A Few Words of Caution!!!

[Shannon Davis]

Here is some info that was forwarded to me- source is Thunder Power.

Series Charging and Usage:

At Thunder Power we do understand many applications will require the use of multiple packs in series to achieve the desired level of performance. For example, some airplanes and helicopters will require the use of two 3s4p packs in series to fly as a single 6s4p pack. While it is possible to use multiple packs in series, Thunder Power /Advanced Energy Tech cannot be responsible for any problems encountered during series charging and or usage.

Again, you are on your own when charging or discharging packs in series – do so at your own risk.

Charging:

- Use only a charger designed for charging Lithium Polymer batteries
- You must use a high quality digital voltmeter (Capable of readings to 0.01v) to check voltage in order to correctly follow the steps outlined below. Your charger or Whattmeter are NOT accurate ways to measure pack voltage, and the use of a digital voltmeter is REQUIRED for safe series charging and discharging.
- When charging packs separately for series use on different chargers, it is VERY important that you check the calibration of each charger. To do this, you must simply charge each pack individually on each charger and check voltage. If the voltage of each pack is within the limits as outlined in the steps below, the chargers are very closely calibrated. If the chargers are not closely calibrated and the packs show voltage differing beyond the ranges listed below, you cannot safely use the packs in series (See “Usage” below for more information).
- If charging multiple packs in series at the same time on the same charger you must:
o Make a visual inspection of each pack to check for any obviously damaged, swollen, punctured cells, etc.
o Check the voltage of each pack independently after EVERY flight and before EVERY charge session.
o The voltage of each pack MUST be within 0.01v. This is very easy to check when using two like voltage packs. For example, you may only charge two 3s4p packs together in series as 6s4p if they read 11.10v for one pack and 11.10v (also safe if 11.09v or 11.11v) for the second pack. Actual voltage will of course vary based on the level of discharge for the packs.
o When using two packs of differing voltage, you must pay extra attention to the voltage of the packs and cells before charging them in series. For example, when charging a 2s4p and 3s4p in series as 5s4p you must first read the voltage of each pack individually. The 2s4p reads 8.10v and the 3s4p reads 12.15v after a flight. You must now divide the voltage of the pack by the number of SERIES cells within that pack; 2s4p: 8.10v/2 cells = 4.05v per cell. Now the 3s4p: 12.15v/3 cells = 4.05v per cell. Because the voltage of the INDIVIDUAL cells within each pack share the same voltage, this 2s4p and 3s4p pack are safe to charge in series as a single 5s4p pack. Again, you may ONLY charge packs in series if the voltage of the individual cells in both packs are within 0.01v.
o Never leave your charger unattended when charging any Lithium Polymer battery packs, whether they are individual packs or multiple packs in series!

Usage:

- You must use a high quality digital voltmeter (Capable of readings to 0.01v) to check voltage in order to correctly follow the steps outlined below. Your charger or Whattmeter are NOT accurate ways to measure pack voltage, and the use of a digital voltmeter is REQUIRED for safe series charging and discharging.
- After PROPERLY charging your multiple packs in series, or separately on different chargers for use in series, you must:
o Make a visual inspection of each pack to check for any obviously damaged, swollen, punctured cells, etc
o Check the voltage of each pack independently, even if packs were charged together in series.
o The voltage of each pack MUST be within 0.01v. This is very easy to check when using two like voltage packs. For example, you may only discharge two 3s4p packs together in series as 6s4p if they read 12.60v for one pack and 12.60v (also safe if 12.59v or 12.61v) for the second pack. Actual voltage will of course vary based on the level of charge for the packs.
o When using two packs of differing voltage, you must pay extra attention to the voltage of the packs and cells before charging them in series. For example, when using a 2s4p and 3s4p in series as 5s4p you must first read the voltage of each pack individually. The 2s4p reads 8.40v and the 3s4p reads 12.60v after charging. You must now divide the voltage of the pack by the number of SERIES cells within that pack; 2s4p: 8.40v/2 cells = 4.20v per cell. Now the 3s4p: 12.60v/3 cells = 4.20v per cell. Because the voltage of the INDIVIDUAL cells within each pack share the same voltage, this 2s4p and 3s4p pack are safe to use in series as a single 5s4p pack. Again, you may ONLY discharge packs in series if the voltage of the individual cells in both packs are within 0.01v.
o If after charging your packs in series or individually the voltage differs beyond 0.01v, it is possible to top off the lower voltage pack so it more closely matches the high voltage pack. This is typically more common when charging packs on different chargers, though you must also check packs charged in series independently after charge as well. Be sure to select the PROPER cell count when topping off a nearly fully charged pack; failure to do so will result in a fire!
- After strictly following all the above guidelines and ensuring your packs are within 0.01v, your packs are ready for use in series. However, there are a few steps which must also be taken during the discharge of the packs in series to prevent problems:
o Do not over discharge your packs. It is recommended to only discharge around 90% of the pack capacity. This creates a buffer and will prevent any LiPo pack (whether individual or in series) from becoming over discharged. When a LiPo pack is over discharged cells within the pack will be damaged and may even swell. Thunder Power / Advanced Energy Tech is not responsible for the repair or replacement of packs which have been damaged due to over discharge.
o Always check the voltage of each pack individually after discharge. Do not charge packs that may have been over discharged. Once packs have cooled, repeat the steps for charging.

