Dynon shunt, alt. output & fuse links

Camillo · #1 10-29-2009, 07:16 AM

Hi. A couple of more questions.

I bought a Dynon shunt, which is 40Amp. 40mv.. I want to use it as a loadmeter. Instructions say it displays from 0 to 60 amp. So, it seems it can handle 60 amp. current. So, I have to disregard its 40amp. rating, isn't it?

Second question. Bob Nuckoll's suggest putting it BEFORE ANL current limiter and use two fusible links between shunt terminals and ammeter instrument. Should I go with these fuse links or can I disregard them?

Thanks.
Camillo

Brantel · #2 10-29-2009, 07:28 AM

Do not run your shunt wires without any overcurrent protection.

If you get a short in one of those wires, they will smoke and burn up big time.

I put fusible links on mine....Easy to do and they work great.

Camillo · #3 10-29-2009, 12:10 PM

Thank-you, Brantel. So, you too suggest to add fuselinks.
But, is that shunt compatible with a 60amp. alternator? I suppose yes. But its engraving (which states 40Amp. 40mV) worries me a bit, because on Bob Z11 drawing I can see a 60Amp. shunt (not a 40Amp.).

On the other side, I have a B&C shunt rated for 60 amp., but I bought the Dynon one because somewhere I read that it is the only one compatible with Dynon instruments...

Brantel · #4 10-29-2009, 12:31 PM

Yep.. This is a perfect application for the fusible links....

Yep the Dynon will work fine. It will handle more than 40 amps but the critical thing is the ratio between the amps to volts output. The Dynon needs 1 amp to equal 1mv. If you maintain that ratio, you can use any brand you want.

Camillo · #5 10-31-2009, 12:59 AM

I connected the shunt with the ANL current limiter and the latter with the remaining system using brass bars (I bought them from B&C and are thinner than copper ones sold by Van's...I hope they will handle 60 amp.). I then applied some pieces of heat shrink to prevent grounding with firewall. I also applied a round of UHMW tape along the bottom portion of the engine mount (hard to see, but it is there...). Finally, I made two 24AWG fusible links with material bought from B&C (according to Bob Nuckoll's instructions) and attached them to shunt terminals. Eventually, I will terminate them with 20AWG to Dynon instrument.

Camillo · #6 10-31-2009, 02:05 PM

A friend of mine, who is an electrical engineer, told me it is not safe to have that ANL current limiter in the firewall area and especially so close to gascolator. He says that if a flame occurs, a fire may start due to fuel vapours.

I installed them there because I saw almost everyone used the same position. Is the flame possibility dangerous? Should I protect the current limiter with a metal plate?

lucaperazzolli · #7 10-31-2009, 02:12 PM

Camillo,

call me, you got my number on my web site.

Your job is 'fatto bene'

Ciao

http://www.rv8.it/log/electrical_sys...g/Pages/2.html

Camillo · #8 10-31-2009, 02:20 PM

Thank-you, Luca.
I wrote you an email asking for your number.
Ciao.

Brantel · #9 10-31-2009, 02:35 PM

There are 2000 things that could cause a fire but I would say that this one is a minimal risk. If you have a fuel leak and pop your ANL at the same time, you got tons of problems! If your gaskolator leaks, fix it ASAP.
The chance of a ANL popping is very slim but it is very nice for it to be there if it is called upon to do its job.

More possible fires:

The fuel pump safety overflow dumps out right at the hot exhaust ....

Fuel can end up in the airbox and if you get a backfire ....

A primer line cracks and you pump a quart of fresh fuel into the cowl and then crank the engine ....

Well you get the idea.

Quote:

Originally Posted by Camillo

A friend of mine, who is an electrical engineer, told me it is not safe to have that ANL current limiter in the firewall area and especially so close to gascolator. He says that if a flame occurs, a fire may start due to fuel vapours.

I installed them there because I saw almost everyone used the same position. Is the flame possibility dangerous? Should I protect the current limiter with a metal plate?