neumee_s23

Hey Guys

I just started in the rc world two weeks ago and man am i ADDICTED! Had my Losi Mini Buggy for 4 days, and already was set on hopping it up I got all the parts a few days ago, and got them installed, however something just doesnt seem right, and my Local hobby shop just doesnt seem to be helping, so here I am First let me tell you the hop ups I got:

Xcelorin 7400kv brushless motor ( Iknow OVERKILL, but i didnt know when i made the order so w/e lol)
Xcelorin ESC
Losi Ball Differential with Outdrive
Losi Dual Slipper Clutch
14T Pinion
Stronger Drive Shafts

The first issue that i ran into was after getting everything installed, is when i pushed the throttle to go forward, the car shot backwards. At the same time, the car was MUCHfaster in reverse then forward... This was fixed by reversing the throttle on the controller, however the speeds are still VERYextinguishable beween the two different directions... Reverse is much slower now then it was when i got it stock... Is this normal when you hop it up?

Next Major thing that i am noticing is when you spin the left tire, normally the right tire would spin in reverse, however this is not the case, it feels like it is just slipping. However this is not all the time, sometimes it will spin the right tire, just as you would assume. I couldnt get this figured out, so i put the stock differential back in, and it seems to have made the problem better, still not solved, and the car did get faster after putting the stock one back in... Any ideas???

A minor issue Iam having is sometimes, after running the car, and i put it on the floor, and just try to push it forward with my hand, the rear tires are locked up, and drag across the floor, i didnt think that this would happen, at all...

Finally, knowing that i got an overkill motor for this Buggy, i assumed it would be MUCHfaster than it is... Dont get me wrong, its definately faster going forward then it was when i bought it, but full throttle i assumed would be so much power that the car would get the front tires up in the air, and really take off, however its only topping out i would say just shy of twice the speed of it stock, it doesnt feel like the motor is even close to overkill.From what i have heard, the ESCComes set up stock at 100% full throttle. Ihavent been able to get the esc and my computer to link up to confirm or not though...

Really any advice You can give a noob like me would be greatThanks in advance guys!!!

Xmoto16

Desert Buggy not desery

and for your first issue if you can reprogram your radio and receiver and if that doesnt work  then flip the motor wires im not very familair with xcelrion systems so you should refer to a losi forum to get best info or ur manual

neumee_s23

Thanks for the quick post

Iwas able to get it going forward when pulling the throttle back on the reciever by just simply reversing the throttle on the controller...I did try to flip the motor leads as well, and it worked in terms of pulling the throttle back to make it go forward, however, It then went super slow forward, and flew in reverse, so it solved one issue and created another lol... Like i said, flipping the throttle on the controller solved that, i just wanted to give everyone a good picture of what i have already done

Slo-V Flyer

OK, so I was gonna say the same thing first, that if it's doing the opposite of your throttle direction, flip the wires. But as you said, you also had to flip the throttle channel, which most newbies don't know or think about. So it sounds like the ESC is doing what you are telling it to do, and the motor as well (so it really is going forward when you tell it forward, and backward when you tell it backward).

As for the slow speeds despite the overkill setup.... what batteries are you using? Are they getting a full charge? I don't know what charger they include with the Desert Buggy, but if it's a wall charger, it is possible it's not getting a chance to full charge the battery. Does the battery get somewhat warm after you take it off the charger? How long is the recommended charge duration according to the manual?

Ok another reason for slower speeds, check your gear mesh, and drive train for binding. Remove the pinion gear, or simply move the motor away from the spur gear, and roll the car on the ground, spin the tires by hand. How smooth is it? Does it coast an OK distance? When replacing the motor/pinion back in place, make sure that it is not a tight mesh. The spur gear (the larger one) and pinion gear (the little one on the motor) have a tiny amount of slack or play between them. This will insure they are not physically pressing against each other and creating tons of friction and resulting in overloading the motor and stuff.

Yet another thing to check, you mentioned the upgrade diff was acting weird when you spin a tire on one side and the other didn't do what you thought it would. The ball diff, assuming you built it right, is designed to limit the "open differential" action that you ordinarily get from the stock diff. That means, if you spin one tire forward, the other should not turn backward if you tightened the differential assembly at the adjustment screw. It will act as a limited slip diff, so you might have the other tire spin in the same direction as the tire you spin by hand (which will result in the motor being turned also..)

If there is any binding in the transmission anywhere it will cause you to lose performance.

If the batteries are not charging right it will not get full power and run slower.

If the motor is under geared (too small a pinion or too large a spur gear) the buggy will not go fast.

If the motor is OVER geared (too large pinion, too small spur) it will overload the motor and the buggy will not go fast (and you will heat up the motor, ESC and battery rather quickly).

Check all this stuff and get back to us. These are basic things I just thought of so don't feel offended if I stated any obvious things.