[ScotY]

I want to add something that should be taken into consideration. The mention of a "high quality" DVM is a bit vague. Just because it can measure down to .01V, does not mean it is accurate enough.

For example, I have a cheap DVM (under $15) that I "calibrated" against a brand new Fluke meter. When measuring 2 series cells, it's about .01v off. 3 series cells, it's about .02v off. 4 series cells, it's about .03-.04v off. You can see where I'm going with this. The calibration or accuracy or whatever you want to call it, changes with input voltage to the meter.

It's probably safe to say I can use the cheap DVM to keep two identical packs (i.e. 5s4p and another 5s4p) within acceptable levels of each other. It's NOT safe to say I could do the same if I were to use two different packs, i.e. a 4s4p pack and a 6s4p pack together.

Hope that makes sense?

[z11355]

We're talking about the old 'accuracy vs. resolution' argument.

the problem w/ your theory is that all DVMs, regardless should be recalibrated every
now and then. I somehow doubt that the majority of the people here are willing to fork over
the $$$ required for a decent 10mV quality recalibration when they will barely spend the
$$ on a decent DVM to begin w/.

and honestly, after reading all that and knowing what I know, I must
say that my goal is to have the hobby of FLYING helicopters, NOT
'managing batteries'. It's a lot like PCs. After a while, you realize
that you're spending a huge amount of time simply managing the PC
and keeping it running instead of doing something PRODUCTIVE
w/ it.

Where's the value here? Cant charge and walk/sleep away, must remove
packs from machines, must get multiple chargers cause you can't
charge in series, etc etc etc

[Shannon Davis]

I to agree that I do this for the fun of flying- not working on or managing the equipment. I will check these batts for a while- but I'm pretty lazy. I should be able to tell you haow critical all of this is shortly.

Remember-"If you going to be stupid- You gotta be tough"

[z11355]

I'm more than happy to watch from the sidelines for a while. Of course it would be
nice to have a nice electric machine but when I look at the issues, I'd rather spend
time cleaning the machine for 10 minutes from the oil residue at the end of the day.

That brings up another question.... since e- machines dont require cleaning, will people
be less likely to go over nooks and crannies looking for loose screws and the like?
I think they will give these machines less maint with the inevitable outcome.

[cdrking]

z11355,

You make some excellent points. I have a fairly technical job and the last thing I want to do when I come home is have a very technical hobby. I enjoy the precision of the hobby and the challenge of the setup for the most part. But I'm with you, I would rather just gas and go for now.

Shannon,

Thanks for posting. If you're going to fly the electrics you gotta know your stuff.

Jeff

[WillJames]

It is a lot to learn and manage, but seeing it fly sure maks me want one. If shannon still likes his in a few months, I will probably get one too. We cannot fly anything that is not electric on Sundays at our field.

[ChrisS]

Hello all

This is all good stuff and enforces the fact that there is a learning curve here. As with any new model, the user must make it a goal to understand how the thing works in order to extract the most use from it.

