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Old 11-19-2002, 02:27 PM   #16
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Kraig,
I agree.....only a couple of the companies mentioned open the motors and do anything with them. Unfortunate, but true.
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Old 11-19-2002, 04:11 PM   #17
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Quote:
Originally posted by acloco
black-knight - you used a 7.2 volt battery pack to power a fantom dyno the must see TWELVE VOLTS and 50 amps? WTF? Ummm.....where is the B.S. protector???

Maybe the reason that all of these companies are using the fantom because of ......um....free dyno's? ...or at least at extremely reduced prices???

Sorry dude....not one of those companies mentioned are motor builders.....just relabelers (except Trinity - the IMPORTER).

Good luck........sorry to flame on you.......but the 7.2v pack being used in a 12 volt application........uhhhh.....yeah........right!
The Fantom Dyno has it's main power connector and a connection to a 12v batt - both to be connected to operate the dyno. We just hooked the leads that go to our 12v car batt up to the 7.2v packs! not that hard to do mate! Dyno worked no issue, just that the results were not consistent. Ask Fantom can be done!

Hey Fantom use the Dyno, Fantom are motor builders and one of the best...that's all that matters.

The fantom dyno only runs 5volts to the motors.
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Old 11-19-2002, 04:41 PM   #18
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Default Dyno "Facts"

Ok guys,

From what I'm see in the replies is;

Robitronics Dyno is best. No more support in the US. Most expensive to buy.

CE/CS ?? Dyno, no longer produced. Repeatability issues.

Fantom "Facts" Dyno. Missing some features, but probally the best still on the market. US made and supported.

Homemade Dyno. No! I want a Dyno to give me USEFUL Data for motor tuning and comparisons. I do not need another "Toy" to play with. (My R/C cars are enough)

So I'm leaning towards the Fantom. Tell me more good or bad about your experiences with Fantom Dynos,

Thanks to all,
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Old 11-19-2002, 04:43 PM   #19
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blackknight....you are missing the point. The Fantom dyno NEEDS to have 12 volt to run the dyno.......7.2 volts will not cut it!!!

Fantom is not a motor builder.......they DO build some other quality items......VERY nice lathe.......but they do not build motors. They buy from OEM resources (Reedy & Trinity).....and go from there.
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Old 11-19-2002, 06:01 PM   #20
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Quote:
Originally posted by acloco
blackknight....you are missing the point. The Fantom dyno NEEDS to have 12 volt to run the dyno.......7.2 volts will not cut it!!!

i never said it was right, it's def not the way the dyno is meant to work. But with a 7.2 volt pack attached it will run and produce results. no matter what u think...i does work...try it!

i only mentioned this in relation the comments made about the cs dyno using 7.2v packs, to support the idea that powering a dyno with 7.2 packs produced inconsistent results. Any yes i know Fantom even state 12v is needed.


The best dyno is my car on the track!
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Old 11-19-2002, 09:51 PM   #21
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Default Dyno Battle Ground

Hey guys,

Let's NOT turn this into a battleground over the semantics of proper dyno use.

How about just sharing some useful information to have in hand when one is ready to plunk down their hard earned $$$. We are all here to help each other, RIGHT?
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Old 11-20-2002, 01:13 AM   #22
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Hi guys. Greetings from Malta.

Does anybody know what sort of dyno people like Oscar Jensen of Orion use.

They are using them all day - every day, so they must produce reliable results.

DTM. You're quite right. Actually that's exactly what CS told me to do, but a 7.2 pack is a 7.2 pack. One needs something with as much OOmph that can go through say 30 tests and still stay consistant.

I have actually used my dyno to test my cells sometimes. Same motor all the time and you get what the cells are giving you.

Regards

Joe from sunny Malta.
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Old 11-20-2002, 03:16 AM   #23
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poopsracer: "Homemade Dyno. No! I want a Dyno to give me USEFUL Data for motor tuning and comparisons. I do not need another "Toy" to play with. (My R/C cars are enough)"

I take that very personally...


...not

just don't bash all DIY dynos in one statement.
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Old 11-20-2002, 08:07 AM   #24
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Default DIY Dyno Bashing

Unless someone has the training in engineering, I believe that MOST homemade Dynos would just be "Toys" to play around with, NOT providing any real useful data to help with motor tuning. The AVERAGE R/Cer does not have the skills or the knowledge to create a USEFUL homemade Dyno. (Myself included)
After re-reading some of your posts, I can see that you are NOT average.
I have been an Industrial Maintenance Mechanic/Electrician for 25+ years and feel that I would not be able to build a Dyno that would provide me with any data of use AND I certainly could not write my own software.

Anyway's, I can afford to purchase a manufactured Dyno and was looking for feedback from current Dyno owners on the + & -'s of any units they may have owned.
I would like NOT to spend $500+ dollars on a paperweight. (even my HPI's are more than paperweights).

Thanks,
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Old 11-20-2002, 08:15 AM   #25
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On the 7.2 volt and the 12 volt discussion there is one point that is missing. When you first run the motor there is a huge current draw from the supply. When this happens the voltage from the supply drops.