Also, RECALIBRATE your ESC to your radio transmitter, since it is a new ESC. That means the ESC needs to "learn" what the throttle range input from your radio means, as in 100% point, neutral, and 100% reverse, and it figures out the in between. In general, anytime you use a new ESC with a new radio (or change radios) you need to recalibrate the ESC to the radio so it reads the throttle properly. That itself might be the reason why you aren't getting all that crazy power.

neumee_s23

Thanks for all the Info Slo-V

The battery that i am using is the stock 7.2v 1100 mah NiMh battery. Ialso have a 11 volt 1350 mah Lipo, but i havent taken it out of the package at all yet, and am unsure if i will or not...I do have a wall charger for it, wel actually two... the stock one that came with it ( usually about a 6 hour charge) as well as a peak charger that i use ( charge time about an hour) The battery does get warm after a full charge.

Idid recalibrate the esc and controller together, so we are good there, however i still cant seem to get the losi esc program installed on my computer to tune the settings... interesting lol...

Iwill post again after i pull the motor back away and try to push the rc forward to check how far it cruises Thanks again for the help

neumee_s23

Alright, so i just pulled out the motor and slid it across the ground, it slid just fine with no catching or anything like that, so that good Getting back to the Diff problem, like i said, i did go back to the stock diff. When spinning the left tire, i can see it moving the spur gear and pinion gear, however the right tire does not move at all.. When spinning the right tire, the left tire spins in reverse, like i assume it should, and the spur gear and pinion gear do not move, again, how i assume it should... Now i am of course talking about having the car off holding it in the air with my hand and hand spinning the tires individually... is this normal operation?

Also my dual slipper spur gear has 60 teeth, and i have a 14t pinion... Does this seem like the right ratio?

Oh and BTW for anyone looking for a LiPo upgrade for the mini desert buggy, the LOSB9829 11.1 v 1300mAH 3s LiPo 20C WILL FIT into this buggy no issues... I only say because i spent alot of time researching online to find the answer to that question, and i couldnt find it any were until i got it home and tried :P

Slo-V Flyer

Alright so the lipo will go a lot faster, but the Nimh generally should provide enough punch, considering the size of the model and typical amp draw.

In any case, what you described about the diff sounds like. Assuming you don' let the motor spin, turning one wheel typically in an open diff (like the stock one) will turn the other wheel (in the opposing direction). Now with the hop up diff it is designed to be adjustable and if you wish, not "slip" or which means it may (depending on how tight you adjusted the screw that holds it together) move the other tire in the same direction as the tire you turn by hand, and of course that means it will turn the motor along with it too if the slipper is adjusted very tight. Now if that is what it does with the new diff, then that *should* still be ok. You should still be able to hold both wheels in your hands and still hold one down and be able to feel some resistance as you turn the other (which will turn the motor too), or hold the spur still by hand and turn one wheel to cause the other to spin the opposite direction, but with some more force.

The gearing is or should be fine for this motor for now, it does not seem excessively tall (though with higher voltage generally it is recommended to go down a couple teeth to ease the heat some).

In any case, it sounds like despite whatever the diff is doing, it is your buggy that you feel is not going much faster. All I can say is try the lipo and see (with a careful trigger finger) if it goes much faster or not. It should fly with that setup really, but if there is something wrong with the ESC or motor then who knows.

The other thing is I don't know what the default settings are on the ESC, so if you get that setup and see what's going on, it may help. Though again most default settings should not hinder performance. Oh and if you get it working, if you can, set the low voltage cut off to "auto lipo" mode if you are able to. This will allow you to run your Nimh and 3s 11.1v lipo and the ESC will know when to stop running once the liop battery reaches a cut off point.

neumee_s23

Thanks for the advice ATMI have it on the charger, waiting to see it get going, i have taken it apart and put it back together following all the info online as i can, and thought that the battery was charged fully, but i guess it wasnt ( i am thinking its got to do with what you were saying earlier about wall chargers sucking lol) becuase i would pull the throttle it would not do anything, but i could turn the tires, then the car would lunge forward (much faster then it was) but stop right away. SO i am thinking a trip to my lhs this afternoon to pick up a multi charger to charge my lipo and nimh... still not sure about the lipo though.... lol

neumee_s23

Ugh. So the battery is definately fully charged. But i am still having the same problem. If i hold the car in the air, and pull back on the throttle, the tires will spin, most of the time, as soon as i set it down, it will take a second, the green light will come on on the transmitter, it will shoot a few feet forward, the green light will go off on the transmitter ( even though i am still holding down the throttle) and the car will come to a complete stop. I wont even be able to turn the tires... Then the green light comes back on the transmitter and repeat over and over and over... Is my transmitter or servo bad now???

Slo-V Flyer

Not your transmitter, you mean to say your ESC (eletronic speed controller) for your brushless motor. Your transmitter is that radio control gizmo in your hands.

I think it is a GOOD chance that the Nimh you have is just unable to power this motor. Being it is a higher Kv motor as you said earlier, it needs a good battery to supply it with current and Nimh usually do suck at it. I was just hoping your Nimh was going to be enough and this wouldn't be the issue considering the size of the motor involved. If I understand this correctly, then you should be able to have the motor go 100% with the tires off the ground right? Again, if you have that lipo ready, plug it up, just test it for a few seconds and see how the car behaves. If it drive steadily (no need to go 100%!!! just pull it half way) for more than a few seconds, then you know your Nimh battery is crapped out for brushless motor duty.

