Hey All,
I have a question,is this battery pack too heavy for the BRAT,I’ve just received it today and I’ve assembled everything,and this battery pack seems to big and too heavy,is it meant for the BRAT? lynxmotion.com/Product.aspx? … egoryID=48
I have one of the 2800mah batteries on my Hex and it looks like it would not fit in the channell bracket of the brat very well. Maybe it would? My brat has the 1600mah pack which fits it pretty well.
I have allready assembled it and it seems very heavy and big,it barely fits in bracket at all,i had to remove some o the screws to get it to fit in there.
I’m running a 1400 mAh 7.2-volt NiMH pack in my BRAT biped. It’s a commercial pack built from 2/3-AA cells that I had sitting around, having purchased it for another project. It fits inside the C-channel with a little bit of gap, but a zip-tie and a strip of non-slip padding keeps it in place quite well (as well as providing a layer between the screw heads inside the channel and the pack’s shrink-wrap coating). The pack provides plenty of run-time, even when holding awkward positions for long periods while I get the servo positions hammered out.
Yours is a 5-cell Sub-C pack, mine is a 6-cell 2/3-AA pack. I don’t expect that there would be all that much difference between the weights, but depending on what servos you are using, and how they perform at 6.0 volts nominal as opposed to 7.2 volts, you may or may not run into issues. I suppose you could always try it, and if it works, then great - you’re in business. If not, then you can pick up a different pack that will fit better, and you have a nice 5-cell pack for use on other projects.
I kind of halfway remembered having one of those 5-cell packs around here, and sure enough, I did.
Tossing them on the scale, it says that…]The 5-cell sub-C pack weighs in at 9.4 ounces (267 grams)/:m] ]The 6-cell 2/3-AA pack weighs in at 5.0 ounces (143 grams)/:m]That’s a difference of just 4.4 ounces (124 grams) - or 22 US quarters - not a tremendous difference, but it might be enough to cause problems if your bot really is on the borderline of functionality.
[EDIT: depending on the servos you are using, the increased voltage of one additional cell may improve the available torque enough to make a noticeable difference, too.]
My 6-cell pack is just a cheapie that I picked up at a local hobby shop. I think it’s a standard size used in the mini trucks and such, since there was a fairly good selection of packs in this form-factor. I didn’t go for fancy or expensive - I just wanted cheap volts, and it’s worked great for me ever since.
The 475’s work well at 6.0vdc. I never run them at 7.2vdc because they become a bit hyper and jittery. The BRAT should work ok with that pack, but if you plan to add additional electronics, cameras, sensors, etc. Then I would recomend switching to a 5 cell AA pack. Looks nice though…