Battery Medic - how to ID the REAL vs FAKE

[methods]

I don't really want more than 500mA - anything over that just gets more complicated and hotter than it needs to be. Double the performance is good.

How many current can the transistor take?

Its a surprise
We will know when the smoke comes out.

-methods

[methods]

Ok - here is prototype number 3

6.8ohm axial resistors
in parallel with stock resistors
4.2ohms total impedance
700mA balance current (after duty cycle)
1W developed on the external resistors

IMG_20120210_165746.jpg (81.37 KiB) Viewed 299 times

IMG_20120210_165812.jpg (58.54 KiB) Viewed 299 times

Good air space in there - though it can only be worse than in the factory configuration.

Give er a test now...

-methods

[bigmoose]

...How many current can the transistor take?

...We will know when the smoke comes out.
-methods

I love the thought of electronics being tortured! "Turn it up," I say... "Turn it way up!!"

[Ypedal]

http://en.wikipedia.org/wiki/Up_to_eleven

[methods]

The Axial resistors resistors seem to work the best so far but they are butt ugly.
They get hot, but not so hot that it takes your skin off. 100C

Thinking about drilling the board so that we can plug them in like thru-hole real fast.

Let me know if anyone has any ideas. I will take them... and make money off of them... with no credit for you

-methods

[amberwolf]

They get hot, but not so hot that it takes your skin off. 100C

So at least I can make my tea with the thing. Just dip it in waterproofing first, then insert into my cup with a teabag, and wait. By the time balancing is done on some really big and badly abused pack, I can sit back and sip away.

[FastDemise]

While testing are you having any issues with the screen getting too hot. I would get black discoloratin from the heat after about a hour.

[methods]

Not at all - but I am keeping mine with the screen facing down so the heat can escape.

If they are set down face up (which is the most intuitive thing to do...) the heat just pools under the LCD.
I am considering drilling holes in the front cover to help let heat out as I suspect most people will set them face up even if we tell them to set it face down.

Still working on ideas over here.
I sure would like to just populate the empty space on the PCB and then improve the efficiency of the cooling design. Even just a moth flapping its wings would make all the difference here....

Awesome would = 250mA - 500mA diode to send the power away in the form of photons
Awesome would = tiny surface mount pager motor with a counterweight that could work the energy away mechanically
Awesome would = 2W fan on every channel - self cooling power dissipation
Awesome would = tiny DC-DC that would take the 4.2V from one channel and funnel it back as 25.2V to the pack

Maybe Poly fuses can play a role here... resistors are linear but the poly fuses would allow more current to flow with better cooling

Maybe we could utilize the duty cycle with tiny little transformers

Ok - back to finding a clean way to dump power the good ol'fashioned american way

-methods

[sn0wchyld]

thanks alot! I got 4 from ebay (cheap! and turns out they have RED PCB! WIN!)
http://www.ebay.co.uk/itm/260753810568?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
This is where i got them from!

yay! That's the one i ordered

I ordered from them too, got the yellow/green model... so no consistency with that seller...


edit

I really love the idea of a dc-dc converter to send the power back to the pack as a whole. how hard would it be to build?

Im using the axial resistors, but I have them mounted at a 90deg angle to the board, so they stand up above the board. Seems to work quite well, though I've always run 'em face down and with a fan blowing over 'em. I think ill build a new case to mount em in with a couple of fans to keep things cool.

[methods]

That seller is probably offering two different models with a small price difference.
I suggest searching his offerings.

-methods

[sn0wchyld]

That seller is probably offering two different models with a small price difference.
I suggest searching his offerings.

-methods

hahaha now that you mention it I think I may have searched his listings thinking 'why the hell does he have two difference prices for the 'same' thing... though that may have been another seller, bought them a month or two ago so cant really remember.

[FastDemise]

Haha, imagine the noise of 6 cellphone motors going crazy. One can make a whole phone shake around the table. 6 would make a great back massage. Just gotta get long balance wires.

