Brushed ESC and lipos

[Fanyak]

Hi there, I would like to know about the possibility of using a old brushed Esc with lipos batteries as I have a JETI 50 connected to a brushed motor and I want to change NMH batteries for lipos. Many thanks

[Richard Wood]

Hi,

You must be able to set the low voltage cut-off of your old Esc

to around 3V per cell to use Lipo batteries.

The NiMH cut off setting of around 1.1V per cell will damage LiPos.

 

[Erfolg]

Just do it! Where is the problem?

 

I had the same fear with a small indoor model, with a brushed GWS twin motor and gearbox. The problem I foresaw was the BEC on the ESC was for a Nicad. Given the stories how you could easily destroy the Lipo by running below a certain voltage.

 

Now the reality, when the motor shows a lack of power then it is time to land. When checked on the charger, I was always in the region of between 3.9-3.8 V. So the predictions of all sorts of trouble were not born out by experience.

 

It is a case of landing when the models motor shows signs of significant sagging.

 

I am sure there will be a more engineered solution, I prefer simplicity and a degree of caution.

 

[Tim Mackey]

Posted by Erfolg on 24/05/2011 18:26:30:

Just do it! Where is the problem?

 

I had the same fear with a small indoor model, with a brushed GWS twin motor and gearbox. The problem I foresaw was the BEC on the ESC was for a Nicad. Given the stories how you could easily destroy the Lipo by running below a certain voltage.

 

Now the reality, when the motor shows a lack of power then it is time to land. When checked on the charger, I was always in the region of between 3.9-3.8 V. So the predictions of all sorts of trouble were not born out by experience.

 

It is a case of landing when the models motor shows signs of significant sagging.

 

I am sure there will be a more engineered solution, I prefer simplicity and a degree of caution.

 

 

Its nothing to do with the BEC Erfolg its an LVC issue.

[Erfolg]

Yes you are correct. The point I was making that the Low Voltage cut of was for Nicads not Lipo, just a slip of the key board and a continuing senior moment.

Edited By Erfolg on 24/05/2011 18:49:10

[Tim Mackey]

Richard is correct - but if you "fool" the ESC into thinking you have say a 7 cell nickel pack this is around 10V fully charged, and is likely to have the LVC cut off power at around 7V or perhaps a bit higher.

A 2s lipo would then be OK, as if the LVC kicks in at 7V, each cell is still 3.5V which is still high enough to not worry about.

Alternatively of course, forget worrying about LVC at all, and simply come in to land as soon as you notice the power to start to drop.

Most experienced leccy flyers never fly to LVC anyway.

[Fanyak]

Sorry, I do not understand LVC

[Fanyak]

Many thanks, Then I only have to pay attention and land when the power start to drop and not wait for LVC. By the way I have bought 2s lipos, thanks again.

[Tim Mackey]

LVC = Low Voltage Cutoff.

Perhaps if you are flying electric you should check out the newbie threads such as here.

[martyn sharp]

LVC = low voltage cutoff this is the point that the lipos acan safly be discharged in order to be then not to be damage and can be recharged . brushless ESC you can set this so at low power it will stop the Motor but will continue powering the BEC conecting the recever . so on a brushed setup if the lipos drop to much then the power to the reciver may fail and you are left with a uncontroled model .I have a brushed setup on my twinstar but have the reciver and servods on a seperate battery but still time my flights so not to run the lipos down to much

 

hope this helps

 

Martyn

 

sorry TIM cross post

Edited By martyn sharp on 24/05/2011 19:10:50