"Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS...

Batteries, Chargers, and Battery Management Systems.

Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Sat Mar 22, 2014 1:05 am

That is strange about the shunts coming on when the factory BMS is attached. Somehow it must be pulsing the line and generating enough voltage to trigger the shunts. Anyway, it sounds like the system is working properly.

I forgot, what Ahr size are the cells in that pack?
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby 2007blueprius » Sun Mar 23, 2014 10:45 am

80 ah, 16s4p 20 ah pouches.

I did have a bad day yesterday, I was wondering how long this lucky streak will go on for, I moved on with a nimh pack for my boy's go kart and somehow cooked the power supply I had rigged up, than I went to plug in the car and it is not taking a charge, my charger senses the pack to engage and its fine I plugged it in directly for a test and it works, but through the Zephyr it doesn't see the pack now, who knows what else, just on this last test I had some sparks flying when I disconnected it.

so now I got to figure out how to go about that power supply so I can run some tests, now this is more like how my electronic projects normally go, I tend to fry just about anything I touch, surprisingly enough I managed to build a Zephyr :lol:

I'll post back once I got a PS up and running


now this is odd, just as I submitted the post, I tried using the above mentioned nimh pack as a PS and the red LED came on and I have 24v going through the Zephyr, it wasn't doing that with the charger, it's still alive, could it be related to temperature? it is still rather cold here and I had the Zephyr inside for a while, just with the 24v pack hooked up as the charger seems to be working

not sure what that was all about but it is taking a charge now, could some of those components be susceptible to cold temps? all I did is disconnect it and take it inside, hooked it to the pack first, than the cell leads, than the charger, plugged it in and it works, I have the LVC plug disconnected at the moment but I tried that before and it did not work, I'll keep an eye on it I guess.

on the other hand I had checked the cells after they rested for over 24 hours, all were at 3.28v except for 15 and 16 were at 3.27, this thing is awesome balancing, I'll report back in a few hours when it is done
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Sun Mar 23, 2014 11:08 am

I don't think temperature should affect it much.

When it was hooked up but not charging, did the LED on the Zephyr come on?
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby 2007blueprius » Sun Mar 23, 2014 11:35 am

fechter wrote:I don't think temperature should affect it much.

When it was hooked up but not charging, did the LED on the Zephyr come on?



I don't think so, actually I noticed it was not on when I installed it in the car before the discharge, I thought that was odd, I remember it being on, mine looks red, I think it was supposed to be orange, maybe I can't see well, it is red now and I have to cup it in my hand to see it, it is very bright outside, I wonder if when I installed it in the car I did it in the wrong sequence or something, you know I am not too bright, I am surprised I made it this far honestly, and apparently I haven't fried it yet, see my previous post I have been editing it.

I think something is odd with my house wiring too, my panel is humming I never noticed it before that outside plug may have some issues too
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby 2007blueprius » Sun Mar 23, 2014 10:13 pm

I think I am on to something, I did install a second remote LED and like I mentioned earlier, the light was red I remember it to be orange, I believe the instructions mention it too, towards the end there it was acting kind of funny, led would go off completely, I noticed moving the wire would start charging again, thought it was coincidence the first couple times , well I squeezed the connections and it turned orange go figure, I had used some liquid tape to seal it and than shrink wrap, guess I shrinked it too much I think the green anode and cathode were shorted and in some weird way it interfered with the operation of the system, I'll have to have a look at it again but unbelievable enough I did not manage to fry it yet.

I'm super happy with this thing if anything human error, as in me, caused some glitches so far, but despite it all it is still running. Richard keep up the good work, this is a personal achievement for me and I would never manage it on my own, I know I am not looking for another bms for any project ever.

quick question, bit off topic but not really, I have the 8s balancing board left over, I was looking at some solar panels this spring, wonder if I could use it as a charge/dump controller. I have some laptop cells and some 3kw worth of pouches left, the lifepo 8s would add up to about 28.5v the way I run them, lipos at 4.1v x8 32.8, 2 panels in series 36v open, normally they use 2 lead acid and they dump the excess above 14.4v, the lifepo4 seem more suited in that aspect, looks to me like the shunt could work as a dump load, may have to get bigger resistors, more like some heating elements to match the output of the panels.


I don't have a good understanding of what the control part of the zephyr does, I assume its functions are mostly the intermittent flashing HVC and throttle control, EOC, appears that the LVC would still work off the balance board, I could maybe have it run a relay, bit out of my lead here but just a thought, I have a bunch of lipos from laptops I can get more could make a mice pack I guess.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Mon Mar 24, 2014 8:33 am

Yes, you could use the leftover circuits as a charge dump for a small solar system. The shunt resistors may need to be bigger depending on the output of the panel. If you had shunts that can take the full output of the panel, you wouldn't really need a charge control circuit. Even with bigger resistors, I think you'd be limited to about 1A by the transistors (but those could be upgraded as well for more current).

