How do you charge the backup battery?

[curriernh]

I'm wondering if I can just turn on the Dynon display with the engine off and put a battery charger on my main battery to keep it charged. My flights are rarely over the 4 hours needed to fully charge and I've been getting low backup battery alerts. Will turning on the display charge the backup as long as my main battery is fully charged?

 

[airguy]

No, not unless you are running a lithium chemistry battery that has a higher resting voltage. The Dynon system will not charge the screen backup battery unless the input voltage to Skyview is above 12.25 volts. You could certainly put a battery charger on the main battery and power up the system as long as you like. Section 11 of Skyview Users Guide revision K.

To conserve your aircraft battery, the SV‐BAT‐320 is only charged when the SkyView HDX
display detects that your alternator or generator is online. Specifically:
• If SkyView system voltage is above 12.25V: SkyView runs on Avionics power and
charges the SV-BAT-320.
• If SkyView system voltage is above 10V, but below 12.25V: SkyView runs on Avionics
power but does not charge the SV-BAT-320.
• If SkyView system voltage is below 10V: SkyView runs on the SV-BAT-320. This
discharges the SV-BAT-320.

Although Dynons documentation says it may take as long as 4 hours to charge a fully discharged backup battery, in my experience it's always been more like an hour and a half - do you know your backup battery is healthy? Has it passed a battery test lately?

 

[Jubilation]

I am having a similar issue with my Dynon backup battery charging. For several years I have been conducting the backup battery test by leaving the master switch on lighting up the display without a problem. It got charged in a decent time so I could conduct the test. My old battery charger packed it in and I bought a new Ctek 10 amp charger. With this charger (switched to AGM as my battery is AGM) I cannot get the backup battery charged fully because I can’t get more than appox 12-12.2 volts shown on my main battery with the charger connected. I left it for more than 12 hours and my main battery voltage had dropped to 11 volts. Is there something about the Ctek wizard the won’t let it charge more tham 12 volts on AGM batteries? What’s the solution?

 

[Raymo]

I'm wondering if I can just turn on the Dynon display with the engine off and put a battery charger on my main battery to keep it charged. My flights are rarely over the 4 hours needed to fully charge and I've been getting low backup battery alerts. Will turning on the display charge the backup as long as my main battery is fully charged?

The master relay must be on/closed to allow voltage from the main battery to charge the Dynon backup battery. Mine charges fine with the charger on my EarthX battery and one display turned off (Dual HDX in my RV-7A). I don't think it will charge both at the same time, since my CTEK Lithium charger output is only 4 amps.

 

[Raymo]

I am having a similar issue with my Dynon backup battery charging. For several years I have been conducting the backup battery test by leaving the master switch on lighting up the display without a problem. It got charged in a decent time so I could conduct the test. My old battery charger packed it in and I bought a new Ctek 10 amp charger. With this charger (switched to AGM as my battery is AGM) I cannot get the backup battery charged fully because I can’t get more than appox 12-12.2 volts shown on my main battery with the charger connected. I left it for more than 12 hours and my main battery voltage had dropped to 11 volts. Is there something about the Ctek wizard the won’t let it charge more tham 12 volts on AGM batteries? What’s the solution?

If your charger is not showing 13.5-14.5 volts when connected to your battery, it is not charging.

 

[Rhino]

It will charge at a somewhat lower voltage, something like 10 if I recall correctly, but it will charge at a much, much slower rate.

 

[RV8JD]

If your charger is not showing 13.5-14.5 volts when connected to your battery, it is not charging.

It will charge at a somewhat lower voltage, something like 10 if I recall correctly, but it will charge at a much, much slower rate.

See Post #2.

 

[Rhino]

See Post #2.

I'll go by what Dynon has said here before. It will charge at a somewhat lower voltage, but not enough to be truly effective.

 

[RV8JD]

I'll go by what Dynon has said here before. It will charge at a somewhat lower voltage, but not enough to be truly effective.

So for all intents and purposes, the info in Post #2 from the Users Guide is correct.

 

[Rhino]

Yes, you could say that. Post 2 (from the manual) says it doesn't charge, but that technically isn't true, which is what Dynon has said here before. Charging doesn't simply shut off at 12.25 volts. The charge rate just becomes too slow to be considered 'effective', but it is still technically charging because a voltage is still applied. At some point below 12.25 volts, the charge rate will reach the point where charging will no longer increase the battery voltage. That will vary slightly, in no small part due to battery condition, and that's what Dynon was getting at when they made that statement here. 12.25 volts is simply the best guess threshold where effective charging should be assumed for a good battery. It doesn't really matter that much in the grand scheme of things, so you could 'effectively' infer that both statements are correct if you want to.

