Noob question, 12v fan on multiple 9v batt

djsfantasi

Joined Apr 11, 2010
7,640
I HAVE had a few concussions from things other people did. Some intentionally delivered and some accidentally happening. Mostly in situations where one would not normally be wearing any protection. And most of them when I was an adult, not a kid. There are some rather nasty folks around, and a few rather careless ones as well.
The perforated helmets for kids seem to have a fair amount of ventilation, but they don't do much to keep the sun off. So I am wondering what a two year old does that requires a helmet. All of the two year old kids that I know seem to be quite well supervised so that they do not get into situations needing a helmet.
Have you ever been responsible for a two year old? Sometimes it seems that they can do things while approaching the speed of light.

Take a sip of water and they can climb up on a table. During the time you are trying to get them down, they jump off the table, yelling “Batman” and land on their head! Or they are in a riding car, powered by their feet, get their feet caught beneath the seat and fall over, landing on their head.

A helmet wouldn’t help the first case, because the danger isn’t anticipated. But, I present it as an example of the challenges supervising a two year old. The second case is more obvious.
 
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Tonyr1084

Joined Sep 24, 2015
5,868
they can do things while approaching the speed of lights.
Grandson was sitting on the balancing ball. Mom watching closely. He got up on the arm of the couch and as mom was moving to usher him off the arm he flew off the arm, on to the ball and bounced into the air. The result was a broken arm. Speed of light is a good analogy. She couldn't have stopped him unless she was sitting on him. Kids happen in a flash.

When she (his mom, my daughter) was swimming at a hotel I was watching closely, standing near by. Turned to blow my nose and she was beneath the water. She didn't need resuscitation, but that's how fast kids happen. Kids are like shit. They happen.

A fan on a helmet? Haven't heard from the TS in a while. From fans to AC to swamp coolers, now to kids happen. Where will this thread go next?
 

Thread Starter

Dosmastr

Joined Jul 3, 2020
17
Grandson was sitting on the balancing ball. Mom watching closely. He got up on the arm of the couch and as mom was moving to usher him off the arm he flew off the arm, on to the ball and bounced into the air. The result was a broken arm. Speed of light is a good analogy. She couldn't have stopped him unless she was sitting on him. Kids happen in a flash.

When she (his mom, my daughter) was swimming at a hotel I was watching closely, standing near by. Turned to blow my nose and she was beneath the water. She didn't need resuscitation, but that's how fast kids happen. Kids are like shit. They happen.

A fan on a helmet? Haven't heard from the TS in a while. From fans to AC to swamp coolers, now to kids happen. Where will this thread go next?
Revision 2.0 the 850 mAh 9v lions run for 3 hours, discharging around .3c
Batts in series, fans In parallel. Seems to be working decently.

I figured I'd let y'all sort out that other product before jumping in heh
 

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ThePanMan

Joined Mar 13, 2020
62
Revision 2.0 the 850 mAh 9v lions run for 3 hours, discharging around .3c
Batts in series, fans In parallel. Seems to be working decently.
How much current does each fan draw? What's the total draw? You can have fans run for 10 hours if you draw a small enough amount of current. Three hours sounds good but how much air does it move? The bottom line is how much work is being done and how fast/slow?
 

Audioguru again

Joined Oct 21, 2019
3,007
You must add a second helmet to protect the Li-Ion batteries because they can explode or catch on fire if the batteries or the wiring is damaged. 9V Ni-MH rechargeable batteries are much safer but can become hot if damaged.
 

Thread Starter

Dosmastr

Joined Jul 3, 2020
17
How much current does each fan draw? What's the total draw? You can have fans run for 10 hours if you draw a small enough amount of current. Three hours sounds good but how much air does it move? The bottom line is how much work is being done and how fast/slow?
The airflow is decent but I wouldn't want less, burns about 250mA when fully charged.
 

Thread Starter

Dosmastr

Joined Jul 3, 2020
17
You must add a second helmet to protect the Li-Ion batteries because they can explode or catch on fire if the batteries or the wiring is damaged. 9V Ni-MH rechargeable batteries are much safer but can become hot if damaged.
True, though these have circuitry to protect them which I did test successfully.
Short, over discharge and overcharge. Rated to be fine at something nuts like 60 degrees C also.

When he gets on a pedal bike and can exceed a brisk walk I'll need to figure something out to keep the batts safe or replace with nimh

Might swap the fans to a 5v variety and use 4aa batts. Not sure yet
 
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