"Improveing the Xlyte Dual" or "How to hose u

[Drunkskunk]

While my bike is down with some welding issues, I decided its a good time to start modifiing things to work the way I want them to.

I've read Fechter's great article on modding the 35A Xlyte controller, and its got me thinking. The only weak link on my bike. Other than flimsy aluminum battery racks, is the amperage limit on the controller.

What I have right now is the centertapped motor, with the dual 20A contoller. I "think" this controller uses the same case as the 35A, but I can't confirm it without some measurements of a 35A. If I understand how this works, its just a 3 pole switch on the output of the standard 20A controller, then stuffed in a 35A case for space reasons. Anyone know for sure?

What I'd like to do is modify a controller to handle 30+ amps on the low speed setting, 20A on high speed, handle 72V reliably, and fit in the same footprint as the controller I have now. The amp switch its self I think I can do by using a 4 pole switch instead of the 3 pole, but as for how to mod the amp sensor, I don't know yet. Anyone built a variable Amp controller yet?

Also, I long ago got rid of all my spec books from school, So no clue what FETs to use, and wear to get them. Anyone have recomendations and sorces on good fets?

 

[maxwell]

Farnell (.com) sell to anyone, reasonable prices and a good parametric search facility. I have just orderd some 75V 170A Fets for my new controller design (will post when construction starts) at a couple of quid each. What I can't see is how you can get 170A down a TO220 leg.

 

[Lowell]

You can't safely unless you add some copper to the leg during install. I think the TO220 package is rated for about 75 amps stock.

 

[fechter]

Farnell (.com) sell to anyone, reasonable prices and a good parametric search facility. I have just orderd some 75V 170A Fets for my new controller design (will post when construction starts) at a couple of quid each. What I can't see is how you can get 170A down a TO220 leg.

Which FETs did you get?

Yes, a TO-220 case is limited to 70 amps by the legs. It can take 170 amps for very short periods of time as long as the average stays below 70.

It's fairly easy to make the current limit adjustable. The circuit is posted in the controller thread. Your controller might be different, so we'd have to see the insides to tell.

I'd recommend getting IRFB4310's If you can find a source with stock, IRFB4110's are even better.

 

[CGameProgrammer]

I'd recommend getting IRFB4310's If you can find a source with stock, IRFB4110's are even better.

I've ordered a few things from digikey.com. They carry the 4110s and claim it'll be ready for shipping in 5 days (they were out of stock of those for a while). They had plenty of 4310s in stock.

 

[eP]

What I'd like to do is modify a controller to handle 30+ amps on the low speed setting, ...

30 + how much ?
+10 ? or +20 ?
or maybe + even much more ?
Did you calculated motor's heat dissipation and efficiency at the amps level you want to go ?

Also, I long ago got rid of all my spec books from school, So no clue what FETs to use, and wear to get them. Anyone have recomendations and sorces on good fets?

I would like give you the hint: the better idea is start looking for source of very good (at very low Rm) motors.
Or start looking for source of very good geared motors. (For get a second one)

Regards

 

[29a]

I'm doing a simillar thing but for different bat configurations
I just orderd the FDP 2532 150V 79A has the lower resistance so less heat
so i can eventually try 96V Nicd (116V)
I'm trying an adjustment of the shunt resistance to give me max A for my batts.
The tricky part is calibrating, the new limits if you don't have the right tools

I did notice my stock Crystalyte rated 35A controller sometimes gives out over forty amps

 

[maxwell]

The FETs are IRF2907 75A package limit and 175A silicon limit, so I suppose you can overload the package for a lot longer (maybe a few ms) without blowing the silicon. This will give time for the capacitors to discharge before the current limit cuts in, as the limit is after those caps. In all the FETs I have blown I have always destroyed the chip never the legs. Did make holes in the outer can of a few TO3 devices once with the insides making a bid for freedom! (huge 3kW audio amplifier design).

