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Anyone having a hard time keeping a Dynon amp shunt from coming apart?

jcarne

Well Known Member
Patron
On my second one and it is broke now too. The plastic seems to always break. First one I chocked up to me getting the screws too tight; I know I didn't make that same mistake on the second one.
 

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I haven’t had any issues on the two or three I have installed. Looks like a bolt tightening issue, but I’m no expert.
 
Only One

On my second one and it is broke now too. The plastic seems to always break. First one I chocked up to me getting the screws too tight; I know I didn't make that same mistake on the second one.

8 years and almost 900 hours - my original one has been just fine.
 
I had the same problem with the plastic holes cracking. I potted the underside with epoxy and milled glass so the the housing can withstand higher compression load from the screw
 
I'm on my third after 250 hours, but mine both broke vertically through the middle.


Gary R Kohler
RV-7A
 
Better Options

For various reasons a Hall current sensor is better https://www.poweruc.pl/products/hal...=1&_sid=834f34193&_ss=r&variant=1961591996460

Clamp on, no bare terminals, eliminates two crimp connections, no issue having to fuse the sense wires, etc. etc.

Now if Dynon would just support it...
I still have (similar) one in the plane from my RMI install. No longer have the RMI, so it just sits there with nothing to do.

OK, one caution - keep it away from *other* current carrying wires to get an accurate number.
 
For various reasons a Hall current sensor is better https://www.poweruc.pl/products/hal...=1&_sid=834f34193&_ss=r&variant=1961591996460

Clamp on, no bare terminals, eliminates two crimp connections, no issue having to fuse the sense wires, etc. etc.

Now if Dynon would just support it...
SNIP

Dynon does support using a Hall Effect current sensor. It discusses using the sensor from Grand Rapids in the install manual. If you really must have an amp meter I recommend this approach.

Carl
 
The shunt mount in my Rocket melted. I made a new one from phenolic, which is far more robust. I also incorporated overvoltage clamps to protect the EMS.
 
Well looks like I am not alone in the matter.

Carl I too would leave it out if I was building again buuut hindsight is 20/20; I only ever look at volts.

I think I’ll get another and try phatRVs idea, I’m betting that will do the trick. If it doesn’t I’m ditching it and straight piping it with some 2awg! Lol
 
Lots of better ones out there, EI, UMA, RC Allen.
Personally I like knowing what the current output is.
 
Lots of better ones out there, EI, UMA, RC Allen.
Personally I like knowing what the current output is.

Ya I thought about this too but I'm going to try PhatRVs trick first as I really don't want to change any of my electrical system on the firewall as nothing else is going to have the same hole locations. Unless of course you know otherwise? :) All other manufacturer shunts look a little smaller in pictures.
 
If I remember correctly the mounting holes are tapered. If the wrong screw is used (wrong taper, AN screws are 100 deg, hardware store screws are not), this might be causing the failure. As another possible cause might be tension or twist in the B lead. Or the B lead not supported between the firewall &engine.
Last thought- is the shunt just mounted to the SS firewall or does it have a backing plate of some sort behind it?

Touching wood - none of my planes have had this problem.
 
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Just to be complete, here is the EMS protection circuitry that I mounted directly on my (phenolic) shunt. This was reviewed by Dynon, and it's been flying for 8 years or so. There were a couple of incidences of the EMS being damaged, presumably due to voltage spikes. Dynon may have redesigned their EMS since, but the following circuitry will work either way.

Shunt-Protection.jpg

Shunt-Protection-PCB.jpg
 
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