Checking and validating the circuit connections

Thread Starter

M3D0

Joined Oct 8, 2020
53
I just finished connecting this circuit together. I wanted to connect all the components (nodemcu, servo motor, and solenoid) parallel to the battery, the solenoid and the servo motor will be activated every 5 hours with half a second difference between the activation signal (this will be handled through the code). I connected a 14ohm resistor to the VIN pin to the nodemcu to lower the voltage from 12V to 5V, same for the servo motor as I connected 6ohm resistor to lower the voltage supplied to the servo motor from 12V to 6V.

I'm not sure about some stuff in this circuit :
1- The connection of the components being actually parallel or not, if not please show me the right connection
2-The value of the resistors I connected to each component, I ohms law to calculate the resistance needed.
3-The solenoid needs 2A to operate and I connected nodemcu parallel to it which needs (0.5A) to operate which will be operating all the time and a servo motor that needs a 1A to operate ( the servo motor will be operating at certain time as stated before). My question here does this connection will provide the solenoid the needed current?

Assume the components used are :
1. Battery Lithium-ion Super Rechargeable Battery Pack (12V, 3000mAh)
2. JF-0826B Push Action Type Electric Linear Solenoid 12Vdc,2A
3. Servo motor (6V,1A)
4. Micro-controller (5V,1A)

Note: the circuit is provided in the attachment to this post.
Thanks in advance!
 

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ElectricSpidey

Joined Dec 2, 2017
1,962
Using a series resistor to drop the voltage to a MCU is not a good idea, I don't know about the servo.

If the current in the MCU changes so will the voltage drop across the resistor.

I assume you are cutting the strip board below the resistors.
 

sghioto

Joined Dec 31, 2017
2,416
I see several issues.
1) Is that solar charger designed for lithium ion batteries?
2) As ElectricSpidey said above you can't use a simple resistor to drop the voltage you will need to use voltage regulators.
3) Where did you get that spec for the Nodemcu (5v .5A)?
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
Using a series resistor to drop the voltage to a MCU is not a good idea, I don't know about the servo.

If the current in the MCU changes so will the voltage drop across the resistor.
Is there any way to drop the voltage other than connecting a resistor in series with the MCU ?
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
What model Nodemcu are you using? Some have a voltage regulator on board.
well, I'm not sure of the model but it's the one with ESP8266 -12E WiFi chip on and I read its datasheet and I read that there is a voltage regulator as it takes 5V from the micro-USB or the VIN pin to lower the voltage down to 3.3v
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
The Vin pin is designed for a 7 to 12 volt input, no resistor or additional regulator needed.
So am I good to go with this connection (after removing the resistor off course)? If so did you notice any other issue with my connections?
 

sghioto

Joined Dec 31, 2017
2,416
Then it looks like all you need extra is a 6 volt regulator for the servo motor.
Something like this should work.
1602518007698.png
 
Last edited:

Audioguru again

Joined Oct 21, 2019
3,836
Your schematic shows a 3.7V Li-PO battery cell but you talk about a 12V battery. A 12V Lithium battery has 3 cells and has 4 wires so that it can be balance charged. Its fully charged voltage is 12.6V that is too high for the 12V control circuit.

The charger shows a car 12V lead-acid battery and only 2 wires for it.
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
Your schematic shows a 3.7V Li-PO battery cell but you talk about a 12V battery. A 12V Lithium battery has 3 cells and has 4 wires so that it can be balance charged. Its fully charged voltage is 12.6V that is too high for the 12V control circuit.
Is there any way to solve this issue?

The charger shows a car 12V lead-acid battery and only 2 wires for it.
can you please clarify what you mean by a "car" 12V?
 

Audioguru again

Joined Oct 21, 2019
3,836
Please post a link to the charge controller. It shows a huge lead-acid car battery not a little 12V 3 cells Lithium battery for models.
It looks like the charge controller will explode a lithium battery.

A voltage regulator IC can reduce the voltage to the control unit.
 

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Audioguru again

Joined Oct 21, 2019
3,836
I was right, the charge controller is for an old lead-acid car battery, not for a little lithium battery.
The lithium battery has no detailed spec's. Its sales sheet says it is 100% safe so it might have a protection and balancing circuit inside it. But the car battery charger will overcharge it since it does not detect a full charge then turn off.

The output of the charger says 10A. The little Lithium battery maximum allowed charging current is maybe 1.5A or 3A.
The maximum voltage from the charger is 13.7V but the maximum allowed voltage for a 3 cells Lithium battery is 12.6V.
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
I was right, the charge controller is for an old lead-acid car battery, not for a little lithium battery.
Can you please send a link for the information you got, because I read the datasheet and I didn't find that it specified any type of battery. Can you suggest another charger controller or a battery that is lightweight that cold go along this circuit?
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
I was right, the charge controller is for an old lead-acid car battery, not for a little lithium battery.
The lithium battery has no detailed spec's. Its sales sheet says it is 100% safe so it might have a protection and balancing circuit inside it. But the car battery charger will overcharge it since it does not detect a full charge then turn off.
I just looked again for the charger I bought, and It stated in its description that it could charge both lead and lithium batteries, I will leave a screenshot for the description.
 

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Audioguru again

Joined Oct 21, 2019
3,836
Now you show a completely different charge controller that says 20A! It also has no detailed spec's.
Some huge car batteries are charged with 20A that might set the protection circuit in your little battery on fire.
 

Thread Starter

M3D0

Joined Oct 8, 2020
53
Now you show a completely different charge controller that says 20A! It also has no detailed spec's.
Some huge car batteries are charged with 20A that might set the protection circuit in your little battery on fire.
I just noticed that there are multiple charge controller with the same model number somehow, I will keep searching for a suitable charger
 
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