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777Dave

777Dave

Well Known Member
Having some starter trouble and decided to remove/replace the battery. New one is an Odessey and has terminals that needed to be tightened using a socket wrench. Old battery had nuts that were tightened by hand.
Anyway, managed to drop the wrench and it touched the aircraft frame and "pop!"
Now most of the electronics are u/s....
digital clock
Flowscan
Garmin GPS/Comm
Narco transponder
Boost pump
Strobes
Great huh?
Also the brand new Skytec starter seems to be defective, engages, spins like crazy but prop no turn.
How was your day?
 
Ouch!

I am sorry to hear about this. It is incredible that a simple little slip can cause so much damage! :mad:
 
Thanks for sharing. I feel your pain and will now be ever so careful with conductors around the battery terminals.

I'll also in-line fuse as much as possible.

Jim Sharkey
RV6 - Wiring
 
OK, I will ask the dumb question. Was the master off? If so, why did the short cause so many problems??? Even if it was on, was there enough of a surge to do this much damage??

Scary stuff.

-Ron
 
Dave, I know this doesn't help much but. . . .

A wise old mechanic once told me how to avoid this.
When disconnecting, always disconect the ground first.
When connecting, always connect the ground last.
 
Hmmmm....don't Panic - Yet!

Hi Dave,

I don't know your background, so forgive me if i tell you something that you already know, but I am not sure that you did major damage to any of the components. If you basically shorted the battery positive to ground, then you could quite possibly have fried the battery (although the Odyssey is pretty tough), but I'm not sue how it would have trashed some of those components - particularly things like the fuel pump. I might suspect that you damaged a ground wire or something. remember that the most you're going to generate is battery voltage, which is less than alternator voltage anyway.

I'd methodically check for a melted wire someplace, or maybe a fusible link in the system that is blown. Then try jumping power to the components indivually using a known good 12 volts. You might be lucky!

Paul
 
Yeah, I don't see how shorting the battery can ruin the electronics. You obviously drew some current, so a wire or two somewhere may have burned up, but it would take a big inductive spike to ruin the electronics, and I don't see how that could have happened. I would start by isolating the wiring, then ohming/inspecting out the main power bus to see if you can find a short or open somewhere.
 
Since you replaced the battery with a different brand, let me tell you about a motorcycle incident when I worked at a shop (30 years ago).

Customer brought in a bike with a totally fired electrical system. He had his dead battery on charge and lit off the bench grinder. Poof! He bought a new battery from Wally world and installed it. Another poof! If it had wires, it was toast. I ordered all new parts (wire harness, regulator, diodes. . . ) 3 weeks later, I had all the new stuff installed. Since I had replaced the entire electrical system, I never found the original problem. I went to install his Wally world battery. Guess what, the terminals were reversed. It only went in the frame one way and the terminals were backwards. He definitely was not happy, especially after I had to sell him a factory battery.

Check polarity.
 
thanks

I really haven't had much time to trouble shoot or investigate yet but suspect the worst. The Master and radio master were off at the time.

The starter issue is a puzzler. Its new and was not installed when the slip occurred. Is there anything else involved that could be causing it not to turn the prop over?

As far as the electronics I noted that 2 breakers had popped. One for the strobes and also the transponder pops when turned on.
The Garmin GPS/com does not respond to the on/off.
The other instruments are also non-responsive when the radiomaster is selected on. Not sure of the situation regarding internal fuses... ??

Thanks for all the condolences, lets hope some stuff is ok. :eek:
 
777Dave said:
I really haven't had much time to trouble shoot or investigate yet but suspect the worst. The Master and radio master were off at the time.

The starter issue is a puzzler. Its new and was not installed when the slip occurred. Is there anything else involved that could be causing it not to turn the prop over?

As far as the electronics I noted that 2 breakers had popped. One for the strobes and also the transponder pops when turned on.
The Garmin GPS/com does not respond to the on/off.
The other instruments are also non-responsive when the radiomaster is selected on. Not sure of the situation regarding internal fuses... ??

Thanks for all the condolences, lets hope some stuff is ok. :eek:
Click to expand...

