Fans shutting off

[Paulcandb]

Hello everyone, I have a kraton 6s exb with spektrum 150amp esc and 2050kv motor and a spektrum sr315 rx. Recently I installed 2 40mm powerhobby aluminum fans one of which is plugged into the Aux 1 port and the other is plugged into the batt port. When I first put them in and powered it on they both turned on but when running it one of the 2 or both will randomly turn off and turn back on. Any help will be much appreciated. Thank you

 

[Edough13]

May have a loose connection or a wire coming undone from the fans. Also could be too much for the BEC to handle with already powering the servo and receiver and then 2 fans. Do they slow down at all when steering?

 

[Paulcandb]

No they don't slow down when steering. I even replaced one fan with another to see if it was a bad wire and still did it.

 

[Engineer]

The voltage rails should be common across all the pins of the receiver, so unless there's something funky with the soldering of the headers to the PCB, it shouldn't matter if you plug it into BATT or AUX1 - what connectors are you plugging into the ESC? Is it a JR male servo plug or the JST from the fans? (I think most fans come with JST connectors).

 

[Paulcandb]

It's just the little 2 wire connector that comes stock on the power hobby fans

 

[Engineer]

It's just the little 2 wire connector that comes stock on the power hobby fans

View attachment 185755

Interesting... never saw that before but it looks like it would work - and, just a dumb question, but you are plugging them into the "+" and "-" of the receiver right? The pins in the middle and closest to the edge of the receiver.

 

[SrC]

Have you tried just one fan each by itself?
Those fans draw only like .65 amps. The BEC overhead of the Firma 150 should handle both no issue. I have these fans also. I run a single on my motor. Like stated above, if when operating the servo and the fans RPMs are not affected in any way, then the BEC overhead amperage is NOT the issue.
I suspect defective fans or Rx header or Plug issues causing this. More than likely it's a connector issue.
I have had issues with those 2 pin female fan connectors before when installing onto the Rx header pin outs. Intermittent issues.
In fact they don't connect to JR/Futaba Servo connectors well. So accordingly, the Rx pin out spacing is probably not correct for these JST fan connectors. IMHO. Sometimes you get lucky and they willl work. But are not a match technically. Depends on the Rx/brand.
Once you make sure the fans themselves will work just fine (not defective in any way) powered off another power source well enough, I would change out the connectors or use a fan connector adapter which has a 3 pin JR/Futaba end at the Rx pin outs.

Below is an example of a JST (2 pin) to JR (3pin connector) adapter. The proper way to do this.

https://www.amazon.com/Female-Conne...9?keywords=jst+adapter&qid=1639373117&sr=8-19
Give this a try.


Edit.
Absolutey make sure to rule out defective fans first before moving onto the connectors. Just Bench test them on an alternative power source. (5-7volts) I have received many bad fans in general. The wire soldering joints at the fan side are delicate and break in many cases. Just bad QC at times. There is very poor strain relief there. Causing intermittent outages.

 

[Paulcandb]

Interesting... never saw that before but it looks like it would work - and, just a dumb question, but you are plugging them into the "+" and "-" of the receiver right? The pins in the middle and closest to the edge of the receiver.

Yes I am connecting them correctly. I ran it an hour ago and one fan turned off so I tapped the center of the fan a few times with my finger and it turned back on again for a few minutes and then shut back off. I have not driven the truck in the dirt since the install of these fans so I feel like it wouldn't be any debris. Idk I'm starting to feel like these fans are just crap!

Have you tried just one fan each by itself?
Those fans draw only like .65 amps. The BEC overhead of the Firma 150 should handle both no issue. I have these fans also. I run a single on my motor. Like stated above, if when operating the servo and the fans RPMs are not affected in any way, then the BEC overhead amperage is NOT the issue.
I suspect defective fans or Rx header or Plug issues causing this. More than likely it's a connector issue.
I have had issues with those 2 pin female fan connectors before when installing onto the Rx header pin outs. Intermittent issues.
In fact they don't connect to JR/Futaba Servo connectors well. So accordingly, the Rx pin out spacing is probably not correct for these JST fan connectors. IMHO. Sometimes you get lucky and they willl work. But are not a match technically. Depends on the Rx/brand.
Once you make sure the fans themselves will work just fine (not defective in any way) powered off another power source well enough, I would change out the connectors or use a fan connector adapter which has a 3 pin JR/Futaba end at the Rx pin outs.

