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-   -   Micro RS4 RTR Review (http://mini-zracer.com/forums/showthread.php?t=4792)

pkh 2002.10.10 04:31 PM

Micro RS4 RTR Review
 
Someone asked me to post a review of my Micro RS4 RTR Kit, so here's my initial impression of it. Keep in mind I'm going from a Mini-Z to the Micro RS4, so my views will be skewed accordingly! I've only run it inside my house so far, as it's been wet and raining outside since I got it (and running outside is where it will really perform). If anyone has some specific questions to ask about the RTR version that aren't covered here, feel free to ask away.

First of all, RTR is not quite right, "ALMOST RTR" is more accurate. I say this only because it takes 30+ minutes for a newbie to mount the tires, install the battery pack, etc. to get it running. With the Mini-Z, you just have to screw on the antennas, pop in the batteries, and go (5 mins or so). I ended up putting a very thin film of vaseline between the wheels and the hubs (on the chassis). Otherwise it was virtually impossible to pull the wheels off again!

I was a little dissappointed in the body. It's prepainted with decals on the outside surface, but whoever applied the decals did a half-a$$ job at aligning them. Being used to highly detailed Mini-Z plastic bodies, this flimsy lexan body is not as cool looking.

The turning radius is much larger than the Mini-Z, which makes it a little more difficult to run in the house. However, the ESC has a "feature" that really makes it a pain in the a$$ to run in tight quarters: a 2 second lag going from forward to reverse (see more below). With the Mini-Z, I could go back and forth to work my way out of a tight spot, but this takes forever with this Micro Pro Control ESC! So far this 2 second lag is probably my biggest gripe about this car... very frustrating to me! If anyone knows a hack or a way to reprogram this ESC, I'm all ears!

Now let's jump to the electronics...

ESC:
The RTR kit comes with HPI's Micro Pro Control ESC. This looks like it will handle just about anything I care to throw at it. It will handle 4 to 6 cells (4.8V to 7.2V) and has current ratings of 200A peak and 80A continuous! As I mentioned above, I don't like the 2 second lag going from forward to reverse, though. The ESC spec sheet says that during this 2 second lag, the ESC is braking. At first I tried the brakes on carpeting and didn't see much of an effect, but running fast on a linoleum floor proved that the "brakes" really do work pretty well. Reverse on this ESC is limite to 50% of the max throttle to "maintain controllability" according to the spec sheet (this is not a big deal to me). One interesting thing to note about this ESC is that it uses discrete power MOSFETs, and there appears to be an additional slot in the case and holes on the PC board to accomodate an additional pair of MOSFETs. I am guessing that this may let you double up on the forward drive MOSFETs to lower the on-resistance and increase your top speed (this is only speculation at this point).

Receiver, Servo, & Transmitter:
These are all Airtronics units rebadge as HPI. I'm impressed that there is virtually no glitching of the steering like the Mini-Z (I'm guessing that this is due to the fact the the ESC and the receiver are two separate units, and noise from the ESC is much more isolated from the receiver circuit). The transmitter has less travel in the steering wheel than the Mini-Z transmitter, and much less travel in the reverse portion of the throttle control, both of which I don't like, but I will probably get used to it! Otherwise, the quality and performance of these components seems OK to me so far.

Upgrades I'm currently considering...

I'm thinking of adding a 5th or even 6th AA cell to my Micro. I've got a couple of single AA battery holders from Rat Shack that I can splice in series with the 4 cell AA battery holder. Looks like one will fit on top of the chassis just behind the front wheels, and another will fit next to the receiver. I don't care for the multi-cell packs since there several times more expensive than AAs, and they have much less capacity (granted, they would be lighter). If I do this I'll use battery connectors so I can use either 4 cells or add in the extra cells by swapping plug connections.

Well, there's my long-winded review for what it's worth! I'm not sure how I came across above, but in general I have to say I am happy with my micro, despite my gripes :) . All wheel drive is very cool! The foam padded tires are also very cool!

Regards,

Paul

ScottMcLeod 2002.10.10 11:16 PM

Got mine too, but it was a kit, not RTR...

Unfortuately the previous owner made a lame-ass choice in ESC... and it's an Novak T1 (no reverse, good power handling, but no reverse...)

You think it was hard to drive YOURS indoors... try mine.

