Old esc on lipo getting hot
09-06-2012, 03:16 PM
#1
Old esc on lipo getting hot
I have several old tekin 420 esc's. I am trying to run these on lipo. I have burnt op three so far with a 5000 40c pack. In a matter of about 30 seconds. I have been testing some others with a 3500 25c pack. The esc gets to hot to touch after about a minute of running. I am running duel brush motors in a clod. I never had this problem even when I ran 14 cells back in the day. Will this esc just not handle lipo or will a bec or anything help?
09-06-2012, 03:31 PM
#2
Somewhat surprising, those are pretty beefy ESCs.
How many lipo cells (voltage)?
Are the motors getting hot? Generally need to gear down when switching to lipo.
What servo(s)?
How many lipo cells (voltage)?
Are the motors getting hot? Generally need to gear down when switching to lipo.
What servo(s)?
09-07-2012, 09:30 AM
#3
7.2 lipo stock clod 13 tooth gearing. Motors don't get hot. Running a futaba s9402. This is in three different trucks. I have rewired one seeing what that would do but it does the same thing. I wouldn't have thought this esc would have had any problem with the lipo.
09-07-2012, 10:06 AM
#4
When changing from nimh to lipo, you need to drop the gearing quit a bit. But Dave H. asked which servo & the futaba s9402 is a high amp servo & I doubt the
420's bec is more than 1 to 3 amps & that will not be nearly enough for that servo.
When your other esc's quit, did they just stop or smoke? You might try a receiver pack or an external bec on the bad esc.s if it is the bec,
Check out the specs on the futaba s9402
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXH305
420's bec is more than 1 to 3 amps & that will not be nearly enough for that servo.
When your other esc's quit, did they just stop or smoke? You might try a receiver pack or an external bec on the bad esc.s if it is the bec,
Check out the specs on the futaba s9402
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXH305
Last edited by TOM MAR; 09-07-2012 at 10:22 AM.
09-07-2012, 10:37 AM
#5
I ran these trucks for years on micd and nimh with no problems. Even ran 14 cells at times. Just can't see why the lipos are causing this problem. They don't smoke just pretty much melt lol.
09-07-2012, 12:34 PM
#6
If you are having melt down of wires then you are way over geared, Melt downs are caused by too many amps. I have seen wires burnt to a fire because of the power difference between lipo & nickle metal batteries. Sub c cell drop in voltage & amperage the instant you pull the throttle, Lipo's DO NOT, a 2 cell will normally run at 3.5 to 2.7 volts depending on the load until discharged. The difference in battery is a lot like comparing a aa battery to a wall socket. (not really just a night & day difference) Not even close!
09-07-2012, 11:39 PM
#7
Not the wires it is the board in the esc. I believe it is just the old tekin stuff. I have ran other old esc's with lipos and no problems. The clod is geared very low and it isn't a gear problem. They run 13 tooth pinions. The motors would get hot and they aren't even warm. I will try a bec but don't see it helping.
09-08-2012, 04:27 AM
#8
It has to have something to do with the amperage the lipo can put out. I've ran the old 420 esc's back in the day with dual motors and or with 3 7cells in series. Never had an issue. I've always preferred tekin over novak because of those 420 and 412 esc's. They were alot tougher.
09-08-2012, 07:03 AM
#10
Not the wires it is the board in the esc. I believe it is just the old tekin stuff. I have ran other old esc's with lipos and no problems. The clod is geared very low and it isn't a gear problem. They run 13 tooth pinions. The motors would get hot and they aren't even warm. I will try a bec but don't see it helping.
09-09-2012, 06:32 PM
#11
Geared down today guess what still got hot. Just made the truck go slow.
09-09-2012, 07:03 PM
#12
There's no way it's an amperage issue. The tekin's number designates how many cells it'll handle, the 412 was 12 cells, 420 is 20 cells, so the 420 is rated up to 24amps, so a 7.4 lipo SHOULDN'T be causing issues. I'd try a running a BEC in case it's the servo like was stated before or the Tekin has just seen it's last days and is spent at this point. Sometimes they do just wear out.
09-11-2012, 09:57 AM
#13
There's no way it's an amperage issue. The tekin's number designates how many cells it'll handle, the 412 was 12 cells, 420 is 20 cells, so the 420 is rated up to 24amps, so a 7.4 lipo SHOULDN'T be causing issues. I'd try a running a BEC in case it's the servo like was stated before or the Tekin has just seen it's last days and is spent at this point. Sometimes they do just wear out.
