Hello. Sorry in advance for my lack of knowledge on the subject as I am new to using batteries in my projects. I need to be able to individually control 5 solenoids with a battery. I currently am using a single 9v battery that is spit between my Arduino's VIN pin and the transistors for each solenoid. I do not think this is a good solution as the solenoids are very weak when they are all powered but too strong when a single one or two is powered. How can I fix this problem? And what battery and wiring should I be using?
It depends on your solenoids - please provide a link so we can see the voltage and current requirements.
Typically a 9v PP3 battery will not supply high currents for very long.
I do not think this is a good solution as the solenoids are very weak when they are all powered but too strong when a single one or two is powered.
do not think this is a good solution as the solenoids are very weak when they are all powered but too strong when a single one or two is powered. How can I fix this problem?
By reducing the voltage.
If it is too strong with only one powered the voltage is too high, so reduce that so the strength is what you want.
Now you have the voltage right, it will be right when one is powered.
If it remains the case that it is still too weak when all are powered you need a battery that is capable of supplying more current.
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom... 
Is not a real battery!
I beg to differ. I use 9V PP3 smoke alarm batteries for many arduino circuits because UNLESS you are trying to power an INDUCTIVE device like a solenoid or large motor, it is fine. I recently used it to power a small 1.5V dc motor powered by an L293 to verify an OP's circuit. He said it didn't work. I found an L293
IC in my parts bins , wired it up and it ran just fine using the 9V battery to power the motor power pin of
the L293. Also, most of the arduino circuits I build do not need to run more that 30 minutes as that is all
it takes to verify the circuit. An arduino UNO draws about 55mA max and a smoke alarm battery is rated
for a minimum of 300mAh so regardless of where you got the battery or what type, you can almost certainly get at least 5 hours of operation for an arduino circuit, especially if it just involves sensors and
a few leds. Yes, they're useless for most motor/solenoid applications but using one of
Item-1
these with one of
Item-2
these
and one of
Item-3
Item-4
this with 22 AWG solid hookup wire soldered to the leads.
That may be but this is a question about multiple solenoids, for which a PP3-sized 9V alkaline battery
is assuredly a poor choice. And this is about current draw, nothing to do with inductance per se.
NiMH rechargable 9V batteries can provide a lot more current typically, but without knowing
more about the solenoids there's no decision that can be made.
It does sound like 9V is too much, and that the current requirement for all 5 is well beyond
a typical 9V.
Agreed.
9V battery is absolutely NOT relevant to this post. (I only brought it up because Paul_B said they were
useless. )
Apparently the Arduino forum agrees with me... (see below)
raschemmel:
Apparently the Arduino forum agrees with me... (see below)
I must agree, for that specific circuit as illustrated, a 9 V "PP3" battery is OK. 
I must agree, for that specific circuit as illustrated, a 9 V "PP3" battery is OK.
It only took 7 years to get Paul to agree with me...
And you clearly have a cupboard full of alkaline PP3 batteries.
The specifications for my solenoids are below.
3V at 0.70A
5V at 1.12A
6V at 1.35A
Resistance: 3.5 ohms
-
If I use a lower voltage, are there batteries that alone can supply the current, or should I wire multiple in parallel?
-
And if I use a lower voltage how can I continue to power the Arduino if the minimum current for VIN is 6V?
samlbaker:
The specifications for my solenoids are below.3V at 0.70A
5V at 1.12A
6V at 1.35A
Resistance: 3.5 ohms
DC 3V 5V 6V Push Pull Through Type Micro Mini Solenoid Electromagnet Stroke 3mm | eBay
If I use a lower voltage, are there batteries that alone can supply the current, or should I wire multiple in parallel?
And if I use a lower voltage how can I continue to power the Arduino if the minimum current for VIN is 6V?
You are misinterpreting the EBAY listing. Your solenoid will operate with any one of the voltages you listed. The difference is: what pull does the solenoid need to supply and more important, how long does it need to supply that pull?
IF you need more pull than the 3 volts delivers, then you need to power the solenoid with 5 volts or even 6 volts.
If you need the solenoid to pull for a long time, it will likely get warm and you battery will also be discharged.
So, what is the application you are working on?
Finally, power your Arduino from a separate supply.
Paul
PS, the spring return on the solenoid shows it is not a "push-pull" type, but a "pull only" solenoid.
The specifications for my solenoids are below.
3V at 0.70A
5V at 1.12A
6V at 1.35A
Resistance: 3.5 ohms[DC 3V 5V 6V Push Pull Through Type Micro Mini Solenoid Electromagnet Stroke 3mm | eBay](http://VENDOR LINK_EBAY)
I didn't see ANY specifications at that link. Take a screenshot of the specifications and post it.
raschemmel:
I didn't see ANY specifications at that link. Take a screenshot of the specifications and post it.
Don't need to!
Scroll down the page a little, then pull down the slider you see.
You evidently don't use eBay much. 
Paul_KD7HB:
You are misinterpreting the EBAY listing. Your solenoid will operate with any one of the voltages you listed. The difference is: what pull does the solenoid need to supply and more important, how long does it need to supply that pull?IF you need more pull than the 3 volts delivers, then you need to power the solenoid with 5 volts or even 6 volts.
If you need the solenoid to pull for a long time, it will likely get warm and you battery will also be discharged.
So, what is the application you are working on?
Finally, power your Arduino from a separate supply.
Paul
PS, the spring return on the solenoid shows it is not a "push-pull" type, but a "pull only" solenoid.
I am using the other side of the solenoid (side without the spring) for push functionality rather than pull.
I do not need very much strength as I am using them for a ratchet mechanism and they just need to reach the 3mm length in order to push in a very weak pawl.
Time is much more important for my application as they may need to stay powered up to a minute.
So would you recommend I use 3V?
Sam
Scroll down the page a little, then pull down the slider you se
What slider ? I don't see any slider.
Can you just pull down the slider and take a screenshot of the specs ?
You just have to scroll to the bottom of the page.
That is simply a representation of the relationship of current to voltage.
There is only ONE spec: coil: 3.5 ohms
The voltage is just a rating (3 to 6V). Technically it is a spec but the critical item is the coil resistance.
Plot on the left shows the resistance is a flat line
Plot on the right shows the power dissipation in Watts is a function of voltage. (and it is almost linear)
What this means is that the 'SPEC' (SINGULAR) for your solenoid is 3.5 ohms @ 3 to 6V.
The reason it is singular is that the current at the higher voltage is no different than the current at the
lower voltage
Note that resistance is a function of temperature and temperature is a function of current.
Also note that the resistance calculated using voltage and current only varies by 5%
4.286 ohms
4.464 ohms
4.444 ohms
raschemmel:
What slider ? I don't see any slider.
Can you just pull down the slider and take a screenshot of the specs ?
Oh really!
Here is the frame with the slider!