 

[eP]

The FETs are IRF2907 75A package limit and 175A silicon limit, so I suppose you can overload the package for a lot longer (maybe a few ms) without blowing the silicon. ...

Hi maxwell

Tell us how much current (amps) need 408 on the low speed setting at 48V ?
Give us an example:
What is batts/controller current ?
How much is duty and motor's current ?

And what about efficiency ?

Best regards.

 

[Drunkskunk]

Fechter, I saw the drawing, but I'm not sure I understand it. From the drawing, it looks like the sensor trace is shunted to ground before it gets to the chip. I think I've spent too many years dealing with Telcom ckts and running everything on Negative voltage, Is the 5 volt side strapped to the Positive, and and the motors running negitive to the controler's refrence point?? That would certainly cure some noise problems, But Positive ground isn't seen much outside of Old British cars and Telcom.

I'd recommend getting IRFB4310's If you can find a source with stock, IRFB4110's are even better.

I've ordered a few things from digikey.com. They carry the 4110s and claim it'll be ready for shipping in 5 days (they were out of stock of those for a while). They had plenty of 4310s in stock.

Thanks! I hadn't been able to find anything better than stock localy. I think I'll go with the 4110s since there back in stock.

Anyone know what the 5 volt side pulls for amps? I'm considering going to a switching 5 volt supply to eliminate the heat soak problems that might come up running this in 110 degree heat down here

30 + how much ?
+10 ? or +20 ?
or maybe + even much more ?
Did you calculated motor's heat dissipation and efficiency at the amps level you want to go ?

I figured 30+ was more technical than saying Thirty-ish. The controllers come as 35 amp, but this is a center tap motor. There is no good data on heat dissipation and max current load on the center taps yet. The best I can do is assume it approaches the efficacy of the 4012 in that mode, with the 408 being 1/3 lower than a normal 408. Testing will tell, but the 4012 can handle 40 amps. 30 is a good starting point for me, with 20+ in 408 mode.

I would like give you the hint: the better idea is start looking for source of very good (at very low Rm) motors.
Or start looking for source of very good geared motors. (For get a second one)
Regards

I think we have a differing opinion of what "good" is. For my needs, anything geared is inferior. If you know of a superior motor good enough to make me want to throw this out and start over, I'll consider it. My needs are the ability to go 20 miles on 250 watt hours used at 15mph, completely silent operation at crusting speed and normal acceleration, and it needs to be well enough hidden that a layman can't tell I have an electric bike. Right now, the Crystalyte motors do that just fine.

 

[maxwell]

A 408 (0.6 ohms) at 48V will take a maximum of 48/0.6 = 80A at an efficiency of zero. This is the maximum, it will be less because of battery/controller/wire/connector resistance, if it is rotating and if the controller limits or PWMs a bit.

It will take more if you force the motor backwards though (for the pedantic).

 

[eP]

A 408 (0.6 ohms) at 48V will take a maximum of 48/0.6 = 80A at an efficiency of zero. This is the maximum, it will be less because of battery/controller/wire/connector resistance, if it is rotating and if the controller limits or PWMs a bit.

408 at 15mph at 26'' rim => 200rpm => 20V (at Kv=10rpm/v). So if you get efficiency above 50% the voltage sag must be less than 20V. At sag=20V you get motor's current Im=33.3Amps.
If the battery sag is less than 4V controller's V_input > 44V and I_input <30A.
20 miles @15mph =>1h20min @250Wh => 187.5 watt average input power.

So it is a wrong idea to use controller wich could allow riding at low efficiency at so tight energy budget.

 

[fechter]

Fechter, I saw the drawing, but I'm not sure I understand it. From the drawing, it looks like the sensor trace is shunted to ground before it gets to the chip. I think I've spent too many years dealing with Telcom ckts and running everything on Negative voltage, Is the 5 volt side strapped to the Positive, and and the motors running negitive to the controler's refrence point?? That would certainly cure some noise problems, But Positive ground isn't seen much outside of Old British cars and Telcom.

