What rechargeable options for a DB917/TW0L/PR-T?

I am thinking about a PR-T head with DB917 converter and a TW0L that is going to be mounted on an E-series two cell power pack, probably my E2e-SG. Something about CPF that makes me spend money...........

What rechargeable options would you guys suggest? I was thinking a single 17650 (Pila 168S equivalent) lithium ion, but then the DB might be running in DD mode. I have what is essentially a universal charger for lithium ions and nickel-based cells so cell types don't really disturb me.

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KevinL said:
I am thinking about a PR-T head with DB917 converter and a TW0L that is going to be mounted on an E-series two cell power pack, probably my E2e-SG. Something about CPF that makes me spend money...........

What rechargeable options would you guys suggest? I was thinking a single 17650 (Pila 168S equivalent) lithium ion, but then the DB might be running in DD mode. I have what is essentially a universal charger for lithium ions and nickel-based cells so cell types don't really disturb me.

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KevinL:

I have DB917's Lux III with J/K bins and have a DB917 Lux-V also. I have used 1xJSB123, 2xJSB123, 1x168S and 2x168S in the Lux-III's but the Lux-V is limited to two cell configuration because of the higher Vf.

Kevin,

The only combination I've tried is 2xR123. These are the 4.2 (3.7) volt version from JSB. They work great. I didn't check the runtime. I've tried this with Luxeon III/DB917.

My Lux Vs are BB750s and two Pilas or 2xR123 would be to much voltage.

I think I read that one Pila runs at about 700ma with a DB917/Lux3. You might ask Chop, I think he was the one that wrote it.

Hi Kevin,

I'm also using 2xJSBR123 for my DB 917 L-1 PR-T

Thanks guys. I'll probably try a single R123 and spacer and see what kind of current I get. Guess I can use R123s if I envision a lot of usage, if not, primary cells. I was hoping single 17670 would cut it (3.7V, one cell that takes up all the space)

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KevinL said:
Thanks guys. I'll probably try a single R123 and spacer and see what kind of current I get. Guess I can use R123s if I envision a lot of usage, if not, primary cells. I was hoping single 17670 would cut it (3.7V, one cell that takes up all the space)

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Try it, 700ma isn't bad.

I suppose I'm the freak who wants all the power, none of the compromises, but then again we all know how practical that is /ubbthreads/images/graemlins/crazy.gif

Even in the U2 I compromise a little, level 6 with 18650s ain't as bright as level 6 primary cells. Oh well. It's a good idea though, I should give it a shot with the DMM and see how it works out. This is also a used PR-T, so the Lux3 will have been broken in and have a lower Vf /ubbthreads/images/graemlins/thumbsup.gif

KevinL,

Since the downboy is a buck converter, the voltage from the batteries (Vin) must exceed the Vf of the luxeon. The L Vf of your luxeon is also kind of on the high side, so you might not see 700mA to the luxeon from a single Pila. If you want regulation from the downboy and lux III on li-ions, you'll need to run at least two li-ion cells in series to get the Vin over Vf. Just keep Vin below the maximum that the downboy can handle, which I think is 16V or so.

As for the 5W light, you can get regulation from a single Pila, but the converter will run really hot if you use it more than intermittently. If you let the heat build up, it could self destruct.

BTW, I don't care what anyone says, DO NOT run unprotected li-ion cells in series. This is dangerous. If you're gonna run more than one li-ion cell in a light be sure it is protected. Like JSB123s or Pilas.

I don't care if I get flamed for this or not. Ignore posts about what people have "gotten away with" when running unprotected li-ons in series. Running unprotected li-ions in series is like a time bomb.

I was one of the people "getting away with" running a couple unprotected cells in a series. If i remember correctly it was in one of Chop's KL1's. Then one day i was using my light and i went to check the voltage of the batteries. both were freshly charged at 4.12when they went in. When i checked them one was at 4.45 and the other was a little under 2 volts. There were no dead shorts and neither cells have ever given me a problem before. Bad news. I got lucky and it was the last time i ever did that. listen to tony, or learn yourself like i did. You may not be as lucky though.
jimmy

Chop, thanks. That is what I figured. The most logical solution would be the protected R123s.

The problem with protected solutions is always the cost, though. While I'm not normally the kind who will complain about cost (after buying things like the U2, etc.), rechargeables present a unique case - they *MUST* be cheaper than a comparable supply of CR123s to even justify their existence, after all, if they were not - then owners should just go straight to CR123 and forget about them. Every dollar added to their cost bites and bites hard, unfortunately. After all, just like investing, you absolutely HAVE to make a profit, there is no room for 'fudge factor' (which I normally use with other things). If you lose even one cent, the money would be better off sitting in the bank or under the bed. Just an example and probably a bad one.

NiMH has solved this problem, as the cells will pay back extremely quickly with just a few discharges. Lithium ion still looks like it has a few eternities to go.

I'll do some testing to see how well the PRT handles under single-cell conditions, and if all else fails, I'll go back to CR123As. Rechargeables can be extremely frustrating at times.