Hyena's e-bike builds (now with HD video)

[Hillhater]

....So I went oldskool with a pen, paper and a cardboard box

"old school" CAD ....Cardboard Aided Design. !

[Hyena]

LOL, I used the latest cardboard version too, it arrived just the previous morning

In other news I've gotten a bit fed up with makeshift leads and test equipment scattered and buried all over my bench and workshop so am making a more dedicated piece of ebike testing and charging equipment. There'll be a lipo cycling set up to test packs more quickly and easily - charging, discharging and manually balancing. A 500w discharger using an array of small GY 6.35 50w globes for very rapidly discharging a pack and a seperate lower powered discharge circuit for pulling back single cells. This will be done either automatically driven off a battery medic style balancer or manually with a cell log to display the cell voltages and a 6 pole switch to drop the load across the desired cell without having to swap plugs around. A single 50w 12v globe pulls 3 amps when connected to a single fully charged lipo cell which is perfect for discharging at the max rate through the balance tap wires. The same set up will be used for manually charging up low cells with a 3 amp power supply. I've been doing this for a while anyway by plugging in a cell log, finding the weak cell and then manually charging it up with a 2 pin balance tap connector onto the right wires, but this way will do away with all the fiddling and make the process quick and easy with a simple one plug click and the twist of a dial.

Bulk BULK charging will be done with 2 server power supplies, put in series to charge 6S parallel groups at 50 amps. ooft
That'll charge my 18S2P (10ah) packs at nearly 2C and the 18ah pack in my stealth fighter at 1C. Noice.

My old power supply is a bit ghetto so I'm also planning planning integrate a new lab style power supply with adjustable voltage and current for general testing and what not. I was going to use a few voltage and amp panel meters and DC converters (one step up and one step down) to give me the range of voltages I'd want to play with when I came across this nifty little board.

It does everything I want and more in one neat package and without any any messing around and construction (not that that's an issue)
CV and CC selection, 0-60v and a CA style display. And under $50 delivered. Sweet!
I'll post more info an a review when it arrives but I figured it might be of interest to other tinkerers like me.
http://www.ebay.com.au/itm/ZXY6005-DC-D ... 2a19b33bae

[icecube57]

I just bought one of these. Thanks for the link mate Its a perfect add on for my 24v power supply but i think you can use one 24v power supply and series two of these for output as long as they arent physically touching....maybe i could be totally wrong I think these are non isolated but im not sure... im still looking up info

[heathyoung]

Looking at the topology they are buck - so non-isolated, and input voltage must be higher than output voltage.

Server supplies aren't usually current limited like you would hope, they are usually hiccup unfortunatly.

[icecube57]

As long as you dont series the output with the input you should be able to series non isolated converters on the output.. correct? It seems like the dc to dc does the current limiting 60v 5A and you can dial in the current limit so its only draw what it needs and it shouldnt overload a server psu 60vx5A plust overhead isnt alot of watts.. lets say 350w for good measures... i know its not going to over loaded my dell sever 1400w psus that would have 24v at 57A.

[Hyena]

Looking at the topology they are buck - so non-isolated, and input voltage must be higher than output voltage.

Yeah I was curious about that. I was originally planning to use 2 for my lab power supply purposes (one step up and one step down) to give the range of voltages I might use. But when I saw these with 0-60v output I thought they'd be perfect and hastily bought one. After a closer look as you say the input has to be higher than the output (I was hoping it'd step both up and down) and presumably the 60v max they refer to is with a 62v input.
Oh well, I guess I can use a seperate 60v meanwell style PSU for that. Not sure what sort of range that will give though...

Server supplies aren't usually current limited like you would hope, they are usually hiccup unfortunatly.

Bummer, they should be on my door step this arvo or tomorrow so I'll soon find out. Is this where you magicly come to my rescue with a current limiting board Heath ?

