Battery Medic - how to ID the REAL vs FAKE

[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...

[neptronix]

IMHO...

A quality battery balancer, capable of balancing within 10+/- mV, and doing so fairly quickly, is worth well over double the cost of these units to me.

http://www.electrifly.com/miscproducts/gpmm3210.html

This is the closest i've came to that ideal. Super accurate, but painfully slow.

I'd happily fork over for a well calibrated battery medic with some uber resistors on it. About $50 is where i'd start to cry though.

[texaspyro]

Make the stand out of shape memory alloy. The unit sits vertical when cool and you can read the screen. Turns LED side down when it heats up.

[izeman]

... I bought 14 dollars with free shipping from ebay under HKRC (seller name). He is excellent guy and easy communication.

thanks. that saved me from buying a bad one. just ordered one from HKRC. really good price and ww p&p included.

[rojitor]

Seems hobbyking has stock again.

[izeman]

Seems hobbyking has stock again.

yep. but they don't send for free. which is a great benefit it you don't have a big order where you can add something like a small battery medic.

[ryan]

So my 3 "fake" battery medics arrived. Is the general consensus after all the testing that these aren't perfect, have to be watched, and shouldn't be left connected after balancing?

Or are they so bad that they are not recommended to use at all? (as in I need to buy three more from Methods or his source)

[methods]

I dont think that anyone has shown that they are unreliable. I think the only thing that has been shown is that they are a little inaccurate - maybe 20mV
Just use them, they will be fine.

You cant leave any of them plugged in for too long - not even the good ones... since after they discharge the pack to 4.X volts the current they draw to stay one will then start to imbalance the pack.

Your best bet is to calibrate the ones you have - so you know what you are working with.

-methods

[methods]

Seems hobbyking has stock again.

I am not convinced that the Hobby King version is as accurate as this batch I have here. I suppose I need to order some and test for myself - but just because the PCB is red does not mean that it is good. I have personal experience with Hobby King taking a good product and screwing it up to save a buck.

BTW: Been getting bad batches of JST-XH-6 and JST-XH-7 extensions from hobby king. After plugging them in only 5-10 times they become completely unreliable and start presenting open circuits. They are using some kind of really bad alloy on the sockets - I just cant believe how cheap those guys can be sometimes.

I love them.... but I hate them to.

-methods

[Ypedal]

the male sides are generally " ok " but the female ends are crap..... on all the one's i've had from HK ( the jst's )

[methods]

What do you mean by male and female?

One end has a male plastic shell full of female electrical sockets
One end has a female plastic shell full of male electrical pins

See how that is ambiguous?

How about we say "Sockets" and "Pins" and refer to the electrical contact.
Plural, and referring only to the electrical contact.

Most military guys refer to the contacts when they mean sex
Most regular guys (aka customers) refer to the *housing* when they talk about sex

So which one are you using

I am talking about the electrical sockets becoming rounded out.

-methods

[methods]

That came off sounding fussy...
sorry.

Just that a lot of customers refer to the housing when they speak of sex... so it really causes confusion.

-methods

[Ypedal]

lmao.. ok mr wize guy..

[texaspyro]

It's the pins that determine the connector sex. If the pins are hermaphroditic, you can use the housing. If the pins look male, but wear feather boas or look female and wear plaid flannel then just wing it.

[FastDemise]

Well that's unsettling to hear. I just received my order of 20 of those exact connectors to just make connections out of the Male-Male connectors. I refer to Male being the part that fits inside the Female. Why should I refer to it any other way?
So if I make a daisy chain of 200cm long balance cable and hook it up so my modified balancer it'll just be a giant pile of FAIL?

[methods]

No - I still use them in a lot of applications.
They are good for the first 10 insertions.

The only reason I am having failures is because I have a testing station where I cycle the connectors over, and over, and over. Basically I will sit down with 40 boards and test them back to back - so my connectors get the shit kicked out of them. I use these extension as "sacrificial" connections so as not to wear out my test rig. For every 20 or 30 insertions the extension sees, my test rig sees only one

Move ahead - just realize that if you start getting some weird behavior it probably has to do with loose connectors.

-methods

P.S. I call a hollow pin (hermaphrodite) a socket. I know you guys are joking around - but I cant tell you how many tens of thousands of dollars I have seen wasted over connector sex miss-communication. Connectors like MDM & Micro Miniature have hollow pins and that is where most of the confusion lies... as each side of the connector has 3 different sexes... the shield over the insulator over the hollow pin over the hole inside... Like having a hollow penis inside of a vagina that is actually a panina.