Hi all,
We are using 4 12V DC motors drawing a current of 5.5Amps to run the base of a heavy duty mobile robot.
We are looking for an efficient battery pack that can sustain the motors for a duration of 2 hours in one cycle. Hence the capacity of the battery pack needs to be around 90Ah. The major constraints involved are weight(<3kg), cost($100 - $150) and size( L,B,H<400mm). Li-ion or Lipo batteries seem to be the best alternatives currently but seem to exceed our cost targets.
We are not experts and are looking for guidance in solving our problem within the above mentioned constraints.
Appreciate any inputs.
Thanks.
IG42.pdf (697 KB)
If you have all four motors operating at maximum current draw, they consume 22A. Over two hours, that would require a 12V, 44Ah battery. Not sure how you get 90Ah?
Big robots cost big money.
@CBencson,
You are right. I just assumed a safety bandwidth of 50%. I guess usually people tend to prefer having a capacity 2-3 times than that is usually needed.
I am willing to spend money as long as the cost vs. benefits are satisfying enough for my purpose. We are actually an Indian startup building robots that can paint buildings. The project I described is the objective for one of the interns working with us. Will be to happy hear your views.
Higher battery capacity always adds weight, so it will depend on your needs. If your robot is climbing up against gravity, a lighter weight battery certain has advantages.
Our robot moves on the floors with the help of 4 Omni-wheels. We can accommodate some weight but we’d like to keep it down to as minimum as possible.
We were thinking of using a few 12/24V 10Ah Li-Po in parallel to serve the purpose. But we are unsure as to whether this works will with components having different rated voltages and currents.
It’s best to use just one voltage, and if you have parts which require other voltages, to use voltage regulators:
robotshop.com/en/power-regulators.html
My main concern is if a Li-Po pack is the best solution for our requirement i.e. capacity in the range of 50-100Ah.
A LiPo pack in that range will still be large, but significantly smaller than a lead acid or NiMh pack. It will also be able to discharge at a much higher current.
Note that a 100Ah pack is large enough to be used on a base which carries a human (such as an ATV).
