Mtr(mechanical Tracked Robot)

CardboardHacker

Canada
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robot video thumbnail

Hey guys!

Here's The first version of MTR. As I mention in the video, more improvements to come.



Tech.

By — Last update
#1  
Just discovered that even with 2 batteries, there's still a huge voltage drop. Is this safe? I'm using 2 9.6V Ni-mh 1000mAH batteries. Should I change to another battery type? What type?
PRO
USA
#2  
Technopro,
I usually run Ni-Cd 2000 on Captain Ann, but when I run NI-MH 2800 I realize less servo chattering.
My Mini 6 ran better with Turnigy 1700 LiPo than the others.
Had no problem with duration on any of the options.
Steve S
#3  
You need to find out how much current your motors are using. A bench power supply with both voltage and amp displays could help in this case. Or possibly a digital voltmeter with at east a 10 amp rating for reading dc current.
#4  
Ok And I would put the amp meter before the main circuit right?(before devices tie into power)
#5  
That would be good. You want the meter in series with the battery and motor.
#6  
Hello,

I'm not sure that I fully understand the issues so take my comments with a grain of salt. The battery looks suspiciously like one that comes with a toy truck. I believe Ni-Cd and NIMH batteries don't hold a candle to Lipo's. Lipo power is smoother across the charge and you can find very high mAH ratings in fairly small packages. Here is a review of a range of 5800 mAH 2s (7.4v) batteries. http://www.bigsquidrc.com/lipo-battery-shootout-4-2s-5800-mah-edition/

My EZ-B runs well on a very small 1600 mAH 2S battery.

A 3S Lipo produces 11.1 volts which may be too much for the EZ-B, but may work for your motors.

With the space you have you could even fit several Lipo batteries in there with no problem.

You would need a charger capable of Lipo batteries. Also you need to be careful to not discharge them completely. The EZ-B has a built in protection for this, cutting off at less than 6 volts which is good for a 2S battery. For the motor circuit there are Lipo cut-off modules available that will plug into an ESC (Electronic Speed Control) to protect against too much discharge. More expensive ESCs have these built in. I am assuming there is some sort of ESC in your tank.

On the other hand, maybe you are running the motors through the EZ-B? If so you already have low voltage protection for 2S batteries.

Well, I am not sure how helpful this is for you project. I do know it took me a while to switch from NIMH to Lipo for R/C and for me it was a smart switch.
#7  
Here:

Max Amp 1.1 used by bot

For battery:
Voltage should be at around 7V for the motors(I can smell them working hard)
Needs to have a higher capacity
Needs to be very small(Current batteries 5-1/2 by 10 by 1-1/2cm)

Thanks.
#8  
The goal that Technopro seeks is to determine the power (amps) that will be consumed when running the stock motors in the tank. Once the power needs are identified then the battery size, chemistry, and capacity can be determined for an easy solution.
#9  
I use a 2.5A motor controller. No fancy ESCs in there. Looking at my research I believe LiPos will probably be the best, but I need one that fits the limited space I have, cause once that cover goes on there's hardly any room left.
#10  
This is what I use to power the EZ-B in my rover. I also use the same size lipo to power the motor and steering for the rover. Seems to work well for both.

It is about 3.8 X 6.4 X 1.59 cm


User-inserted image



This one may be too big. It is a hard case Lipo that has a lot more capacity.

Dimensions about 13.3 X 4.1 X 2 cm.


User-inserted image
#11  
If you can help me find the charger for cheap the 1600MAH's will be the batteries! The hard case is too big.
#12  
This is what I have and it works great, but at $90 may not be what you consider cheap.

http://www.ebay.com/itm/Duratrax-Onyx-235-AC-DC-Balancing-Charger-LiPo-LiFe-NiMH-NiCd-Brand-New-DTXP4235-/181616596593?pt=Radio_Control_Parts_Accessories&hash=item2a49315671

Here is a versatile charger for $45. I don’t know much about them. You can often get discounts from Hobby king if you put the item in your cart and wait a minute or two. This is where I buy my turnigy batteries which have worked very well.

http://www.hobbyking.com/hobbyking/store/__30917__IMAX_B6_AC_Charger_Discharger_1_6_Cells_GENUINE_US_Warehouse_.html

You can get a clone (fake) of the same unit for less. I have just read, though, that quality may not be as good as the genuine one.

Here’s a clone for less than $22 shipped. You would need a 11-18 volt wall wart).

http://www.ebay.com/itm/130935654729

A dual power clone (no need for wall wart) for $32 shipped.

http://www.ebay.com/itm/iMAX-B6-AC-B6AC-Lipo-NiMH-3S-RC-Battery-Balance-Charger-Adapter-Blue-US-STOCK-/141052565774?pt=Radio_Control_Parts_Accessories&hash=item20d763590e


For Lipo batteries, search the Hobby King site. they have lots of choices and maybe you can find the perfect size. The 1600 mAH worked for me size wise. I think you will be looking for a 2S (7.4 volt). Also it is bit easier if they are in the US Warehouse.