Basic Battery Questions

[Ambassador Spock]

Hi everyone, I'm new to the hobby and I have a few questions about batteries. I bought a Hobbyzone Carbon Cub RTF which came with a 30C Spektrum 2200 mAh 11.1v LiPo battery that looks like this:

I also bought a 55W S155 G2 Spektrum charger, and two extra batteries which seem to be the "G2" version of the battery (above) which came with the Cub:

My questions:

1. Once I figured out how to enable the auto-discharging function I enabled it on all three batteries and expected them to self-discharge down to around 30-40%. However, a few days after charging (only one ended up getting used, and only to 74%) all three batteries were around 65%. Does the self-discharge take longer than that? Or do they only discharge down to 65% by default? I've read "storage voltage" should be closer to 40%, maybe these are different?
2. I poked around in the smart battery settings using the S155 charger and while the "older" battery was set to charge at 5a (well under it's 3C maximum of 6.6A) the "newer" G2 batteries (with max charge rates of 5C - 11A) were set to charge at 2.3A... I manually set them to charge at 5A - is that okay? I assumed if the G1 battery was set to 5A, charging the G2 batteries at that rate shouldn't be harmful, right? Should I take advantage of the higher max C and set the G2 batteries to charge at 10A (which should theoretically cut their charge times to under 15 minutes) or should I just charge all three at 5A for long-term battery health? (Both of my cars are EVs so I'm familiar with many aspects of batteries, but I recognize there are some big differences too...)
3. The G2 batteries say "Lithium Ion" on them not "LiPo" - is that the same thing?
4. I bought a fireproof bag to charge the batteries in - if they are not charging and self-discharged, do I need to leave them in the bag 24/7? Or is the danger only really while they are charging/discharging?

 

I'm sure I'll have more questions later but that is all I can think of now!

[GrumpyGnome]

Soy, can't help with 1. or 2. as I don't use Spektrum stuff much.

 

3. No, different chemistry so may need different treatment - Google will throw up loads of facts

 

4. Most issues occur at charge/discharge, but they should always be treated with respect.  I have fire-proof storage for unused packs, another for charged packs, and one for those discharged by flight.

[Frank Skilbeck]

1. How are you measuring the 65%? The chargers discharge down to a set voltage per cell, the percentage reading is based on the voltage, at 65% they should be 3.9v per cell and 40% 3.8v per cell, so if you are measuring on different devices this may be the reason.

 

2. I typically charge my batteries at 1c, it's a bit kinder and as the balancing circuit operates at 150 ma it allows the charger to more easily balance the cells during charging, 

 

3 The photo you posted says the GS are Lipo, so I am 99.9% sure they will both be Lipos, but check on the spektrum website.

 

4. It's not a bad idea

[Nick Cripps]

Just to expand on item 2: the charger has a power output of 55W which means that the maximum current you can charge a 3s battery to will be 55/12.6 (Watts/Volts) = 4.36A. As Frank says though, most people limit the charging rate to 1C (ie 2.2A) which helps to extend battery life.

 

You might find these guides on the 4-Max website here useful to expand your knowledge on the care of batteries and electric flight in general.

[Allan Bennett]

6 hours ago, Ambassador Spock said:

 . . . The G2 batteries say "Lithium Ion" on them not "LiPo" - is that the same thing? . . .

 

As someone has already pointed out, the batteries in your photo say "LiPo" on them.

 

Actually "Lithium Ion" can mean almost any type of battery, so long as lithium is part of it.  When lithium is used in conjuction with other chemicals ("ions") it may result in slightly different output voltages.  I have had "lithium ion" batteries with nominal per-cell voltages of 3.2v, 3.3v, and 3.6v as well as "LiPos" which are usually nominally 3.7v per cell with a maximum charge voltage of 4.2.

[leccyflyer]

If you want your batteries to have a long and useful life, forget the hype and charge them at 1C wherever possible. 