Amps, Not voltage. Big difference. A bad or internally shorted motor can run & draw in excess 50 amps, way above the 420's rating. A voltage limit is a voltage limit only. If the esc is rated at 24 amps then you connect a battery (5000 40C) that can deliver a constant 40 amps all you have to do is have an issue with the motor, gear or anything creating a load on the esc & poof. There is no way you should be running 2 motors on a 24 amp esc with a lipo.
Been racing electric rc since 79, if you think I am still wrong contact TEKIN
I can live with it if they disagree. I'm not trying to be arrogant, only help. but we disagree. You said it yourself that it can handle 4 to 20 cells, so voltage is not the problem. That leaves only the BEC & amperage.
http://www.teamtekin.com/support.html
09-11-2012, 10:18 AM
#14
Tech Regular
OK, first of all my first thought was a failing BEC in the esc.
Amps, Not voltage. Big difference. A bad or internally shorted motor can run & draw in excess 50 amps, way above the 420's rating. A voltage limit is a voltage limit only. If the esc is rated at 24 amps then you connect a battery (5000 40C) that can deliver a constant 40 amps all you have to do is have an issue with the motor, gear or anything creating a load on the esc & poof. There is no way you should be running 2 motors on a 24 amp esc with a lipo.
http://www.teamtekin.com/support.html
Amps, Not voltage. Big difference. A bad or internally shorted motor can run & draw in excess 50 amps, way above the 420's rating. A voltage limit is a voltage limit only. If the esc is rated at 24 amps then you connect a battery (5000 40C) that can deliver a constant 40 amps all you have to do is have an issue with the motor, gear or anything creating a load on the esc & poof. There is no way you should be running 2 motors on a 24 amp esc with a lipo.
http://www.teamtekin.com/support.html
One thing, though is that a FET or 2 can just die and the ESC will continue to work fine... Problem is that at some point, you may end up with to few FETs handling to much current and thus get very hot. That ESC is obviously quite old and might at some point have been damaged without you knowing. It happened to me once.
Martin Paradis
09-11-2012, 12:15 PM
#15
Scott obviously mistyped 24 amps, should have been 24 volts, he was talking roundy cell counts.
It is weird though. I actually have a 420, one that is about as old as they get. It’s fairly recently been in my buddies Savage with twin 550 motors on 4S, had tons of speed and power, with no issues. Same stock 12 round cell gearing. No heat sink on the 420 transistor tabs. Don’t know for sure what servo it has, but it has to be fairly powerful, never noticed any problems getting those big tires to turn. The reason he had it is the stock BEC fried, the 420 kept him going until he got an external BEC.
If the brushed motors work it’s hard to believe it’s pulling too many amps for a 420, even a lipo can’t push many amps past brushes. Also hard to believe 3 of them have just died off, I also have several other Tekins of that era and older even that at least seem to work fine. In my experience switching to lipo on brushed was a motor concern, never experienced an ESC issue.
Does make sense to check the BEC though. Unhook the steering servo for a trial, perhaps lock up steering up somehow, or install a weaker servo, etc, see if you can run it a bit and see if the heat goes down. Or like Tom mentioned use a receiver battery, pull and insulate the red wire from the 420 servo plug. Then you can pinpoint whether the BEC and servo is the issue.
One more thought, where is the torque limiter set? Probably runs coolest with it turned all the way up, no limiting.
It is weird though. I actually have a 420, one that is about as old as they get. It’s fairly recently been in my buddies Savage with twin 550 motors on 4S, had tons of speed and power, with no issues. Same stock 12 round cell gearing. No heat sink on the 420 transistor tabs. Don’t know for sure what servo it has, but it has to be fairly powerful, never noticed any problems getting those big tires to turn. The reason he had it is the stock BEC fried, the 420 kept him going until he got an external BEC.
If the brushed motors work it’s hard to believe it’s pulling too many amps for a 420, even a lipo can’t push many amps past brushes. Also hard to believe 3 of them have just died off, I also have several other Tekins of that era and older even that at least seem to work fine. In my experience switching to lipo on brushed was a motor concern, never experienced an ESC issue.
Does make sense to check the BEC though. Unhook the steering servo for a trial, perhaps lock up steering up somehow, or install a weaker servo, etc, see if you can run it a bit and see if the heat goes down. Or like Tom mentioned use a receiver battery, pull and insulate the red wire from the 420 servo plug. Then you can pinpoint whether the BEC and servo is the issue.
One more thought, where is the torque limiter set? Probably runs coolest with it turned all the way up, no limiting.