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Old 04-14-2006, 11:01 PM   #1
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Default brushless motor question for a 1/8th buggy conversion

hi i was just wondering what the best brushless motors there are to haul the 1/8th scale buggy around i have seen people recomend the hacker or feigao motors. but im just not sure which one to get they are graded by winds and come in say example 540 9l with a kv rating anyone know which one i should be looking for to race with?
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Old 04-14-2006, 11:04 PM   #2
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A friend of mine did this with their Hyper 7 PCR and it would eat up spurs like popcorn or in your case vegimite I wouldnt do it, they got 5 minutes of run time and would eat another spur
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Old 04-15-2006, 12:25 AM   #3
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Default torque and rpm

yeah it depends on what its made of ive seen a few of these done on the net and they recomend using plastic spures with the mod1 pinions.
maybe a less torque motor might effect the spur and pinion mesh making it lighter on the spur.
but im just not sure on what brushless to go for a more rpm = more kv and a lower kv means less rpm but higher torque how does that work? does the more torque lower rpm and lower kv mean more power under load?
correct me if im wrong im not sure.
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Old 04-15-2006, 12:34 AM   #4
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Actualy you can get great runtime out of them. If you run a parallel circuit from two 8k mah 14.2V lipos you should be able to get around 3 bhp and 30 minutes of run time. A good place to check for motor/esc recomendations would be an r/c boat forum. They have regular classes that run 12-24 cells and should be able to point you in the best direction and give you a recomendation on what will allow you to run a 14.2 volt setup w/ 16k mah for 20 minutes or so.
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Old 04-15-2006, 01:41 AM   #5
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My Hot Bodies Lightning Pro II conversion is running two Flightpower 4S LiPo's, Feigao 9L and the BK 12020 Warrior Controller. It is as fast as any nitro buggy I have ever seen. It flat out hauls!
An 1/8th buggy conversion is fantastic and there is a lot of talk re. them on RC-Monster and Radio Control Zone.
The issue stated above re. the spur gear problem. If you are not running a hardened steel Mod 1 pitch pinion, you have to use a plastic spur gear. There are adaptors available for you to switch out your metal spur and run an OFNA plastic spur.
Hope that helps.
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Old 04-15-2006, 04:42 AM   #6
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yeah cool im converting my x-ray xb8 (the race one) and just need to figure out what motor to use in relation to what battery type and specs to use in relation to the motor i choose.
i see alot of people use the lipo's and some use nimh from 12 -16 cells.
i know the li-pos are lighter and can have more mah but the price is alot though if i sell my kyosho inferno buggy with engine and all my nitro stuff from the xb8 with the starter box i might be able to afford it.
ok couple of main questions what kv rated motor is best for the lipos beacause if i ran them in series it would have to much rpm = overkill.
i want something fairly even not over the top good torque and good rpm with plenty of punch.
so if i take ur advise mpetrich and go for lipo's can ya connect them up in series or do they last longer in paralel?
whats the deal with hooking batts up in paralel and series i know in series they increase voltage but not in paralel though do they increase in mah capacity in paralel??????
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Old 04-15-2006, 05:24 AM   #7
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The best brushless would be a Lehner. I'm runing a 1940 series 8 turn in my revo on 14 cells with a BK warrior 12020 controller. It's just as fast as any nitro with tons of torque. A 1950 might be good for an 1/8 scale. Run lipo's if you can afford it. Two of those ORION packs wired in series to make a 4s pack would be a good set up. rc-monster.com is a great sorce for bl info, that's where I got everything for my revo. Get on their forums and read some threads and ask some questions, they are very helpfull.

The only bad thing is with the high end Lehner's you need deep pockets, My bl cost as much as a good big block nitro would, lol.
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Old 04-15-2006, 11:23 AM   #8
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If your pressed for $$ you could order 4 3k mah nimh sport packs from tower hobbies. Set them up so that you will get 14 volts and 6k mah. Take the possitive of one end and connect it to the negative of another pack. Now you have a possitive and a negative end which you will keep loose. Do the other pack the same way. Now take the two loose possitive ends and connect them togather. Then connect the two loose negative ends. This will give you a $60 6k mah 12 volt battery. If your still pressed for run time or power then add batteries accordingly. The ones with opposite ends connected will increase voltage and the ones with the same ends connected will increase run times. If you can afford the lipos. You will just connect each negative end. Then connect each possitive end. Now you attach each separate pole to the car. The reason wires get soo hot when you hold them togather with one battery is because you complete the circuit so the battery will dump the power through the circuit. There is tons of amp draw and tons of resistance which help to create the heat.
Set them up like this diagram here. A cheap nimh charger and a dynapulse should charge and keep your packs in good shape. If you plan on running more then once a week then a 2nd charger& dynpulse may be neccesary. When you connect the packs use some sort of plugs so that you can unassemble them for easy charging. If you are running an electric 1/8th scale then odds are you are running indoors on a smaller track. This means you aren't hard pressed for a stellar engine & setup. Perhaps all you need is something like the novak setup for the t-maxx. It suposedly puts out around 2.2 hp.

