Smart Battery Explained... (and why it's so stupid) ... :-\

[Luap]

Re: Smart Battery Explained... (and why it's so stupid) ...

Modern LiPo cells allow very high discharge rates but on cost of lifetime. E.g. I had two first-generation 4s4p battery packs from ThunderPower since 2002 and have used them in my helicopter until 2012. No puffed cells and still about 80% of capacity, but increaed inner resistance when disposing them. In contrast, new cell types can only dream of such a durability as they may be just good for 2-3 years or even less until they are usually puffed and need to be disposed.

I don't know the cells DJI is using, but I would prefer using cells with lower discharge rates and better lifetime, so maybe DJI did exactly this.

Regards, Gerd

ThunderPower only came out with LiPo batteries in 2003. (http://www.rctoys.com/pr/2007/07/06/abo ... n-history/)
Maybe you mean Kokam?
What helicopter were you flying since 2002 on the same LiPo until 2013 ?
I flew the Ikarus Piccolo - moved from Nimah to Lipos end 2002. Man I've been through dozens of LiPo packs. Especially 1st generation Kokams! At the time there was no cell ballancer
Congratulations on having a pack that lasted that long!
But its amazing the contradictory posts I've read on LiPos -
Certainly lots of black magic to them.

 

[N017RW]

Re: Smart Battery Explained... (and why it's so stupid) ...

What I see coming from this thread now is the belief that parallel LiPo cell configurations are BAD (practice).

This is NOT the case and should not be perpetuated by assumptions about this being the cause for certain flight time anomalies.

 

[enterprise1]

Re: Smart Battery Explained... (and why it's so stupid) ...

After reading this post I was inspired to research other lipo battery manufacturers charging recommendations. Now I'm confused even more. :? Some manf. say do not charge puffed batteries, others say slight puffing batteries are normal. They recommend checking voltage of each battery cell after use. Evidently good battery packs have ports built in so you can check each cell. Wished DJI batteries had this feature. I would be happy to spend a few minutes with this extra chore to safe guard my bird.

Questions I now have are, if DJI battery has 6 cells why do we only get a 3 cell read out on the assistant? Does the assistant average the voltages of 2 cells to give us a voltage number? Why do bad batteries give out fairly equal voltage values for each of the 3 cells? Is the DJI Smart Battery charging each of the 6 cells independently? If not I can see as DBS explained about cell voltage mismatch how our batteries are failing after just 1 cycle. Last flight was good now battery failure.

Hears my non-expert advice for all DJI batteries. 3 bad batteries so far and none replaced yet. Working on Amazon to replace 3rd battery, 95 days old. If you have any puffing of batteries less then 90 days old get them sent back asap. Even if they are still working ok. They could go bad on the next cycle. Check your batteries for puffing after every use. All 3 of my bad batteries were puffed and working well before finally giving low battery warning.

 

[DBS]

Re: Smart Battery Explained... (and why it's so stupid) ...

What I see coming from this thread now is the belief that parallel LiPo cell configurations are BAD (practice).

This is NOT the case and should not be perpetuated by assumptions about this being the cause for certain flight time anomalies.

I completely disagree with that statement... it is , however , your right to have that opinion...

I've been doing a lot of reading since I posted this last night... basic Google searches and forum searches etc... and I dislike the build of this battery more than I did yesterday based on what I've read.

Would you take two single cell lipos and just twist the wires together and run them in parallel to make a bigger battery 3.7volt to fly your micro quad with? Yeah... I probly would ... but would you leave them that way permanently and charge them that way over and over and have no way of balancing them or checking them individually on your $1400 bird... No... I wouldn't do that thanks...

If given the choice I will choose to have 3S1P every time ... period

It seems the reason for building these batteries as 3s2p is all over the **** place... too many different answers and nobody really proves the deal... weight isn't it ... there are measurements out there that prove that wrong ... One thing I read was a shipping requirement that requires individual cells to be under a certain limit and that's what started this whole practice... but there is no clear benefit from the design and the potential for failure is ultimately increased by this practice....

But like others have said... The sky isn't falling and under perfect conditions there's nothing wrong ... there will be a thousand naysayers that come thru and say "never happened to me" or "mine have all been fine"... I get it ... doesn't make it a smart way to wire up a battery and send it through multiple dozens of cycles that way... I'd do it all day every day on my rc monster truck... but not on my fpv bird that's gonna be 800ft up and 3miles down range... no thankyou

 

[N017RW]

Re: Smart Battery Explained... (and why it's so stupid) ...