[sn0wchyld]

LOL, I used the latest cardboard vers....
Bulk BULK charging will be done with 2 server power supplies, put in series to charge 6S parallel groups at 50 amps. ooft
That'll charge my 18S2P (10ah) packs at nearly 2C and the 18ah pack in my stealth fighter at 1C. Noice.
....

how are you regulating the output? or have you found some server ps's that self limit the current?

[Hyena]

It seems like the dc to dc does the current limiting 60v 5A and you can dial in the current limit so its only draw what it needs and it shouldnt overload a server psu 60vx5A plust overhead isnt alot of watts..

I was talking about charging the lipo direct with the 50a odd output from the server supplies.
Mine are 47 amp HP DPS-600PB
I guess worst case I could put 2 in series with the voltage turned down with a 3rd 200w 5v supply that IS current limited...

or just use 14ga wire to charge through

[icecube57]

With this dc to dc i think it would even be a worth while investment to get a 60v meanwell or series some 20-21v laptop power supplies to this. You could current limit the power supply viat 24v bulb or lamps in series but it would have an uncontrollable voltage or yeah you could just use a small gauge wire to limit the current also... dirty but it gets the job done... have it routed and coil in a watter bottle for cooling lol

[icecube57]

Just a thought since these power supplies will supposedly trip if overloaded under a dead short cant you put a brushed motor controller with a rectified output and a bank of caps to smooth out the voltage ripple even more to control the voltage range and use the current limit of the controller to limit the current so you dont overload the PSU. I would be willing to bread board it up if its a viable solution even though i dont know squat about electronics... as you can tell by my vauge logical reasoning i can put things together well though lol....I though these power supplies would have Foldback protection. I think one of them does measure current I saw shunts in one power supply i worked on...

[heathyoung]

Nah unfortunatly they don't do foldback current limiting as there is a requirement for a VERY stable output on a server - you don't want your 12V at 10V!

There are ways and means of doing this, I have a box full of server power supplies (about 14KW worth including those HP supplies. I've considered trying to figure out how to adjust the output, but they are too damn smart for their own good.

Easiest way is to make up a current mode buck converter - with a whopping great inductor and a bank of mosfets - As long as your supplies are the right input voltage to charge your cells, you only need it to be current mode - that is, use a voltage mode controller like a TL494 or use a proper current mode buck controller IC. Lemme think what would be best for this... The LED world is full of these.

<edit> A contender - LM3409N - PFET driver, up to 75V, 14 Pin DIP (rather than SSOP) - only for P channel fets (doah!) but scaleable to whatever output current you want though

[Hyena]

I have a box full of server power supplies (about 14KW worth including those HP supplies.

Yikes!! What on earth are you planning to do with those ? Charger for you vectrix ?
Mine arrived yesterday, I shorted the pins as required to get them to work but one of them was DOA

Speaking of which, I've got a 400w BMS battery charger here that's died if you're still interested in collecting and playing with such things.
I've considered trying to figure out how to adjust the output, but they are too damn smart for their own good.

Easiest way is to make up a current mode buck converter - with a whopping great inductor and a bank of mosfets - As long as your supplies are the right input voltage to charge your cells

Yep voltage out of the box is fine - I'm just looking for 25.1v from the 12v units in series, so 12.55v each. I just need to limit the current to 50a or what ever won't make them self destruct/hiccup.
I defer to your experience with these though Heath so look forward to what ever solution you can come up with

On an unrelated note I've got a pretty sweet little 24v 600w cube meanwell unit here that I got from fullthrottle that I'm using as my current fast charger. It's rated at 25a but puts out 31a out of the box and runs happily for the duration of the charge with no mods. At just over 1C it's all over with pretty quickly so it doesn't get hot and bothered. I'd be happy with another one of those if I could get one but they're not commonly available - or cheap!

