Jump to content
Sign in to follow this  
bitten192

VOLTAGE CREEP

Recommended Posts

I installed a new LiFeP04 in my REMOS (912 ULS) and a Voltage Limiter (VL) to protect the battery from high voltage ( a REMOS requirement SB-013). After 10 minutes of flight the VL trips. I've measured voltage at the battery and it is a steady 13.6 volts until 10 or 12 minutes when I observe it creeping up to 15 volts and the VL trips. After I land, shut down and immediately restart the VL is reset and after a few minutes of flying it happens again. Any ideas? The Voltage Regulator is a 4 year old Schicke GR6.

Share this post


Link to post
Share on other sites

Make sure your C wire (red, thin) coming off the regulator has a VERY SOLID connection. This is the "feedback" wire for regulation. This is likely the culprit.

Make sure the regulator's case ground is VERY SOLID. If not the C wire, then this is probably the culprit.

Verify that the greenish cyanish wire, coming off the overvoltage protection, has a good solid ground connection to the battery.

Verify your capacitor is not bad.

All three of these things can lead to improper regulation. Remember that I've posted before, electronics are designed around a reference, commonly ground. If the ground connection is poor, you can have floating voltages. This will raise the reference, which means the regulator will raise the voltage ceiling. In the case of the C wire, this measures the system bus voltage, and compares to ground voltage in the case. When it's high enough, it stops the alternator output until the voltage drops again. It does this very, very rapidly, so the cleaner the connections, the better!

That capacitor is also important. The battery smooths out the lower frequency oscillations from the alternator. The capacitor smooths out the high frequency, which is what electronics are sensitive to.

Share this post


Link to post
Share on other sites

The problem was the line voltage sensing 20 AGW wire to the VR (C wire). It had a weak spot. Apparently when the engine compartment heated up, it caused the resistance to build and drop the voltage in wire which told the VR to charge more. I replaced the wire, Now the VR is a solid 14.2 volts at the battery and the V Limiter does not trip.

Share this post


Link to post
Share on other sites

Sounds like we both were thinking the same thing!

Either that or you were in the hangar with cowling off when you read my post!

Share this post


Link to post
Share on other sites

Corey, if I understand correctly, the B+ wire provides charging current to the battery and the C wire is how the VR "senses" buss voltage (so that output can be regulated to maintain the VR set point voltage).  So, what is the "R" terminal on the VR for?  

Share this post


Link to post
Share on other sites
12 hours ago, Anticept said:

Sounds like we both were thinking the same thing!

Either that or you were in the hangar with cowling off when you read my post!

I wish I asked for help and read your post a week ago before I spent a week trouble shooting!  Your diagnosis was exactly right! 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×