"Help!" for: Electronics
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no it wasnt
thatdecade
Well-Known Member
Yeah, 2 x 12v fans on a 24V AA battery pack. Don't do that. You exceeded the max current the AA batteries are capable of. With 2 fans pulling 500mA each, you were pushing 1 Amp through each of the little AA.
The correct way to wire it is use the same number of batteries, but in parrellel at 12V. That will double the current your battery pack can provide. The fans would still be pulling 1 amp, but divided into two, half to each parrellel battery pack.
Did I mention I don't like 12V pc fans?
/making up numbers
http://data.energizer.com/PDFs/E91.pdf 1 amp max discharge (hot and kaboom), 300mA - 500mA above ideal (warm to the touch), 25mA - 250mA ideal (cool to the touch)
Generic pc fan specification sheet
http://www.ustoyofan.com/media/documents/USTF12038DC.pdf
The correct way to wire it is use the same number of batteries, but in parrellel at 12V. That will double the current your battery pack can provide. The fans would still be pulling 1 amp, but divided into two, half to each parrellel battery pack.
Did I mention I don't like 12V pc fans?
/making up numbers
http://data.energizer.com/PDFs/E91.pdf 1 amp max discharge (hot and kaboom), 300mA - 500mA above ideal (warm to the touch), 25mA - 250mA ideal (cool to the touch)
Generic pc fan specification sheet
http://www.ustoyofan.com/media/documents/USTF12038DC.pdf
thatdecade
Well-Known Member
This is the fan I recommend using. It's the same one I use to make kits for people.
http://www.digikey.com/product-detail/en/MB40100V2-000U-A99/259-1565-ND/2757776
Really, those 12V fans are making things way too complicated. Never meant to be run on alkaline battery packs.
Untitled by thatdecade, on Flickr
Untitled by thatdecade, on Flickr
http://www.digikey.com/product-detail/en/MB40100V2-000U-A99/259-1565-ND/2757776
Really, those 12V fans are making things way too complicated. Never meant to be run on alkaline battery packs.
Untitled by thatdecade, on Flickr
Untitled by thatdecade, on Flickr
He did have them wired in parallel.
thatdecade:
Clovis was running the battery packs in parallel, making a single 12V supply from 2 12V cells. The 2 fans were also in parallel, resulting in a load of ~16 ohms. This results in a total draw of 0.76 amps, which is 0.38 amps from each of the 12V cells. It also results in each fan getting 0.38 amps and using 4.56 Watts. Which is exactly what they were rated to do.
The smaller 5V fans work in a similar fashion to the larger 12V fans, except they move less air, and consume less power. It's more a matter of personal preference. If you want less air being moved, and likewise, less battery power being used, then you use the 5V fans. If you want more airflow, you use 12V fans.
I've ran all the numbers 3 times to make sure I'm not making a silly mistake. There is no reason that any battery should have exploded. The maximum current draw from any single battery was 0.38 amps.
Here's some data sheets from Energizer on their AA batteries:
http://data.energizer.com/PDFs/E91.pdf <- Regular "Energizer Max" cheap battery. Can run at a constant 500 mA (0.5 amps) discharge for 3 hours before dropping below nominal voltage. Maximum current draw = 10 amps.
http://data.energizer.com/PDFs/nh15-2300.pdf <- Rechargable "Energizer Recharge" NiMH (Nickel-Metal Hydride) battery. Can run at 460 mA for over 4 hours before dropping below nominal. Can also run up to 4600 mA (4.6 amps) discharge and last for like 10 minutes.
I can't see any possible way that the circuit that was described could cause a battery to explode. You can wrap a commercial battery in tinfoil and toss it out onto the pavement and it would leak a little bit. Commercial batteries have so many safety features built into them to prevent them from exploding. It boggles my mind. I wish Clovis was nearby so that I could go over and do some experiments to figure out what is going on.
Clovis was running the battery packs in parallel, making a single 12V supply from 2 12V cells. The 2 fans were also in parallel, resulting in a load of ~16 ohms. This results in a total draw of 0.76 amps, which is 0.38 amps from each of the 12V cells. It also results in each fan getting 0.38 amps and using 4.56 Watts. Which is exactly what they were rated to do.
The smaller 5V fans work in a similar fashion to the larger 12V fans, except they move less air, and consume less power. It's more a matter of personal preference. If you want less air being moved, and likewise, less battery power being used, then you use the 5V fans. If you want more airflow, you use 12V fans.
I've ran all the numbers 3 times to make sure I'm not making a silly mistake. There is no reason that any battery should have exploded. The maximum current draw from any single battery was 0.38 amps.
Here's some data sheets from Energizer on their AA batteries:
http://data.energizer.com/PDFs/E91.pdf <- Regular "Energizer Max" cheap battery. Can run at a constant 500 mA (0.5 amps) discharge for 3 hours before dropping below nominal voltage. Maximum current draw = 10 amps.
http://data.energizer.com/PDFs/nh15-2300.pdf <- Rechargable "Energizer Recharge" NiMH (Nickel-Metal Hydride) battery. Can run at 460 mA for over 4 hours before dropping below nominal. Can also run up to 4600 mA (4.6 amps) discharge and last for like 10 minutes.
I can't see any possible way that the circuit that was described could cause a battery to explode. You can wrap a commercial battery in tinfoil and toss it out onto the pavement and it would leak a little bit. Commercial batteries have so many safety features built into them to prevent them from exploding. It boggles my mind. I wish Clovis was nearby so that I could go over and do some experiments to figure out what is going on.
thatdecade
Well-Known Member
I agree with your math rabbit. I've seen alkalines leak, burst, but never never explode flinging acid / casing material on people nearby.
