TTXGP Australia July 1st - 3rd

Dual motor tuning guide from Agni would be really helpful.

Chris's Voltron blew the new Agni we spent the night installing after a lap on the final race of the Easterm Creek round. I've got some video to upload. The bike showed great potential with better acceleration and top speed than both of the other bikes however tuning the motor pair under load is clearly crucial.

If that gets sorted with another motor plus some sticky track tyres for the next round, Voltron could be quite the weapon.

The Glow Worm crew and I were proud to be able to help Chris with his efforts this weekend even though it was a minor contribution compared to all the time and funds Chris has put in to get to this point. We wish him the best for the next race!

Cheers, Abraham
 
I take it the two Agni's are downstream of one controller?
 
bigmoose said:
I take it the two Agni's are downstream of one controller?
Click to expand...

Directly paralleled.

This is always the worst way to run motors, but I never realized how tough it is to do until we were setup on the synopsis making pull after pull. It seriously only loads a single motor at a time, until you have the brush timing dialed to be exactly the same KV. This meant a tiny hair of distance in clocking the brushes made it shift from one motor or the other taking 90% of the current. Shift it a hair back, and the other takes 90% of the current. Then when you snug down the screws to lock it in place, it shifts it a tiny bit and blows the setting you had.
 
liveforphysics said:
bigmoose said:
I take it the two Agni's are downstream of one controller?
Click to expand...

Directly paralleled.

This is always the worst way to run motors, but I never realized how tough it is to do until we were setup on the synopsis making pull after pull. It seriously only loads a single motor at a time, until you have the brush timing dialed to be exactly the same KV. This meant a tiny hair of distance in clocking the brushes made it shift from one motor or the other taking 90% of the current. Shift it a hair back, and the other takes 90% of the current. Then when you snug down the screws to lock it in place, it shifts it a tiny bit and blows the setting you had.
Click to expand...

Sounds like a PITA !!!
 
Luke, have you considered two controller set for current control? Then the throttle is like a torque control. You have a nightmare with two motors of that low R in parallel. Even if you exactly match them at "room temperature" at race speeds, with cooling changes, they will go out of "synch" during the race. The harder you push them, the more they will go out as the copper changes R with temperature. I'll bet even the riders leg position could have an effect on motor balance during the race.

How I wish my little company was bigger than just me... so many ideas, so little time...
 
Hi All!

I'm back in Perth now and I have a bunch of things to do before I get all my photos up and so on. Like, get the bike back to SplinterOz's place. Still, nice to be back.


Luke - would putting the motors in series be any better? I'd probably need to change my battery configuration, but there has to be a better way with these silly motors. With a bit of luck I can salvage the magnets from them, but the rotors and brushes are rooted.

As for EC Raceway - man it is one sweet track!! Hard to compare to Phillip Island but definitely better than Wanneroo. I was happy that when the bike was running well, I got better and better lap times, and when I did put one full lap into the second (and ill-fated) race I went right back to my average lap times from a standing start, so that's good. The lil' RG doesn't like being pushed into corners much :lol: the front was squirming pretty bad on the hairpin, but I wonder if sticky boots would stop that.

Anyway, I have to save up for some new motors. Anyone got a better idea for conserving these things?

Cheers,
CHRIS
 
Yes, if you run them series, they share current perfectly even. I used to think parallel motors could work out, but I think series is really the only way after playing with them in parallel.
 
I think Moose's suggestion is best. Series motors works perfect, but it would require an IGBT based controller since fets really suck past 150v, and re-doing your packs also sucks.

Getting another controller that you can also set in torque control mode is the best path for you. It will rock that way.
 
OK So two ~500 A Kelly controllers instead of one great big one... I could possibly remove one battery pack and stick the controller in it's place, but my charger and everything are set up for 32 cells ... :x

Use the one throttle paralleled to both of the controllers and hope they play nicely together... Hmm. Worth a thought...
 
Some thoughts:

If run in series, doubling the voltage from the present 32S, 105.6v nominal would put it beyond the range the Kelly's are capable of.

What about rewiring your 96 cell pack to 48S2P (158.4v nominal, 175.2v charged, 40Ah)? You would end up needing to re-gear but you also wouldn't be over-volting your motors then either. Re-configuring your pack may be far too difficult though, I'm not sure.

Can the motors be run in series through your 1 controller? I'm not sure what your controller's max allowable voltage is...

Cheers, Abraham
 
I didn't know you were voicecoils!! :lol:

Yeah, basically re-configuring the pack would a royal pain in the arse, so I'm inclined to try and stick with the 105.6 V nominal system (32 cells). Interestingly I didn't use more than 60% of my pack for a 5 lap race, but if you're only running on one motor that's probably about right.

Currently I'm trying to put >650 amps at 85-105 Volts, through both motors in parallel, meaning if the motors were perfectly balanced I'd be giving each one ~325 each. Since this is not the case, something like 1000 amps were going through one of them and very little through the other.

