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Old Mar 01, 2016, 07:17 AM
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Blade CX3 No Power

I have a Blade CX3 that I got used, it came with 3 batteries. It now always behaves like the batteries are dead, or too dead to fly, it will get about a foot off of the ground, then slowly settle back down. The chargers indicate everything is normal with the batteries, but ZI am beginning to wonder. Is there anything other than batteries I should be looking at? Both upper and lower rotors seem to be free and straight.

Thoughts?
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Old Mar 03, 2016, 03:35 PM
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hello
it sounds like a classic example of battery voltage sagging under load.
Then it reaches low voltage cutoff point and the heli returns to ground.
As the batteries came with the heli, also tends to hint they may be past their prime.
When you say the charger indicates they are okay, unless it's a one of the better chargers with functions to determine the true condition of a battery, then it's not a reliable indicator.
Another way is to measure the battery voltage with a meter, straight after the heli has landed. Keep in mind that the voltage will have recovered slightly after it is no longer under load.
Anyway, this would be the first thing to prove definitively before looking for more complex problems.
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Old Mar 05, 2016, 11:02 AM
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What should voltage be if the battery is OK?
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Old Mar 05, 2016, 11:39 AM
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I tried it and right after trying it, and not being able to get more than a few inches off the ground (about 1 minute of power up time) and I had 7.74, that sounds fine, doesn't it?
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Old Mar 06, 2016, 12:45 AM
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Yes... perhaps.
The voltage may still be dropping quickly under load and then bouncing back, particularly after only 1 minute, if a battery has lost the capacity to deliver with a constant power demand placed on it.
Just to be sure, try to leave it running for longer than a minute, even sitting on the ground, then check the voltage when the rotors slow right down. But, just the same, keep a check on the amount of time involved, to get a clearer indication of whether the batteries have lost their capacity.
The batteries won't bounce back so easily if run for say, 2 minutes, and the rotors are hardly turning.
If voltage has dropped below 6.5v after that time, then you know for certain they are duff.
With these batteries, through charge and discharge cycles and general aging, the chemical loses it volatility and what may have been a 15-20C pack when new, becomes like a 1-2C pack. It's possible to still see relatively normal voltage after charging, but that drops quickly with load.
If you had a new battery to test with rather than 3 used ones, then you would know fairly quickly what's going on. Getting the same symptom with a new battery, would then warrant looking for another cause, possibly worn out motors.
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Old Mar 07, 2016, 12:26 PM
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I have a new battery on the way so I can check that. Seems odd that all 3 batteries would go at once, but it had sat for a few months I think before I bought it and started using it again.
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Old Mar 09, 2016, 02:35 AM
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Okay, at least that will answer the question one way or the other.
It may seem unusual for all three of those batteries to be faulty, but it depends on a number of factors, e.g. how old they actually are, how many cycles they've done and whether they were left sitting with a storage charge, or fully charged or discharged.
A storage charge (3.8v per cell) gives lipos the best chance of remaining healthy.
Something else you could check in the meantime, if not done already (I took it that you would have done this) is to check the power connector and wires on the heli, looking for partly broken connections at the plug and where they connect at the 3 in 1, if those wires are subject to movement at that end.
Sometimes you may see the plastic on the power connector distorting due to the heat that gets generated from a bad connection.
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Old Mar 25, 2016, 12:15 AM
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Me thinks you need new batts

Mike.
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