Lipo 101 for a n00b

[OhDonPiano]

Building helis... easy.
Flying helis... doable with practice...

Understanding Lipos? Impossible...


Honestly, this has been the most frustrating part of this hobby. And I even have an EE degree - though Lipos have more to do with chemistry than EE.

Anyway, I am the proud owner of a brand new T-Rex 450 and 3 batteries... I am also in the process of building a 500 - with batteries on the way.

Is there a Lipo guide anywhere which goes over the basics of conditioning, storage, usage, do's, don'ts, etc?

So I have read something about the first 5 times to not discharge more than 50%.

After that no more than 80%.

Never let the cell voltage get lower than 3.0v.

Ok. So unfortunately, I got one of the T-Rex helis WITHOUT artificial intelligence. So I am left to figure all this out on my own.

I have a Bantam e-station charger. Should I do all of the prelim conditioning on it? Any advantages to doing the conditioning in the field? How do I know when I have reached 50%?

The ESC has low voltage cutoffs, but not 50% cutoffs.

How should I store batteries for periods of between 2 and 4 weeks? More to the point, what if I don't know the period between flights?

At this point, I would almost rather deal with the risks of an atomic energy battery. This chemical stuff is too much to keep up with.

[Efliernz]

Clicking on "quick reply" doesn't seem right here!!!

First off, congrats on buying two great helis. I wouldn't be too concerned about limiting to 50% usage in the first 5 flights - just take it easy. I don't 3D new batteries... but I still still go to approx 80%.

Stopping at 80% is proving to be important. I have stopped at 80% with all my packs for the last two years of flying. Some packs went to over 100 flights. Some didn't. They were all treated the same. Some of the longer lasting packs were the cheapest. My worst performing 6S pack was the most expensive @ $15 per 8 minute flight!!! Cheaper to fly full-scale!!!

How to stop at 80%: If you can set a lvc on the esc to 3.3v, do it. I can't so I use a low-volt alarm. Yes, I make them - but it doesn't matter whose you use, just get one. I set mine up conservatively at 3.4v/cell and land when the lights stay on. If I only put 65% back in, I drop the voltage limit to 3.3v/cell and fly again. It may take several flights to get close to 80%. You are better landing at 70% usage than 90%.

I balance-charge every time. I have the new Align 6S charger and a Hyperion 1210 but both use the Align balancer. Both tell me how many mA I have put back into the pack. 80% refers to the amount of mA you put back into the battery - not the voltage drop of the pack.

LVC cutoffs are often at 3v/cell which is too low. Lipos drop voltage quickly below 3.2v/cell. That is where the alarm idea at 3.3-3.4v really works.

Storage: I store my packs charged up to 3 weeks as a rule. I fly nearly every day so they don't sit around. If I knew they were not going to be used for a month, I would discharge to approx 50% by either hovering for 4 minutes on the lawn... or discharging with a charger/discharger.

I hope some of that helps. Read lots here - there are some great threads in the Trex-450 and 600 lists. Good luck - electric is different but the clean & quiet side of this hobby is worth it :YeaBaby:

[Pinecone]

A few tings, 50% charge level is about 3.8 - 3.85 volts per cell. I charge or discharge to that level if the packs will not be flown for a couple of weeks.

I do treat my packs mildly and only go to 50% for the first few cycles. Not sure it helps, but it shuoldn't hurt.

AGAIN do NOT discharge below 80% depth of discharge. This is one of the largest factors in long pack life.

The other is the 3 volts per cell, and that is UNDER LOAD. So if you come down and have the pack after resting at 3.1 volts per cell, you have dome damage to that pack.

As for how to do this. I use a combination of the timer and one of Efliernz's lipo alarms. I fly a 3 or 4 minute flight and see on recharge how much was put back into the pack. Figure out the mAH used per minute, and what 80% is and figure out how many minutes are safe (I give myself at least a 30 second margin). Then I tune the lipo alarm to go off just after I should be on the ground. This covers me if I forget to start the timer, or forget and use a not fully charged pack, or something is going wrong in the heli and the amp draw has gone up.

And of the lipo alarms out there, Elfiernz makes soem of th ebest ones, IMO. They work, and work well, most models are adjustable. And if you have some wierd heli, he can make one to work. Reasonably priced and to yrou door, quite quickly for halfway around the world. And he is a nice guy. :)