Was a non-alkaline battery used? Something with a liquid core instead of the alkaline's paste.
Edit: yep, agree on the preference. For fans blowing on your face and visor, a lower speed is more comfortable for your eyes. For chest pieces or body fans, want those running fast and hard. Doesn't make armor outside in the sun comfortable, but it is bearable.
Was a non-alkaline battery used? Something with a liquid core instead of the alkaline's paste.
Edit: yep, agree on the preference. For fans blowing on your face and visor, a lower speed is more comfortable for your eyes. For chest pieces or body fans, want those running fast and hard. Doesn't make armor outside in the sun comfortable, but it is bearable.
No it was a alkaline battery...black pasty stuff. I wish I had my glasses on rather then my contacts cuz it was the most painful thing I've experienced. I'm just lucky to still have vision in that eye.
I wish you were nearby too because driving to the hospital by myself wasn't fun
EDIT:
ok im getting really pissed off! it happened yet again only as you can see it was both batteries at the same time...and i **** you not the same time and multiple batteries my clothes and apartment are covered in acid!! what the hell am I doing wrong!
Edit 2.0 thanks to thatdecade i just ordered 4 of those 5v fans....how much oomph do they push out?
I wish you were nearby too because driving to the hospital by myself wasn't fun
EDIT:
ok im getting really pissed off! it happened yet again only as you can see it was both batteries at the same time...and i **** you not the same time and multiple batteries my clothes and apartment are covered in acid!! what the hell am I doing wrong!
Edit 2.0 thanks to thatdecade i just ordered 4 of those 5v fans....how much oomph do they push out?
thatdecade
Well-Known Member
Spec sheet says 7 cfm (cubic feet per minute), feels like a light breeze to me. Gerenerally used as helmet exhaust and visor defogger.
My only thoughts is that something is very wrong. Do you have a multimeter? Put it in Amp mode and connect it in series with the batteries. What number reading do you get, is it similar to the 760mA number that rabbit said?
http://www.allaboutcircuits.com/vol_6/chpt_2/4.html
Draw a picture where your wires go.
My only thoughts is that something is very wrong. Do you have a multimeter? Put it in Amp mode and connect it in series with the batteries. What number reading do you get, is it similar to the 760mA number that rabbit said?
http://www.allaboutcircuits.com/vol_6/chpt_2/4.html
Draw a picture where your wires go.
thatdecade
Well-Known Member
Sounds like damning evidence to me, you have a short.
thatdecade
Well-Known Member
Really? lol, I imagine they are compared to full 12V fans. The cfm is ~1/10th as much (wind power) looking at the spec sheets.
5V 7.0 CFM http://www.digikey.com/product-detail/en/MB40100V2-000U-A99/259-1565-ND/2757776
12V 85 CFM http://www.ustoyofan.com/media/documents/USTF12038DC.pdf
CFM = Cubic Feet Per Minute
May or may not see those numbers in practice, those are low pressure numbers, does your torso have lots of openings for the airflow to exhaust / escape?
5V 7.0 CFM http://www.digikey.com/product-detail/en/MB40100V2-000U-A99/259-1565-ND/2757776
12V 85 CFM http://www.ustoyofan.com/media/documents/USTF12038DC.pdf
CFM = Cubic Feet Per Minute
May or may not see those numbers in practice, those are low pressure numbers, does your torso have lots of openings for the airflow to exhaust / escape?
thatdecade
Well-Known Member
I run them on 3 AA, but the fan probably will be ok with 4 AA. 6V instead of the rated 5V.
CrazedOne1988
Active Member
- Member DIN
- S088
So I have a soundboard for my assault rifle build, does anybody know where I can get some high quality sound effects for the Reach variant? (firing and reloading)
thatdecade
Well-Known Member
Can try here
http://soundfxcenter.com/download-sound/halo-3-assault-rifle-long-burst-sound-effect/
What I do is find a video clip I like on youtube then use a youtube to mp3 converter website to get the audio on your pc.
http://www.youtube.com/user/HaloSoundChannel/videos
https://www.google.com/search?q=youtube+to+mp3
http://soundfxcenter.com/download-sound/halo-3-assault-rifle-long-burst-sound-effect/
What I do is find a video clip I like on youtube then use a youtube to mp3 converter website to get the audio on your pc.
http://www.youtube.com/user/HaloSoundChannel/videos
https://www.google.com/search?q=youtube+to+mp3
Revenant1988
Active Member
Hey guys,
I just got some new fans to play around with for my next suit, and was wondering if anyone here has a preferred 12v battery you like to use. I just hooked up a 9v to get an idea of what it sounded like (they are supposed to be near silent at the right voltage) and I'm pretty happy with them but I can't run them at 9v as it's not generating enough air movement.
I thought about running out to get a small 12v battery but I don't think they would last long.
Here's a link to the same kind of fans I bought
http://www.amazon.com/Scythe-Mini-U...F8&qid=1344966093&sr=8-10&keywords=scythe+fan
What do you guys like to use for 12v supplies? Thanks!
I just got some new fans to play around with for my next suit, and was wondering if anyone here has a preferred 12v battery you like to use. I just hooked up a 9v to get an idea of what it sounded like (they are supposed to be near silent at the right voltage) and I'm pretty happy with them but I can't run them at 9v as it's not generating enough air movement.
I thought about running out to get a small 12v battery but I don't think they would last long.
Here's a link to the same kind of fans I bought
http://www.amazon.com/Scythe-Mini-U...F8&qid=1344966093&sr=8-10&keywords=scythe+fan
What do you guys like to use for 12v supplies? Thanks!
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