 

[rjones560]

I'm wondering if I can just turn on the Dynon display with the engine off and put a battery charger on my main battery to keep it charged. My flights are rarely over the 4 hours needed to fully charge and I've been getting low backup battery alerts. Will turning on the display charge the backup as long as my main battery is fully charged?

The backup battery will stay charged up in normal use if it is still serviceable. If you are getting backup battery alerts, perhaps the battery has gone bad. Have you run the test to see if it will pass?

 

[Jubilation]

If your charger is not showing 13.5-14.5 volts when connected to your battery, it is not charging.

Is the problem with my main battery or with the Ctec charger? Setting the Ctec to “supply” makes no dfference.

 

[vlittle]

I purchased a 12V, 30A power supply and adjusted it to 14V. I connected a 7A breaker to the output to make a GPU.
I charge the SkyView battery by plugging into my 12V 'cigar lighter’ port and pulling all of breakers except the SkyView and 12V port power.

To simplify, I also fabricated a dedicated SkyView power plug that won‘t power the rest of the panel, and is a bit safer to leave on. This is shown below.

 

[Jubilation]

Thanks very much. That's great.

 

[dj-tentacle]

I‘ve disassembled a couple of backup batteries. What I‘ve found were some industry standard cells and various models of industry standard battery management boards. I don‘t think there is anything Dynon specific beyond the case but I might be wrong.

What I know about the BMS‘s is that below a certain threshhold, power output is cut entirely to avoid deep discharging.

I also know that most BMS need a higher voltage than the output to charge. I doubt that charging the backup batterie from a 12v starter battery will work. If you connect to 14.x volt it sure will charge and then it should charge regardless the device bing on or off.

You could connect the battery directly to any power source. Charging is done by the BMS, not the device.

 

[swatson999]

I'm wondering if I can just turn on the Dynon display with the engine off and put a battery charger on my main battery to keep it charged. My flights are rarely over the 4 hours needed to fully charge and I've been getting low backup battery alerts. Will turning on the display charge the backup as long as my main battery is fully charged?

So I don't think you need to make a single flight of 4 hours just to charge the backup battery. It should simply recharge over the next n flights, however many that may be (depending on voltage from the alternator/buss, time of flight, some minimal time spent on backup battery during engine start, etc.).

I've never worried about the SV backup battery getting recharged...just go fly a few times. Presto!

 

[BWW312]

I'm wondering if I can just turn on the Dynon display with the engine off and put a battery charger on my main battery to keep it charged. My flights are rarely over the 4 hours needed to fully charge and I've been getting low backup battery alerts. Will turning on the display charge the backup as long as my main battery is fully charged?

You can run the system with a battery charger, but I really did not like doing that, I had a bunch of issues with 3 different battery chargers. I bought a 12v power supply from Amazon for about $30 that supports the system perfectly for as long as you like, it also charges the Dynon batteries fine. I put a permanent connector inside the oil check door so hookup is very convenient . If you want I can send the details of the p.s. I am not at my hanger right now.

 

[Europaul]

The backup battery will stay charged up in normal use if it is still serviceable. If you are getting backup battery alerts, perhaps the battery has gone bad. Have you run the test to see if it m passed

My battery passed the test but, about a month later, popped up with a low charge warning a few times... this has gone now, but any ideas what caused this (a) to happen and (b) to stop happening?
Cheers,
Paul

 

[Raymo]

See Post #2.

I did. My response is about the voltage a normal charging system should produce, not the minimum a backup battery needs.

 

[Raymo]

Yes, you could say that. Post 2 (from the manual) says it doesn't charge, but that technically isn't true, which is what Dynon has said here before. Charging doesn't simply shut off at 12.25 volts. The charge rate just becomes too slow to be considered 'effective', but it is still technically charging because a voltage is still applied. At some point below 12.25 volts, the charge rate will reach the point where charging will no longer increase the battery voltage. That will vary slightly, in no small part due to battery condition, and that's what Dynon was getting at when they made that statement here. 12.25 volts is simply the best guess threshold where effective charging should be assumed for a good battery. It doesn't really matter that much in the grand scheme of things, so you could 'effectively' infer that both statements are correct if you want to.

Any rate of charge must be higher than the voltage of the battery that is being charged. The EFIS logic will not allow the backup battery to charge a a lower rate than documented (unless they changed that logic recently)