[sn0wchyld]

I am working on ordering 50 more pieces.
........................
$13.98 shipped (expect 1 month)
http://www.ebay.com/itm/RC-Lipo-Li-Fe-Battery-LCD-Voltage-Meter-Tester-Balancer-/180703582293?pt=LH_DefaultDomain_0&hash=item2a12c5d855#ht_2233wt_1110

$14.99 shipped (expect 1 month)
http://www.ebay.com/itm/LCD-RC-lipo-battery-Voltage-Meter-Balancer-Discharger-/180692663771?pt=LH_DefaultDomain_0&hash=item2a121f3ddb#shId
......................
-methods

were these prices for a certain quantity? I just contacted the same guy to confirm the $1499 one was the high quality and he's saying they're $16 for the high end ones....

[amberwolf]

NIf they are set down face up (which is the most intuitive thing to do...) the heat just pools under the LCD.
I am considering drilling holes in the front cover to help let heat out as I suspect most people will set them face up even if we tell them to set it face down.

How about a little wire frame that normally sits around the body of the unit, but can be folded back outward at the bottom to make it stand up when in use, like a DMM or a mirror typically has?

Ok, a 5-minute version made from some solid copper house wiring I had out back. Would be better out of steel or something, but I cant' find any coat hangers or similar right now. I know I have some stainless thin wire that'd be perfect, long lever springs out of some copier or printer, but I have no idea where it's at.

There's a little hook on the left top piece that points toward the back, which makes it stay extended by sticking on the plastic. I actually meant to bend it *forwards) so it acts like a spring, but I screwed up. Still worked.

Of course, this only works for those charging their stuff on a table or other flat surface.

[adrian_sm]

I have the Hobbyking Battery Medic, RED PCB, and it is ~20mV out. Enough for me to not trust it to balance correctly.

Here are the readings with Battery Medic, Cell Log, and a cheap Digital Multimeter.

6s LiPo

HobbyKing Battery Medic / HobbyKing Cell-Log / Cheap DMM
1 - 4.16 / 4.161 / 4.15
2 - 4.14 / 4.161 / 4.15
3 - 4.16 / 4.153 / 4.14
4 - 4.14 / 4.159 / 4.14
5 - 4.16 / 4.159 / 4.15
6 - 4.16 / 4.167 / 4.15

[methods]

I bought a large lot - and why are you fussing over $1?
Chinese guys gotta eat..... it is this type of cheap consumer behavior (looking for the cheeeeeeeapest) that brings those garbage units to market. Just be grateful that you have the opportunity to buy a good one and pay what he asks.

-methods

I am working on ordering 50 more pieces.
........................
$13.98 shipped (expect 1 month)
http://www.ebay.com/itm/RC-Lipo-Li-Fe-Battery-LCD-Voltage-Meter-Tester-Balancer-/180703582293?pt=LH_DefaultDomain_0&hash=item2a12c5d855#ht_2233wt_1110

$14.99 shipped (expect 1 month)
http://www.ebay.com/itm/LCD-RC-lipo-battery-Voltage-Meter-Balancer-Discharger-/180692663771?pt=LH_DefaultDomain_0&hash=item2a121f3ddb#shId
......................
-methods

were these prices for a certain quantity? I just contacted the same guy to confirm the $1499 one was the high quality and he's saying they're $16 for the high end ones....

[methods]

Ok, a 5-minute version ...

I like that

-methods

[methods]

It has already been shown that the Hobby City PCB is *different*
Yes, it is red, but it is a totally different design than those I reviewed above.

Lets get away from talking about RED vs YELLOW PCB's as this is not a good way to differentiate them.
Better to talk about where we sourced them from - or maybe some other method.

Why would you not trust it?
Accuracy and reliability are not necessarily related. A pack balanced to +/- 20mV is better than an unbalanced pack.
Reality is... most electronics are that sloppy. People just dont know it.

-methods

I have the Hobbyking Battery Medic, RED PCB, and it is ~20mV out. Enough for me to not trust it to balance correctly.

Here are the readings with Battery Medic, Cell Log, and a cheap Digital Multimeter.

