Depends what you want to use it for.
Killing spiders on a high ceiling, fine.
Very nice idea, I think the driver would like to get 42 volts…
How many volts can it handle?
I ordered one with 2 tubes. Has anyone tried 4 or 5 * C batteries? I am thinking about it. I have two other 3 * 26650 lights that run off C batteries. Not as well as 26650 but good enough in an emergency
Could always use C high cap NiMH.
It’s sold in up to 3s configurations. I’d assume that 12.6v is the highest sanctioned input voltage. I haven’t made a list of QX9920 based drivers, but this is what I came up with just now:
- HX-1175b - spec’ed a few different ways, but the highest input voltage spec I’ve seen is 15v. Other listings say 8.4v.
- 16MM 8.4V 5-Mode 3A LED circuit board For 2*Cree XM-L at Lightmalls - No real spec. They might be trying to say up to 8.4v.
- Solarforce XM-L2 dropin driver at Solarforce-Sales - Spec’ed at up to 9v. My (brief) earlier look into this indicated that they skipped the (semi) “regulated” PSU section for the QX9920, so this driver is probably limited by that more than anything else.
- Patrol King - no spec, but it’s physically setup for 2s, so take that FWIW.
It’s been mentioned that the light functions on 1s, although I don’t think anyone has tested to see where it drops out of regulation. Let’s assume 3.65v, since that’s the XM-L2 vF at 3A from djozz’s chart plus the 0.25v sense voltage of the driver. Everything above that should regulate. This is a buck driver, so higher input voltages will require lower input currents. If you want to use alkaline in a pinch, try to keep the voltage as high as possible (within reasonable limits).
With only 4*C (alkaline) I don’t think “High” would work for very long. Maybe about 20minutes. Ref HJK’s Panasonic Pro Power C review here. In order to get approximately 1hr of battery life in High mode I think you’d want 8*C.
You could also consider using 4* Lithium AA with a sleeve. If you made caps for the sleeve, that could easily be stored alongside the light with batteries installed in it for an emergency. I think that 4*AA (Lithium) could do almost an hour in “High”! See HKJ’s Energizer Ultimate Lithium AA review here.
Oops, I forgot to account for dropout voltage while doing the 4* runtime calcs. Lithium is probably about the same, 8*C is the same as well, but 4*C may suffer a little. These are all quick and dirty things anyway, back-of-the-napkin type math.
I could still use it with 3 real batteries and a bunch of dummies though, right?
Sure. Or one big dummy, that’s probably what I’d do in your shoes. Less connections is better, and while you can’t do anything about the plethora of connections between the extension tubes you can do something about all the end-to-end dummies. If you intend to make it exceptionally long, try for a lightweight dummy. Otherwise the combination of length mismatches and weight could potentially overpower a tailspring, giving contact issues. You’ll be a better judge of that with everything on hand though.
I just ordered another extension for a total of 3 extensions + Y3. Figure that 5 C size NiMH batteries will fit. I have about 10 Tenergy C size 5000mAh from the fire sale a couple of years back. 650x4=2600 to 500×5=2500
I have two extensions coming, will that accept C batteries, or do I need to order a 3rd extension to get the correct length?
How many C-cell batteries do you want to fit?
No particular number, but I am curious of how they match up with various numbers of extensions.
4 C cells (200mm) are about the same length as 3 unprotected 18650/26650's (195mm). So 2 extensions on a Y3 should hold 4 C cells. Three more extensions to hold 8 C cells.
Thanks, that gives me an excuse to pick up some C rechargeables.
Ordered one. Thanks the!
Thank you for this post. I purchased two extension tubes with this light, and am excited to learn that I can now also run 4 rechargeable C cells in this Y3 when it arrives. I do not own many 18650 cells.
Your very welcome. 4 cells should work pretty good since the driver is designed to work with the voltage of one Li-ion cell.
EDIT: I just remembered that 3 unprotected 26650's need a spacer in my Y3 to work. I checked with 4C's and a short spacer will be needed for them too. The light seems to work fine on 4C's.
What kind of spacer?
Is the run time better or worse on C batteries?
I just taped together a about 4 pennies for the time being. When I get around to modding the light, I plan on replacing the driver spring with a short piece of copper pipe to fix the length issue permanently.
Don't know the answer to your second question. I don't have any Ni-mh C cells. I guess it would depend on what C cells you uses and what Li-ion cell you would have used.