[heathyoung]

Yep I gave some thought as to using them for a charger for the Vectrix, but since it is using Chundersags, you only have 1C charge capability, and those extra 30A would be going to waste

Would have needed 3 phase power to run all of it though

I'll swap you a working server PSU if you would like for the dead 400W charger, it will be interesting to do a reverse engineer of these. What model was it?

I'll give the constant current circuit some more thought - the P channel FET is useful in this configuration as it will just pass when your input voltage = output voltage.

[Hyena]

I'll swap you a working server PSU if you would like for the dead 400W charger, it will be interesting to do a reverse engineer of these. What model was it?

Deal! The guy I bought the others off sent a replacement which arrived this morning but I haven't had a chance to test it yet. Either way it'll be good to have a matching pair of those and then I'll use an additional one just to power a RC charger. Doesn't need to be too gutsy, 400w is fine.
I dont know the exact model of my 400w one off the top of my head, I can send you pics if you want but its the standard kingpower or what ever they're called. It's probably an easy fix for you if you have a box of donor parts, which I'm fairly sure you do

I'll give the constant current circuit some more thought - the P channel FET is useful in this configuration as it will just pass when your input voltage = output voltage.

Cool. I found a number of current limiting circuits online, would it just be a matter of beefing up the parts used in those ?
Eg this one

In other news, trying to trouble shoot ebike problems at midnight after a long day can be bad for your health.
The mildest of KFF but it's been a loooong time coming

KFF.jpg (41.25 KiB) Viewed 238 times

Noob mistake, I was testing an 18S battery pack I didn't have the original discharge lead for. Rather than making up another 6 pin anderson series discharge lead for the pack I used another one I had, but that was assembled with the voltage reversed. No biggy, red to black on one end of the plug as long as I do the same at the other end. That was the previous night. Then last night I picked up the battery and went to connect up another controller colour for colour as you'd expect. black to black, click, red to red - BOOM - andersons reduced to a blown apart and melted stub. Must be mighty strong diodes in the controller, I threw on some new connectors and it powered up fine!

In unrelated news, any Aussies got a few halls sensors they could spare ? I've got a motor here that's playing silly buggers and I it looks like all 3 halls are sus. The voltage of all 3 change when you turn the wheel, but not by much (~3.5V-2.8V) which I haven't seen before...

[heathyoung]

The current limiter is linear - so you drop a lot of heat (especially with high differential voltages and currents - a 6S lipo pack at 16.2V (yeah, pretty flat at 2.7v per cell) - start with 25V and 50A (yikes) - you need to drop (25-16.2 X 50) = 440W! Hence my comments on requiring a switchmode solution.

Get me the HP part number from the supply, I probably have one (from G3/G4 HP DL380's - decomissioned heaps of them).

[Hyena]

There wouldn't be THAT much voltage drop, I infrequently go below nominal voltage so it's more like a 3v voltage differential (4v max if I pull it right down) and with a charger belting out 50 amps I reckon you wouldn't be below 3.8v/cell for more more than a minute or 2. So for the bulk of your CC charging you're only talking 2.3V * 50 A = 115w, which is much more managable with a small heatsink +/- fan

I think the power supplies I have here are DPS-600pb's but I'll check when I get home. As I said if these 2 I have here work I don't need one that powerful for the RC charger as it only needs 25a @ 12v

[heathyoung]

Well, that's not too bad then, an LM317 and some pass transistors could do it - I had a pair of coherent Argon-Ion laser supplies that ran some show lasers that used a linear reg (!!) - Boy did that get hot (never mind the tube - the water-cooled ones ran so much quieter)

[voicecoils]

Interested to see what you end up doing with your power supplies Jay.

I've got 6 of them for the moment and just bought one of these:

http://www.electusdistribution.com.au/productView.asp?ID=13800
(waiting for it to arrive)

I'll run the ESP-135 server supplies in series with the lab supply which will add 1-16v and allow current adjustment from 0-40A. Doesn't let me use the full 50A+ potential of the power supplies but doesn't cost thousands either. With the 6 server supplies + the lab in series I should have a 76-90v window and up to 3.6kW of charging power. That's the theory anyways!