I was thinking of doing something like this for a 12v standby battery that could power my cable modem and wireless router in the event of a power failure.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby 2007blueprius » Mon Mar 24, 2014 8:12 pm

that is kindof what I had in mind, I just picked up a HF kit off CL its only 45 w 3 panels of 15w each, I haven't opened it up yet but I assume each is 12v and they are supposed to be hooked up in parallel,

what I was going to try is take 2 panels and wire them in series for a nominal 24 v, but that would only be 30w max output, 1 amp shunts should handle it. question is what would be better? 8 lifepo4 at 3.6v which I consider full is 28.8v, it perfectly mimics the lead acid commonly used for this application, I think 14.4v is pretty common for a dump voltage, and I got 8 funky pouches leftover from my old pack no good for EV but something to tinker with, maybe a pack for my boy's 200w razor, at 20 ah, well whatever is left of it that is about 500w, those panels will never fully charge them, it would take like 15 hours, especially if they already have high resistance, but if they were full with 8 shunts fully on, 28.8w I honestly don't think those panels can push much more.

I also have a bunch of 18650 laptop cells I want to do something with, but those would add up to 32.8v full, unlikely those panels will ever fully charge a decent size pack, I wonder if I should use them, and those TC parts for LVC, what were the values? 3v I think on the instructions for lipo, what was the next one up? for I am mostly interested at a cell level to make sure one or the other doesn't get too far off, but granted this is just a small scale experiment, ultimately I am looking for a couple decent panels, there is an outfit locally that sells 230w at cost about $170, now those would push too much for the shunts to keep up, thing with solar can be disconnected unlike wind, not sure how those circuits operate but if it anything like the LVC, NO, maybe I can have it run a relay, I'm told a mosfet would be better, I honestly don't really know what a mosfet is, I read about it once, I need to go back on it, same on the lvc side it could disconnect the load to protect the batteries.

I am thinking if I go for lifepo4, on a larger scale, with 4x230w panels in series, and the Zephyr I already built, in theory I should be able to charge my 4kw pack in about the same time I do off the wall, ( without the charger, maybe its a bad idea), and it had been suggested to me out of the old pack scrap the bad cells and make it a 3kw, or I guess I could buy a few pouches, and have 2 packs, they are not that hard to swap.

so which one should I try, lifepo4 or lipo? that is the question, I know at some point there were some custom panels made, like 32 cell instead of 36 and while they would never overcharge a lead acid, they never did any good either, I am thinking a decent size 8s lipo will have a similar behavior on a standard panel, temporary manual balancing may be required, so I am inclined towards lifepo4 for an experiment but the cells I have are too large for these panels, maybe at say 6 hours a day X 30w, I should build a couple 200wh lipo a 4s? packs for the gokart, charge 1 a day, and manually balance them on the bottom? cell logs have an alarm don't they? save the Zephyr balancing board for a decent size setup?

but I am not smart enough to make a decision on my own

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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Tue Mar 25, 2014 7:10 pm

I think it depends a lot on what you want to use the batteries for. Solar charging is generally pretty slow and good for standby power or something like LED night lights.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby Zenid » Wed Mar 26, 2014 4:33 pm

ejonesss wrote:broken link

Sorry, the name changed when it got updated. Here's the new link. I updated the link in the original message also.
http://www.zenid.com/docs/Zephyr%20LiPo-LiFePO4%20BMS%20BOM-v4.4a.doc
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby johnnyz383 » Fri Mar 28, 2014 5:56 pm

Ok i stumbled across this post. Are you selling these units?...i have a 72 volt lifepo4 battery that needs a BMS, but only 22 series not 24. If your selling them what is the price?


Thanks

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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Fri Mar 28, 2014 6:51 pm

You can use the 24s board and just not populate 2 cell circuits. You could also mount all the parts and just not hook up 2 channels.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby johnnyz383 » Fri Mar 28, 2014 7:15 pm

fechter wrote:You can use the 24s board and just not populate 2 cell circuits. You could also mount all the parts and just not hook up 2 channels.


Ok that sounds great...(i tried that with a signalab bms and it didnt work... how much for the BMS?