I just found your post to be completely reactionary, if not hysterical, and not supported with any references.

With just one quick search I have discovered LiPo configurations up to 6S3P with little effort (thanks to Google).

There's obviously a reason for such configurations despite your declaration that "... there is no clear benefit from the design and the potential for failure is ultimately increased by this practice.... "

I'm sure you could do the same to support you view as well... no?

But hey it is your money and your quad so the final say for that is you.

TEHO.

 

[garrock]

Re: Smart Battery Explained... (and why it's so stupid) ...

Benefit vs Risk:

• 
  Lots of P2 batterys out in the world now.
  Parallel battery's do statistically come at a life expectancy risk.
  But, they do increase performance while the battery cells are still ideally matched.

SO.. we must accept that to fly these contraptions (dated 4th quarter 2014 in the 21st century).


In an industrial environment, once two parallel battery's degrade and become mismatched during their power discharge curve, they typically won't get back in line with each other. They might top out at the same charge voltage as they find a common balanced charge point but the dynamic discharge curve for each can become skewed as power is demanded. This heats both the weak and dominate cells during each charge and/or discharge cycle more than they would if fully matched.

Once physical anomalies are significant enough, this creates a Self Eating Watermelon.

Shorter than nominal battery life times will accelerate as they become even more mismatched.
Once significantly dynamically mismatched, the battery-device becomes more of a heat generator than a power source.

Question/Inquiry:

• 
  How many people are charging and leaving their battery fleet mostly charged and/or in a car or other uncontrolled environment ???
  
  Thermal cycles affect the outcome of physical properties which can accelerate parallel battery mis-matching. Cold or hot weather.

BOTTOM LINE.. its somewhat of a gamble with the atoms constructed to make each battery; so enjoy flying your drones with a known statistical risk.

Perhaps a mod-hack breakthrough is around the corner; or warp drive first.

 

[DBS]

Re: Smart Battery Explained... (and why it's so stupid) ...

Nice investigation DBS and before it turns into a faulty battery topic i wright some of my idea's on why its a 3s2p battery.

First of all your right DBS, the setup is kinda odd to balance the parallel ones and indeed it spells disaster ( hence the large faulty battery reports ? ).
Anyway as i was looking into why it struck to me that it could be maybe to power/weight ratio.
Seems odd but does a lower rated lipo pack store more power to its weight ?
The non DJI lipo's are all heavier for that 5200mah. Even with the electronics and casing included its still significant lighter.
I follow this topic with much interest as i intended to do the same ones i got a faulty battery.
Sended in the first one ( round data contacts ) @ my expense even when it was replaced for free ( also one with round data contacts ).
Anyway i love your DIY things and investigation.

Thanks TTP... appreciate your point of view here on the forum many times... I also prefer to look at things from both sides ... I don't like being one of the sheep ... I'm not gonna sit back and say "I found that other batteries are being made this way so there's obviously a reason for such configurations" ... What if the obvious reason is "it's cheaper to produce" ... I'd rather go with the one that's "more dependable long term" if i have the choice...

I'm getting more disenchanted with this smart battery idea the more i look into it... The smart battery is made for the "plug and play" marketing of the phantom... just plug it in and it works right? That doesn't impress me much anymore but I realize that is MY problem because I bought into what is essentially a high priced "toy drone for dummies" and I'm modding it to do things it wasn't designed to do... so it is up to me to eliminate as many potential faults as possible if I wanna see it come back home on every flight... and that's all it is... to swing the odds in your own favor to increase "chances" of success.

I would much rather have the smart board independent of the battery... and a solid three cell battery that can be put on a much more intuitive charger that let's me know status and cell voltages in real time instead of having to fire up the **** computer and plug in the phantom and run the assistant and click to the right tab to see my cell levels only to find out that these are not individual cell values but rather a single value for a pair run in parallel....

I think a battery mod is in my near future here somewhere... :ugeek:

 

[yorlik]

DBS, I know this is an older thread, but it is still very valid today.

Have you learned any more that you might share, about our smart batteries?

 

[zgrocks]

can someone please help me hack my battery so it can go on multistar lipo batteries? thanks