It's a good idea to store them in a safe container that would mitigate against them lighting up - a fireproof bag, fire safe or other suitable container, away from flammable items. Although the highest risk of unfortunate thermal events happening is whilst being charged there have been recorded instances of batteries "venting with flames" whilst in storage.

[Ambassador Spock]

I apologise for not replying before, I did not get the reply notifications I thought I would get! Thank you all for your answers, I will take them into account when charging in the future!

[Simon Chaddock]

Ambassador Spock

The conventional wisdom for the longest LiPo life and to reduce the risk of any thing serious happening is to charge a 1c.

I may a cynic but extending the battery life is not the top priority of the sales and marketing team whereas high charge and discharge rates look good.

Most serious incidents occur during charging so do not leave them unattended.

 

As has been identified it is the individual cell voltages that are important. 4.20V for full charge and around 3.8V for storage. The important factor is they should all be very nearly the same. If a cell voltage differs by more than 0.1V after charging or use it is a warning that the lowest voltage cell is getting weaker. It will only get worse with the high discharge rates typically used in an RC plane.

LiPo cells make electric RC viable but they are highly stressed batteries that need care and attention.    

[SIMON CRAGG]

Agree with all the above.

 

The period that needs the most care IMHO is when charging.

 

How many modellers have come unstuck when charging, by somehow plugging red into black and black into red?.

 

We had somebody do similar, which promptly burnt down his garage and half his house........not a pretty sight.

 

The BMFA mag. used to regularly give warnings on what not to do etc. based on letters and insurance reports they had received.

 

I would have a good read up on "Lipo safety in rc model aircraft", if treated with respect they are excellent!.

[leccyflyer]

It needs to be imperative that battery connectors are polarised to make it impossible to plug red into black and black into red. Any decent charger should also have reverse polarity protection to warn against incorrect battery charging lead connections.

 

There have been examples where old school, non-balancing, manual chargers have resulted in catastrophic fires. A recent example in the USA cost an experienced modeller his garage and house. The capabilities of the charger were a contributing factor, as was leaving the battery charging due to misinterpreting the signals from the non-balancing charger and going out. Basic lipo safety protocols not followed or abandoned due to familiarity breeding complacency.

[Ambassador Spock]

All of these comments are why I went for the (more expensive) Spektrum batteries+charger+checker... 😅

 

Presumably the 'fancier' setup they use helps to avoid such issues?

[leccyflyer]

Personally I won't use the Spectrum Smart batteries, because I want to be completely in control of my battery charging - I don't want the battery deciding that it wants to discharge itself, thanks very much.

[Ambassador Spock]

1 minute ago, leccyflyer said:

Personally I won't use the Spectrum Smart batteries, because I want to be completely in control of my battery charging - I don't want the battery deciding that it wants to discharge itself, thanks very much.

If it helps, the self-discharging is an option - I had to turn it on in two of the batteries I got, the third had it on by default (but could be turned off). I also like being able to set the charge rate in the battery, and have the cell balancing as painless as possible. It is very possible I'll change my mind at some point, but right now I am new enough to the hobby that I like not having to worry about the battery bit as much.

[Chris Walby]

There is a lot of good advice, however technology and materials move on and sometimes the "we always do it that way" is not necessarily relevant with modern technology.

 

Perhaps Spektrum know know a bit about battery technology and think their advice is relevant to their product, just saying.

 

 

[Allan Bennett]

Just curious; how do you set the charge rate and other parameters for Spektrum Smart batteries?  Is it done through Spektrum Smart charger, or do you have to connect via an app on your computer?

 

The idea of the battery, rather than the charger, controlling charge rate etc. sounds good because it should prevent you inadvertently charging at the wrong rate when you're getting a bunch of different size batteries ready for a day's flying.  But it's at the expense of extra weight and cost of having a mini computer in every battery.

[Ambassador Spock]

13 minutes ago, Allan Bennett said:

Just curious; how do you set the charge rate and other parameters for Spektrum Smart batteries?  Is it done through Spektrum Smart charger, or do you have to connect via an app on your computer?