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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby 2007blueprius » Sat Mar 29, 2014 7:36 am

folow the link on zenids post, I think it was something like $70, not enough to mention considering what it can do, all in all I think I am just a bit over $200 with parts for 16s, I use it on a 48v 80 ah does the trick just fine, better than anything I could find comercially and I looked and asked arround. luckily Zenid had some boards made

George
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby johnnyz383 » Sat Mar 29, 2014 8:48 am

ok thanks so its a board minus everything you need to make a bms?




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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby Zenid » Sat Mar 29, 2014 9:45 am

johnnyz383 wrote:ok thanks so its a board minus everything you need to make a bms?
john

That's right. There's a full BOM parts list in the documentation referred to earlier (which can just be pasted into an order from Mouser), plus instructions for assembly and testing:
http://www.zenid.com/goodrumfechter.htm
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby 2007blueprius » Tue Apr 08, 2014 11:07 pm

I figured I'd wait a few cycles before I report back, I had set the charger and Zephyr rather conservative just like Richard has been preaching, once the cells were about as charged as they would ever be I turned the charger down to where the shunt LEDs, were barely on, than turned down the eoc pot till it turned green

about a half dozen cycles into it the shunts barely even come on at all, last time I saw 2 of them briefly, but at that point the carger was on CV mode probably wasn't pushing much amps at all and with those 80 ah blocks, they were just hovering there, I have been monitoring it towards the end of charge and also on the low end after a full discharge once they rest, tonite I pluged it in a bit prematurely, had some charge left, I checked the cells about 1/2 hour after they have been resting 3.29v, dead on all of them, pretty impresive by my standards, and likely anybodys,

for a minute there I was debating weather I should revisit the settings, maybe bump the charger a bit now that the cells are so even, just so all the shunts come on before the EOC, maybe turn the EOC pot down just so they balance longer, but everytime I check them they are within 10 mv of eachother so I am figuring why bother, one can't ask for more.

initially I thought that is waistfull with the dump resistors burning the excess, they hardly do that at all any more, I wish you guys come up with more such ghismos, should have never stopped,

ever thought of reviving that last version with the resistor arrays....., read about it briefly it was looking pretty good just before you all went bankrupt.

thank you for the experience, I still suck at electronics yet you all made a solderer out of me.

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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby Altair » Sat May 03, 2014 11:54 am

I'm in the hunt for a good BMS. Been all over the internet, can't find one that I really thrust, keep coming back to this thread.

It's really a pity that the version 4.5 has been abandonned just before it was finished. Design was done, PCB was done, prototype was assembled, and (probably) tested.
With all the improvements that had been added, it would have set a new standard in BMS technology. It would also probably have sold like pancakes if produced in quantity, alrerady assembled, for the masses.
In quantity production, the cost goes down drastically, so there is no point in selling only PCBs because the cost of having the boards professionnally assembled is immediately compensated by the much lower cost of the components.
Limiting production to PCBs only also drastically limits your customer base.

I'm sure that there would be a way for you, Fechter & Goodrum to finally recoup your investment, make money and evidently at the same time, finally allow this excellent design to see the light of day.
I think it's been 2-½ years now since the project has been stopped, and most of the other BMS available are still of the same old Chinese design, (for which NO schematic has ever been made available, IMO) and these same crappy designs will continue to be produced and sold over & over again for as long as Lithium battery technology will exist.

Would it be really too ambitious to make a poll for example, just to see how many people would be ready to prepay $100 or $150, with the promise that they will get that new BMS ?
Or, what about a campaign on Kickstarter ?
You're almost there, you just need money to go into the first production. And from then on, the profits from the first production run will easily pay for the next production...
You could sell the completed boards from your home, direct to the customer. If your wives are at home, that's one job they will gladly do.

Well, for my first post here, I sure went a bit over my head.
But anyway, it had to get out.
I understand that the main reason for "pausing" your project was the lack of time & money, but considering the fact that the job is mostly finished already, you should really take the last step.
The least labor-intensive way for you to get the product out is to sub-contract the assembly & testing to a professional firm.
Every major town has at least one electronics assembly business, they are not difficult to find.
Ask for a quote for something like 100-200 boards, you will be surprised.

I'm hoping that my post has not been taken as too arrogant, because that was surely not my intention.
I have a lot of respect for you guys.

Cheers
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Sun May 04, 2014 12:24 pm

There's a pretty big investement needed to make a large run of boards, and you need to have every little bug worked out before you pull the trigger on it. For machine made boards you'd also want to go with surface mount parts, which would require a complete layout redesign. I just don't think it will happen anytime soon.

Version 4.5 was close, but still had a bug in the design where it wouldn't turn itself off it the charge was interrupted before it was finished. This could be worked around in several ways but to do it right was going to take yet another redesign and test cycle. Ver 4.4 does not have this issue.