Which drawing?

The current limiter is based on a voltage divider and comparator. The voltage drop across the shunt is small, like 1mv per amp.

From the battery, there's a linear regulator that first goes down to around 14v. The 5v regulator runs off that (around 100ma max). The primary regulator does throw off a fair amount of heat at higher voltages. If you wanted to replace it with a switcher, you'd want a 14-15v output.

 

[eP]

For my needs, anything geared is inferior. If you know of a superior motor good enough to make me want to throw this out and start over, I'll consider it.

I don't think so 70% efficiency is inferior to 50% for silent gearless.

My needs are the ability to go 20 miles on 250 watt hours used at 15mph, completely silent operation at crusting speed and normal acceleration, and it needs to be well enough hidden that a layman can't tell I have an electric bike. Right now, the Crystalyte motors do that just fine.

Right now, at flat and very slow accleration maybe you will be able to drive 20 miles at 250Wh.

But on 50% +2%slope and 50% -2% slope 18 miles only.
On 50% +5%slope and 50% -5% slope 12 miles only.
0n 50% +8%slope and 50% -8% slope 5.8 miles only.

Above could be true if you and your bike is weight under 95kg.

So i'm not sure that just fine.

Regards

 

[Drunkskunk]

Which drawing?

The current limiter is based on a voltage divider and comparator. The voltage drop across the shunt is small, like 1mv per amp.

From the battery, there's a linear regulator that first goes down to around 14v. The 5v regulator runs off that (around 100ma max). The primary regulator does throw off a fair amount of heat at higher voltages. If you wanted to replace it with a switcher, you'd want a 14-15v output.

My bad. I was badly missreading your diagram. its been too long since I've done this sort of thing. It all makes sense now.

Knowing that I'll be building the 35A controller later, I decided to experiment with the one I have. I'd rather screw up now with this controller, than latter with the one I plan to use.
It is a 35A sized case, but modified. The controller board is similar, but half the size, with only 6 FETs. The other half of the case is the motor selector switch and headroom for it's wiring. As expected, it is just a selector switch added to the output of a normal controller. While I was in there, I shortened the leads down to only 6 inches, eliminating 2 feet of resistance in the motor wires. I also ditched the pedal start, cruse, and brake leads as I'm not using them.

It has just 2 shunts, so I added a small solder bridge between them for more amperage. What I ended up with was a new regulated amperage of 28A, and the Bike feels amazing! At this level, you can feel the diffrence in the power curve of the two motors, you can't at 20A. The controller was still cool to the touch after a 10 mile run, even in the area of the heatsink. the motor did get hot, though. Not too hot, but I'm aproaching it's limit. I'm sort of amazed I didn't blow the thing apart running it 40% over spec.

I'm going to build the regulator first for this box, with a knob fitted were the reverse key used to go. Maybe build it for 25A on the 4012, and adjustable 25A to 15A on the 408 side.


A question on the 14V side of the regulator, How critical is this side of the voltage? What part of the Controller uses voltage above 5V? I found this: http://www.dimensionengineering.com/DE-SWADJ.htm They're built for RC planes, and are repute to be high quality, but it's 13V max. They also have a 5v non adjustable. I have one of those already, and it's roughly the same size as a standard Voltage regulator, bbut it doesn't need a heat sink, so it can me remotly mounted.

 

[fechter]

I think 13v would be OK. It supplies power to the gate drivers amongst other things. The internal 5v regulator will be fine with 13 going in.

The spec sheet on the regulator says 30v input max. The stock regulator transistor is rated for 400v. The amount of power dissipated by the regulator is fairly small, depending on voltage.

 

[Drunkskunk]

I hadn't worked on the controller much this week, as I had an SLA die and mess up the charger. Now that its sorted out, I'm back to working on the controller plans.