Below is an example of a JST (2 pin) to JR (3pin connector) adapter. The proper way to do this.

https://www.amazon.com/Female-Conne...9?keywords=jst+adapter&qid=1639373117&sr=8-19
Give this a try.


Edit.
Absolutey make sure to rule out defective fans first before moving onto the connectors. Just Bench test them on an alternative power source. (5-7volts) I have received many bad fans in general. The wire soldering joints at the fan side are delicate and break in many cases. Just bad QC at times. There is very poor strain relief there. Causing intermittent outages.

Thank you for the in depth answers!! Very helpful. Unfortunately I took a brand new fan out of the package tonight that I had for another project and plugged it in and did the same thing but when I tap the fan a couple times it turns back on for a few minutes so I think that rules out a problem with connectors, rx, or loose connections right?

 

[SrC]

Take them out and look closely at the fan side wire connections. Tapping them or tugging the wire, and them shutting off is a sign of a bad fan(s). Bad solder joint(s) at the Fan's PCB. I had numerous fans get bricked like this. When new, I put a small amount of liquid electrical tape over or as close as I can at the solder joint, and let dry for several hours. This provides some strain relief. It is almost impossible to re solder these wires. Been there. Dissected many. Bashing hard makes this happen. Cheap fans do this most of the time. I have bins full of bricked fans and I keep new ones stocked up for this reason.
Making sure there is no stress onto or loose flopping fan wires prevents this in most cases. But badly soldered fans is also a big issue.

 

[Paulcandb]

That's really crazy then because that means I got 3 bad fans all with the same problem!!! I'm not denying what you are saying at all and at this point seems to be the most logical cause of the problem after eliminating all other possible causes!
I want to try different fans but I have a sneaking suspicion that they all come from the same factory somewhere in china.

 

[SrC]

Yeah sometimes you can get a bad production run of 100's of bad ones. Poor QC and just never tested at production. Chinesium stuff. Nothing new. I spend a bit more and buy them here in the states ( AMZ), so am able to return them immediately. I always check them on the Bench as soon as I receive them. Let them run for 10 minutes or so. Make sure the wires are not loose and so it runs fine while I play with the wires. Fans can be delicate. They are actually just repurposed PC fans and not designed for abuse in general. I eat fans and keep them stocked up here. It sucks. That's why I try not to use many of them on one rig. The more you have, the more likely one will break. And if it is a large fan (35-40mm) I can usually put a drop of liquid electrical tape over the wire solder joints for some strain relief. Works for me. I have gotten many bad fans before. Probably 3 out 10 are DOA. Mostly the smaller fans.
Some ideas.

 

[Paulcandb]

Yeah sometimes you can get a bad production run of 100's of bad ones. Poor QC and just never tested at production. Chinesium stuff. Nothing new. I spend a bit more and buy them here in the states ( AMZ), so am able to return them immediately. I always check them on the Bench as soon as I receive them. Let them run for 10 minutes or so. Make sure the wires are not loose and so it runs fine while I play with the wires. Fans can be delicate. They are actually just repurposed PC fans and not designed for abuse in general. I eat fans and keep them stocked up here. It sucks. That's why I try not to use many of them on one rig. The more you have, the more likely one will break. And if it is a large fan (35-40mm) I can usually put a drop of liquid electrical tape over the wire solder joints for some strain relief. Works for me. I have gotten many bad fans before. Probably 3 out 10 are DOA. Mostly the smaller fans.
Some ideas.

Yeah it sucks! Are there any 40mm aluminum fans you have had better luck with?