Just to confirm, can you at least give it partial throttle and keep that Nimh from browning out? As in, just pull the throttle a little bit, say 1/3 power, does that still cause the motor to stop-go-stop?

That sounds like a very typical response when using a Nimh battery that is not able to supply the amps to the motor when you gun the throttle from a stop. The battery is struggling to supply the motor with enough current, which means the voltage probably drops big time (normally voltage drops a few decimals or 1 unit when under a load) the receiver and other electronics brown out and shut down, the battery gets a chance to go back up in voltage, the ESC comes on again, sees the throttle is being pulled WOT (wide open) tells the motor to spin, the motor pulls the amps again needed to get moving, the battery struggles, the electronics die out again.... and on and on.

Motors take a lot of juice to get started from a halt. Brushless motors are a bit more intense that way. That is why you'll see most people not bother with Nimh when moving to brushless motors. They are just not good enough in the long run. Hopefully you figure it out.

neumee_s23

I tried pulling it one third of the way... it feels like even pulling it a little bit the throttle still responds as an WOT state, its either all or nothing... Only reason the Lipo isnt hooked up yet is the lack of a charger... any ideas on a good one?

Also kind of an update on the differential progress... I tore it back apart and just flipped the differential from how i had it ( right to left and vice versa, the tire spinning issue seems to be resolved, for the most part, however the speed feels like it was cut in half... Why would this happen?

Slo-V Flyer

I am not sure why you're having difficulty with the ball diff, it may be that you don't have it tightened down enough, so it's actually slipping altogether and not putting all the incoming power out to the axles.

The 2 pressure plates are pressed against the ball bearings with force, and when they are too loose they actually slip like the slipper clutch, and if too tight, they don't provide much diff action, which is how you get your posi-traction or limited slip to work.

I'm sure someone with more experience with the diff can chime in, I've got one in my Mini-T which is identical to yours I think, but never had such issues.

As for the motor turning either full or nothing at partial throttle, seems like there's something not right about that whole thing, the radio and ESC either are not calibrated right, or your battery is soo pooped, that it's just not even able to spin it to proper RPMs.

As for a lipo charger I'll let someone else chime in, but from what I hear, hobbyking.com has some good ones for cheap, Turnigy ACC6 or similar clones are good for all kinds of battery chemistry, and they need a 12 volt / 5 amp power supply, also found on their site. In total these 2 pieces should cost you about $50-$75 + shipping, which is actually a damn good deal. These chargers also have a built in balancer for lipo cells, so it keeps it in good shape.

neumee_s23

I just want to sy thanks Slo-V the information you have given has been proven to be invaluable... I think I was just assuming it was much slower becuase it would only "pop up" and then die... i was able to get the tires spinning then let it down on the ground and it took off like a bat out of hell lol... went about 50 feet with the front tires up in the air, and the tires still spinning so fast they were slipping on the pavement lol. ( lol keep in mind that i have the throttle on the esc set at only 60% lol)

I think i am going to go and buy a lipo charger real quick, get my lipo battery charged, HOPEFULLY that will solve my issue... The only thing about it being the battery that doesnt make any sense to me, is with everything installed yesterdayas it is right now in the car, i was able to open it up and go no issues... but then again i was on dirt/gravel, not asphaly like i have been all day today... HMMM as soon as i get this beast running right i guarantee that i will put some wicked vids up

Thanks again guys, keep all this Info coming

neumee_s23

Another Question: So we have decided its either the battery itself messing up, or the esc. Assuming its the battery, your saying that its too weak to handle the power of brushless. Is this becuase its only 7.2v or because its NiMh? if i went to a 7.4v Lipo 1650 Mah would that be strong enough to handle the power? Wich brings me to question 2. If it will be able to handle the power, and i get the LOSB9630 battery/ charger will that charger also charge my 11.1v 1350 MaH Lipo as well?

Slo-V Flyer

I can't answer about the Losi specific charger, but if you get a 2s lipo battery, then yes, assuming it is rated to handle the Losi mini buggy brushless system, it will most definitely be a night and day difference. So yes your battery is having a common issue that many Nimh systems end up having. They are simply not able to provide the current the higher Kv motor is trying to pull, so it is causing all sorts of problems (dropping way too low in voltage and cutting out power to the ESC and receiver for one thing). I think if you already have one lipo, the 3S, just testing with it first before spending any more money would be wise in the short run. But yes, given the motor's RPM I would say a 2s lipo is probably going to save you from broken parts and still provide PLENTY of punch and power.

neumee_s23

lol i know i got the 3s at the same time i bought everything else lol... Wish i would have researched everything more than i did lol... I didnt really start really looking into it until i started running into problems, so my overall cost has shot to about 500 dollars in two weeks, in the car itself and the replacement parts / hop ups lol eh, live and learn

bhchan

don't know if you solved this or not, but reading this, I'm wondering if your new ESC might be in the 'training' mode that I see mentioned on some models... (at least the 1/10 ones that have mode 1 = normal, mode 2 = racing (no reverse), and mode 3 (default) = training (half speed))