Why are my 6V servos inconsistent at 6.2v?

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Yang

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I don't get it, it seems to defy logic.

I'm using a 1600mah 5s nimh pack to power the servos and RX in my nitro car.

I charge the pack up to 6.9v-7v on my HOTA D6, and it reads 100% full on a capacity checker.

I can then drive the car for about 1 hour before the servos start to become inconsistent. Sometimes commands are delayed between my input and the action of the servo, sometimes they don't centre and the throttle sticks open or they stick in a left or right hand turn. Sometimes they don't respond to my input at all.

I check my pack on the capacity checker and it says 6.2v 70%. So I stick the pack back on my charger and it reports fully charged in 10 minutes after 200mah has been put back into the pack. I check on the capacity checker and I'm back up to 6.9v/7v 100%.

With the pack now fully charged the weird behaviour of the servos goes away for another hour.

My question is... why are my 4.8v-6v servos not ok with being driven at 6.2v? 6.2v is not too low so why are they having this behaviour? They should not have this behaviour until under 4.8v.

And why does my 1600mah pack only seem to have a "useful capacity" to actually do work of 200mah?
 
What kinda pack is it? When batteries get old, they will experience more voltage drop under load sometimes. This causes them to have a lot lower voltage than the battery has with no load on it. If it is a lipo, check the IR on each cell to make sure you don't have some high resistance causing problems.
 
What kinda pack is it? When batteries get old, they will experience more voltage drop under load sometimes. This causes them to have a lot lower voltage than the battery has with no load on it. If it is a lipo, check the IR on each cell to make sure you don't have some high resistance causing problems.

5s Nimh hump pack. With no balance lead so no way to check IR of cells. It's brand new and came with the car.
 
You would have to test the battery under load to see what kind of voltage drop you are getting. You said it's happening with both the steering and throttle, so it shouldn't be any kind of binding issue. You could try buying a better pack and see if that resolves your issue. Or maybe going with a 2s LiPo pack and toss a BEC in there to deliver the 6v you need.
 
are you kidding me no balance plug. when was the last time you seen a balance plug on a nimh? ill answer that for you never,, you can monitor every cell with a futaba cdr 5000, i really dont think you understand things in rc. batteries die some a fast death others slow, you can try to properly charge that nimh but i dough it will have any effect..id get a new style battery with a ubec to set voltage to 6.v a 2 cell lipo that will fit in your battery box with a ubec that is at 6v..more power that will last if properly taken care of. sorry if I sound harsh its just the way
I am.was a conditioning charge done to that 5 cell pack to begin with? did you then progress charge amps up in several charges to make pack last as long as possible?.
 
I am familiar with working with lipos not nimh. Nimh seem like archaic tech to me and seem kinda crappy.

I'm used to getting feedback on how close to fully charged a battery is while it's charging and I'm used to predictable performance.

I am coming from drones and I'm not sure why rc cars have this whole 6v thing going on. Why are they not just 9v to make everything more simpler? Like drones and planes.
 
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ubec and becs offer the 6volts your looking for either by jumpers or programming them.nimh and nicad is old school. many still use it in nitro but to me why bother when we have all this technology to get use away from nixx.used it and raced it since the 80's ill never use it again since like 98 ish
 
ubec and becs offer the 6volts your looking for either by jumpers or programming them.nimh and nicad is old school. many still use it in nitro but to me why bother when we have all this technology to get use away from nixx.used it and raced it since the 80's ill never use it again since like 98 ish

I'll try looking for one of these modern lithium packs with a bec then. This is my first experience with Nimh and I already hate them.

I have lots of 18650 batteries lying around so maybe I can make a 2s pack with a bec.
 
I have lots of 18650 batteries lying around so maybe I can make a 2s pack with a bec.
I have several 18650~s li-ion cells. I added 1s protection chips to each and use them as I like. I run electric, so I'm usually 2s5p or 3s4p. Several of my rc's have twin ESC's and currently one of them has 3. (Do not connect multiple BEC's though.)
 
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