The battery anvil just dropped on my head... - RC Groups
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Oct 06, 2011, 12:00 PM
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ausf's Avatar

The battery anvil just dropped on my head...

I'm right-brained, so I need to witness things to appreciate them.

All the RTF planes and helis in my house are Horizon UMs, so over time, between deals and gifts, we've amassed quite a pile of Eflite batteries. I know a lot of guys don't like them, but we've never had problems with performance.

When I got a F4U, I picked up 5 Hyperion 240s to help with weight distribution. I eventually swapped out the motor with a Bravo SX and GWS 5043 prop. Flies great as expected.

I put a Bravo SX (and 5043) in my Stevens Hummingbird. I ended up building it a bit tail heavy, so taking a cue from the Corsair, I used the Hyp 240s again to balance it out. Flies like a dream.

I just finished MM's Art Chester's Jeep and installed, yep, you guessed it, a Bravo SX with 5043. Why mess with success? No balance issues on this build, so I went with an Eflite 150. Pushing the throttle I hit LVC a few seconds in. Change it out, LVC. Checked the batteries, all 4.18-4.20, but all hit LVC. I plug in a Hyp 240 and it sings.

So, I guess I painted myself into corner, only being able to use 4 batteries (I lost one somewhere) over 3 planes when I have a pile of 150s.

Is it a matter of motor or prop draw or both?

I don't have any specs on the Bravo SX vs the HH, except they're both 8.5 mm brushed. The Eflites are 12C, I think the Hyperions were 25C (I bought them without connectors and they are shrink wrapped now).

My sons will be able to fly their Champs non-stop for about 20 hours now.
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Oct 06, 2011, 02:43 PM
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150mAh 12C is capable, in theory, of supplying 1.8A; 240mAh 25C is capable of 6A. How many amps your motors want depends mainly on what props/gearing they've got, but as you can see, your smaller batteries are going to drop down to lvc long before the larger ones do.

One thing you can do is run your small batteries in parallel. Two of them Y-leaded together will give you up to 3.6A. Maybe that's enough for your Bravo SX -- I don't know how many amps it should be drawing.
Oct 06, 2011, 03:47 PM
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Thanks Abenn, that's a great idea.

I run two 150s in series to power my 2s brushless Mustang, I guess parallel as a 1s would be the logical step here. I have plenty of leads...
Oct 06, 2011, 07:42 PM
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Once again, RCgroups to the rescue!

Worked like a charm Abenn, thanks.

I won't use it on the Jeep or Hummingbird since I set them up for the 240s, but you just saved me a motor change on my son's Champ. It was hitting LVC shortly after swapping out a bum motor with one I had in the drawer. I just assumed it was a case of the spare being on it's way out too, but before yanking it, I plugged in two 150s in parallel and no cutoff. I guess the loose one was an old Solo Pro and it wants more juice.
Oct 07, 2011, 02:57 AM
Registered User
Glad the parallel setup works. You could even parallel three or more, subject to weight and balance, to get longer flight times if you want.

Time for a wattmeter, so you'll know for sure what amps and volts are being used in your setups

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