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Jan 19, 2012, 01:49 PM
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Help!

HobbyKing 150A 4 cell lipo problem


Hi guys.

Get today problem. Instealled on Summit Motor trackStar 4068 and ESC HobbyKing 150A. Today 2nd run. Connect 2 Lipo 2S 5000 mAh = 4S. Have snow about 3 inches. Fast run with max speed. After 1-2 min, car run so slow looks like not 4 cell and 1 cell lipo. After I turn off / on switcher, summit again run fast for 1-2 min. I try another 2 packs of fresh charged LiPo but same result. Than I try drive on with only one 2 cell battery and speed so good without problems. So what can happened and how to fix that.

Thanks all!
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Jan 19, 2012, 03:40 PM
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wparsons's Avatar
What kv is the motor? Did you change the gearing when doubling the voltage? How hot is the motor or ESC getting on 4s?

It sounds like you're overloading something by doubling the voltage with no other changes.
Jan 19, 2012, 04:37 PM
Registered User
2560 kv. Gearing is default 14/68. As weather -7 celcium so motor and ESC cold.
Jan 19, 2012, 09:17 PM
Registered User
wparsons's Avatar
Did you actually check the motor and ESC temps when it slowed down, like right away? You might be surprised how hot they can get even in cold temps.

You're either overheating something, or hitting the LVC under load.
Jan 20, 2012, 03:25 AM
Registered User
Hard image that I overheat in one minute ESC or motor at winter with really cold weather. Also my summit all stock so right configuration from factory. Couple days before I run with more warm weather and all work perfect.
Jan 23, 2012, 06:40 AM
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wparsons's Avatar
Did you run it on 4s in warmer weather? Did you keep the stock gearing from the brushed motors when putting in the brushless? I would imagine that the stock motor is a much lower kv?

Until you actually check the motor and ESC temp, I have a hard time believing the ESC isn't overheating.
Feb 02, 2012, 12:46 AM
True Modder.
Had the same problem once..... Check if esc lipo setting and low voltage cut out is correct. Also check all connectors again and again. I think wparsons might be right also. 36864rpms is not that high on 4s, but check gearing.
Feb 02, 2012, 07:25 AM
Registered User
LaTuFu's Avatar
Have you done anything to protect the LiPos and ESC from the snow and water?

Neither one like water at all. If the ESC got any water in it, you could have fried the electronics.
Feb 05, 2012, 07:02 PM
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wparsons's Avatar
^^ He said it worked fine on 2s afterwards, so I don't think he fried anything.

LiPo's are fine getting wet, I know a few boaters that have sunk boats and recovered packs days later that were in perfect shape still.
Feb 06, 2012, 07:11 AM
Registered User
LaTuFu's Avatar
As long as the battery pack integrity remains intact, yes. If water gets into a pack and into a cell, no.

But reading the OP's post again, I am wondering if there is a cell out of balance in the packs, and that is what is causing it to hit LVC 1-2 minutes in.
Feb 06, 2012, 10:54 AM
Registered User
Quote:
Originally Posted by LaTuFu
As long as the battery pack integrity remains intact, yes. If water gets into a pack and into a cell, no.

But reading the OP's post again, I am wondering if there is a cell out of balance in the packs, and that is what is causing it to hit LVC 1-2 minutes in.
I think it is just temperature. Lipos do not like cold. Take a look at this plot I did showing how the IR of a lipo varies with temperature. Going from 25degC down to 7degC will likely double the IR so that the output voltage drops so far that the the Esc goes into LV mode. Try it with a thoroughly warmed pack at 25degC.
https://www.rcgroups.com/forums/thum...ttach&u=140524

Wayne
Last edited by Wayne Giles; Feb 06, 2012 at 10:56 AM. Reason: Forgot Link!
Feb 07, 2012, 10:28 AM
Registered User
wparsons's Avatar
^^ That's very possible too, I wasn't thinking about how cold the packs would be.

The current draw would be way lower on 2s so they're probably ok at that load in the cold.
Feb 07, 2012, 10:30 AM
Registered User
wparsons's Avatar
Quote:
Originally Posted by LaTuFu
As long as the battery pack integrity remains intact, yes. If water gets into a pack and into a cell, no.
What do you mean by pack integrity? The shrink wrap is far from water proof, the bare cells would definitely have gotten wet if the pack is submerged, but it'll still work. The only issue would be if the cell itself was punctured, but that's a huge problem on its own.
Feb 15, 2012, 06:25 PM
Harry from Atlanta, Ga.
Old Sloppy's Avatar
I have a 1/5 scale crawler, when the lipo gets cold, when it is snowing It hits the LVC a lot.
Lipos really like to be 100+ degrees F.
They do not work well cold and really hate freezing tempatures.
The cold causes the voltages to drop to excessively low levels.


Harry


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