BykrDan

Hi;

I dropped a pair of E-Tech 700mAh Li-Polymer cells in my Rare Bear this summer, and it flew great, for a long time.

I've used the batteries every few days - I'd fly for about thirty minutes, then put them back on the charger (Potensky) the evening before I planned to fly next, at 100 or 200 mA. They've worked great, until recently. The plane has been getting more and more sluggish over the last few flights - this morning it would not even hold altitude at full power.

Actually, I kind of suspect the motor. When I put the battery back on the charger last night, it only charged for a few minutes, which would indicate to me that it was practically full (I was only able to fly for a very short while yesterday).

The voltage level of the pack last evening, even before charging, was about 7.8v with the analog voltmeter; nominal is 7.4 for this pack. Does that indicate a good pack?

The motor in the plane is a GWS mini-geared motor, 5.86:1.

What's your best guess? Is the motor bad, the battery, or the charger? (I didn't say ESC, because I don't believe they behave that way when they go bad )

I do have one more test to perform; I'll try dropping my old 150mAh NiMH back in for a while, after I get it woke up, and see if the plane still lumbers around. That may not be so easy, though, as the planes performance on that battery was less than stellar to begin with!

Thanks for your consideration.
Dan.

Arrow>>-->

If you are using an IPS/ EPS motor that would be my first guess. Some people get long lives out of them others get only a few hours. That is typical of an IPS to slowly loose power. Before you give up on the battery you may want to pick you up a new motor and try it.

Matt Kirsch

My Feedback: (21)

After the Potensky charger indicates a complete charge, the voltage on the pack should measure 8.4V. That's a fully charged 2S (2 in series) LiPoly pack.

It doesn't take too many 30-minute flights to rack up several hours of flying time, and the IPS drives are not known for their longevity. Really long flights don't help, as the heat tends to build up in the motor. In all likelihood, you've simply worn out that poor old motor...

I really doubt it's the battery, as it sounds like you've been babying it.

BykrDan

Yahoo! I've finally "worn out" a plane, and not from crashing!

Thanks, guys - whoever built this plane put the cowl on pretty good - I'll fiddle around with it and try to get it off to put in a new motor....

Thanks,
Dan.

Matt Kirsch

My Feedback: (21)

If it's like mine, the cowl is stuck to the paint. I needed to do some careful work slipping an Xacto blade in between the fuse and the cowl to get it off.

e-bird

I sure like the small bbirds but like you guys say the motors goes south in less than 10hrs a lot of the time. But built a small outrunner 1.5 oz now they sell them. CU

BykrDan

I did get the cowl off last night - it was stuck to the paint pretty hard in some places, so much so that it took the paint and a little foam with it! Now I can get at that motor.

I have looked at the outrunners pretty hard, but man, for eighty dollars for the motor alone, I can go through a LOT of little IPS motors!

I imagine you'd want to break in an IPS in water, just like any other brushed motor, no? Or is the IPS so small or short-lived that break-in isn't worth the trouble?

Thanks,
Dan.

BuzzBomber

My Feedback: (4)

IMO, water break-in just uses up some of the service life of an IPS motor. Just install it and fly it. Some last longer than others--my last IPS lasted over 20 hours until the GB shattered--the motor's STILL ok though.