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Old 09-28-2009, 07:21 AM   #1
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Default Lipo issues with HV servos?

Befuddled – I am running 2 Hitec HV servos (the high torque ones), Losi 2000mah Lipo and Spektrum radio. Now when I was running the JR servos on a regulator, I can run all day 3 – 7min quals and a 20 main with no problems.

Now once I switched to the HV servos, After a full charge (or what my charger say is full) it just died on me in 15 min in the main. When I got home I checked the voltage of the lipo receiver pack and it read 1.7v and 1.9 volts. Now I have never seen this pack under 4v

So I guess my question is, Will the HV servos at 7.4v drain the receiver pack faster that regulated at 6v? I really don’t understand the characteristics of LIPOs and the output ect.

Yes I charged it before the main and sure of it.
I tested the off and on switch and it works.
I charged another lipo with the charger and it was fully charged.

Could it be the receiver? It was BRAND NEW.

Im at a loss- any help or ideas would be appreciated
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Last edited by token; 09-28-2009 at 07:33 AM.
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Old 09-28-2009, 07:30 AM   #2
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I dont know the answers to your questions but my first thought is your lipo battery is dying.
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Old 09-28-2009, 07:35 AM   #3
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I started running hv servos and lipo packs at the same time about 3 races ago. I noticed that with a new lipo pack the first 2 times it seemed to drain fast, but now after 3 or 4 charges the packs took about 650mah after 15 mins of practice and a 30 min main. The 1st time withthat sam situation the same pack took 1300mah so they seem to be broke in now. I run the exact same setup in the buggy and truggy and they behave the same.
Are you balancing your pack? And it sounds like the pack is done as 2.6v per Cel is the minimum that a pack can have and still be good. I would try a new battery and give it a couple of cycles before you mak a decision. I would say a lipo pack should be able to do 90 min no prob on hv servos.
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Old 09-28-2009, 07:43 AM   #4
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"I'll tell you this bud", let me crawl back in my hole now




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Old 09-28-2009, 08:24 AM   #5
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Old 09-28-2009, 08:40 AM   #6
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I have the same setup and didnt have any issues. I havent balanced the Losi pack yet (my charger had the wrong adapter and so did the balance plug I bought ).
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Old 09-28-2009, 10:33 AM   #7
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I have the same setup and didnt have any issues. I havent balanced the Losi pack yet (my charger had the wrong adapter and so did the balance plug I bought ).
hummmmmmm, i think I have a bad pack........ thanks guys
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Old 09-28-2009, 01:53 PM   #8
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When the HV first came out a racer at our track had the same problem you had. He phoned Losi up and they said at the moment they don't have a pack that will last the amount of time. I couldn't believe when I heard that found it pretty hard to believe that they would come out with servo's that they can't even run for an A-main. Now I don't know if the Losi guy was covering his ass on a defected product that they didn't want to replace, or was actually telling the truth. If people are able to run them with the same setup as you I guess you have your answer.
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Old 09-28-2009, 02:12 PM   #9
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I run the JR HV servos and the DX3R on the Losi 2S Lipo.

I can run about 1hr to 1:30 mins on my packs with no issues. I can tell when they are losing their punch though, but they still run great.

I bet your Lipo is gone just from the fact that you said your below 3.2v p/cell. Do a discharge test on it with your Charger.

The Losi Lipo is 2000mah. Lipo should never drop below 3.2v p/cell.

That being said on a full charge (4.2v p/cell) you should be able to discharge the Lipo to the cutoff voltage (3.2v p/cell) and have drained if not all very close to 2000mah. That's the best way to check the Lipo, and make sure you are getting the maximum usage out of it. Anything dropping below 3.2v is dangerous for the cell and it will become unstable. You have to charge the battery at 0.1a until you reach 3.2v p/cell, or you can risk blowing the pack. That's why they are not suppose to drop below 3.2v.


Hope this helps. I just took the Lipo101 class from my LHS electric guru.
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Old 09-28-2009, 02:22 PM   #10
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Ya I think you have a bad lipo pack. The servos are good.
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Old 09-28-2009, 02:36 PM   #11
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Originally Posted by token View Post
So I guess my question is, Will the HV servos at 7.4v drain the receiver pack faster that regulated at 6v? I really donít understand the characteristics of LIPOs and the output ect.
yes..

IMO the HV servos are overkill but it's nice to get rid of the regulator.. After dumping that pack i would pick up some new ones and just re-peak them during the day..
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Old 09-28-2009, 04:05 PM   #12
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If this is a Losi 2000 7.4v lipo pack, it should have a low voltage cutoff. I know, since it refused to show any power one time after we shut the car off. Once a charge was placed back on it, it came back up. Pretty odd to run the lipo down to 1.7v-1.9v. Its usually toasted and will die off with no voltage reading at all.
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Old 09-28-2009, 04:26 PM   #13
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I don't know if this matters, but he's talking about the Hitec HV servos. Everyone else is talking about the JR HVs.
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Old 09-28-2009, 05:34 PM   #14
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Quote:
Originally Posted by RJNicholson View Post
I run the JR HV servos and the DX3R on the Losi 2S Lipo.

I can run about 1hr to 1:30 mins on my packs with no issues. I can tell when they are losing their punch though, but they still run great.

I bet your Lipo is gone just from the fact that you said your below 3.2v p/cell. Do a discharge test on it with your Charger.

The Losi Lipo is 2000mah. Lipo should never drop below 3.2v p/cell.

That being said on a full charge (4.2v p/cell) you should be able to discharge the Lipo to the cutoff voltage (3.2v p/cell) and have drained if not all very close to 2000mah. That's the best way to check the Lipo, and make sure you are getting the maximum usage out of it. Anything dropping below 3.2v is dangerous for the cell and it will become unstable. You have to charge the battery at 0.1a until you reach 3.2v p/cell, or you can risk blowing the pack. That's why they are not suppose to drop below 3.2v.


Hope this helps. I just took the Lipo101 class from my LHS electric guru.
X2 on the NOT going below 3.2 ...i also took some lipo 101 classes from a Flyboy who uses big dual 10S in heli's...he also told me a few other lipo tid bits that have come in handy over the last couple years.
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Old 09-29-2009, 09:16 AM   #15
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OK guys, thanks for all the feedback. after checking and re checking - its the of-on switch
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