Powering Hexy

IMPORTANT NOTICE: DO NOT OVER-VOLT OR REVERSE:

The voltage limits are printed onto the Servotor32 board (4.8v-7v). The logic power supply is only rated up to 10v, but nothing above 9v is recommended. Please be mindful of these limits and do not exceed them, as this can damage the board. Please do not reverse the batteries, as this can also damage the board.

Which batteries to use

Use High-Capacity NiMH or NiCads

It is also not recommended to mix/match batteries of different power levels or types. To be more specific, The Arcbotics team recommends the Powerex 2700mAh Rechargeable Batteries.

Do Not Use Alkaline Batteries.

This includes almost all one-time use batteries bought in stores. Alkaline Batteries often do not supply enough current to power Hexy (up to 5 amps peak), especially during power-heavy moves such as dancing. Alkaline batteries aren’t designed to deliver as much current as NiMH/NiCad batteries are, they have a lower current capability or ‘C-rate’. This can lead to the ‘dead-spider’ effect even with ‘full’ batteries, with the legs and feet curling in.

Do Not Use Lipo Batteries

LiPo batteries are NOT recommended, as their voltage is either high enough to damage the servos (7.4v) or too low to be effective (3.7v). ArcBotics is looking to offering voltage converters.

How many batteries to use

Hexy comes with both 4AA and 5AA battery cases, so which one to use? Start by using 4xAA. This will put less stress on the servos, and reduce any jitter. If you need more power, you can switch to using the 5xAA case. This will have the effect of causing more ‘jitter’ in the servos though, as the servos will start ‘overshooting’ their positions.

Operating Hexy Remotely

Use a power supply on the logic input if Hexy is not connected to USB

Hexy comes with a bluetooth-serial adapter. You can use this adapter to control your Hexy from a bluetooth-enabled device. However, using on the servo battery pack, the voltage can sometimes dip too low for the electronics and reset Hexy (see Servo-Battery-only Reset below for specifics). The solution is to use an extra power supply on the logic power input socket. You can use a 9v battery, 4xAA or 5xAA. You can place both a 9v battery and 4xAA battery case for remote usage underneath hexy, or if you are using the 5xAA case, you can place the 9v ontop of the servotor32 board.

Operating Hexy remotely without a logic power supply causes issues

If you’re powering Hexy off of battery power only (Say, running it on bluetooth), Hexy can sometimes start to move, then suddenly lose all servo power, then reset and begin this cycle all over again. This is caused by the voltage ‘dipping’ too low. When the servos move, they draw power from the batteries and thus lowering the battery voltage. If this voltage goes too low the Servotor32, Hexy’s ‘brain’, doesn’t get enough voltage to keep going and resets. The reset causes the servos to stop getting signals, stop moving, and the voltage goes back up enough to let the controller boot up. But as soon as Hexy starts moving again, the voltage dips, and it starts all over again.

The fix is to power the brain from an extra power source, one that will have a high enough voltage that in case the battery dips too low, it has a backup supply to keep going. This can be seen as the ‘logic’ power supply port on the controller. a 4xAA, 5xAA or 9v battery pack plugged into this port will work, and keep hexy going no matter how low the servo voltage dips. The USB power supplied when plugged into a computer works as well, and this problem won’t occur when Hexy is plugged in.

External Power Supply

Hexy can be externally powered with any power supply that maintains a constant 5v and a minimum of 5amps. Here are some places you can purchase one:

Mouser

Adafruit