hopefully the lithiums will hold up better than the alks.

Have a Happy New Year,

Cheese