There are some chinese units we've reverse engineered and have full schematics for, like some of the BestechPower boards. http://www.bestechpower.com/ Still, these have very limited balancing current and are not really made for large capacity cells. For Lipo or Li-ion cells, the small balancing current is generally adequate once the pack is balanced. It would be possible to make a simple "balance booster" board that would tie into the board to increase the balancing current to something suitable for large cells. The booster could be removed when you don't need extra balancing current.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby Altair » Sun May 04, 2014 2:50 pm

Thanks for the reply, Fechter
Yes indeed, surface mount would be the way to go.
And as you would have to redo the board layout anyway with a program that can generate Gerber files, that would be the occasion to go to SMT.

Well, you seem pretty much determined to let it go. That's very sad.
Would you be willing to publicly (or privately) share the schematic of V4.5, for comparison with 4.4?

Still hoping this is not really the end...
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby marcexec » Mon May 05, 2014 5:20 pm

Can one of the experts check my BOM changes please? Two parts became obsolete or are unavailable - appreciate a quick sanity check, too. 24S LiPo pack (12 AESC (Nissan LEAF) 7.6V 60Ah 2S2P modules actually, details in my thread).


594-K104M15X7RF53H5|2
810-FK16Y5V1E475Z|4 to be replaced with 810-FK11X7R1E475K|4
78-1N4744A|3
512-1N4004|2
512-1N914T50A|4
650-LVR008NK|1
696-SSL-LX3059IGW|1
512-FQP6N40C|1
512-2N3906TAR|1
FDP036N10A|1
299-1M-RC|4
66-OAR5R005FLF|1
299-10K-RC|4
299-100K-RC|2
299-2.2K-RC|2
299-1K-RC|1
576-1.5KE82A|1
595-TLV3702IP|1
595-TPS2812P|2
652-3362F-1-102LF|1
538-22-03-2021|1
649-65474-002LF|1
647-UMA1C470MDD1TE|24
78-1N5231B|24
859-LTL-1CHA|24
512-BD13616STU|24
512-2N3906TAR|24
270-73.2K-RC|24
270-120K-RC|24
299-220-RC|24
283-6.2-RC|48
299-47-RC|24
299-1K-RC|24
270-210-RC|24
270-100-RC|24
512-FAN431LZXA|24 to be replaced by 512-LM431BIZX|24
512-MCT6|24

BTW, does anyone happen to recognize this connector: Image?
It seems to similar to some used in car stereos and comes with the LEAF wiring harness.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Wed May 07, 2014 9:49 pm

The parts substitutions look fine.

No clue on the connector. If it's from the Leaf, it may be hard to find outside a junkyard.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby midwest mayhem » Fri Jul 11, 2014 12:21 am

GGoodrum wrote:I've also added the TVS diode that Richard added in the latest variant, which is now v4.4.2. The TVS diode basically goes across the charge control FET (or FETs...), and is really there just to add an extra level of protection for higher voltage setups, maybe up to 150V, or so. For 24s, or less, setups, I'm not sure if it is needed. Anyway, that is the only change between v4.4.1 and v4.4.2.


Could someone further elaborate on where to put the tvs diode? I don't know which legs of the FETS it should go across and in which direction... here is a photo of my board.

Image

I am building a 30s LiFePO4 setup and I'm almost done! Did tests on the first bank and control circuit and it checked out okay. Thanks for all the great work on this project everyone.
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby fechter » Sat Jul 12, 2014 6:48 pm

On some versions of the board, there were holes for the diode that placed it between the two main FETs. You can put it there or on the side, whatever is easier. It should look more or less like this:
Zephyr TVS Diode.jpg
Zephyr TVS Diode.jpg (74.11 KiB) Viewed 1600 times
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby midwest mayhem » Fri Jul 25, 2014 6:15 pm

Awesome, thank you. One other question - in the charge control section, it states:
Use a current limited bench power supply set to around 100mA. Set the End-of-Charge (EOC) cutoff pot about half way. Connect supply to Charger + and Pack – terminals. Slowly turn the voltage up to around 20v. The master LED should not light up and current should remain near zero.

I've done this without any cells connected and the master LED faintly lights up (red, I believe) around 8v, but goes up to 20v without drawing any current registered on the power supply. The board passes all the other tests. Is this bad or can I ignore it as long as everything else functions correctly?
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Re: "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS.

Postby midwest mayhem » Fri Jul 25, 2014 6:15 pm

Also, for anyone looking for a v4.4a board, I have an extra for sale in this thread: viewtopic.php?f=31&t=61903
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