Any electronics experts here? - DPChallenge Forums

06/09/2008 06:07:06 PM · #1

I want to know if this is possible and if so if it is safe.

I have a Nikon SB-800 flash unit, it takes 4-5 AA batteries, which would be 6-7.5v obviously.

It accepts rechargeable batteries which have a mAh of around 1500-2500.

My D300 uses EN-EL3e, which is a 7.6v 1500 mAh battery.

The SB-800 flash unit has a connection for an external power source, currently the only compatible battery seems to be a $600 Turbo Battery.

I would like to know if there is a safe method to use the D300 batteries to power the SB-800 flash. (I do have some electronics knowledge so I can build something if needed).

Thanks in advance!

06/09/2008 06:18:58 PM · #2

Possible? Maybe. You'd need to know more about the current draw of the flash and the capability of the battery to supply that current. My guess is that the draw of the flash is beyond the capacity of the camera battery, but I can't say for sure.

Safe? That depends on what you mean by "safe". I suppose the worst that could happen is the battery might get really really hot and explode. Might not be much fun with the camera to your eye.

Message edited by author 2008-06-09 18:22:31.

06/09/2008 06:24:58 PM · #3

Originally posted by Spazmo99:

Are you my first real fan? You seem to follow me around. ;)

Anyway safe would be, it does not burn out or damage the flash or battery within the first 3 years of use. i.e. as safe as an official product from Nikon.

06/09/2008 06:35:44 PM · #4

Oh you expanded your answer, thank you :)

Well I would have the flash off cam with the battery probably attached to the light stand, however I do suppose I might want to use it on cam also, so good note about it exploding like a cheap ipod...

I have some thinking to do, the main problem is, I want it to be use rechargeable batteries, save the money, save the fishies, get the girls, you know what I am talking about hehe. ;)

However to use rechargeable AAs the SB800 needs 5 of them, but chargers usually come in sizes of 4-8-16-32. So I would need at least an 8. I was hoping for a better solution to that.

06/09/2008 08:11:20 PM · #5

Originally posted by togtog:

Originally posted by Spazmo99:
Possible? Maybe. You'd need to know more about the current draw of the flash and the capability of the battery to supply that current. My guess is that the draw of the flash is beyond the capacity of the camera battery, but I can't say for sure.

Safe? That depends on what you mean by "safe".

Are you my first real fan? You seem to follow me around. ;)

Anyway safe would be, it does not burn out or damage the flash or battery within the first 3 years of use. i.e. as safe as an official product from Nikon.

You ask interesting questions.

Canon EF 17-40mm f/4.0L USM

06/09/2008 08:24:10 PM · #6

I suggest that you check this out: Black Box

Significantly cheaper than the $600 Turbo Battery and has a good rep.

LoudDog

Canon EOS-350D Rebel XT

06/09/2008 08:35:22 PM · #7

A little soldering and rigging and it's very possible. Although actual output on a AA is 1.2 volts so the 7.6 volts will be pretty high compared to the AAs.

Prof_Fate

06/09/2008 09:22:30 PM · #8

You can get 2500 Mah AA batts for $2 each, sometime less. So 5 is $10. I don't know the cost of the Nikon camera batt, but even generic canon batts are $20 or more.

You might consider other options - a holder and D (or C) rechargables, gel cel bats, etc. I agree that I don't understand why the aux/ext batt packs are so damned coslty.

Message edited by author 2008-06-09 21:22:59.

Canon RF 24-70mm f/2.8 L IS

06/10/2008 06:31:36 PM · #9

I think I have decided to go with that Black Box, looks perfect for my needs. Thanks for the suggestion and what you said Spazmo99 :)

The big thing is that cable he makes, with that it shouldn't be too hard to use larger batteries like Prof_Fate suggests.

One question though as far as batteries go, do I need to be concerned with anything except for their voltage? I.e. would 4 D's be as safe as the default 4 AA's?

Thanks again guys! :)

kirbic

Canon EOS R5

06/10/2008 08:37:10 PM · #10

Originally posted by togtog:

One question though as far as batteries go, do I need to be concerned with anything except for their voltage? I.e. would 4 D's be as safe as the default 4 AA's?

Thanks again guys! :)

Yes, definitely you'd be safe with 4 D's. You *could* even use multiples of 4, each set of 4 in parallel with the other sets.

kawesttex

Apple iPhone 11 Pro

Canon EF 17-40mm f/4.0L USM

06/10/2008 09:59:39 PM · #11

Originally posted by togtog:

As long as the voltage ratings are the same it won't be a problem. What some folks don't understand is the current. A battery may be rated at 2500 mAH, which can deliver over 1 amp for a short period, but the device will only draw the amount of current it needs (ie. 100 mA). EXAMPLE: A car requires a 12 volt battery, you can install 4 batteries in parallel and there would not be a problem (of course your alternator may complain and it would take longer to get to a full charge). The parallel circuit would provide enough current to turn your motor over for say 90 minutes vs. the 15 minutes one battery would.

Multiples (parallel circuits) of battery packs will give you greater endurance. Recharge as necessary!

Canon EF 17-40mm f/4.0L USM

06/10/2008 10:27:39 PM · #12

You guys are awesome, each and every one of you!!!

kawesttex

Apple iPhone 11 Pro

06/10/2008 10:36:07 PM · #13

I might add that the more current (parallel circuits) you add, the greater risk of a bigger fire if something shorts out! :-)

FireBird

06/10/2008 11:38:07 PM · #14

Another thought about using batteries with capacities higher than original Nikon design parameters is over use. Should you suddenly decide you're the god of flash lighting in your sector of the universe and fire off hundreds of almost full power shots with your new super powered SB800, you might find that you'll melt your flash. I'd spread those hundreds of shots over a fairly large time frame. Say 30 minutes to an hour. And this time would be directly proportional to ambient temperature. Flash carefully!

06/10/2008 11:41:02 PM · #15

Thank you fir3bird. Thanks to the Black Box I already knew about the risk of melting the flash but it is important enough to repeat often. :)

Would be nice if for $300 the thing had an optional temperature cutoff.