Power supply options for Ultimate 2.0?

[andye]

I’m looking for a way to use rechargeable batteries and have some specification questions:

1. Are the spec for the power supply the same as for arduino?
   “9 to 12V DC, 250mA or more, 2.1mm plug, centre pin positive”

2. It says 6-12 volt but i’ve noticed that you need at least 8V for anything to work
   What can you do with 6-8V?

3. The “MegaPi Encoder/DC Motor Driver” says “6 V to 12 V” so no more limits here, right?

4. What about the three “25mm DC Encoder Motor” from the Ultimate 2.0?
   In the spec it says 9V, is there any lowest/highest?
   Does the power supply “fall through” the motor driver and goes directly to the motors?
   Does this imply that the voltage span for Ultimate2.0 robots is a small span around 9V?

[tech_support]

Hi Andye,

The input power for the MegaPi is 6-12V, normally we use 7.4v rechargeable lithium battery for test and there is no issue to drive the Ultimate 2.0, we’d suggest that you buy high quality batteries.

The spec for “MegaPi Encoder/DC Motor Driver” is 6V~12V, there is no special limits, so the encoder motors which have rated voltage range from 6V~12V can work with this driver.

The spec for 25mm DC Encoder Motor of Ultimate 2.0 is 9V, the actual power it can get from the driver affects the motor’s speed.
As for the deep power supply principle between the electric circuit, we may don’t have enough ability to explain, you need refer the schematics of the boards.

[andye]

Thank for a fast and explicit answer (and thanks for great products )

Would you say that one should look at 9V as a max voltage for the 25mm motors?
No matter the complex issues related to motors and power supply,
if I measure the output from the motor driver to be max 9V with the motor disconnected I should be safe enough, right?

I’ll buy a 7.4V Li-ion or Li-Po then and try out. What are you using? Li-ion or Li-Po?

And just to have it written out and something to be used for double check before power on:
Is the barrel connector centre pin positive or negative?

[tech_support]

Hi Andye,

9V is the rated rated voltage for the 25mm motors. But if you use batteries with power from 9v~12v, it won’t hurt the motors since the driver will still output appropriate voltage the motor needs.

9V voltage shouldn’t harm the human body though you may have a feeling,haha

We use the following kind rechargeable battery which was bought from manufacturer in China, you may buy a similar one.

As for your last question, normally the center pin in the barrel connector is positive, not sure if it is industry standard worldwide. Anyway, you can test it.

[andye]

Thanx! Now I have all the information I need for now

[Humots]

I am also interested in a rechargeable battery for Ultimate 2.0.

I have found several 7.4 V 18650 batteries on Amazon, but I don’t know if they have the proper connector. Is there a specification (i. e. barrel connector) to look for?

Also, would a separate charger be required?

Thanks.

[tech_support]

Hi Humots,

Some batteries don’t have barrel connector, in this case, you can put them into the AA battery holder coming from the Ultimate 2.0 package.
If you buy the battery with barrel connector, I think the connector type should be DC 5.5*2.1.
The Megapi board can’t charge your battery, so I think you need a separate charger.

[KCOS_STEM]

We have six Ultimate 2.0 and quickly decided to go to rechargeable. We are now using 8.4 V, 2200 MAh, 4+3 AA Cells, NiMH with a JR Connector. We had to rig up some leads to go from JR to DC plug but that was simple. The robots run for hours without any issues. Considered NiMH a safer option than LiPO for student use. We also spent up on a high quality charger. Used for STEM based problem solving scenarios ages 10 up to 16.Battery pack easily attached to position of AA holder with twist ties.

[bombicri]

Hi there,
I just bought Ultimate 2.
I want to have a powerful battery and I want to order a battery from 6 Li-Ion cells. Every 2 cells will be connected in parallel and then the 3 groups of two cells will be connected in series. That means that I shall got maximum 12,6V DC, 4000 mAh (one cell has 2000 mAh) when the batteries are full charged. Is there any problem with 12,6V? Can I order this package?
Thanks.

[KCOS_STEM]

Using these with Ultimate.
You just need to rig up a connector.

Rechargeable NiMH Battery Pack: 7.2 V, 2200 mAh, 3x2 AA Cells, JR Connector

[bombicri]

Thank you Kcos-Stem.
The battery pack you suggested me deliver only 7,2 V DC as every cell deliver 1,2 V.
My question was if the battery pack I want to make, which is delivering 12,6 V when is fully charged can harm electronics of motors. So I am comming again with the question if 12,6V DC is acceptable for Makeblock Ultimate 2.
Thanks.

[tech_support]

Hi bombicri,

I’d suggest that don’t use the battery which can deliver power more than 12V since it may burn the electronics.
Please use the battery which provide power not larger than 12v, usually, we use 7.4v rechargeable battery or 6 AA battery (1.5V for each) with good quality. If Kcos-Stem has tested the 7.2V rechargeable battery, then the 7.2V should be able to drive the Ultimate robot too.

[bombicri]

Thank you tec_support. I shall follow your advise. But 7.2V is really enough for powering the robot? I am thinking that 7.2V will be just for short time, when the battery will be discharged 10% the tension will fall.
I shall come back with final decision.

[tech_support]

Hi bombicri,

I haven’t tried the 7.2v battery, but I use the 7.4V, so I can tell the 7.4v is okay!
As for how long time the battery can last, normally,it depends on the capacity of the battery. If you worry about that 7.2v may not be able to drive, you can choose the battery with power from 7.4v to 12v.

[rojoamigo]

Also looking at rechargeable for ultimate 2,0
Would this work?
https://www.robotshop.com/ca/en/74v-2000mah-5c-lipo-battery.html
Is it the correct barrel connector?

[tech_support]

Hi rojoamigo,
The power specific is okay for the MegaPi, but looks like it has different kinds of connector types. You can tell the customer support that you need the battery with connector type as DC 5.5*2.1 and the center pin in the barrel connector is positive.

[rojoamigo]

Then this one would be better?
https://www.robotshop.com/ca/en/dfrobot-74v-lipo-2500mah-battery-arduino-power-jack.html

• Arduino Compatible DC2.1 Power Jack
• Great way to power any R/C, robotic, or portable project
• 7.4V 2-cell pack
• Excellent choice for anything that requires a small battery with a lot of punch

[tech_support]

It looks okay, you can try it.

[rojoamigo]

I now use two different power supplies for my ultimate.

When I am doing bench work, I use a 30w AC/DC wall plug in adapter which has settings for 6/7.5/9/12V and has a 5.5mm x2.1mm plug.

In freedom mode, I have a 8 AA battery holder with 2600mAh rechargeable AA 1.2V batteries to gives me 9.6V

Lots of power and all within the megaPi specs.

[system]