birdmun

There is something a bit ironic about a robot

that uses ultrasonics given the name fluffy. Soft, fluffy objects are somewhere between difficult and impossible for ultrasonic sensors to detect.

When you can, would you be so kind as to find out what kind of run time you get out of two fresh 9v batteries? Specs for 9v batteries say they offer only a few hundred milliAmp hours. It is considered a given around here that 7+ volts, if used with a typical non-Low voltage DropOut (LDO) voltage regulator (think 7805), from AAA or AA rechargeable batteries will give you significant improvements in run time. OddBot has mentioned many times that standard alkaline batteries have a noticeable voltage drop over time vs NiMH or NiCd being a fairly consistent 1.2v over their discharge cycle. Plus, they can be recharged many times vs once and done with alkaline batteries.

1 reply

passero

At 9v the motor is drawing

At 9v the motor is drawing 60ma so together that is 120ma. The battery is rated at 200mah so I will probably not be able to run them for 2 hours. 

I will do a test with no load and see how long they run. 

I have thought to use 6 AA batteries (also NiMH) instead but the weight of the 9v is far less than the 6 AA block so that’s why. 
Because they are recharchable I didn’t really care about how long they would run. The charge time on these is about an hour and I got a few.