Does not show battery charge current
- Thread starter Legon
- Start date
dlloyd
Member
Both should be fused near the shunt. I had one fail early on, not blown, just open due to bad fuse.
DBRV10
Active Member
I have had a EMS module fail on one of the shunt inputs.....no idea why, I just bought a new EMS module. Extremely rare but it could happen.
Had catastrophic stator alternator failure in my Sonex Aerovee engine. Off airport landing. 30 amp circuit breaker popped and "appears" shunt in series with alternator, loads and battery was burned, ? destroyed and amps widget x'd out. Replaced shunt and still amps through pins 24/25 still do not display. Inline fuses intact. Other engine parameters display normally. Could just the area of amps display from the EMS module FAIL? What is preventing Amps display on my SV?
Thanks.
Tom Wasser
Thanks.
Tom Wasser
kurtfly
I love flying!
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- Jun 21, 2014
- Messages
- 282
Yes, it is possible for just that part of circuitry to fail. The alternator amp reading is using a differential amplifier circuit. It is measuring the voltage across the shunt (two inputs). This is a different circuit from the other “single ended” inputs. I think Dynon told me it could withstand about 50 Volts. I suspect when your alternator failed, it failed in a way it did not regulate alternator output and allowed voltage to exceed the common mode voltage by a lot. This fried the differential amplifier in EMS, battery, etc... I had a similar failure a few years ago. It fried my ems module. I have since installed two18 Volt transzorb’s between the 2 inputs and the input fuses. These devices will protect the EMS module by "shorting" to ground and blowing the fuses if the alternator ever goes above 18 Volts. These are very fast acting, in the Nano-second range.
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Thank you. This appears to be exactly what happened. A large voltage surge killed the part of my EMS that reads amps. I was looking for a way to prevent this from happening again and appreciate your suggestion. Dynon was not helpful when I asked how I could have prevented this beyond the 30 amp circuit breaker in the alt circuit and the inline fuses I installed. My amps shunt was very discolored at the soldered ends of the metal bar. It would be interesting to do an experiment with voltage to a new shunt and see how much voltage it would take to cook the shunt and produce similar discoloration. YOU are very helpful.
Tom
Tom
DBRV10
Active Member
More victims of Plane Power alternators by the sound of it :-(
Are you saying that Sonex uses this product in the Aerovee engine build as the stator assembly and the trigger shaft of their complete "alternator assembly" of the Aerovee engine secondary ignition? With failure of this assembly in a number of possible ways the entire electrical system is vulnerable to a voltage onslaught. True? The whole assembly held by 14 screws seems, 4 of which seem to be particularly troublesome, are a weak link in an otherwise great VW engine. Thanks for input.
Tom
3159460123
Lyons, NY
Tom
3159460123
Lyons, NY
To all that read this series. My EMS was fried when I had a stator alternator destroyed by one cap screw backing out on my Aerovee secondary ignition. Now rebuilt. Dynon repaired my EMS by installing their upgraded circuit board I am told has additional features that protect the AMPS circuit. I wonder if they found that the 1 amp inline fuses on 24 and 25 do not afford protection from high voltage and are now adding protection to this circuit. It will be comforting to have an upgraded EMS and have more internal protection from a voltage spike, for which I am grateful to Dynon.
kurtfly
I love flying!
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- Jun 21, 2014
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- 282
If you are installing the Transzorbs and Fuses to protect your EMS module the components should be wired as shown below. The 18Volt Transzorb acts as a switch to ground if teh voltage goes to +18Volts. This will immediately blow the fuse protecting the EMS module. This is for a 14 Volt system. A 28Volt system will require a different Transzorb part.
