hello all, i have never used any of these little module's before and need some help.
I am an industrial electrician, but when it comes to these chips i don't have a complete understanding of how they work.
What i am looking for is a simple hydrogen sensor to turn on a fan to remove the hydrogen made from charging batteries before it reaches a level that could be dangerous.
I have 2, someday maybe 4, batteries in a plastic tote that are charged from solar panels. there are fans at the top of one of the sides that will be connected to a thermostat to cool the tote as needed. in parallel i want a hydrogen sensor to also be able to turn the fans on as needed.
what i need to know is will my idea work?
Using a MQ-8 hydrogen sensor, 5v relay, and a 12v to 5v dc-dc converter. I have made a cad drawing of how i would connect these items. i attached a cad image of how i would connect these below. Can someone tell me if this will work to turn the fans on until the hydrogen level drops?
The Hydrogen sensor is an analog device, so you will need to use an Analog input on your Arduino, run a sketch to track the signal voltage from the sensor (calibration, alarms, etc. Can be done here too) and then when the signal is higher than your preset, lower a digital output pin connected to a transistor/FET to activate the relay coil that will turn on the 12 V fans.
Here is a wiring diagram for the device:
Arduino stuff on this site in this location: playground.arduino.cc/Main/MQGasSensors
i dont want to get into an entire system. all i need is a sensor to turn on and off a relay. i wanted to use the DO because my understanding is that this is a discrete output that is turned on when at max level of 10000 PPM. this should be 5v.
my other option would be to connect it to the AO, when the sensor hits the max reading it should put out 5v turning on the relay. As the AO voltage drops the relay may stay on until the voltage drops to 3v-4v. that's normally how a relay operates.
i dont want to get into an entire system. all i need is a sensor to turn on and off a relay. i wanted to use the DO because my understanding is that this is a discrete output that is turned on when at max level of 10000 PPM. this should be 5v.
That was obvious to me from your circuit diagram; however this statement in the link referenced suggests the sensor output is a varying voltage proportional to the ppm detected.
Reads values from an air quality sensor connected to the analog input pin 0. The value read from the sensor is proportional to the air quality measured by the sensor. The value read is printed to the serial monitor
my other option would be to connect it to the AO, when the sensor hits the max reading it should put out 5v turning on the relay. As the AO voltage drops the relay may stay on until the voltage drops to 3v-4v. that's normally how a relay operates.
Yes, I have an opinion; that is, you can approach this issue multiple ways, from the use of a transistor/FET and a couple of resistors to using an opAmp to drive the relay.
Personally, when I charge lead-acid batteries, I always run a brushless fan to disperse and expelled H2. If you do not want a system, just ventilate all the time.
i thought about venting all the time, but that keeps a consistent draw on the batteries. the idea is to keep them full, so i wanted a sensor to work in parallel to a thermostat for those "as needed" times. i wish that i could just drill some holes in the top of the tote, but then if its out side and it rained i will end up with water on my controls.
if this setup will not work, do you have suggestions for another setup that will, on a shoestring budget?
[ but that keeps a consistent draw on the batteries.](http://but that keeps a consistent draw on the batteries.)
Solar power a small fan? I've seen Chinese units for positive automobile ventilation in that As Seen on TV section of stores for under $20... I suspect surplus parts would run half of that. It's not a 7x24 thing and only works when the sun shines, but maybe a thought.
i have been doing that. i installed 5 fans along the back of the tote. the middle fan is currently connected in parallel to my solar panels where they enter the charge controller. This way when there is enough voltage/amps to turn on the charge controller the fan should already be running, and stop when the v/a drop at night. i am using 12v 0.16a for the fan during the day. i don't know what the usage would be to operate a sensor system. the fan connected this way may be the best/cheapest/easiest way to vent gasses and lowest power draw, but when the batteries are full and not charging the fan will still be running unnecessarily. until i find a better way to control the fan this is what i will continue to use.
the other 4 fans are in parallel through a thermostat, as soon as the thermostat gets here.
i have my old solar power setup on instructables.com. i am working on the instructable for this new setup and will get it posted as soon as get it finished.
