lucid
Newly Enlightened
I'd like to run a P7 off a 6V battery. Can anyone suggest a good way to do this? Thanks.
How to run a P7 off 6V?
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LukeA
Flashlight Enthusiast
Enough buck drivers in parallel to supply the P7 with the current at which you want to run it.
Packhorse
Flashlight Enthusiast
I think the OP was actually asking for what type of buck drivers? And where you could get them would also be a great help im sure.
SOB is a buck driver. SOB = Son of Buck = Next generation Downboy.
There's the KD multimode buck driver too: http://www.kaidomain.com/ProductDetails.aspx?ProductId=1866
smopoim86
Enlightened
When did KD hack off the amazon layout? It seems to make the site much more useable
LukeA
Flashlight Enthusiast
The site was completely down the other day.
Because of the amount of heat this sucker generates, you really want an efficient buck driver. I would use a voltage regulator POL type of circuit due to high efficiency. These have efficiencies of low to mid 90's. If you consider that the P7 is in the 9W to 10W range, you want to maximize efficiency. An efficiency of 75% means the regulator will dumping 2.25W to 2.5W which means you will want to heat sink the regulator itself. Cut that down to 1W or less and you can probably manage without heatsinking the regulator. You will still need to heatsink the LED.
They are also more efficient in bucking down from a higher voltage than any buck LED driver that you can get.
Der Wichtel
Enlightened
I have some drivers left
http://candlepowerforums.com/vb/showthread.php?t=201981
http://candlepowerforums.com/vb/showthread.php?t=201981
baterija
Flashlight Enthusiast
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The thing that occured to me was whether a 6V battery could even supply the 2.8 amps the cell is rated at. A little search turned up this. (Wow talk about a tough rater on yahoo answers. He gets all that info and sounds like he wants a Silverfox discharge curve on top of it. :sick2
Assuming the poster is close to accurate, he says 2.86 amps max from the 6V battery when it shorts.
A little quick calculation (assuming you can parallel the drivers for 2.8A to the emitter, 90% efficiency driver, and 4.8 V in after assumed voltage sag) gives about 2.27A drawn from the battery. Sag to 4.4V shows needing 2.55A from the battery or 91% of shorted max current. Sounds like its possible but you wouldn't be able to sustain 2.8A to the emitter if you could even get that.
To actually provide an answer to the OP's question - here's an as yet to be named example of a Maglite P7 mod that uses 2 drivers in parallel for 2.4 amps. Good luck.
Assuming the poster is close to accurate, he says 2.86 amps max from the 6V battery when it shorts.A little quick calculation (assuming you can parallel the drivers for 2.8A to the emitter, 90% efficiency driver, and 4.8 V in after assumed voltage sag) gives about 2.27A drawn from the battery. Sag to 4.4V shows needing 2.55A from the battery or 91% of shorted max current. Sounds like its possible but you wouldn't be able to sustain 2.8A to the emitter if you could even get that.
To actually provide an answer to the OP's question - here's an as yet to be named example of a Maglite P7 mod that uses 2 drivers in parallel for 2.4 amps. Good luck.
lctorana
Flashlight Enthusiast
The 11,000mAh lantern battery is a super-heavy-duty 4F battery - e.g. Eveready 1209.
Standard-duty zinc-carbon 4F (409) have about 7Ah, Heavy-duty (509) about 8Ah, and alkaline ones have 24-26Ah.
So let's summarize. Zinc-carbon 4Fs will not be up to the job at all, Zinc-Chloride (super havy duty) will be marginal, and alkaline will be OK - for a price.
Far better, IMHO, to pop 4 D or F rechargeables in a dead 4F shell. (We can make a carbon-arc lamp with the rods from the old F cells later...)
Then we have guilt-free P7 lumens.
Standard-duty zinc-carbon 4F (409) have about 7Ah, Heavy-duty (509) about 8Ah, and alkaline ones have 24-26Ah.
So let's summarize. Zinc-carbon 4Fs will not be up to the job at all, Zinc-Chloride (super havy duty) will be marginal, and alkaline will be OK - for a price.
Far better, IMHO, to pop 4 D or F rechargeables in a dead 4F shell. (We can make a carbon-arc lamp with the rods from the old F cells later...)
Then we have guilt-free P7 lumens.
lucid
Newly Enlightened
Thanks everyone for the quick replies; some great info here. Those drivers from Der Wichtel look good. TBH I hadn't considered the discharge rate of the battery. Also I should have been more specific, and it is indeed a lantern battery that I was thinking of using - probably one of the SLA types. I'm considering retrofitting a "Dolphin" torch. However it looks like I might kill the battery with the sort of current I'm looking for.
