KHR-3HV Battery options
KHR-3HV Battery options
by Thex1138
Tue Jan 10, 2012 12:31 pm
Good morning builders and modders.
My KHR-3HV battery has died and I want to look at lipo battery options.
I expect I will need a power regulator.
I am also working with RoBoard so I will be looking for power supply for that as well. With RoBoard I will be using the same 2552 servos that I use in KHR-3.
Has anyone used this combination successfully?
I may also incorporate a battery balancer with the lipo batteries just in case.
Any thoughts, suggestions or pointers are greatly appreciated!
Regards
Thex
My KHR-3HV battery has died and I want to look at lipo battery options.
I expect I will need a power regulator.
I am also working with RoBoard so I will be looking for power supply for that as well. With RoBoard I will be using the same 2552 servos that I use in KHR-3.
Has anyone used this combination successfully?
I may also incorporate a battery balancer with the lipo batteries just in case.
Any thoughts, suggestions or pointers are greatly appreciated!
Regards
Thex
by PedroR
Thu Feb 02, 2012 6:15 pm
Hi
We've tried using 3 cell Lipo batteries in our Lab with KHR 3HV.
Although they work, they seem to supply excessive voltage to the motors: the KHR stock battery is 10.8V where a fully charged LiPo is 12.4V.
From our experience what we've seen is that servos tend to get damaged faster (ie blown mosfets usually).
If you're the hacker type, you can try getting 9x 1.2V AA rechargeable NiMH batteries and building your own battery pack probably reusing part of the damaged one you have.
There 1.2V AAs that have higher capacity than the stock ones that come with the KHR.
Make sure to proceed with caution - and at your own risk! - if using this approach!
With regards to using a LiPo, if you choose to go down this road, we would strongly recommend getting a voltage regulator or otherwise using one or two diodes to drop the voltage.
It is quite hard to find regulators that can provide either 10.5V or 10.8V and enough amps. The largest variety can be found with the "BEC" denomination (they're for the RC world) but they're typically for 5V, 6V or 12V (some also offer 8.2V).
The only regulator we found capable of doing 10.8V was the Castle Creations BEC Pro.
The BEC Pro does have a few things to it: you need to get the programmer in addition to the Regulator to set the desired voltage and it has a bit of size.
Also (and this is unconfirmed) we've read some rumours it causing brownouts. (the concept of brownout is a bit exquisite but I'm sure wikipedia or google can explain it).
We haven't tried the BEC Pro ourselves but maybe with a bit of research you may find similar regulators (or BECs) that can output the steady 10.8V.
Using a regulator also improves the robot's performance as the performance remains constant: ie it always gets the same voltage regardless of the battery level meaning torque is constant.
Another issue you may be encountering is the need to power the Robot continuously when programming.
We've improvised a PSU using a 12 connector from a computer PSU and placing 1 diode between the +12V and KHR.
(this is how we learned about the solution of using diodes). I don't know what was the exact type of diode we used but it dropped about 1V which was enough to put the voltage output at a safer 11V.
This will certainly extend the lifetime of the motor and save you a lot of issues.
Regards
Pedro
We've tried using 3 cell Lipo batteries in our Lab with KHR 3HV.
Although they work, they seem to supply excessive voltage to the motors: the KHR stock battery is 10.8V where a fully charged LiPo is 12.4V.
From our experience what we've seen is that servos tend to get damaged faster (ie blown mosfets usually).
If you're the hacker type, you can try getting 9x 1.2V AA rechargeable NiMH batteries and building your own battery pack probably reusing part of the damaged one you have.
There 1.2V AAs that have higher capacity than the stock ones that come with the KHR.
Make sure to proceed with caution - and at your own risk! - if using this approach!
With regards to using a LiPo, if you choose to go down this road, we would strongly recommend getting a voltage regulator or otherwise using one or two diodes to drop the voltage.
It is quite hard to find regulators that can provide either 10.5V or 10.8V and enough amps. The largest variety can be found with the "BEC" denomination (they're for the RC world) but they're typically for 5V, 6V or 12V (some also offer 8.2V).
The only regulator we found capable of doing 10.8V was the Castle Creations BEC Pro.
The BEC Pro does have a few things to it: you need to get the programmer in addition to the Regulator to set the desired voltage and it has a bit of size.
Also (and this is unconfirmed) we've read some rumours it causing brownouts. (the concept of brownout is a bit exquisite but I'm sure wikipedia or google can explain it).
We haven't tried the BEC Pro ourselves but maybe with a bit of research you may find similar regulators (or BECs) that can output the steady 10.8V.
Using a regulator also improves the robot's performance as the performance remains constant: ie it always gets the same voltage regardless of the battery level meaning torque is constant.
Another issue you may be encountering is the need to power the Robot continuously when programming.
We've improvised a PSU using a 12 connector from a computer PSU and placing 1 diode between the +12V and KHR.
(this is how we learned about the solution of using diodes). I don't know what was the exact type of diode we used but it dropped about 1V which was enough to put the voltage output at a safer 11V.
This will certainly extend the lifetime of the motor and save you a lot of issues.
Regards
Pedro