Backup battery isn't working

[Kevin D]

Not flying yet, ground based commentary.
Often operating Skyview HDX to intentionally run on and deplete BU Battery.
When on Battery charger, charging aircraft battery, system voltage at 13.4V it takes approximately 4 hours to charge the BU Battery to full charge before it will be fully charged and pass the BU battery test. If good there, it will take about an hour to deplete the BU battery as the only source of power to the Skyview. When my BU battery is low voltage it does exhibit behavior similar to your observations. Make sure there is a Full Charge on the battery.

 

[Rhino]

Contact Support.

 

[dbuds2]

Contact Support.

Thanks Rhino, doesn't Dynon HQ monitor this forum?

 

[RV8JD]

... doesn't Dynon HQ monitor this forum?

From the link below:

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[kblack]

For the most part, Dynon products are the very best. But the backup battery design is terrible and unsafe. Do NOT overly rely on it. Reason: It is nothing more than a package of several separate lithium cells that are recharged/maintained as a stack - the same way lead-acid battery cell stacks can and are recharged/maintained. Lithium cells do not self-balance like lead-acid and cannot be reliably managed like this. A stack of lithium cells should each be independently charged/maintained. The known, unreliable design used by Dynon can result in a stack passing a drawdown test one day, and then failing to keep your system online the very next day. Imbalanced charging can fail one of the cells on the very next cycle after a test. This happened to me. Be careful.

 

[jsalak]

For the most part, Dynon products are the very best. But the backup battery design is terrible and unsafe. Do NOT overly rely on it. Reason: It is nothing more than a package of several separate lithium cells that are recharged/maintained as a stack - the same way lead-acid battery cell stacks can and are recharged/maintained. Lithium cells do not self-balance like lead-acid and cannot be reliably managed like this. A stack of lithium cells should each be independently charged/maintained. The known, unreliable design used by Dynon can result in a stack passing a drawdown test one day, and then failing to keep your system online the very next day. Imbalanced charging can fail one of the cells on the very next cycle after a test. This happened to me. Be careful.

The Dynon battery has in integrated BMS board, so it is a bit more than a 3S2P stack of 18650 cells. If you check SV-BAT-320 Specifications in Appendix B of the SV Installation Guide you will see integrated circuit protection is listed, along with a nominal cell voltage of 11.1v. I check the battery voltage after shutdown and typically see 12.24v after a two-hour flight on an 8-year-old battery. I like Dynon's approach to recharging the battery and have no issues with the safety aspect.

 

[GalinHdz]

Took me a day to get back to the plane.

I powered up the Skyview with a long press of button 1 without powering up the plane with the master. Skyview started fine, so the BU battery is working.
1. This all unlite or dim : Battery Connected (Battery Detected) yes. Battery Status: 10.44V.
2. Powered the plane with master on: Battery Status: 11.18V. Saw a status of standby and charging cycle 2-3 times then steady with Standby.
3. Voltage reported by Skyview on the main engine page and measured with separate voltmeter; 13.1v.

Last time I flew and skyview was reporting 13.2v, the charging status never came up.

Thanks for your reply and input, what next?

11.18v at the SkyView is not enough to start charging the BU battery which may explain your issue.

With the engine and alternator on, the voltage as measured at the airplane battery terminals should be between 13.8v and 14.2v. Check your voltage regulator setting, adjust as required and fly for at least 45minutes. It should bring the BU battery up to 12v or slightly higher. A full BU battery charge takes a bit longer.

 

[dbuds2]

11.18v at the SkyView is not enough to start charging the BU battery which may explain your issue.

With the engine and alternator on, the voltage as measured at the airplane battery terminals should be between 13.8v and 14.2v. Check your voltage regulator setting, adjust as required and fly for at least 45minutes. It should bring the BU battery up to 12v or slightly higher. A full BU battery charge takes a bit longer.

I measure 13.0 at the aircraft battery terminal without the engine running, I see 13.2V on the main Skyview engine info window with the engine running.

 

[GalinHdz]

I measure 13.0 at the aircraft battery terminal without the engine running, I see 13.2V on the main Skyview engine info window with the engine running.

Is the 13.2v with the engine running measured at the battery terminal? That is a bit low but it "should" be enough for SkyView to charge the BU battery. Although, it might take longer to bring the BU battery to full charge so you may need to fly a bit longer.

Just another sacrifice we must endure!

 

[dbuds2]

Well flew yesterday and now seems all ok, status showing charging, new BU battery ended up at about 11.8V after :45 min flight.