Dave, I just can't see where shorting the battery to ground would damage any of your equipm$$$nt. Folks have been dropping wrenches (and wristwatches and wedding bands, and...) on batteries since day one!

I suspect (as has been stated) that a wire burned in two (though I'm still trying to figure out how shorting the battery would do that). I haven't thought this through (the brain is working slowly at the moment) but did you have the all the big ground wires connected? If not, maybe one of the little wires on the avionics bus took the entire ground load and melted in two.

Mag P-leads have been cooked when an engine start was attempted when the firewall ground strap wasn't connected. The little wires try to carry the entire load and burn. I have to wonder if something similar happened in your case.

Get a good night's sleep (!?) and tomorrow start at the battery with a systematic look at all the wiring. I suspect all the goodies will come back to life once you find the damaged connection.
 
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I've touched the firewall more than a few times while having a wrench on the positive side of an Odesey, I'm sure your fine. I even burned a hole through the firewall once. :eek: Just take a good look at everything in the AM.

Always remember aluminum is a good conductor of electricity.;)
 
Polarity Check

A couple of anecdotal points which hopefully will be good news:

Either the 625 or 680 is made to fit ancient BMW bikes like mine. The poles are backwards from other batteries I have used in the bike.

I do not know skytec guts, but an old style "bendix" would never engage if the starter was running backwards. Maybe Skytec is similar.

Panel stuff probably will not run on negative 12v.

Good luck on the next round of debugging. :(
 
I agree...

rzbill said:
A couple of anecdotal points which hopefully will be good news:

Either the 625 or 680 is made to fit ancient BMW bikes like mine. The poles are backwards from other batteries I have used in the bike.

I do not know skytec guts, but an old style "bendix" would never engage if the starter was running backwards. Maybe Skytec is similar.

Panel stuff probably will not run on negative 12v.

Good luck on the next round of debugging. :(
Click to expand...

I agree with Bill, from this distance :) the only common issue I can come up with is reversed polarity. It would cause the starter issue, but I have no clue how the avionics would respond.

John Clark
RV8 N18U "Sunshine"
KSBA
 
John Clark said:
I agree with Bill, from this distance :) the only common issue I can come up with is reversed polarity. It would cause the starter issue, but I have no clue how the avionics would respond.

John Clark
RV8 N18U "Sunshine"
KSBA
Click to expand...
I don't know about avionics but many electronic devices are polarity protected with a diode. Normally if reverse polarity is applied a fuse will blow and the device itself will be protected.
 
If you havent checked this as why the starter wont turn the engine over, carefully check your ground connection to the engine.
Had a friend install a new stater and still had the engine hardly turn over.
Checked engine ground and found a poor conection, After fixing was surprised how fast the starter turned the engine over.
Gerry
 
Thanks again, I will double check some of the suggested items this morning and report back. I did reinstall the old battery, pretty sure polarity is correct. Appreciate all the suggestions.

Dave
 
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Although this is probably obvious and I've sure 777Dave has already checked it, if the battery terminals were reversed it may cause some of these strange behaviors.

edit: oops...just saw the polarity comment.
 
YES!

All I can say is that all of this info proved useful and solved my problem with NO apparent damage...
I went over to the hangar first thing (6 AM)this morning and was disappointed to see that the polarity was ok... red to positive, black to neg.
After a few minutes of thinking I figured I should trace the cables to see where they ran... Also called the mechanic at the place where I picked up the new Skytec and he said that the polarity shouldn't matter.... wrong.

Started with the red and followed it to the firewall, huh? Then on the other side, another RED cable grounded to the engine block... were these things wired like the old British bikes and cars? Positive ground? Traced the BLACK wire to the Master solenoid! Did not seem right... Quick call to a friend who said "No Way! Negative ground!"
So I switched things around, Red to Neg, Black to Pos and voila! All worked normally including the Radios and starter.
Apparently the newer radios are protected by internal diodes, suggestion was made to wire in separate diodes at both the master and starter solenoids to help protect the radios, easy to do and cheap.

Thanks again for all the quick help, I will sleep better tonite ;)
 
A friend who happens to be an A&P was telling me about a grumman that had a dead battery. Hooked the wrong terminals up - all the old radios did not have protection against reverse polarity. Everything was fried
 
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