I have the wild thumper 4WD chassis.
I read somewhere that anything over 5V is a waste for the EZ-B. Not sure this is true...
IF this IS true, should I have two battery packs? 6V for EZ-B and a higher voltage, higher AH battery for the chassis?
I'm looking for the best solution, not the cheapest.
Can anyone recommend a link to buy the best battery pack?
Which chemistry do you recommend? I would prefer to avoid anything that is finicky as I can be hard on batteries.
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The EZ-B needs 6v to support internal operation, but it's on-board regulators can handle up to 18v so there is no problem using a 12v automotive type battery for large projects. The "waste" is referring to the nature of the voltage regulator (excess voltage is dissipated as heat)... this is normal and not limited to the EZ-B. There is math involved as to how much battery capacity is reduced through regulation... but in my experience it is negligible at worst.
Dual battery's are an option for use wherein one device needs higher voltage then another and one does not want to use, or put excess loads, on a voltage regulator or step-down transformer option, but introduce the need for multiple charging solutions.
Battery chemistry is somewhat subjective at the beginning stage... RC type batteries are common and compact. Lead acid types may be better suited for heavy duty use, of which an AGM (Absorbed Glass Mat) type is best for a non-spillable solution on a mobile platform.
As you learn and experience, then you will find your own preference for differing applications. But the most important to remember is matching the charging requirements to the battery type to ensure safety and long battery life... next will be a balance between weight, cost, capacity and current draw for your particular application.
My current robot platform uses a small AGM 12v battery for ease of charging, lower cost and high voltage/current for the drive train I am running. The battery weight also acts to provide a low center of gravity for stability. I don't have any links, but you could check out a hobby store for 7.4v RC LiPo battery and charger combo that might work best for your Wild Thumper 4WD chassis.
Don't forget that you need a H-Bridge motor controller to link the EZ-B and the drive train, do NOT try to drive the motors directly off the EZ-B!
Other members will also have experience they will share with you.
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I could have sworn that DJ said you need on H-Bridge per axle.
Is this not correct?
With the little 2.5amp controller, then one per axle (three on that unit EDIT: two on the 4WD) might be required. Each H-Bridge would run the left and right motor for that axle and you just wire each H-Bridge's input wires together in parallel to the EZ-B so they act as one.
Alliteratively, a larger controller could handle all three motors per side in parallel.
-oops i realized right after this it was 4wd
Lead acid batteries are the bomb. They are easy to use for beginners and cheap. 12v like the guys said is great.
@mcbaker01_and_everyone I still believe that with a sufficiently sized controller (admittedly not the L298n), you could run the motors parallel (per side)... as long as they are of same model/type... subtle differences should not matter. In fact, if there is such clear differences in current and resistance between motors, then even with separate controllers for each pair the individual motors on one side could rotate at different speeds or with differing torque, causing all sorts of other issues... unless you also have discreet control of each H-Bridge to compensate... which then eliminates use of the simple moment panel (only one per ARC instance) and complicates the controlling altogether for a new user.
Of course, in the end each robotisist will determine their own way based on advice, ingenuity and experience Don't take just my advice (or anyone's) take them all and experiment, at least that's how I learn.
@mcbaker01 I know your initial question was regarding battery's, but since the motor controller is so vital as well, here is a few components I have looked at that will hopefully assist you in your build.
High Power Switch
And this motor controller may be overkill as it also combines a "rudimentary" brain I think it can be master-controlled itself via the EZ-B. And as it is designed explicitly by Dagu for the "Wild Thumper" series it will do the job within all power and stall specs.
Dagu "Wild Thumper" Dual 15A Motor Robot Controller
One site is saying that you need a 14A controller because the chassis can draw as much as 14A for brief periods such as reversing direction at full speed.
The bridge offered on this site is only 2.5A. Is that really going to work?
Does the 2.5A controller allow for a higher peak current?
The 2.5a L298 offered in the store is great for most converted toy motors, but even when using one for each pair of Wild Thumper motors (In your case, 1st for front, left and right and the 2nd for back, left and right) you might run into cases where it is overloaded. But in general, using two of those controllers on the 4WD may work in ideal conditions (i.e. no heavy loads or rat racing it through the tar pits :P)
That's just my two bits though