Back Up Battery

[bignose]

Dynon support:

Is it mandatory to install the SV-320-BAT Back UP Battery, or can the system operate only on the main master battery? (VFR)

Looks like these batterys are producing some troubles, is that true?

Is there any fix programed?

Thanks.

 

[preid]

you are not required to use the Dynon battery in the US. It is suggested you have a redundant battery supply however if your primary goes out. unless you have steam gauges.
The backup battery is quite expensive.

 

[n223rv]

I have 2 screens and 2 back up batteries with no issues ever. Both powering 10" SkyViews.....

 

[mmarien]

I had to unplug my backup battery because of the problems (fixed with v3.2) with serial ports one and two and I really miss it. Turing on SV without it requires powering up everything on the master switch. I also have a bad habit of powering off the master before I record flight time/fuel burn etc. With the backup battery there is a countdown before shutoff. It is a nice feature in addition to the extra safety in case of an electrical failure. It maybe have a high cost/weight ratio, but compared to a fully redundant power supply it's cheap - and small. It powers the entire SV system (ADAHRS/EMS) except the servos.

 

[dynonsupport]

It is not required, and there is a small issue that a few customers are experiencing which is temporarily solved by unplugging the battery. That will be permanently solved (allowing those customers to plug their batteries back in) in 3.2, which releases next week barring any last minute bug-finding.

Having the battery does keep SkyView working if your electrical system fails. The other big advantage: in some aircraft, voltage will drop below 10V momentarily during engine crank. This will cause SkyView to reset, which takes about 20. If you don't have the battery, your engine information (particularly oil pressure) won't be available during that critical time after engine start. So many customer opt for the battery for those reasons.

 

[dynonsupport]

Actually, quick edit: SkyView will dim below 10V, but it won't shut down until the aircraft bus gets down to 6V. Some airplanes will do this on crank, but not all.

 

[mkbreezy]

A related question. What is the reason to not allow the backup battery wires to be extended? It makes for an awkward install. If I could make the wires just another 18" longer, it would put the batt in a much more accessible place.

 

[dynonsupport]

The longer the wires, the less time the battery will last due to the loss of energy in the wires. Plus, there is some high frequency switching on the battery lines, and this can cause interference with radios if you make a longer (better) antenna.

If you really have to do it, you can try, but use larger gauge wires, replace as much of the wire as you can, make sure you twist the wires, and don't call us if it causes radio noise

 

[thibault]

Are you implying that the best location for the backup battery is right beside the screen it is feeding and with the shortest possible battery wires?

 

[mkbreezy]

OK, using your advice, I moved the batt to a better location. Lengthened the wires, as you indicated. No adverse effects. No radio noise, and the screen recognizes the batt fine. My original question still stands though. What is the technical reason for not lengthening the wires. I would have assumed that it was just a straight DC circuit, but from your reply thats not true. Can you tell us what is going on in that charging circuit?

 

[dynonsupport]

The technical reason is right there in our previous post. The battery will last less time and has a higher chance of causing RF noise. Those are the only reasons we ask you to not extend the wires.

Just because one install doesn't have an issue doesn't mean all won't.

When switching power supplies are involved, there is no such thing as a "straight DC circuit." When charging, the current to the battery is pulsed, and this by definition is RF noise at some frequency.

 

[dynonsupport]

Are you implying that the best location for the backup battery is right beside the screen it is feeding and with the shortest possible battery wires?

Technically, yes. A good tradeoff between performance and ease of install is the length of wires that we include in our harnesses, which is why our install manuals ask you to not increase the length. You don't need to shorten the wires from what we ship.