Electronics question--BEC/fan/3s glitching

[kjr2]

I'm not sure whats wrong but here's the situation.

I have a brushlesshobbies.com 120 amp esc connected to a 4000kv sensorless motor. I ran 2s and 3s on it fine for a while. Then one day after running around with 3s I pulled the body to unplug the batt and noticed the fan died. After contacting brushlesshobbies I found out that was my bad. I burned up the fan. Turns out if you want to run 3s you have to disconnect the fan from the side of the esc and plug it into the receiver. I'm not the type to read the directions

So I went to my lhs and got the only fan they had, a muchmore super high rpm fan. And I plugged it into the receiver this time.

Now when I run 3s, the radio will randomly cut out and the car just sits there making a weird lettle sound from the servo. I have to turn off the esc then back on and it works for a little bit again. This only happens on 3s. Does not happen on 2s.

Radio is ofna 2.4. Gearing and temps are fine.

Do you think the high rpm fan and 3s are too much for the receiver? It don't make sense to me why it happen on 3s and not on 2s.

Think I need a battery pack for the fan?

 

[william g]

sounds like the fan is over powering the BEC output dropping the voltage to the receiver and servo.
Either get a external BEC, or use an aux power source for the receiver or fan
or
wire that fan directly to the battery plugs

 

[kjr2]

I would try soldering the fan wires to the battery lead on the esc but then the fan will be getting too much voltage I think. If I plug it into the side of the esc on the fan port, it will run and not cut out but the fan spins suuuuper fast and loud and I don't think itll last too long like that.

On a side note, can the sv2 handle 3s and a 4600 motor without giving me crap? This is in a rustler. I know on paper they say it can do 3s but can it actually? Can I hook it up and it'll work? And do they make a fan for the sv2? Would the sv2 need a fan on 3s? I noticed the hpi rebadge vapor pro 2 has a sick looking fan on it.

I think you can see where I'm going with this...

 

[JKRacing37]

Have you tried running 3s without the fan plugged in at all? Also, what radio and servo are you running?

 

[william g]

Have you tried running 3s without the fan plugged in at all? Also, what radio and servo are you running?

agree, try that and see what happens

SV2 and a 4600 in a rustler is no big deal on 3s. Lots of guys do it. A fan, you can get a fan for the sv2, or put the sv2 guts in a mamba pro case. Check castles site for the s2 fan p# or suggestions

 

[kjr2]

Have you tried running 3s without the fan plugged in at all? Also, what radio and servo are you running?

no i never tried that i was afraid to cook the esc. im running stock xl5 servo whatever that is and ofna/hongnor/hk 2.4 fhss http://www.hobbyking.com/hobbyking/store/__12177__HK_300_3_Channel_2_4ghz_FHSS_Ground_Radio.html mine is hong nor but theyre all the same afaik

agree, try that and see what happens

SV2 and a 4600 in a rustler is no big deal on 3s. Lots of guys do it. A fan, you can get a fan for the sv2, or put the sv2 guts in a mamba pro case. Check castles site for the s2 fan p# or suggestions

ill try it no fan and see what happens.

 

[kjr2]

heres the actual radio i got
http://www.ebay.com/itm/380435880353?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

 

[JKRacing37]

Well, does the incident happen right away with the fan plugged in or does it take some time for it to happen? I'm not recommending bashing a whole pack minus the fan, but if it happens right away just test it a short time and see if it does it.

 

[kjr2]

It seems to happen when I'm turning and blipping the throttle at the same time. But not everytime just sometimes. If that makes any sense!

 

[JKRacing37]

Does that radio have end point adjsutment for the steering? If so make sure your end points are not set past the mechanical limits of the steering. If so the strain on the servo might be over drawing the BEC causing a brown out of the receiver. It could happen only on 3s due to the increased current drawn by the fan on 3s.

 

[william g]

that is a weak BEC unit
I'll bet it's only a 1amp BEC output and your servo or throttle draw that alone never mind adding things. I'll bet good money you put a receiver pack or external BEC and it goes away

 

[kjr2]

Does that radio have end point adjsutment for the steering? If so make sure your end points are not set past the mechanical limits of the steering. If so the strain on the servo might be over drawing the BEC causing a brown out of the receiver. It could happen only on 3s due to the increased current drawn by the fan on 3s.

Ill check that and make sure the servo EPA is ok

that is a weak BEC unit
I'll bet it's only a 1amp BEC output and your servo or throttle draw that alone never mind adding things. I'll bet good money you put a receiver pack or external BEC and it goes away

OK I'll see what happens when I check the EPA. then I'll look for one of those little 4 cell battery packs for nitro trucks and plug the fan into that

 

[JKRacing37]

BH ESC's have a good BEC in them (3A). I can run a Savox servo in my SCT without a cap or external BEC which is quite a feat.