450 Lipo Care

[pj1969]

i'm trying to work out or find out the best ways to take care of my trex 450 and 600 lipo's??? I've just flew 2 3s 11.1v lipo's for 8 mins normal flight and just wondered whats best for them?? leave it at 8 mins (checked volts and they are both down to 3.80 and 3.68v) dont know whats best run them down or a safe time to run?? On my trex 600 batts which are 6s 22.2v i'm thinking maybe 10mins normal flying time. I'm still in only in basic flight, but can manage to keep her up for 8-10 mins. What are your thoughts guys???

 

[Lee]

Your batteries after a flight should read 3.7V which during flight will be lower, around 3.4V under load. If you run them down to the low voltage warning, its already getting to damage levels. Think of it like a car. If you wait for the oil warning light to come on, its already damaging the engine.
Best way is to do a shorter flight say 5mins, then charge the battery back up. If you have a charger that tells you the MAHs put back in, then it should be no more than 80% of the capacity.
Example
2200mah battery 80% is 1760Mah
So if you are putting more than 1760mah back into the battery, you are draining it down too far.

 

[pj1969]

I've just got back from the field and did 3 x 3s @ 8 mins and 2x 6s at the same and checked volts, all were at around 3.7/3.8 so im happy with that. just put them on balance charge and seee how long they take to hit full. I'm using imac b6x charger. thanks for info Lee

 

[Dirk]

I also get around 8 mins on a 3S 11.1V pack. When I land they read 3.7 volts per cell. My charger puts about 1750 mAh back into them when I charge them. I only fly for 7 and a half minutes now just to make sure. I use the telemetry module on my 450 and my voltage alarm is set to go off at 10.1 volts.

 

[pj1969]

Cheers Dirk, i'm not sure i have telemetry or voltage alarm on my dx6i? The 3s's balanced back up in 28 minutes so i'm happy with that. i do have one of those little volt meters and buzzer thing that plugs into the balance lead. i think like you i'll do 7 and a half mins, just to be sure. happy flying mate

 

[Tony]

What Lee posted is exactly correct. Fly for 5 minutes, then charge your battery. If you are putting more than 1760mah back in your 2200's, then you are flying too long. If you only put in 1500mah, then you cna extend your run time by 30 seconds until you find your 80% discharge rate. The lipo alarm is a bad idea as Lee stated since you are already at damaging levels when it goes off.

 

[Stambo]

What Lee posted is exactly correct. Fly for 5 minutes, then charge your battery. If you are putting more than 1760mah back in your 2200's, then you are flying too long. If you only put in 1500mah, then you cna extend your run time by 30 seconds until you find your 80% discharge rate. The lipo alarm is a bad idea as Lee stated since you are already at damaging levels when it goes off.

For once I have to disagree with you Tony.
It depends on the lipo alarm.
Some are programmable, mine is and it was less than $5 from Hobbyking.

I do monitor how much goes back in though, and flight times.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=18588

 

[Tony]

it's all good, the alarms I was referring to are the ones that go off at about 3.2vpc, which is way too low. If you have one that you can set to 3.6vpc, that would be perfect and you can dial in the number that works best for you.

 

[Lee]

Lets clear this up a bit. I was talking about the Low Voltage Cut off on the ESC. Which in most cases will be around 3.2V If you get to that level, you are risking damage.
The Low Voltage Alarms, are a different thing. I use them as a device to set up my timer. Adjust to go off at 3.7V, see how your battery charges, then reduce to 3.5V and check again. I find if i set my alarm to go off at 3.5V, the battery at rest will read 3.7V which is perfect.

 

[Dirk]

+1 Lee. Got mine set up the same way now. Works a treat.

 

[Tony]

Right on.