Battery Medic - how to ID the REAL vs FAKE

[methods]

0.030 is quite a bit off... thats 30mV
Hobby king unit?
Ebay unit?

Anyway - I suspect what you are experiencing is that the Medic actually does balance the pack (to +/- 30mV)... but then after that it starts to imbalance due to the current it draws to power itself. Do a test with a 5Ah pack. Charge them up to 4.11V each then set it to discharge to 4.10V. It should balance while you watch and be done in a few minutes. Then walk away for 2 hours.... My bet is that it will be way off.... probably on cells 1 and 2? (not sure which cells it draws from - have not tested for that)

I would venture a guess that the cheap units draw more current - anyone want to test that? To compare to my numbers, measure that current on the ground wire.

With our larger 20Ah pack I suspect that we can leave them hooked up all night and not see this negative aspect since they probably wont get all the way balanced in that time period... depending on what voltage folks start with.

-methods

[JoramsWeapon]

I received the good one!!!

[Hyena]

Seems hobbyking has stock again.

Sorry, but I just cleaned them out
I did graciously leave 1 in stock, so get in quick if you want that one
I'll report back on the accuracy when the arrive, though if it varies batch to batch who knows what you might get when they restock...

[methods]

I have been blowing through mine over here. Only a hand full left and I did not even get a chance to mod them

Got a chance to test out one of my modded units the other day when I paralleled two 6S packs with a 5S pack and balance charged It worked great to bring the 4.4V cells down to 4.10 across the board. Really never got hot either - but they do stand very proud of the housing.

-methods

[liveforphysics]

I paralleled two 6S packs with a 5S pack

D'oh! I did that same thing yesterday. lol

[methods]

right....
I should have marked the 6S pack more clearly. When cell dies in the middle of a pack I just short across it with 10AWG and shuffle the balance pins. I think it causes more wear and tear to try and pull all the cells apart - so I just leave them in there.

But then I do stupid stuff like this.

-methods

[Hyena]

Got a chance to test out one of my modded units the other day when I paralleled two 6S packs with a 5S pack and balance charged

Nice one! I can go one better, on the weekend I had a DC-DC converter set to 4.19v hooked to an old pack with a weak cell (charging through balance taps) It was at 3.8v when I first check, then 3.9v when I came back half an hour later. Being nonchalant with lipo these days I then went out for a few hours and came home to to find the cell at 4.9v!
My some time during my absence my DC converter shit itself, allowing the 12v supply powering it to flow straight through from the input to the output. Good thing I didn't leave it overnight like I often do or there would have been some fireworks.

When cell dies in the middle of a pack I just short across it with 10AWG and shuffle the balance pins. I think it causes more wear and tear to try and pull all the cells apart - so I just leave them in there.

Yep I do the same, though I don't use them for my general ebike packs due to the size and mismatched cell counts - just testing or other projects. My 3 year olds electric quad bike that was powered by a 4ah 6v SLA goes pretty good now

[HumboldtRc]

I received a fake one from HK. The screen is a dark color, and the pcb is yellow/green color. Also the resistor layout is really close together. Damm HK!!! Who knows which one you will receive when ordering one.... This sucks.

[methods]

I know which one you will receive if you dip into my stash

-methods

[Hyena]

I received a fake one from HK. The screen is a dark color, and the pcb is yellow/green color. Also the resistor layout is really close together. Damm HK!!! Who knows which one you will receive when ordering one.... This sucks.

As methods said above, we shouldn't determine "fake" on PCB colour alone as these are highly likely to vary. It does suck when we're trying for find a reliable source that they seem to chop and change as to what product you'll actually receive but as long as they're accurate I don't care if the PCBs are pink and glittery!