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Old 04-16-2006, 03:52 AM   #9
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yeah id probably be inclined to go with the lipo packs seeing as though they are more efficient,lighter and have more power and mah available i just need to know the engines ability with different packs like 6000 mah is probably enough but if i connect 2 together wont it be double and be 12000 mah or does it only double the voltage when connected in series. i know if i connect 2 7.2 packs it will be 14.4 volts total or should i go for a higher voltage lipo and connect them in parralel which means the volts stay the same but the mah is double? and go for a lipo with 14.4 volts on its own and double it in parralele to keep the volts as is and not double like it would in series.

and if so what kv rating should i be looking for to race. too high of a kv and its low torque but high rpm, not enough or small kv rating it will have alot of torque and less rpm meaning less top speed.should i just be going for mid range kv rating of the hacker range? and have mid range torque and rpm ,top speed.

ive seen the ratings of the hacker b50 series and the c50 series and was recomended to get the c50 series and they range in kv from 1900 or so kv right up to 4000 kv.
and was told that each volt input equals that of the kv rating so you times the kv rating of the engine by each volt input to it to get the max rpm. but dont the motors have a max rpm limit i can use as a guide for how many volts should use when connecting lipos up, so then i know whats gonna be to high and settle for what the engine needs without all the overkill that could occur.

confusing if your with me and follow what im on about then reply if not keep ur mouth zipped because its nerly confusing me.
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Old 04-16-2006, 10:03 AM   #10
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Hi downunder23,

I have done a conversion for my sacker 1/8 scale buggy. I use a kyosho plastic center diff with a 5mm bore mod 1 pinion. I am using a feigao 10L motor with a BK warrior 9920 esc & 5S lipo 3200mah. I'm not really sure how long the run time is like as my driving is poor. This system is pretty stable so far (I had a 7XL in place of the 10L but ran into esc overheating issues).

Do have a look at a couple of videos my friend shot a few weeks ago :

http://www.rctech.net/forum/showthread.php?t=107432

If I am not mistaken the 10L is rated at around 2248rpm/V. That translates into around 41000rpm with 10% loss under load & 5S lipo (@3.7V/cell). More than enough I think. You can get something hotter in the form of a 8L but you'd be pushing over 50K rpm with 5S lipo.

If you put cells in series you add up the voltage while the capacity remains the same. If you parallel the cells the capacity adds up with the voltage remains the same.

Another thing to note is that batteries, even with lipos, are heavy things. With 5S lipo rate at only 3200mAh, my e-sacker is already around 500g heavier than its nitro counterpart. This affects handling.

Regards,
Joe Ling
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Old 04-16-2006, 10:30 PM   #11
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hi thanks for your help much appreciated .
how many rpm did your 7L motor go?
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Old 04-16-2006, 10:54 PM   #12
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Default battery packs.

hi can you answer this joe ling what if i have 2 battery packs with all the cells in series like a stck pack premade for example then can i connect them 2 individual packs in paralel to get more capacity but use 14.4 volt lipos in like 4000 mah in paralel would make 8000 capacity with the 14.4 volts remain the same.
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Old 04-17-2006, 07:56 AM   #13
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downunder23,

The 10L is rated at 2458RPM/V under no load (small error in my earlier post) while the 7XL is rated at 2382RPM/V. However, the 7XL's max current draw is rated at 95A while the 10L can pull only 61A. More torque to the 7XL with a slight penalty in ultimate speed compared to the 10L.

I'm not exactly sure what you seek in your last question. If you have 2 battery packs of the exact voltage & capacity & type, then they should be able to be stacked in parallel with doubling of capacity while voltage rating remains the same. E.g. 14.4V 4000mah per pack after making 2 of them in parallel will give 14.4V & 8000mah capacity. Do not parallel packs with different voltage rating. Packs with different capacity but same voltage rating is also a bad candidate for putting them together in parallel. Hope this is helpful.

One advise. If you have to ask the question about parallel & series effects of battery packs, please seek assistance from friends or persons at your local hobby shop. Better to play safe.


Regards,
Joe Ling

PS : Which part of Australia are you from ? I used to stay in Perth.
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Old 04-18-2006, 05:04 AM   #14
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Default VOLTS/MAH

joeling i am in the illawarra region of nsw.....
hi i was just wondering if you could answer this what would be best to have for the 1/8th electric conversion either more voltage or more mah?
because i think i will have to settle for the nimh over the lipo's due to price though was wondering would it be better to link 2 6 cell nimh in series to get the 14.4 volts for more punch which then leaves me to settle for 3800mah which is the highest mah for a nimh battery or alternatively connect two 6 cell packs in paralel and get 7800 mah whilst having to make do with only the 7.2 volts.

im thinking to connect in series for the more volts for more punch outta my yet to buy HACKER C50 MAXX motor. am i correct?
and just hope that 3800 mah is enouph for a couple of heat races.

so basically would more volts be more appropriate for this set up or is 7.2 v enough/not enough?
3800 mah cells should last at least two 5 minute races shouldnt it, not to mention the fact its duel battery.......................... im unsure.

thanks regards Aaron.
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Old 04-18-2006, 05:45 AM   #15
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Default amp draw

hmm joe i am now unsure of what batteries to go for the lipos or the nimh i just checked out the team-orion packs and there best packs of 3800 mah 7.2 volt matched packs only give a discharge rate of 30 amps this is so limited compared to that of the lipos which i seen were discharging at like 90 amps or so is this true to get more amp draw more torgue, power, speed and acceleration. shall i spend a bit more money for longer running higher power lipo's ? the higher amp draw of the lipos should make the power difference alot more than that compared to the best of the nimh packs am i right on this amp draw part?
sorry for all the questions just want to know what im in for when i do the conversion.
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