Using the existing controller to run both motors in series would mean ~900 amps going through the motors at 43-52 V, but at least they would both be getting 900 amps exactly. So I could f^ck two motors at a time instead of one.

Two separate controllers working on two separate motors, joined at the shaft, would mean the individual motor characteristics are still going to be at play, but the power delivered to each is going to be much closer. No doubt Luke and his crew have worked out which system is best but I would totally understand if he kept it a secret.

I want to go brushless, but not on this bike. Might save it for a better machine...
 
Glad to hear your bike showed so much promise Chris, but sorry to hear about the motor problems, especially as I was one of the people who suggested running paralleled motors at the start of your build :oops:

It makes sense that any differences in motor resistance will diverge under heavy load, but I never imagined they would diverge so much or that it would take such extreme tweaking of the brushes to get the motor resistance balanced in the first place. It just goes to show the value of racing for eliminating unreliable setups ... but a shame it's such an expensive process.

It does sound like the one controller per motor route would be the most reliable way to go, and involve the minimum change to your battery pack.

Many thanks for keeping us updated. I'm sure loads of people are benefitting from your steep learning curve :)
 
Great job on getting there and competing! We are all pioneers on getting this to the mainstream. Electrics are our near future.... Ed
 
Chris, to the best of my knowledge you were never able to check that the 2 motors you have give the same RPM per volt (unlikely considering you grabbed a last minite replacement).
There were some problems with one of Agni's suppliers last year that meant a wide spread of RPM/V motors were sold before they realised what the problem was, this was a major PITA for all parallel setups last year, and makes it impossible to balance 2 motors.
Checking with an RPM meter at 10v will verify this..

Running in series causes it's fair share of problems too, as does 2 seperate controllers, one way or the other 2 motors is a pain!
Although the Agni bike has 2 controllers and has a fairly good reliablility record, this is mainly due to those controllers being the older Kelly's and not able to overload a motor before it gets hot and delimits (you remember the power difference when you upgraded chris?).

Keeping the power down until you are sure the motors are balanced however is a good way to stop blowing them up, I've lost count of the number of folks who have given a quick balance, then gone ripping round the track at max allowable power....only to overheat one on the first lap! As with any racing, whatever setup you use you will push it too the max and beyond, test it carefully to find the limits before the main race! Took me most of last season to figure this out on the 4 Mavizen bikes, but last race I sent all the bikes out to a hot world final in Spain having very carefully checked and double checked, and they all came back in one piece.

Steve
 
You burned out 4 Mavizens! :lol: I don't feel like such a clown now :D

Yeah, it's all a steep learning curve. I'm looking into a dual controller option, but I will also try to contact Agni and get their advice. If they answer their emails... Oh, and Andy says hi! :D
 
Yeah we had early problems, burned out a lot of brushes when brush quality dropped during the season, and burned one pair of motors (which isn't bad). Riders binned a couple more by falling off and scraping them up. Not too bad I guess, but then, I'd already had a few years of Agni experience from my single motored Aprilia. Others wern't so lucky, there were a lot of other teams using the same drive package as the TTX02 last year, and between them devestated Agni's stock!
This thing about motor RPM also cropped up last year for the first time, seems the engineering firm that produced the endplates had left the same milling bit in the machine for the entire run, and towards the end the plates were a lot thicker than at the start. Before Agni had realised what had happened, they had been shipped all over the place and mixed with older stock, where we were busy slinging them on bikes by the side of the track and wondering why we could no longer balance the timing.

It can work well in parallel as long as you get the setup well balanced throughout, making the motor leads all the same length, checking brush resistances are close, setting timing.
Running motors in a bit when new or after heavy abuse is another tip, and whenever a set of brushes has been burned or a motor partially overheated, then regrind the commutator and run in again. All things the drag car/killacycle guys have been doing for years come to think about it..

I will start a thread this week on how to take an Agni racing without hurting it, Agni are in aproval..

Steve
 
Agreed! Very professional work there by Andy, really sums it up nicely!

Well done! :D
 
Best TTXGP vid yet Andy, great to see the tech side behind the scenes on camera for once! Very Pro, well done!
 
jonescg said:
Yeah, it's all a steep learning curve. I'm looking into a dual controller option, but I will also try to contact Agni and get their advice. If they answer their emails... Oh, and Andy says hi! :D
Click to expand...

Well done Chris, you gave it your best shot, keep pluggin away and you'll get there, and

The more I look at these Brammo's the more I like them

Mark
 

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dingoEsride said:
The more I look at these Brammo's the more I like them
Click to expand...
Remember, the Brammo is the red, blue and black thing under and behind what you are looking at. ;)
 
Hey guys,

Just catchin' up on this thread. Chris, I hope you get your bike sorted for the next race. Mark and Steve, I am putting together some signage for the next TTXGP round here in Aus and if you want me to put some logos up there just send me the best quality ones that you have. andy@evmotorcycle.org

Lots of ev brand placement in the backgroundof the next vid. Oh and Brammo, If you want to send the Brammo chicks I am sure the lads here could pitch in for the shipping costs! >:)

Andy.
 
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