Review: Turnigy Ultimate 4600mah 2S2P Hardcase Lipo Short Pack

So I decided upon the Turnigy nano-tech Ultimate 4600mah 2S2P 90C Hardcase Lipo Short Pack because I was able to get it to fit inside the WL Toys 12428.

First thing I did was to plug it into my charger and charge it to capacity (at 1C which is 4.6A) and it ingested about ~3500 mAh in ~83 mins.  The charger is a SkyRC iMAX B6AC V2 and is connected to my Ubuntu pc running GNU DataExplorer:

But the real test is discharge.  On paper my battery charger/discharger maxxes out at 2A discharge, but I was only able to get it to discharge at 0.6A .. not sure what's going on there. 

UPDATE 1: Real world test; since I installed these packs (two cars) we've been out for two RC adventures, we kinda played till we'd had enough and came home, and in neither case did we run out of battery ;) I didn't time it, but I'd say we had fun for 90 mins or more.  Very impressed.

Wltoys 12428b (part 7; 0.7c charging and rwd conversion..)

It occurred to me that i could be using the iMax to do discharge profiling on the standard 12428b batteries (2s 1500mah LiIon); that would be much more efficient than this weird play time discharge testing.  Except that's very boring .. ;) maybe later.  For now here's the charge graph, noting it accepted 1297mah this time (at 0.7c or 1 amp).  Also note that at the end of the last play the batteries were quite out of balance:

..fast forward to some time later.  Well.. The second half of this post was supposed to be about how the car performed on that charge, and well.. it was AWESOME!! I went to a new as yet empty subdivision near my house and the thing went off!

1. Awesome power in a straight line (now that i can control it)
2. Steering track doesn't seem to be so bad (now i've fixed the steering)
3. Great looks, handling.. I LOVE this thing.

But.. ..i broke it :(

It's now running rear wheel drive only, the front drive shaft (?) has come out of the front diff.  At one point I'd thought it might be cool to have a rear wheel drive car, but with this power and these tyres there was very little traction off road. 

Wltoys 12428b (part 6; voltage protections and standard battery charging)

So after i fixed the steering, i took the car out and was able to have a play.  When the car eventually stopped, i was pleased to see that it obviously had a voltage protection circuit (as in didn't run the battery flat) and when i checked the battery (2S LiIon) it showed 7 volts remaining (or 3.5v per cell).  I'm not sure if that's a sensible rating or not.  Note to self, look at that later.

So then set the battery to charge on my b6acv2 charger using the 2s LiIon charge setting*.  The standard battery is 1500mah so if we assume a safe charging rate is 1C then that means i set my charger to charge at 1.5A.  I then set DataExplorer to monitor the charge and this is what i found:

Forgive me the weird colors, i run my computer
with colors inverted; it looks great to me ;)

Compare this then to the nominal charge provile of a LiIon battery from Battery University, they do appear somewhat simiar, which is cool :)

 ..right enough chat.. lets play!!

* I did stuff up the other day and set the charger to use the LiPo setting, which uses a terminal voltage per cell of 4.2v.  That meant the 2s ended up with a total voltage of 8.4v and i was initially shocked then pleased that the 12428b refused to run.  After i discharged the battery a bit it ran fine.

iMAX b6acv2 battery charger (part 1: logging and graphing)

I purchased a iMAX B6AC V2 multi-chemistry battery charger for use with RC cars, and immediately installed the official application under Windows.  It allowed me to control various functions as per the display and buttons on the actual device, and in addition offered realtime graphs.  They worked!  however, it was immediately obvious that this would never do.  I couldn't save the graphs, nor could i access the raw data, and starting a new charge/discharge resulted in the previous data being destroyed.  wtf!!

I went on a bit of a hunt and found Logview and a reboot called Logview Studio.  I installed both on Windows.  Logview didn't recognize the charger at all.  Logview Studio did, however when it came to recording data nothing actually appeared.  More concerning was that it seems development stopped with the most recent versions for both being released around September 2014.

So then went to my old faithful, why did i ever doubt you, the open source community.  Pretty quickly i found GNU DataExplorer and being a Java app it ran ok on Windows.  On OSX i need to do some rubbish to allow me to access the device via USB, so i shelved that.  Under Linux (Ubuntu 18.04) it's sufficient to be root, although with the correct permissions i shouldn't need to sudo.

Here's a pic of me proving to an ebay vendor that their 1800mah battery really isn't.  Leave positive feedback they said..!