My HK batch arrived this morning, I'll test tonight and post pics and results

[Hyena]

Ok so I have the following to report:
Hobby king sucks balls

I ordered 5 medics from them last week, looking through the backs 4 had yellow boards and one had green.
The green one was at worst 10mv off from another known good medic, a cell log and a multimeter (which all read much the same)
The green one had very few smd resistors on the back (shown below) The yellow one had many more in a row and seemed to be the same design as the reds
All the yellow board ones are crap. Some cells are spot on, some 20mv out (which I'd be happy with) but all of them have 1-2 cells that read 40-50mv low. This is pretty crap when I had a perfectly balanced pack with all cells being 4.16v and 2 of them read 4.11
Also worth noting is that the green board which was accurate used a central "blob" chip while the others (including an accurate red one I got from the ebay seller methods linked earlier) all used normal surface mount chips and actually seemed to have more other components too (hard to photograph without pulling apart and I only used my phone but you get the drift)

First pic - 2 boards from hobby king. Green one is good, yellow one is bad (green one has QC sticker on it so maybe that's why! )
The 2 red boards are from the ebay seller methods linked. One is accurate one was DOA and doesn't power up.

Conclusion: Roll the f*%#ing dice!

4 boards.jpg (204.78 KiB) Viewed 488 times

The second pic shows the internal components as mentioned above.

boards-comp.jpg (153.85 KiB) Viewed 488 times

[methods]

HA HA !

ROLL THE DICE PHOOLZ!

I am raising my prices $5

Known good Medics for sale by the rapist - the scalper - the money whore - the guy who does not even ride ebikes ---> methods
$25 EACH HAHAHAHA!

Or roll the dice
lol....

-methods

[nicobie]

And that's still a good deal. I ordered 4 from different people and 2 out of the 4 didn't work at all. They all had the red pcb too.

[sn0wchyld]

just received 3 from HK. all the green type with the limited resistors. measured at 22ohms, so a sad sad 190ma max balance current (vs 10ohms for the better units). I'm also wary of doing the usual adding of a 6-ish ohm resistor in parallel, as the FETs (I think they're fets) look really small compared to the proven 'quality' red ones I have (yes, I know red doesnt = good, but in this case they're close enough for my use). I'm thinking I might try and de solder/cut off the lcd and stick it on another good unit I have with a smashed screen, rather than rely on the tiny fets of these green units.

Also, of the two other yellow boards I received from a 'bay seller, one functioned ok, but inaccurate to about 30mv, the other had an internal short somewhere, as soon as I plugged it in it read about 60+mV difference, and my cell log alarm which is plugged in in parallel went nuts stating unbalanced pack for 2 cells. they returned to normal once I removed the BM. so be careful with the highly inaccurate ones... it could be an internal short. and a pretty bad one, to create that sort of voltage drop ! Im amazed it didnt blow the traces on my parallel boards... it probably would have had I left it pluged in for more than a few seconds.

anyone got any good methods/ideas on how to remove the screens on these things? I tryed a Stanley knife but ended up cracking the screen

edit
went to order another 'good' unit from the ebay seller methods linked... but there's no listings at his store! where's he gone?!?

[Duc998]

dont use the one methods linked snowchyld, I got 3 from him all over 70mv out with cream pcb. Like methods said its roll of the dice . I managed to get my money back though

On another note I get some from HK that arrived this week. Dark green PCB and Hobbyking sticker, They seem good and match the readings to 10mv+- on my CellLog 8.

[sn0wchyld]

dont use the one methods linked snowchyld, I got 3 from him all over 70mv out with cream pcb. Like methods said its roll of the dice . I managed to get my money back though

On another note I get some from HK that arrived this week. Dark green PCB and Hobbyking sticker, They seem good and match the readings to 10mv+- on my CellLog 8.

the green ones I got from hk seem ok in terms of accuracy... but if you check them internally you'll see they have only 2 discharge resistors, and much smaller fets. so they're likely less sutable for modding for higher power, and worse yet... they have even weaker discharge abilities! the new ones are 22ohm, vs 10ohm for the original units. this means your balancing power is less than half what it was... down to just 190mA max from about 420.

[methods]

We had set up a large order of "good units" but I let it fall through the cracks. Folks just don't want to pay any more for "known good" so it is not even worth our risk/time to do the deal. I moved 50 of them and actually lost money on the deal. The old methods used to like to do a lot of that ( ) but now I have and ol'lady and kids to feed so I actually have to profit on my business sometimes

-methods

[RichiePA]

Are you going to start selling modded high discharge units?