[Hyena]

Well, that's not too bad then, an LM317 and some pass transistors could do it - I had a pair of coherent Argon-Ion laser supplies that ran some show lasers that used a linear reg (!!) - Boy did that get hot (never mind the tube - the water-cooled ones ran so much quieter)

Cool, got a circuit I could try ? Would doubling up the LM317s on 2 smaller heat sinks be beneficial to share the load ?

voicecoils, that power suppy looks good, pretty pricey though! I hope they're cheaper than that with an electus trade account.
I was looking at one of THESE but decided to build something more versitile and suitable to my ebike needs. But yeah, running something like that in series looks like the easiest off the shelf way to limit current like this on a big scale. Thats why I suggested previously a 5v meanwell, because your standard 350w one can put out a metric bucketload of current and they're easily current limited - though not as variable as the ones you've got

[voicecoils]

Yes I thought about meanwells with the server supplies, good for if you just want to bulk charge a set pack.

I'm hoping to have something I can tweak for different chemistries and voltage ranges and trickle charge if needed or smash the pack with current when necessary.

That reminds me of when I was pulling 30A in and out of a 24v frog battery trying the iCharger regen mode, it hated it and then blew the cell vents. Good thing the frogs have a handle so I could throw it outside

[Hyena]

Yeah that voltage range with however many additional server power supplies in series will make for a good, versatile charger.
I'll be able to leave my charger at home next time I drop into glow worm!

LOL @ the frog pack.

Speaking of bulk charging, I had a cell in a lipo pack die today. I've been getting progressively worse and worse range from my 10ah 18S pack, hitting the CA LVC just before home at 7ah lately. Today it dropped out 500m shy of yesterday so I decided to check the balance. One cell in one pack is at 1.8v - so it's gone. The rest are still fine but I'll probably ditch the whole thing and start afresh. I never bother with LVC monitoring and was especially casual with this pack as it was made from recovered packs I pulled from my original old norco dirt jumper - atleast 2 years ago. The real key point though is that the cells were abused by the new owner - half the packs got run down to 2v some how and the rest were overcharged to 4.4v/cell. Deeming the pack dead/unlikely to recover and deliver full capacity I kept it to test and experiment on. I managed to recover and balance them out and after some initial tests that showed they still delivered full capacity I have been using them ever since. I'd say I got a solid extra year of use from them - with a 70% discharge twice a day most days (with a 6 month period of disuse in the middle during the worst of my cancer treatment) So that's a testament to how good these batteries are, even when abused. Even if I had to replace them every 12 months it'd still be worth it in fuel savings alone.

[RallySTX]

Good job on getting the most of a set of cells, Jay. Congrats on 100 pages as well.
Brian L.

[Scruffoid]

Jay really luv to hear stories about lipo packs like that. I think its like most things they have a really bad wrap from the early days they they cant shake but they are much better and more resilent they people think they are.

Every time i tell someone i have Lipos in my bike they always say something about fires etc its like the old NiCad Memory stuff. I guess there stuck with it.

Youll have to make another pack up from your spares again

Scruff

[Hyena]

Yeah people who are scared of lipo deserve to lug around around SLA and lifepo4

Now, importantly, I've just announced a Sydney group ride for July. Plenty of notice for everyone to get their builds road worthy - including myself! (stealth fighter is still in pieces)

SYDNEY ENDLESS SPHERE / GENERAL EBIKE GROUP RIDE - JULY

BE THERE OR BE SQUARE!

Click here: viewtopic.php?f=25&t=40444

[Hyena]

New vid uploading, usual deal, it's ready when you can see the image below.
Nothing hugely exciting, just some footage from my commutes to work in IR seeing as I haven't been riding lately to film anything better. Guess which segment is there for your Greg