cagey Posted July 31, 2012 Share Posted July 31, 2012 I'm going to use a 2100 mah 2 cell LiFe pack to power a full house machine, 2 electronic U/C retracts,2x 9g on flaps, 2x 9g on ail, a12g on elev, 9g on rud, & a 9g on the tailwheel steering. Flight power will be a 4 cell 3900 thru ubec ESC. My concern is will the LiFe be man enough and will the single power lead from the pack through the batt / bind socket be able to take the required load ? It's very unlikely that flaps will be used very much, if at all. Rudder used on take and landing only. U/C up and down once so the system isn't going to be caned. My 550 Trex has a similar set up and as it has a spare aux port in the 8000 r/x I doubled up the inputs to spread the load as it were, but am now thinking that it matters not how many and how big the leads are because they're all going through the same very small pos and neg circuit board tracks. Any electrickery advice on this would be most appreciated peeps. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 31, 2012 Share Posted July 31, 2012 The LiFE pack will be for just powering the radio yes?? You will disconnect the ESCs BEC?? Which LiFE pack is it? One of the A123s or a foil pack?? Certainly I think the battery will be OK in supplying enough juice...its surprising how little current servos actually take....what size are the retracts..? I think the biggest ones only take 1A max..... My personal opinion is that it will be OK....I think I would opt for a heavy duty switch though........ Quote Link to comment Share on other sites More sharing options...
Alan Cantwell Posted July 31, 2012 Share Posted July 31, 2012 Mate of mine is using the A123s for his B25 mitchell, 118" span, about 14 servos, and 2 recievers, he recharges after every other flight, and could leave it for longer, Quote Link to comment Share on other sites More sharing options...
cagey Posted August 2, 2012 Author Share Posted August 2, 2012 Thanks for the replies Steve and Alan. The LiFe is a Hyperion 2cell, powering the radio and servos. Haven't a foggiest as to the retract units size, they came with the kit, a FMS 57" P51d foamie job. I have given the LiFe six successive flights of 5 minutes each on the Trex 550 E and on charging put back no more than 780 ma, so I think the packs up to it. I still wonder if it's not asking a bit much for the single battery supply through the R/X circuitry though ? That's my main concern at the moment. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted August 2, 2012 Share Posted August 2, 2012 Stop worrying, it will be fine. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 3, 2012 Share Posted August 3, 2012 I would always power retracts from a separate battery. It's too easy for something to get knocked out of adjustment on the taxi/take-off run and stall the mechanism which will drain the battery quickly. Unless your retracts can detect a stalled condition and trip out, perhaps? Edited By Martin Harris on 03/08/2012 01:29:36 Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted August 3, 2012 Share Posted August 3, 2012 Have a search Cagey, lots of LiFe chat here. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 3, 2012 Share Posted August 3, 2012 I think it will be fine Cagey.....servos take a lot less power than we like to think....... Sir Timbo of Mackey did some most excellent work on this very subject here & here which you might like to read...... I myself performed a highly controlled experiment by thrashing my hack around for 40 minutes (four ten minutes flights approx) using all the controls as much as I could & then seeing how much went back into the LiFE battery......a bit of maths showed the average current drawn by ALL the servos was about 120mA. So if we ignore the throttle servo that means each of the other servos took an average of 30mA...... Which is not a lot.... Given that your model is a foamy warbird I can't see that hot doggin' 3D action will be on the cards......more graceful carving turns & aerobatics & this will put very little load on the servos.... Martins point about the retracts "jamming" & flattening the battery is a valid point from ye olde dayes of servoe operated retracts but I'm pretty sure the electric retracts have a current sensor to prevent this happening..... In short....stop worrying.....go fly it......Enjoy!! Quote Link to comment Share on other sites More sharing options...
cagey Posted August 3, 2012 Author Share Posted August 3, 2012 Okay folks, I've got the message and am not worrying diddly no more, thank you for the leather injection confidence booster. Mind you tho', if you had my history of soil hardness trials you'd probably worry a tad occasionally . Apart from the 550 heli this LiFe caper is new to me and those links are a treasure trove of info, many thanks for them fellas. All '.m waiting for now is the new ESC to arrive, with a shed load of good weather to accompany it. Bit much to hope for ain't it, but it can't rain and blow forever ( Can it ! ? ) Obliged everyone. Quote Link to comment Share on other sites More sharing options...
Ultymate Posted August 3, 2012 Share Posted August 3, 2012 Posted by cagey on 03/08/2012 21:25:39: Bit much to hope for ain't it, but it can't rain and blow forever ( Can it ! ? ) Obliged everyone. I don't know the rehearsals have been going well !! Quote Link to comment Share on other sites More sharing options...
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