So if you start out with 7.2 volts and then you have that huge draw you risk the chance of dropping that supply voltage below 5 volts which is what the motor runs at. That is why they recommend the 12 volt supply. A 7.2 will work but after a few dyno runs you most likely will not get the same results.

Once you have a motor that really rips on the track put it on the dyno and record the numbers. Then you have a baseline. It doesn't matter what dyno you have, the numbers are just for reference. I would stick to the CE, Fantom, and Robi only because I don't know much about the CS unit other than what I have read.
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Old 11-20-2002, 08:40 AM   #26
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Default Re: DIY Dyno Bashing

Quote:
Originally posted by popsracer
I have been an Industrial Maintenance Mechanic/Electrician for 25+ years and feel that I would not be able to build a Dyno that would provide me with any data of use AND I certainly could not write my own software.
I guess you didn't study hard enough...

Anyhoo, what I did is used 2 motors, a breakin stand, a couple of resistors, and a multimeter. With the multimeter, you measure voltage, which is ESSENTIALLY your RPM, it just isn't in that form. If you want to find and use the equation for RPM's, go ahead but it isn't too useful. Basically, what you do is use a certain spring/brush combination and then turn the system on. You take your voltage reading under no load and write it down somewhere. You then flip the switch putting electric resistance on the system (I used a 1ohm resistor on one side and a .47ohm resistor on the other). If your resistance is too high, then your motor wont be able to overpower the resistance.

Anyhoo, putting electrical resistance on the slave motor is essentially like putting rotational resistance on the test motor, giving us a voltage for torque. What you do is take all these numbers as soon as you pull the motor out of the packaging. You then change springs/brushes and see which gives you the most voltage for what you want. If you want lots of torque, go for high voltage under resistance, if you want RPM's go for high voltage under no load. It's not the most advanced thing in the world but it gets the job done. If you had a variable power supply (which I didn't so I just used a battery) you would get much more consistent results, but if you do it right, your results should be fairly accurate, even with the battery. Here is a picture:

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Old 11-20-2002, 08:59 AM   #27
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Aeon Racer: I think your dyno is cool! For those of us who don't have big race bugets, this is just the ticket! How do you set up that switch? What type of switch is it, two position or what? I'm buildin one guys! What are you getting for numbers? What is the range? I guess what I'm trying to say is how observable is the number change?

Just a side note: Can't remember who makes it, RPM, Racetech, or somebody, but I've got a motor work stand made out of plastic that has two clamps and can hold the motors in the same configuration as in your photo! Yahooo! Soon to be a "AeonRacer dyno" owner......

I just thought of something: If I use two or three packs in parrallel (I think thats the term) keeping the voltage 7.2, but providing a larger capacity to draw from, more consistant voltage.....hmmmmmmm! More consistant results?

Don't worry Aeon Racer, I've been beating the big buget boys with "junk and toys" for years.....


Last edited by Graphitedust; 11-20-2002 at 09:19 AM.
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Old 11-20-2002, 03:49 PM   #28
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Default Nice, but not for me.

I have been very good at designing and building any special tools that I've needed over the years. But I just don't have the time or desire to build my own Dyno. I also want software to do the calculations and be able to keep data files for comparison on my PC.
Besides, why would I COBBLE together a "Hack" Dyno when I can afford to buy a "Real" one? (just getting even )

BTW; if you do a Internet search for RC motor dynos. There is a link that tells you how to build one for testing 540 boat motors. Looks similar to yours.
If you've built one for yourself then that's GREAT. I am always impressed when someone can be so creative (except for the guy that made plywood suspension arms).
Every week I have 4 to 5 cars, electric and nitro to check, repair, set-up and charge the batteries on. So my free time is just about maxed out now.


Last edited by popsracer; 11-20-2002 at 04:06 PM.
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Old 11-20-2002, 05:32 PM   #29
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Here is a diagram for the switch. It's a 3 way switch (middle is neutral/no load, up is one resistance, down is the other):



You don't really need an exact number for RPM's, all you'd be doing is gloating to other that your motor has such and such RPM, and that's not what a dyno is for. A dyno is basically something to use as a reference point when tuning a motor. You take results, write them down, change something on the motor and see if you've made it better or worse. Anyhoo, if you have the money and want a "Pro" dyno, go ahead and get one. I'm only 18 so I'm on a tight budget (damn college). This was the better choice for me...

As for the battery thing, yeah, what you're saying is true. The power drain would be more consistent, which will more than likely give you better results. The voltage would remain at 7.2. As for results, I've noticed as much as .5 volt difference just by changing the springs around. I haven't even begun playing with brushes and all other little things that affect electric motor performance. Once I find some time I will start doing extensive testing...

Last edited by Aeon Racer; 11-20-2002 at 05:36 PM.
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Old 11-20-2002, 06:02 PM   #30
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Aeon Racer: Thanks! Is that two .47 ohm resistors or one? Looks like a "x 2" after the .470....hard to tell.

Ohhhh! I see now, one .470 on one side, two .470 on the other, Close to 1 ohm. Got it!

Popsracer: Aeon Racer is just trying to contribute positively, I hope your not as sarcastic as your post sounds.

Last edited by Graphitedust; 11-20-2002 at 06:06 PM.
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