Gfeldman Posted May 16, 2020 Report Share Posted May 16, 2020 My Phoenix, like most, has a dual battery. One is a sealed lead acid and the other a lithium battery. One is located directly behind the passenger seat and the other far aft behind the baggage compartment netting. The 4 position switch behind the passenger side head rest controls current flow. How can I selectively trickle charge each battery without removing them? Is there an easy way to distinguish which is which? George Feldman N33GF Quote Link to comment Share on other sites More sharing options...
Jim Lee Posted May 16, 2020 Report Share Posted May 16, 2020 George, Most Phoenix including yours, come with a dual battery and battery switch system, also incorporating a power outlet next to the battery switch. Normal switchology is thus: pointer forward=forward battery ("1"). Pointer rearward=rear battery ("2"). Both is to one side and Off is to the other side. You use and charge in flight either the forward, rearward, or both batteries at the same time. The power outlet on the rear shelf is wired directly to the forward battery with a 5 amp fuse. No matter where the battery selector switch is, you will always use the forward battery with the power outlet. You can plug a battery charger into the power outlet to charge the forward battery. If you select "both" on the battery selector switch, you can charge both batteries with the charger in the power outlet. If you select either "1" or "2" you are isolating the two batteries, and you will only charge the forward ("1") battery. It is not possible to charge only the rear battery with the power outlet. If you are charging both batteries at the same time, use a LiFePo charger which works fine with lead acid batteries. Do not use a lead acid charger with desulfate capability as this will ruin the LiFePo battery. A small amperage trickle charger is best, on the order of 1 amp or so. Quote Link to comment Share on other sites More sharing options...
Registered Eric Greenwell Posted May 17, 2020 Registered Report Share Posted May 17, 2020 You can also use the panel power outlet: select the battery you want to charge with the Battery Master switch (on the package shelf) turn on the Panel Master Switch the battery you selected is now connected to the panel power outlet plug the charger into the panel power outlet charge at 4 amps or less, due to 5 amp fuse on power panel outlet Quote Link to comment Share on other sites More sharing options...
Gfeldman Posted May 17, 2020 Author Report Share Posted May 17, 2020 Thanks so much Jim and Eric. This is exactly the info I need. George Quote Link to comment Share on other sites More sharing options...
Doug Levy Posted June 4, 2020 Report Share Posted June 4, 2020 I didn't know you could use a lithium battery with the Rotax. I was told by one Stemme repair shop not to do that. I think he said there are issues with the voltage regulator. Good news as my 8 hour soaring flights have been a drain on my lead batteries. What batteries do you recommend and use? How many amp hours? Quote Link to comment Share on other sites More sharing options...
Jim Lee Posted June 6, 2020 Report Share Posted June 6, 2020 Doug, For your fantastic long flights you need as much juice as possible. Also 30 pounds in the baggage compartment help move the CG to the rear making thermalling much better at a lower speed without stalling the elevator. I have a 30 pound lead acid car battery in place of the forward battery and it is perfect. A LiFePo battery can also be used, but it is 5 times the expense for comparable amp hours, and you need the aft weight of the lead acid anyway. Construct your own battery holder for the large battery and make sure it is bolted securely to the bulkhead. Quote Link to comment Share on other sites More sharing options...
Registered Eric Greenwell Posted June 6, 2020 Registered Report Share Posted June 6, 2020 On 6/4/2020 at 1:28 PM, Doug Levy said: I didn't know you could use a lithium battery with the Rotax. I was told by one Stemme repair shop not to do that. I think he said there are issues with the voltage regulator. Good news as my 8 hour soaring flights have been a drain on my lead batteries. What batteries do you recommend and use? How many amp hours? Some LiFePO batteries, often referred to as "powersport" batteries, are compatible with many (but not all) 12 volt alternators/generators, but are only for engine starting. They can supply the high amps needed to crank an engine, but have limited energy capacity and can not run the instruments for very long. How much current does your Phoenix use when you are gliding with the engine off? That will set the lower bound for your battery capacity. Russ Owens has a full glass panel, strobe running lights, and more, but turns those off when gliding, and Russ has had good service from the Harbor Freight 12 volt, 35 AH sealed lead acid battery that sells for about $70. It's 25 lbs, I think, so close to Jim's suggestion. Give Russ a call! Quote Link to comment Share on other sites More sharing options...
Doug Levy Posted June 7, 2020 Report Share Posted June 7, 2020 Thanks for your replies Jim and Eric. I have a new lead battery in the original rear battery box. I don't remember it's amperage. My second battery is a Odysee PC680, 12 lbs; 18 amp; 170 CCA. I don't have the Dyon system. I'll have to figure out my current draw. I'm now using radio, Trig T22 transponder, 72 ADS-B, power flarm brick, Butterfly vario, and Oudie. I now have an Ipad running Foreflight software for seeing traffic. (far better than Flarm). The fully charged I pad is good for about 4 hours then I've been plugging that into the 12V outlet. My plans are to do more x-c touring. Space and weight are issues. Tent, sleeping bag clothes, toothbrush, battery chargers, O2, laptop, food, water all have to fit and add to the weight. I like soaring with less fuel but don't want to run out. A great, exciting adventure, as long as things go well. Might be a problem to remove a heavy battery to get it to where it can be recharged. What battery brands do you recommend Eric? As stated you can't have too much power. I have a good voltmeter in the Butterfly. The radio blinks errors at 10.5 V. I switch away from my soaring battery before reaching that voltage with plans to start the engine with the back battery if it starts getting low too. Quote Link to comment Share on other sites More sharing options...
Jim Lee Posted June 9, 2020 Report Share Posted June 9, 2020 Doug, Since weight is your determining factor, this is the battery that you need. The Butterfly is an energy hog. https://www.bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-40ah-lfp-battery-pvc-blf-1240as Quote Link to comment Share on other sites More sharing options...
Doug Levy Posted June 9, 2020 Report Share Posted June 9, 2020 Thanks Jim. I might postpone this until the fall. Time for some x-c right now. Quote Link to comment Share on other sites More sharing options...
Registered Eric Greenwell Posted June 11, 2020 Registered Report Share Posted June 11, 2020 On 6/7/2020 at 9:59 AM, Doug Levy said: I'm now using radio, Trig T22 transponder, 72 ADS-B, power flarm brick, Butterfly vario, and Oudie. I now have an Ipad running Foreflight software for seeing traffic. (far better than Flarm). I estimate your current draw, including the iPad (half-time), at about 2 amps. If you want 8 hours of engine off soaring, the minimum battery you'd need is about 20 AH. A 30AH battery would give you plenty of reserve and about 12 hours of soaring; a 40AH would give you two 8 hour days and some reserve. They are physically the same size, 2 lbs and $80 different. At 8 & 10 lbs respectively, they'd be easy to remove and carry to a motel, etc. Quote Link to comment Share on other sites More sharing options...
Doug Levy Posted June 13, 2020 Report Share Posted June 13, 2020 Thanks Jim. I'll stay with what I have right now and plan to make changes after x-c season. Hopefully I'll see you and some other people in Utah and Nevada this summer. Quote Link to comment Share on other sites More sharing options...
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