Yesterday I took it out for its first run on the repaired pack, plus a 6 volt booster battery to give me 54 volts. part of my goal is a 30mph bike, so I figured I'd step up the voltage on this little controler and see how it does untill it fails. I planned on a 72V bike. What happened next was semi amazing.

48v=22mph, occasionaly would give me 23 under ideal conditions and a fresh charge. it's done this for the last 50 cycles.

54V=29.7mph. after a mile or so, it backed off to the mid 28's and held that for about half the normal range of the 408 before the little 7 amp 6V battery ran out of juice.

Thats at least a 6 MPH boost from just 6 volts!~!

I need to do more testing, but it appears there is a dramatic increase in efficancy that occures above 48V. I don't know were 54 volts falls on the curve right now, but when the voltage fell below around 55 volts under load , the bike dropped fairly rapidly back down to 22mph.

The 4012 seemed to have a similar effect, but not as dramatic. it may follow a diffrent voltage/efficancy curve.

I'm a complete noob at this, but does this sound like anything anyone has run into before? A dramatic upshift in efficancy above a certian voltage?

 

[Mathurin]

Dunno, per the simulator it looks like you were running 60v?

 

[Lowell]

Being on the far side of the power drop off, you can see pretty large gains from a few extra volts. Sounds like you'll be going to 60V+ to meet your 30mph goal.

 

[Drunkskunk]

If you mean the Ebike.ca site calc, yeah. I'm getting results like I would have expected at 60V, but much lower. that calc seems to indicate that increas in voltage has a near linear effect on effancy, but what I'm seeing is, atleast on the double motor, its not linear, and it jumps up sharply just above 48 someplace.

60V would be nice. If I replace the stock, egg shaped Schwinn tires for some more efficant and thinner tires, I should be able to reach the last 0.3 mph on just 54V.

Right now, the advantage of 54v is the 6V battery fits in the bag, and a 12V wouldn't. I like the stealth aspect of my bike. I'm going to try 60V, but if it doesn't have the same dramatic speed/efficancy boost, then I may stick with 54V

 

[Lowell]

Is a NiMH or lithium booster an option?

 

[Drunkskunk]

Is a NiMH or lithium booster an option?

Absolutly!

SLA is temporary for the bike. Its cheap and easy to get from local sorces, but I'm willing to use anything.

 

[Ypedal]

Your 22 mph with the previous pack.. have you ever hooked up a volt meter during use by chance ?

I suspect some severe voltage sag using small sla's..... your new battery might be conpensating for this sag resulting in bigger numbers.

DB's are soo cool.. i rode to work today without one and i'm totally lost without it lol... i'm such a geek.. :lol:

 

[Lowell]

Is a NiMH or lithium booster an option?

Absolutly!

SLA is temporary for the bike. Its cheap and easy to get from local sorces, but I'm willing to use anything.

For a small to medium Wh pack, Emolis seem like a good choice. Or save $$ now and buy NiMH, and by the time the pack is worn out lithiums will be cheap.

 

[Drunkskunk]

Your 22 mph with the previous pack.. have you ever hooked up a volt meter during use by chance ?

I suspect some severe voltage sag using small sla's..... your new battery might be conpensating for this sag resulting in bigger numbers.

DB's are soo cool.. i rode to work today without one and i'm totally lost without it lol... i'm such a geek.. :lol:

SAG sucks. I'm envious of your DB, but I do have a Watts up meter wired into the pack. at 48V, the pack seems to have a peak voltage of 58V, but sags to 52 volts under any load. the good news is it seemed to hold that 52V for most of the charge, and only sagged to 48V when I was pulling 30 29amps out of it. I quit riding when the voltage under normal load drops to 47V


Emolis would be great! Last I priced out NiMH was Two, 12 amp, 36V packs from Ebikes.com. I was waiting for them to reopen to buy them, but now I'm still waiting.. And to buy my drain brain... and to buy my 35A controller wired for the DB...

And since that time, I've found these LiFEpo4 packs are competitivly priced with good NiMH.