The Ion-X manual talks about over charge and over Dis-charge. It talks about the use of a good charger. It says that it is a good idea to use partial cycles while at the field. There is even an addendum in there asking the user to call MinAir for final last minute advice on the use of the model and it's batteries.
A couple things that should perhaps be further emphasized are:

1) Use full charges on the batteries at least every four or five cycles to re-balance them. Use partial cycles ONLY if you are in the habit of NOT dis-charging the packs to the lower limit. That last video of Shannon flying, right there at the end where he took off one last time, he was probably seconds away from damaging (swelling) his packs. It cannot be over emphasized as to the importance of staying away from the limits of these batteries...use timers.

2) When you are first learning just how far you can go before your batteries need recharging, follow this procedure:

A) Charge your packs to full capacity.
B) Go fly, fly like you want to but listen to the heli, if it's getting bogged down a lot, back off. Do this for five minutes even, then land.
C) If warm, let the batteries cool.
D) Re-charge the batteries and make note of how many mAHr's go back in. All good chargers give this data.
E) Take the number for mAHr's you attained above and divide it into the full capacity of your pack.
F) Take that number and multiply it times 5.
G) Take that number and multiply it times 0.8, this is the final flight time (in minutes) you can fly...ONLY if you start from a full charge. Never exceed it.

As an example: Let's say I went out and flew for 5 minutes and put 2700mAHr's back in. I know my battery is good for an advertized capacity of 7600mAHr's so, 7600/2700=2.81. Taking the 2.81 times the 5 minutes = 14.05 minutes. And now take the 14.05 times the 0.8 = 11.24 minutes maximum. Yup, this is really conservative, but it helps us to account for things like variances between flights, energy lost to heating etc. And, it will keep you out of trouble. This formula will not work for anything but a FULL charge. Land a few times during the flight to check temps. If anything is hotter than it should be, discontinue the flight.

2) The speed control should be shipped with the proper programming already in place. You enter programming mode by putting your throttle stick full up and then powering up the flight system (please remove at least the blades while doing this). FUTABA radios MUST have the throttle channel reversed. JR radios do not. When you power up the model, use the following routine:
A) Turn on your transmitter
B) Turn on your receiver
C) Wait for gyro to initialize
D) Plug in the batteries, you should hear one beep, in a few seconds it will be repeated. This is the correct mode for the Hacker motor. You may begin throttle up at any time after the first beep.

There are other things in the speed control parameters that can be altered:
Frequency....use 8KHz for Hacker motors.
Brake on/governor off....this is the mode you want, the governor programming in the speed control does not apply very well to this application. Use throttle curves.
Timing....use mode one for the Hacker. You can run the next notch up (mode 2) but you may find the motor runs too hot.

Something else that cannot be over emphasized is to think of the speed control as a switch, it's either on or off. What this means is that you should never be up in the sky with anything less than 80% at the lowest point on your throttle curve. If you want a lower headspeed, change your gearing or cell count, we can help with this. You may get away with a lower than 80% throttle setting for just hovering stuff, but as soon as you head for the sky, get that percentage up above 80%.

Hope this all helps to clear the water a little

Chris

[ChrisS]

"That brings up another question.... since e- machines dont require cleaning, will people be less likely to go over nooks and crannies looking for loose screws and the like? I think they will give these machines less maint with the inevitable outcome."

They do still need oil and grease once in a while along with all the usual maintenance and there is still the pride of ownership thing. I doubt people will tend towards a "fly and forget" mentallity...at least I hope not. The e-fliers I know are really anal about thier machines, just like liquid fliers.

On a positive note, electric is smoother and tends to need less maintenance than liquid propulsion so people will probably find that they actually do have less maintanance than thier gas helis. Of course, there is the battery maintanance thing, so in the end it all probably balances out.

Chris

[Shannon Davis]

Chris, thanks for the info. I would like to add that I did not rev. my throttle servo, so when I plugged in the batts for the first time at low stick- the SC thought I was at full throttle and went into its setup mode. I then inadvertently changed the Timing and the Brake settings. So next I got the opportunity to learn how to change these parameters back to MA spec.

It's all good now- but you do need to read and FOLLOW the instructions.

In the last video I posted of me flying- I was about 10-20 secs away from spending $650.00 on batts because I was not following the guidlines I had been given--It was just too much damn fun to stop.

Heres a Link:
Shannon Davis TRYING To Fly his Ion-X (13 meg)

[z11355]

I'm not trying to be too much of an ahole but I see the Ion as the breakthrough electric
machine and you're going to see a surge in users who may or may not understand
the different mindset involved w/ batteries, etc.

