Ezrun 9t Battery

[Boothy]

I have seen a couple of posts over judder when setting off with EZrun brushless systems and after setting mine up tonight I have found the same problem. My battery is an Mtronics 3700nimh type which I have not had for very long as I am a newbie.

The thing is as I have just forked out for a non LIPO charger I really dont want to make everything I have redundant so I would rather stick with nimh for now. I would also really like to stick with tamiya connectors if possible, the ezrun came with a tamiya connector so I am guessing its up to the job?

One thing I noticed with my current battery is it runs for ages but it will run for a good 15 mins at a reduced output, I read that this means the cells are not so great? So What sort of stick pack do people reccomend? I have seen the team orion rocket packs which look pretty nice, would a 4500 rocket pack run the ezrun without judder? And what are other 9t EZrun users running?

cheers

Boothy

p.s. I have set the punch right down and still have a slight judder on start.

[PaPeRo]

It sounds like the judder you're referring to is not the same judder that's related to lack of battery current. I tested my 9T eZRun motor with an old NiCD pack and there was no judder from lack of current. The judder you're referring to is likely the hesitation/cogging that is normal on a sensorless system. This normally only shows itself under light taps of the throttle especially after braking.

Here is a video of my car with the sensorless judder at 22 seconds. Car is running a 100A LiPo so it's not the battery.

[Power Surge]

I have the EZrun 9T and the 5.5T and I have never had even the slightest hint of "sensorless cogging".

I had the stutter on starts when I first used it too.... it was my battery packs. Got me some new ones and a peak charger and never had a problem since.

I'm using 3000mah ni-mihs with no problem (well, Li-Po on the 5.5 setup).

[PaPeRo]

I have the EZrun 9T and the 5.5T and I have never had even the slightest hint of "sensorless cogging".

Seriously? ALL of my sensorless eZRun systems have the slight cogging/hesitation when going slow forwad/backward and this is due to the ESC not knowing exactly the position of the rotor especially after braking. I've talked to many people who have the same observations. You must be very lucky to be among the few with no cogging issues. The cogging is especially bad on the 5.5T in my TA03 and the car even sometimes briefly goes slightly backwards before going forwards. I set the ESC's punch level on the lowest so maybe that has an effect on the cogging who knows.

[Boothy]

The judder does happen on light starts and not really if you push forwards harder on the stick, it is better with the punch turned down though.

What is the difference with a sensorless system?

Boothy

[Rayman011]

I have a sensorless HSP setup and I only get the judder when I try to reverse.

[VinceVegaUK]

I have seen a couple of posts over judder when setting off with EZrun brushless systems and after setting mine up tonight I have found the same problem. My battery is an Mtronics 3700nimh type which I have not had for very long as I am a newbie.

The thing is as I have just forked out for a non LIPO charger I really dont want to make everything I have redundant so I would rather stick with nimh for now. I would also really like to stick with tamiya connectors if possible, the ezrun came with a tamiya connector so I am guessing its up to the job?

One thing I noticed with my current battery is it runs for ages but it will run for a good 15 mins at a reduced output, I read that this means the cells are not so great? So What sort of stick pack do people reccomend? I have seen the team orion rocket packs which look pretty nice, would a 4500 rocket pack run the ezrun without judder? And what are other 9t EZrun users running?

cheers

Boothy

p.s. I have set the punch right down and still have a slight judder on start.

Is the judder on a gentile throttle start or when you slam it on full whack for a hard start, or when putting power on hard when already moving?

You will get cogging on gentle throttle, i haven't found it so much on my 9t or 5.5t but i get it more noticeably on my 13t, when racing i don't notice it and i can use the sudden punch in throttle to my advantage. Also when controlling a brushless you have to work it different to a brushed, brushless is less smooth when blipped like a brushed. You will find that coming on and off the throttle is best kept as one smooth on and off movement and not blips

E.g

Coming into a corner you might brake or throttle completely off but then coming back on the throttle, come on slow and build it up don't blip it. Or when going around the corners hold it at a low throttle point to keep the motor rotating forward.

I would strongly recommend ditching the Tamiya plugs they are really poo, i know its a pain to solder on new ones on all your connectors but once you do you will never look back. I use 4mm gold plated bullet connectors with plastic covers, a set of 10 is about £4. rated over 100amps and have good low resistance (larger versions of the ones that connect the EZrun motor to the ESC). I have had myself and friends have tamiya plugs melt together as the resistance was so high they heated up and fused together. Or you can use Deans, if you have friends with a similer good connector maybe change to them so if you need a pack you can still share.

