What should the voltage on a 3S lipo drop to under load?

[felborn]

Im having some trouble with my Trex450, and im not sure if it's something with the heli or somethig with the packs. When checking the E-logger after fligh, I see the packs im having problems with have been drawn down to 9,41V, causing the ESC to go into low voltage mode.

On brand new Evoligth 2500mAh packs tho, everything works great, but when I check to log I see the voltage have dropped down to 9,81 on this pack as well. Is this normal, aint that abit low?

Check my post on the Trex450 forums for a look at the actuall graph: http://www.helifreak.com/showthread.php?t=61478

[Raydee]

That does seem a bit on the low side. You may want to upgrade to true 25c cells. In my boats (which draw average of 90 amps) my 25c cells generally never drop below 3.3 volts per cell. You may also want to check your heli and make sure you have a free drive train ( pinion mesh, tail belt) and that you don't have cyclic binding anywhere. There are a lot of area's that will cause extra amp draw. Have you tried to gear the heli down a bit and see what the graph looks like after that? If I had to guess I would say the 18c packs you are using just aren't up to the job.

[felborn]

Thanks for the feedback, this thing is really starting to get under my skin... Everything seems to run very smooth, head spins for several turns when pushed, engine does the same when I push the gear, as fare as I can tell there's no binding on the servoes, everything running smooth. Yet even my brand new Evolight packs seems to struggle. My Evo25 packs cuts down as soon as I hit idle-up (100-95100). I got no clue what the heck is going on here, but something seems to be drawing alot more power then it should...

[Raydee]

Ohh so even your Evo 25c packs are cutting just as bad?? What charger and balancer are you using? Are you getting a full 12.6 volts when your packs are charged? Something doesn't sound right. What ESC are you using?

[felborn]

Well, it's the Evo25 who having the problem, the Evolight packs works okay actually. I charge them all using a Bantam BC-6 and a Hyperion 1210I. Always balanced and always fully charged. Im running this on a Trex450 V2 with stock enigne and ESC. Im adressing this issue from several forums and with help from friends, but nooone seem to understand what the heck is going on here. I will try to test my packs in a friends helicoper and see how that goes, should atleast explain if it's the pack or something with my heli acting up,

[blueviewlaguna]

Well, it's the Evo25 who having the problem, the Evolight packs works okay actually. I charge them all using a Bantam BC-6 and a Hyperion 1210I. Always balanced and always fully charged. Im running this on a Trex450 V2 with stock enigne and ESC. Im adressing this issue from several forums and with help from friends, but nooone seem to understand what the heck is going on here. I will try to test my packs in a friends helicoper and see how that goes, should atleast explain if it's the pack or something with my heli acting up,
Switch out the motor - it may be drawing more amps than usual.

[liaan]

felborn, did you manage to figure out what this was? my mini titan doing this now on FP 2170...

thanks
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[felborn]

Still working on it, but seems some of this was caused by two bad packs (both from last year), and some bad wooden rotorblads. After building it up again, and replacing the blades voltage seem much better. But the pack from last year still cuts, so im pretty sure it's bad,

[liaan]

thanks!

i'll just do some mild flying for now until new packs arrive..

L: