Lipo esc vs Nimh Esc
02-25-2006, 02:58 PM
#4
RE: Lipo esc vs Nimh Esc
Just to expand on this.
Low Voltage Cutoff is set to cut power to the motor when the battery is getting low. However the critical voltages are differenet for Lipos as compared to NiXX batteries.
NiMh and NiCd batteries can stand being discharged down to about .8v without damage. However you want to be sure you have at least about 4.4V for the servos and receiver to work properly. So the cut-off with NiXX batteries is there to make sure you don't run the pack flat and lose control of the surfaces. Some ESC cut the voltage and some simply reduce the max throttle setting so you know you are getting low when the plane starts to lose power.
With LiPo batteries, the low voltage cut-off serves the same purpose but with Lipos, you don't want the battery to get below about 2.7V or it can be damaged. So most LiPo friendly ESC have LVC set for about 3V per cell. When a Lipo cell gets to about 3V it is about 80% discharged so there really isn't much left anyway.
Some ESC have preset LVC and some are adjustable.
If you are using a lipo pack with 2 cells, you want to set the cutoff to about 6V. If it is a 3 cell pack, 6V would damage the pack, so you have to set for about 9V.
This should all be coverd in the manual.
Low Voltage Cutoff is set to cut power to the motor when the battery is getting low. However the critical voltages are differenet for Lipos as compared to NiXX batteries.
NiMh and NiCd batteries can stand being discharged down to about .8v without damage. However you want to be sure you have at least about 4.4V for the servos and receiver to work properly. So the cut-off with NiXX batteries is there to make sure you don't run the pack flat and lose control of the surfaces. Some ESC cut the voltage and some simply reduce the max throttle setting so you know you are getting low when the plane starts to lose power.
With LiPo batteries, the low voltage cut-off serves the same purpose but with Lipos, you don't want the battery to get below about 2.7V or it can be damaged. So most LiPo friendly ESC have LVC set for about 3V per cell. When a Lipo cell gets to about 3V it is about 80% discharged so there really isn't much left anyway.
Some ESC have preset LVC and some are adjustable.
If you are using a lipo pack with 2 cells, you want to set the cutoff to about 6V. If it is a 3 cell pack, 6V would damage the pack, so you have to set for about 9V.
This should all be coverd in the manual.
02-28-2006, 11:07 AM
#5
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RE: Lipo esc vs Nimh Esc
And to expand a little further.
Some ESC's designed for NiCad or NiMH can also be used with LiPo's. Many of the the cheaper ESC's for brushed motors have a fixed LVC of 5 volts which is no good for LiPo's but some have an adjustable LVC. These are therefore usable with any battery type. If it's a brushless ESC it will have an adjustable LVC.
Mike
Some ESC's designed for NiCad or NiMH can also be used with LiPo's. Many of the the cheaper ESC's for brushed motors have a fixed LVC of 5 volts which is no good for LiPo's but some have an adjustable LVC. These are therefore usable with any battery type. If it's a brushless ESC it will have an adjustable LVC.
Mike
