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mark.bitterlich(at)navy.m
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 Posted: Mon Jul 17, 2017 8:47 am Post subject: Battery Charging CJ-6 (in this case Yak's) |
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To add to what Chris said:
On all of the YAK aircraft I have worked on, the electrical junction boxes are very close to identical. The way they operate is pretty simple as regards power, and this will answer your question in more detail.
In the cockpit, the Master Power Switch has three positions. Up is battery power. Middle is OFF. Down is Ground Power. This switch controls TWO identical relays in the main electrical panel, one of which connects battery power to the main electrical bus, and one that connects external power to the main electrical bus. This is an "either/or" situation, as it is wired, meaning you cannot connect external power to the aircraft and have it charge the battery.
To the electrical guru's out there, the fact that these two relays are identical is important to know. They tend to fail now and then, and when that happens to the one that connects the battery to the aircrafts electrical bus, you will lose all electrical power, but it can be insidious. If this relay fails in flight, the generator will pick up the load, and you will never really know it happened. As soon as you bring the engine to idle, you will lose all electrical power for the aircraft, run the engine back up and you will get power back again. The trick is this, since the ground power relay is exactly the same, you carry a spare with you at all times! You can just switch them, and you're back in business. The down side is that this electrical panel is difficult to get to and work on and in the long run it is usually easier to just remove the complete panel and work on it outside of the aircraft.
Going back to charging the battery, yes ... the external power relay could be re-wired so that when you connected a charger to the external power connector, it would close the external power relay and instead of powering the aircraft, would send the power directly to the battery for charging. Wiring it like that would keep battery power off the external power connector unless you had the charger attached. However, the danger to that approach is that if someone connected "true external high current power" to that connector, you could end up having unlimited charging current going to your battery, which would not only ruin them, but also would gas them and possibly split the case. This could end up being an example of what Chris was talking about! Very much less than good.
In the long run I'd advise against that method, it's an accident waiting to happen, which I would guess is why the original design did not allow it. In my experience the Russians did everything for a reason, usually very good ones.
I did see a neat trick done by the previous owner of my SM1019. He took the excellent "Battery Minder" brand of battery charger, and actually mounted it in the battery compartment semi-permanently. He then wired in a permanent 115 VAC female plug (with rubber cover) directly through the aircraft. Yes, he cut a round hole where you can take a 115 VAC extension cord, remove the cover on the aircraft, and then plug the 115 VAC extension cord right into the aircraft! The Battery Minder then gets powered up and charges your battery. I think that was a brilliant idea actually, and I wish I had thought of it!
Lastly, I agree with Chris when charging batteries "in situ" but with a Battery Minder properly connected, it checks battery temperature plus controls charging current plus pulses the battery after charging with a 3 MHz pulse extending the life of the plates, so to a large degree, safety is in the design.
Mark
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drc(at)wscare.com
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| Posted: Mon Jul 17, 2017 11:14 am Post subject: Battery Charging CJ-6 (in this case Yak's) |
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I agree w Mark on the top quality battery minder. I would charge “in vivo” (Physician)
After owning turboprops and having friends w jets, The very expensive batteries will list 2-3x longer with a battery minder.
I would not mount the battery minder in the plane though. It comes with a pigtail that can attached to the battery and run to a convenient access point.
Be sure to get 12v or 28v as it may apply. The other difference in models is amperage. If I recall they come in 2A and 8A. If the batteries are healthy to begin with I believe the 2A is sufficient.
On the other hand, I have wired a 115 ac male mounted on the back of the cowl louvers on my TW to plug in the heater pads on the engine and oil tank.
Herb
[quote] On Jul 17, 2017, at 11:46 AM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil> wrote:
To add to what Chris said:
On all of the YAK aircraft I have worked on, the electrical junction boxes are very close to identical. The way they operate is pretty simple as regards power, and this will answer your question in more detail.
In the cockpit, the Master Power Switch has three positions. Up is battery power. Middle is OFF. Down is Ground Power. This switch controls TWO identical relays in the main electrical panel, one of which connects battery power to the main electrical bus, and one that connects external power to the main electrical bus. This is an "either/or" situation, as it is wired, meaning you cannot connect external power to the aircraft and have it charge the battery.
To the electrical guru's out there, the fact that these two relays are identical is important to know. They tend to fail now and then, and when that happens to the one that connects the battery to the aircrafts electrical bus, you will lose all electrical power, but it can be insidious. If this relay fails in flight, the generator will pick up the load, and you will never really know it happened. As soon as you bring the engine to idle, you will lose all electrical power for the aircraft, run the engine back up and you will get power back again. The trick is this, since the ground power relay is exactly the same, you carry a spare with you at all times! You can just switch them, and you're back in business. The down side is that this electrical panel is difficult to get to and work on and in the long run it is usually easier to just remove the complete panel and work on it outside of the aircraft.
Going back to charging the battery, yes ... the external power relay could be re-wired so that when you connected a charger to the external power connector, it would close the external power relay and instead of powering the aircraft, would send the power directly to the battery for charging. Wiring it like that would keep battery power off the external power connector unless you had the charger attached. However, the danger to that approach is that if someone connected "true external high current power" to that connector, you could end up having unlimited charging current going to your battery, which would not only ruin them, but also would gas them and possibly split the case. This could end up being an example of what Chris was talking about! Very much less than good.
In the long run I'd advise against that method, it's an accident waiting to happen, which I would guess is why the original design did not allow it. In my experience the Russians did everything for a reason, usually very good ones.
I did see a neat trick done by the previous owner of my SM1019. He took the excellent "Battery Minder" brand of battery charger, and actually mounted it in the battery compartment semi-permanently. He then wired in a permanent 115 VAC female plug (with rubber cover) directly through the aircraft. Yes, he cut a round hole where you can take a 115 VAC extension cord, remove the cover on the aircraft, and then plug the 115 VAC extension cord right into the aircraft! The Battery Minder then gets powered up and charges your battery. I think that was a brilliant idea actually, and I wish I had thought of it!
Lastly, I agree with Chris when charging batteries "in situ" but with a Battery Minder properly connected, it checks battery temperature plus controls charging current plus pulses the battery after charging with a 3 MHz pulse extending the life of the plates, so to a large degree, safety is in the design.
Mark
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jay-dub
Joined: 31 May 2014
Posts: 99
Location: UK
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| Posted: Wed Jul 26, 2017 3:47 pm Post subject: Re: Battery Charging CJ-6 (in this case Yak's) |
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Thanks folks, interesting info.
In my part of the planet, modification is a dirty word as anything modified clearly spontaneously combusts (must be a different kind of air), so I suspect acquiring a second battery and swapping is probably the way to go.
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