[methods]

I made a few but nothing came of it.
The problem is that we have to buy in lots of 100pcs... which means we are putting up about $1.7K for months at a time.

Then - at best lets say I can sell them for $25 each.
That would be an $8 "profit"... minus risk, minus broken units, minus warranty, minus opportunity cost, minus parts, minus labor, minus testing...

We would lose our asses doing it.

I cant even justify buying them at that price and distributing them as a courtesy (which I do often). Just too much money and risk involved.

I wish I could!

-methods

[dimpirate]

There being sold on eBay For $50 and $100 dollars
If you sold them for even $30-$35 it would still be a bargain...
Fred

[Scruffoid]

Hey i think i can see my One in that picture of yours there Jay!

Please Mr Methods PM has been sent

Scruff

[methods]

Lol..... I will get to my PM's but just FYI

Sorry guys - I dont sell these

We wanted to make them available to folks but it is just too expensive and risky. Take the information here and do more research. Find a way to make them reliably available to all of us at a good price

-methods

[miro13car]

[quote="Hyena"]Nice work methods. Another way to potentially tell them apart is some say "made" instead of "mode" on the bottom left button.
I'll have to start checking my sources, I've used several and noted that some come in a plain white cardboard box, some in a nicer looking blue and black coloured cardbox box with a picture on the frontand some in a clear hard plastic case - that almost always arrives cracked from postage![/quote]

there are ones with red boards on eBay with MADE word on the front
So it is rather mix and match

[methods]

I have had a few members bring some new flavors to my attention that really look promising. At this point (and it is a moving target) my personal belief is that the best solution would be:

Bulk charge to a comfortable level on a daily basis
Once a week/month/year use a cell level charger like the one Hyena is selling.

Pushing the cells up to 4.2V is a hell of a lot easier than trying to pull them down to 4.2V - especially as our packs get bigger and there is more and more energy to dissipate.

I got out of bed last night and finally finished the design for my new Battery Breaker. It is an aluminum box that gets built into your battery and interfaces with my LVC/HVC boards. It can flow 100A+ to the controller and 50A+ from the charger. If any cell level trips (high or low) the box disconnects your battery completely. No more tapping into the throttle, no more worrying about leaving a controller on. This will be a "real" hardware implemented cell level protection. Ironically - it is almost identical to my HVC Breaker design but with one more set of mosfets hooked up Source to Source. We are going to go with a TO-247 this time around and shoot for 200V+ capability. Going to try and do it by spring time - but the way I have been going... could be spring after next

Anyway back on topic
I would be interested to hear results from anyone who has tried out the newer flavors of this Medic. They are still super small and simple for what they are.

-methods

[Arlo1]

I have had a few members bring some new flavors to my attention that really look promising. At this point (and it is a moving target) my personal belief is that the best solution would be:

Bulk charge to a comfortable level on a daily basis
Once a week/month/year use a cell level charger like the one Hyena is selling.

Pushing the cells up to 4.2V is a hell of a lot easier than trying to pull them down to 4.2V - especially as our packs get bigger and there is more and more energy to dissipate.

I got out of bed last night and finally finished the design for my new Battery Breaker. It is an aluminum box that gets built into your battery and interfaces with my LVC/HVC boards. It can flow 100A+ to the controller and 50A+ from the charger. If any cell level trips (high or low) the box disconnects your battery completely. No more tapping into the throttle, no more worrying about leaving a controller on. This will be a "real" hardware implemented cell level protection. Ironically - it is almost identical to my HVC Breaker design but with one more set of mosfets hooked up Source to Source. We are going to go with a TO-247 this time around and shoot for 200V+ capability. Going to try and do it by spring time - but the way I have been going... could be spring after next

Anyway back on topic
I would be interested to hear results from anyone who has tried out the newer flavors of this Medic. They are still super small and simple for what they are.

-methods

Very cool methods.
Do you think that people can just run this as a first line of defense then balance charge every so often??