6s LiPo

HobbyKing Battery Medic / HobbyKing Cell-Log / Cheap DMM
1 - 4.16 / 4.161 / 4.15
2 - 4.14 / 4.161 / 4.15
3 - 4.16 / 4.153 / 4.14
4 - 4.14 / 4.159 / 4.14
5 - 4.16 / 4.159 / 4.15
6 - 4.16 / 4.167 / 4.15

[adrian_sm]

Why would you not trust it?
Accuracy and reliability are not necessarily related. A pack balanced to +/- 20mV is better than an unbalanced pack. Reality is... most electronics are that sloppy. People just dont know it.

Fair call. I just balance with my charger now, which agrees with my Cell-Log & DMM.

Maybe once I start bulk charging more often, I'll stop being so anal about 0.02V.

[methods]

I used to fuss over my cell voltages - but after bulk charging about 500 times it is the last thing on my mind. I don't even really care if cells are at 4.3V... just so long as they are not below 3.0V with smoke coming out

-methods

[sn0wchyld]

nah your right that I shouldn't sweat a few $... more that I'd be pissed to end up with lower quality units if I'd paid extra, and getting a different price didn't fill me with confidence... I missed that you'd gotten a bulk discount too. nvm

how closely do you keep yours in balance anyhow? I generally don't worry about it till it gets over about 30-40mv, but I'd be interested to know the thoughts of someone with more lipo experience. 4.3v seems kinda high, but then I am a bit paranoid since my bike is usually inside.

I bought a large lot - and why are you fussing over $1?.......

[Arlo1]

I used to fuss over my cell voltages - but after bulk charging about 500 times it is the last thing on my mind. I don't even really care if cells are at 4.3V... just so long as they are not below 3.0V with smoke coming out

-methods

Uhmm what about 0v with no smoke? I have 48 cells that are at 0v lol. Left my pack plugged into my bike while I was out of my shop for ~2 months in the cold... I would say it might have got to -5 degC but I think Either my controller was what drained it or I accidently left the power on and the CA drained them.
Dam! I did get ~400 cycles before this so not bad but I would have liked to get ~1000 cycles then better and cheaper batteries would be out. For my new pack I will be using methods LVC HVC system. I pounded my pack into the ground <1v a cell with full power trying to help a guy who I thought was my friend who crashed my brothers ebmx I just finished and lost his keys so I found them then had to search for buddy in the meenwhile I killed my lipo and when he crashed my bothers bike he wrecked some shit and never offered to pay for it so I asked if he would help at my shop to make up for it and he said he would need money for that IM done with that looser! End rant. Moral of story Use methods shit so you dont end up like me!

[Hyena]

Ok - here is prototype number 3

6.8ohm axial resistors
in parallel with stock resistors
4.2ohms total impedance
700mA balance current (after duty cycle)
1W developed on the external resistors

That's my preferred method - not having to mess with SMD components existing or otherwise is a big plus in my book.
Quick and easy and 700ma of balance current is pretty good for the majority of applications.

I used to fuss over my cell voltages - but after bulk charging about 500 times it is the last thing on my mind.

Yep, I used to be an adventurer like you, but then I took an arrow... hang on, wait
I'm the same, I used to carefully watch the balance but then after 100 bulk charges when nothing ever needed balancing I stopped bothering even checking! I bulk charge twice a day and every few months I check but I don't bother balancing unless they're more than 50mv out of whack. I bulk charge to 4.18v/cell average and sometimes the cells get up to 4.22 while others are 4.15 but meh, it's trivial. I rarely take my pack past 80% discharge so in practise it's of little consequence. Mind you, I tell noobs and others others to carefully check the balance. Do as I say, not as I do

Oh, and that supplier that you suggested methy is the same one I've been buying from for months. An alignment in the force across the globe, no doubt

[methods]

That is an alignment in the force...

He is a good guy. His English comes through Google Translate - and it is terrible - but he is smart and honest. Can't ask for more than that. I think we should cultivate him into our new Kenny/Keywin replacement. Both of those guys stuck it in my butt the last time we did business - and I am still a little sore.

-methods

[nicobie]

It would be nice to have a replacement for those 2 characters. I got a kick when the 9c motors took off. Prices sure went down, didn't they...