Mondo 2002.10.11 03:04 AM

Re: Micro RS4 RTR Review
 
Quote:

Originally posted by pkh
I'm thinking of adding a 5th or even 6th AA cell to my Micro.
A word of advice.
Don't waste your time and effort with AA batteries.
Rather go for a Team Orion 7.2V 1100mAh NiMh battery pack.
Using the battery alone will unleash the true potential of the Micro RS4.
Fortunately, I've never run a Micro with 4xAA cells, but I have seen them in that trim and they are slow.
As you are aware, there's a huge Micro RS4 Thread on the go.
Take the time to read through it and share the trials and tribulations of the The Microteers, namely, DAMZer, The Thunderer and yours truly.
I am sure you will learn a lot from that Thread.

The Thunderer 2002.10.11 04:07 AM

Quote:

Originally posted by ScottMcLeod
Got mine too, but it was a kit, not RTR... You think it was hard to drive YOURS indoors... try mine.
I'm sorry about your woes Scott, but at least you've got a micro now! No Reverse is no problem. Just go outside to a basketball court or tennis court that isn't in use. OR, just go in the street... just beware of cars... remember, you can't REVERSE out of the way! LOL.
Nah, an ESC will come your way soon. You're a persistent guy, I'm sure you'll find one somewhere!

Good luck!

Oh, PHK! I concur with Mondo whole-heartedly about the pack! THAT will knock your socks off and you won't be running it in your house afterwards. Only "the streets" would be a big enough playground for that.

You can also solder your own. I just soldered an 8-cell pack together and it is AWESOME. A little quicker than the typical 6-cell pack so much more fun!

ZGhostDogR8Dr 2002.10.11 09:50 AM

pkh - Great review of the RTR. Looks like you give an overall thumbs up. I am glad you are happy with the purchase.
Seems like a fair enough deal.
I agree that a batt and motor upgrade will turn night into day. I saw that coming though;)

So the MRS4 RTR comes in two kits eh? Skyline and BMW? Which do you have? I have a Toyota shell that actually looks very decent after paint and decal !

pkh 2002.10.11 12:47 PM

Mondo,

I was planning to get to 7.2V by adding two of extra AA bat holders to string together 6 AA cells! Total cost: $8 ($2 for the batt holders and $6 for another pair of AA NiMH batts). This will give me 7.2V @ 1700mAh, 50% more capacity than the Team Orion batt pack, and much less $$! Also, I can use my AA charger, and don't have to shell out $$ for a multi cell batt pack charger. Granted, I'll have more weight with this option, but I think the $$ saved and extra run time will be worth it to me. Plus, if I add in these extra cells in via another battery connector, I can drop back down to 4 cells easily to run indoors by swapping the battery connections and popping the 2 extra AAs out of their holders (reduce the weight if they're not used).

Thunderer,

There are actually 3 different RTR kits for the Micro RS4: BMW M3 (mine), Corvette C5, and the Nissan Skyline. Pro-Line has a Lexan Ferrari 360 Modena body I'm thinking of getting. I really like the look of my Mini-Z Modena body, and after seeing the quality of the Micro RS4 RTR pre-painted body, I figure even with my poor hobby/painting skills, I can produce a painted body just as good!

Scott,

OK, you've got me there, now I don't feel so bad about my ESC reversing problems! Actually, after having run this some more around the house, I can see that the braking function will be a very nice feature to have when I can finally run this thing outside! It's just a pain inside my house!

Regards,

Paul

Mondo 2002.10.11 02:21 PM

ESC Reverse
 
PKH,

The delay between brake and reverse is there for a reason
Can you imagine slamming on the brakes hard during a race because the driver in fornt of you has lost it, then while your still moving forward, the ESC kicks into reverse?
The result is obvious.
That is a shyte example, as most clubs wont allow racers to compete if their ESCs have reverse
Most ESCs have this delay between brake and reverse, including my pair of Novak SPYs and my M-Tronik.
All my ESCs have a "reverse disable" feature.

pkh 2002.10.11 09:34 PM

Yeah, Mondo, I understand the reason for the delay between brake and reverse, but I would have preferred it to be implemented differently, or at least be able to disable it. For example, it sounds like the Mini-Z F1 doesn't use a delay, but brakes with the first reverse throttle application, and then goes into reverse the second time you hit reverse throttle. This would be much better for me... a quick double tap into reverse would allow me to back up. Instead I have to wait a couple of seconds every time I want to change directions.

We each have different needs in an ESC. Sounds like your into racing, so you probably want good braking and could care less about reverse. However, I want maneuverability (quick fwd-rev changeovers) in tight quarters indoors, and braking outdoors.

As they say... to each, his own... :)

Paul


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