As for batteries i would have gone Lipo im using Yeah racing 3200 packs with an esky imax b6 charger after using Nimh for over 2 years and never look back there so much better performance wise and easier to maintain and charge, lighter too. I got a Twin battery pack inc safe bag £50 and charger inc power pack £50 off ebay.

If you are sticking to NiMh i would suggest a good cheap but quality brand www.vapextech.co.uk which offer cheap but good packs myself and several friends always run them (until we went lipo, but i still have mine i use in my drift car and lunch box).

Hope this helps, also check all your wiring and solder to make sure all connections are good. One more thing Mtronics packs are prone to bing a bit dud form time to time, my one that came with my car new lasted a few weeks and started loosing power, my friends one didn't work out the box, his replacement didn't last long either so you could have a duff pack or cell even if its new.

myself and two other friends all have 10 ezruns between us and race every week so IhHope this helps if you need any more help give me a shout,

Later

VV

[WillyChang]

some units cog less than other (otherwise visually identical) EZRUNs

sometimes if you switch around the 3 motor wires (the colours DON'T have to matchup!! ) ... cogging can be less

assuming ESCs are all the same, can only presume there's a bit of manufacturing tolerances between motors

[Boothy]

Cheers Guys,

Very helpful as always

Vince, the judder is on light starts, if I punch it (Sounds like top gun ) there is no judder, I also tried a light start whilst holding the car in the air (no friction) and there is no judder.

I tried to look at deans connectors but I could not really work out what I need or if what I was looking at would fit the thick battery leads? My missus would go spare if I went lipo now so I am sticking with nimh, plus its just bashing about for now really so nothing serious just yet.

Have we any links to the correct deans connectors or the gold plated ones?

cheers

Andy

[VinceVegaUK]

Cheers Guys,

Very helpful as always

Vince, the judder is on light starts, if I punch it (Sounds like top gun ) there is no judder, I also tried a light start whilst holding the car in the air (no friction) and there is no judder.

I tried to look at deans connectors but I could not really work out what I need or if what I was looking at would fit the thick battery leads? My missus would go spare if I went lipo now so I am sticking with nimh, plus its just bashing about for now really so nothing serious just yet.

Have we any links to the correct deans connectors or the gold plated ones?

cheers

Andy

yea the judder does sound normal, try as willy said and swap the wires around se if it makes any difference. Running the car in the air has little resistance so judder is less noticed. Also never run you brushless without load up to full throttle, the magnets can't take the g force of that magnitude and can separate and jam up the motor ready for the bin, running it in the car off the ground counts as load all be it a lot less load than on the ground but still best not to do it.

As for connectors the deans have a flat plate to solder too and usually come with some shrink tube to cover the plate, the bullets have hollow back ends, you just make them hot with the iron and fill it full of solder and plunge your tinned wire in and let it set.

Click Here Bullet

4mm Shrouded Bullet Connectors (Superior) 5 Pack 100A

Click Here Deans

5 Pairs of Gold Plated Deans Connectors + Heat Shrink

Click Here Vapextech

7.2V RX POWER PACK RECHARGEABLE BATTERIES 3300 MAH (or higher MAH for more run time)

Thanks

VV

[Boothy]

Thanks for that Vince! What sort of out put would you reccomend for say 20 - 25 mins run time on a 9t ezrun? will I need the 4300?

thanks

Andy

[VinceVegaUK]

Thanks for that Vince! What sort of out put would you reccomend for say 20 - 25 mins run time on a 9t ezrun? will I need the 4300?

thanks

Andy

yea i get about 15mins of hard racing with my 9t on a year racing lipo 3200 in a 4WD TA05 on carpet with foams (my car is weighted back up to what a nimh would be so it carries the same even though the lipo is lighter) get a 4300 should do 20 mins or so. It depend on how you are driving, what surface your on and what drive train your car has and its weight, also i guess everything is ball raced for less friction?

In my F1 with the same batteries i get about 25 - 30 mins of hard racing as its lighter and only RWD and runs a 13t ezrun.

The trick is to have at least 2 or 3 packs so when you are running one the other is on charge, i find running at least 3 gives enough overlap to keep going for as long as you want (does help if you let things cool down a little between running)

:-)

thanks

VV