Powering circuit & Recharging Battery Pack

Thread Starter

djsfantasi

Joined Apr 11, 2010
6,174
I apologize in advance. I know this but keep getting confused.

I have a 5000mAH NiMH C cell battery pack. With it I’m powering an Arduino, Amplifier shield and a servo shield. There are a couple of LEDs and four servos. I purchased a charger with the battery pack.

I suspect most of that detail is irrelevant.

Do I need to diode isolate the charger? Or can I charge while everything else is connected?

I could wire the power switch so that the charger is disconnected while the remaining circuitry is connected.

?

I’ve confused myself and clarification is welcome. Op
 

KeithWalker

Joined Jul 10, 2017
675
I apologize in advance. I know this but keep getting confused.

I have a 5000mAH NiMH C cell battery pack. With it I’m powering an Arduino, Amplifier shield and a servo shield. There are a couple of LEDs and four servos. I purchased a charger with the battery pack.

I suspect most of that detail is irrelevant.

Do I need to diode isolate the charger? Or can I charge while everything else is connected?

I could wire the power switch so that the charger is disconnected while the remaining circuitry is connected.

?

I’ve confused myself and clarification is welcome. Op
How many cells are in your battery pack and how is the battery connected to the Arduino and servos? A simple circuit diagram would help us to answer your question.
 

crutschow

Joined Mar 14, 2008
24,370
I would think you could charge when the circuit is operating, as long as the higher charge voltage (up to about 1.6V/cell) is not a problem.
 

Thread Starter

djsfantasi

Joined Apr 11, 2010
6,174
@KeithWslker

It’s a five cell battery. As far as I’m concerned since I have a matching battery pack and charger, that’s not an issue. The Arduino and Servos are powered in parallel from the 6VDC supply.

@crutschow
The charging voltage might be a problem. The servos are rated at 6V and with your estimate of the charge voltage (1.6V per cell), there’d be 8V in the circuit. The Arduino and shields are good. The servos are questionable.

With crutschow’s information, I plan on using a SPDT or DPDT switch to connect the battery pack to either the charger or the system.

BTW, I’m building an animatronic T-Rex for my 2 yr old Grandson. The Easter egg is that randomly when he roars, instead he says “Papa loves Coley”.
 

KeithWalker

Joined Jul 10, 2017
675
@KeithWslker

It’s a five cell battery. As far as I’m concerned since I have a matching battery pack and charger, that’s not an issue. The Arduino and Servos are powered in parallel from the 6VDC supply.

@crutschow
The charging voltage might be a problem. The servos are rated at 6V and with your estimate of the charge voltage (1.6V per cell), there’d be 8V in the circuit. The Arduino and shields are good. The servos are questionable.

With crutschow’s information, I plan on using a SPDT or DPDT switch to connect the battery pack to either the charger or the system.

BTW, I’m building an animatronic T-Rex for my 2 yr old Grandson. The Easter egg is that randomly when he roars, instead he says “Papa loves Coley”.
Your servos will not last too long if you run them at 8 volts. I recommend that you use a LM7805 regulator between the battery and the servos (and audio amplifier if you are using one). The LEDs can be powered from the Arduino 5 volt output.
With that arrangement, you can charge the battery while the T-Rex is running.
 

Thread Starter

djsfantasi

Joined Apr 11, 2010
6,174
Your servos will not last too long if you run them at 8 volts. I recommend that you use a LM7805 regulator between the battery and the servos (and audio amplifier if you are using one). The LEDs can be powered from the Arduino 5 volt output.
With that arrangement, you can charge the battery while the T-Rex is running.
I’m sure you missed the point. The servos will run at 6VDC. There’s only 8VDC present when charging. By using a SPDT or DPDT switch, the 8VDC will not be present on the servos.
 

crutschow

Joined Mar 14, 2008
24,370
I’m sure you missed the point. The servos will run at 6VDC. There’s only 8VDC present when charging. By using a SPDT or DPDT switch, the 8VDC will not be present on the servos.
Okay.
But if you used a low-drop 6V regulator for the servos, than you wouldn't need the switch.
Take you pick. ;)
 

Zoe123

Joined May 20, 2019
5
You can power the microcontroller while charging. Moreover, the charger does not need to be diode-added because there is no reverse charging phenomenon.
 

Yaakov

Joined Jan 27, 2019
1,612

Thread Starter

djsfantasi

Joined Apr 11, 2010
6,174
@djsfantasi you could use a switching power jack like this one so that simply plugging it in to charge would disconnect the power from the device.

https://www.amazon.com/uxcell-5-5mmx2-1mm-Socket-Mounting-Connector/dp/B01ERPCV1Y/

If you wanted to power it while charging, something like this might work, and could be switched inline by the jack.

https://www.ebay.com/itm/30W-DC-4A-Buck-Boost-Converter-Voltage-Auto-Step-Up-Down-Regulator-5V-6V-12V-24V/192248525820
Great idea! I didn’t think of it because the battery pack and charger came with Tamiys connectors.

As to your second suggestion, I really don’t see using it while charging. His parents might like the respite!
 

Yaakov

Joined Jan 27, 2019
1,612
I do like things that “just do the right thing” and switching connectors makes that easy. No one will make the mistake of plugging it in and not switching to charge.
 
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