 

The idea of the battery, rather than the charger, controlling charge rate etc. sounds good because it should prevent you inadvertently charging at the wrong rate when you're getting a bunch of different size batteries ready for a day's flying.  But it's at the expense of extra weight and cost of having a mini computer in every battery.

I set the battery parameters by connecting it to the Spektrum smart charger and changing values that way. I believe the parameters are stored on the battery's chip, bu can only be modified using the charger.

 

The downsides of Spektrum batteries are the proprietary connector (no balance leads since it is all done via the chip) and the added cost. I can't imagine the chip adds much weight, but I absolutely could be wrong on that.

[Andy Stephenson]

It likely that the Spektrum battery is like a laptop battery where the cell balance is handled internally. Also there will be overcharge, over-discharge and over-current protection as well, this is all standard in consumer electronics. If it is a so called "smart battery" there will be more electronics which will may indicate to the charger what to set the charge parameters to and the possibly some kind of fuel-gauging.

[GrumpyGnome]

12 hours ago, Chris Walby said:

Perhaps Spektrum know know a bit about battery technology and think their advice is relevant to their product, just saying.

They probably do know more than most of us.  But the cynic in me says they want to lock you into their own world, where you have no choice but to continue buying their products, and theirs alone.  Then they have total control over pricing and profit.

 

P.S. I'm not a Spektrum hater - I've had several of their transmitters, and still use a number of their receivers.

Edited December 28, 2022 by GrumpyGnome

[leccyflyer]

I think you have a point and when I see a lipo manufacturer recommending the end user to charge their batteries at 5C I'm not convinced that battery life is uppermost in their considerations.

[Chris Walby]

You are not being forced to use Spektrum, so you are fee to go and do what you want. What Spektrum are doing is removing some of the possibility getting its wrong and causing injury or fire (plugging bullet connectors together). They no doubt would like to be dominant and dictate to the global market of RC, but with other platforms and open systems available that is very unlikely.  Spektrum have tried collaborating with model manufactures, but even then you can still buy the model without the Spektrum RX so it stands to reason that even they know sales of non RX models must be significant or they would not do it.

 

I would like to see someone plug an XT 60 incorrectly together, but as a friend said once "nothing is fool proof to the most ingenious idiot"

 

To this day I can't understand why TX/RX manufacturers don't all do some form of model match.....the number of times I see people power up an electric model and then announce they have the wrong model selected in the TX...Fortunately the clubs I belong to carry out pre maiden checks with covers throttle cut/loss of signal, but then don't get me on the unrestrained electric model debate.

 

4Max has good advice for their products and should I need detailed technical information then I would give George a call and place an order, if its just a lipo for general use then GNB will do the job. If I wanted hassle free then a Spektrum battery is available.

 

1. Try asking Spektrum? If its SMART then perhaps the discharge is managed based on pack temperature and some other factors? If you are relying on product to "manage" then just be happy its knows what its doing. 
2. Take advantage of the faster charging if it suits you or adjust to your preferences or that of "general" advice (anything that is not pressed to its limit will last longer)
3. Nothing to add that already has been said
4. If you have a fire "resistant" bag then it would be good practice and probably convenient to store the batteries in the bag/bags. Always so much fun getting to the flying field and remembering where you left the wing tube, batteries/battery adaptor etc...

 

 

[Simon Chaddock]

Ambassador Spock

Given you are new to electric RC I actually applaud your decision to adopt the Spektrum smart battery technology to avoid some of the pit falls with LiPo technology but as you have noted it does rather tie you into their proprietary batteries as well as to a degree having to rely on a chip built into them.

 

Just remember there is a lot of energy stored in a LiPo, more then enough to ignite their flammable contents into a runaway condition if things go wrong. Treat all LiPo with caution and do not abuse them in any way.

 

Do feel free to ask any questions about anything to do with the hobby.

Experience and advice are things this web site is not short of!