My absolute prime concern is safety and all of sudden, you have a lot of people w/ very
high energy density batteries and systems where 'where I can find the cheapest' mentality
doesn't play well.

[bob00]

Thanks for the pics and vids.

Excellent post Chris - please keep the info coming.

- Rob

[ScotY]

Hey guys,

The point of my original post was that Thunder Power's user guide could be a bit misleading. I think it's wise to find/borrow a good, calibrated DVM just to check your charger when you first get it. Chargers are very good these days (and getting better all the time) but when you're talking about $600-700 batteries, it's probably a good idea to know with 100% certainty that your charger is properly calibrated and will not over charge your big investment.

That being said, there's not much to it...I simply check one pack against the other every once in a while to make sure they're close (not much harder than checking the rx pack in the glow helicopters) and follow guidelines similar to what Chris suggests above. The learning curve is only as steep as you make it. :?

Thanks, Chris, for always bringing more and more useful info to us...really appreciate that! Re. maintenance on electric helicopters...instead of wiping the oil and grease off, you have to put oil on! I live where it's humid and everything rusts so must keep bolts and stuff well-oiled or it ends up looking like crap pretty quick.

[lowandslow]

Wow, old post but I'll stick this in for the record. I'm still plenty satisfied with my rounds. May be a good starting point for all newbie's to e-helis at least the larger ships to fly with rounds for a bit to get the technology figured out.

[Laurens]

Rounds can explode too.

[lowandslow]

Originally Posted by Laurens

Rounds can explode too.

I don't hear very often of round cells burning down someone's car or home. You can hit rounds with a lot of amps, charge them faster, not worry about balancing or running packs in series, they are a lot less money and take a lot more abuse. You can even run them down to almost nothing in the air and unlike a lipo they won't instantly dump.

[Laurens]

You'll hear more often about lipo's because they're new. Most of the time the problem is the guy charging them instead of the lipo's self.

Ask your local old fart how charging was back in the days they didn't have chargers and nicd's where as new as lipo's :mrgreen: . You'll get some funny stories.

[lowandslow]

I am one of those "old farts." I've been doing R/C cars, helis, planes, boats, motorcycles, gliders, electric, glo and everything in-between for about 25 years.

Rounds are safer, cheaper and in some cases depending on the need better. Don't get me wrong, I have lipos too. For my ION and for my particular application rounds are the better and safer choice. Especially for a newbie rounds are a lot more forgiving charging and discharging.

[busted blade]

i would like to share my recent experience with the TP 4500 5s1p packs and tp1010c/210v charger/ balancer im using in my razor and to say that the above statement from TP at the top of this thread should be taken very seriously. first off i would like to say im a seasoned modeler always considering safety paramount.this is my first expeireince using these larger packs and the 4500 is the only large pack i have used. i beleive it is impossible to charge these particular packs(at other than a rediculasly low charge rate) in series or seperatly maintaining the correct balance as stated above throuhout the charge process until the end of the charge cycle when the balancer aggresively brings the cells together.ive consistantly seen the cells vary as much as .04V until the end of the charge. my packs have always been broken in very carefilly, handled very carefully, and never over discharged. these particular packs have never been pulled down more than 75%. my brother in law has the same set up and has expeirinced the same situation. we have both witin a week lost a pack each due to a cell going off. unfortunantley neither of us can say without a dought what the exact cause was. when his went off he was able to get it out of the house in time which was followed by 5 minutes of fireworks which prompted me to go out and purchase ammo boxs to keep our packs in. tonight after a three our car ride i went to pick my ammo box up and a pack went off. luckily i wasa able to get it out before it killed the 1000$ worth of other batts. i would like to end by saying if you dont have a secure place to keep yor batteries, get one and keep them there unless they are in the air.

[MrMel]

Hmm,
Ive been flying alot of flights with series connected batteries, never ever checked the voltage on them. Granted, I never go past 80% usage, but still they hold up nicely.

I would bet that everytime they are NOT within 0.01 volt, since I balance each charge and the balancer need to do his magic, they tend to end up differently.

However, if you start with one full and one half full, and dont know about it, you will ruin the pack, no doubt about it.

And I never charge the packs in series, always as single packs (with balancer).

Anyway, thats my 2c