Replacing the innards of a lantern battery with D cells is an ingenious idea, but I was hoping that this project would be a bit more "off-the-shelf". This might be my only option though.
Replacing the innards of a lantern battery with D cells is an ingenious idea, but I was hoping that this project would be a bit more "off-the-shelf". This might be my only option though.
James35
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Lantern battery? 5 NiMH (6V) or 2 A123's (6.6V) would be an excellent alternative for similar voltage. They provide a lot more amps. The A123's can dump up to 90 amps continuous
Here are a few options:
1. A driver board is a good solution when we have more volts than the P7 is designed to handle.
2. Two P7's in series can sometimes be an option with 6V.
3. The upcoming Cree MC-E looks to be a perfect solution to direct drive up to 7.4V by wiring the die's in parallel. I'm looking forward to that option.
Here are a few options:
1. A driver board is a good solution when we have more volts than the P7 is designed to handle.
2. Two P7's in series can sometimes be an option with 6V.
3. The upcoming Cree MC-E looks to be a perfect solution to direct drive up to 7.4V by wiring the die's in parallel. I'm looking forward to that option.
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Juggernaut
Flashlight Enthusiast
The cheapest I've ever seen rechargeable F cells was $100 for 4! Hey you can always use a rectangular alkaline battery, "can you say 53,000 mah:devil:" but seriously at such point I would just go for the time tested SLA batteries.
baterija
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That's what I was hoping/thinking it was. Heatsinking would be another issue - probably need to be extra generous with heat sink since the plastic body won't carry heat out well. Lots of space if you go with something else as a power source though.
lctorana
Flashlight Enthusiast
53,000 is for an alkaline 8F not a 4F lantern battery...Juggernaut said:
Now if we're talking SLA, then we are in Rechargeable Dolphin territory, so let me say three things:
1) Your typical spring-terminal SLA is rated between 4 and 5 Ah, so we are talking circa 2 hours' runtime, if we are using a buck driver. And preferably much, much less, discharge shallow and recharge often is the golden SLA rule.
2) At 4.8V, we can get double the runtime with 4 D cells, and triple with 4 F cells. Oh how I wish they were cheaper, too!
3) With 6V SLA, the Dolphin Rechargeable already pumps out 210 bulb lumens. The P7 is going to have to be driven quite hard, 2 amps or more, to beat that by a sufficiently wide margin to be worth all that trouble and expense.
That said, I'm planning to do the P7 Dolphin mod myself.
I'm curious to know what you had in mind for a heat sink, this is a project that I've thought of doing as well. Why use the standard battery? I think I would be using 4 D Nimh and one of KD's drivers. Should give you heaps of grunt in the battery department.
Norm
Juggernaut
Flashlight Enthusiast
That's why I said rectangular 6V "=8F"
, How does the stock dolphin make 210 lumens? The 6D Maglite with xenon bulb only makes 228 and it's 9 volts at .75 amps. The old Dolphins used Krypton bulbs at 6 volts they would have to pull at least 1.2 amps or something which is impossible, because their run time was so good:thinking:.
lctorana
Flashlight Enthusiast
An 8F will not fit in a Dolphin - it is WAY too big.
But - you' didn't actually say it had to fit in one, other posts around you did, so touché.
But if it does have to fit in one, 26Ah for an alkaline 4F 529 is not too shabby though. Or 24Ah for a Duracell MN908.
***
I didn't say stock Dolphin, but stock Dolphin Rechargeable. Very, very different animal. More of a killer whale, really.
For clarification, have a look at this thread, in particular posts #28 and 30:
http://www.candlepowerforums.com/vb/showthread.php?t=197923
But - you' didn't actually say it had to fit in one, other posts around you did, so touché.
But if it does have to fit in one, 26Ah for an alkaline 4F 529 is not too shabby though. Or 24Ah for a Duracell MN908.
***
I didn't say stock Dolphin, but stock Dolphin Rechargeable. Very, very different animal. More of a killer whale, really.
For clarification, have a look at this thread, in particular posts #28 and 30:
http://www.candlepowerforums.com/vb/showthread.php?t=197923
lucid
Newly Enlightened
Norm, I was thinking of using a large piece of 6 or 8mm aluminium plate and mounting everything on that. Might be able to bolt the whole assembly onto the plastic frame that you remove to get to the battery. I haven't tried this yet so I'm not sure how sturdy it would be - it's just the first idea that came to mind.
