36V on a 48V controller ?

[tifalou]

Hello everybody,
I am French and not really used to talk in English, so please don't be cruel...
I have got a Goldenmotor with 36V 15Ah lithium battery, and I would like to boost it occasionaly with an additional 12V battery, like Xyster does for example.
Of course I am aware that I need a 48V controller, but I suppose it has a "low level" cut-off, maybe 40 or 42V ? In that case, how do you manage to use it with only the 36V battery when not boosted ?
Thank you and best regards from France.

 

[fechter]

It depends on the controller. If the controller is 48v and has a low voltage cutout too high for a 36v battery, then you must do something to bypass the cutout.

Some 36v controllers work fine on 48v. This would solve your problem.

Otherwise you would need to figure out which part of the controller circuit does the low voltage cutout and modify it. This is usually difficult unless it's a Crystalyte controller (because I've identified the parts already).

One other possibility is many controllers use a separate wire to power the logic. This is ususally a small wire that goes to the on/off switch. The big wires go to the battery. If you kept the small wire attached to the boost pack, so it always "sees" 48v, the low voltage cutout will stay happy. The big positive wire to the controller could switch between 36v and 48v spots on the battery pack. The power drain of the logic wire is very small compared to the motor, so it won't drain the boost pack much when you're running 36v.

 

[Ypedal]

Bonjour ! Welcome to the forum !

I think you may have reversed the subject line.. you want to run 48v on a 36v controller..?

Don't worry bout the language, we usually figure these things out !

I speak french, but from Atlantic Canada, probably better that we both stick with english ! lol..

 

[xyster]

I think you may have reversed the subject line.. you want to run 48v on a 36v controller..?

Don't worry bout the language, we usually figure these things out !

Sounds from this line, "In that case, how do you manage to use it with only the 36V battery when not boosted ? "
like the subject line is correct and he wishes to run 36V on a 48V controller.

May I just say "Wow!", tifalou -- you write English better than most native speakers here. I can count to five in French, but have no idea the spelling. Uh, deux, twaw, catz, sank.

 

[tifalou]

Hello,
Thank you very much !
Xyster is right : because Goldenmotor sells a 48V controller, I suppose that it means their 36V one does not work well with 48V. So I mean that I want to buy a 48V controller, not to burn the 36V, and run it (the 48V) even with 48V or 36V.
Considering I don't know if it will work, maybe I can keep the 36V too, and switch between one and the other.
Because of your nice welcome, I will not hesitate to place some other questions... in a new post !

 

[xyster]

because Goldenmotor sells a 48V controller, I suppose that it means their 36V one does not work well with 48V.

Not necessarily. Many 36V controllers work fine at 48V too. On some, the difference is only the low-voltage cutoff mark. I have no idea about your specific controller. Perhaps someone else here knows? The voltage ratings of the internal components can provide clues, but the only way to know for sure if a controller sold as 36 volts, will work at 48 volts, is to try it.

I went from 36v to 48v on my scooter, using the same 36v controller; and 24v to 36v on my Currie ebike using the same 24v controller.

Considering I don't know if it will work, maybe I can keep the 36V too, and switch between one and the other.

If you can afford to, it's always good to have an extra controller nearby in case the primary dies.

If you can stand the extra weight and expense, you could buy a fourth battery just like your other three, and wire it in series for full-time 48 volt operation. Then charge that fourth battery with it's own 12 volt charger. Or, charge the entire 4-battery string with a single 48 volt charger. 12 volt chargers are generally much less expensive, and you can also use that 12 volt charger to occasionally balance the other batteries individually, alligator clips connecting leads from the 12 volt charger.

Like this!

 

[tifalou]

Here is the new question, for which I didn't find a solution in France. Maybe here...
Rather than buying a new 12V battery for my 48V controller, it would be nice to use my two 36V batteries.
But 72V (84V full) would be too much for the 48V controller. It seems that 60V is the max it can admit.
I can't find a dc/dc converter with enough power. Is there really no solution ?

 

[tifalou]

xyster, I didn't see your reply before I post the new question.
My battery is a boxed one, I can charge it only with a 36V charger. So if I take 12 extra volts, I will buy a 12V charger for them.

 

[xyster]

Here is the new question, for which I didn't find a solution in France. Maybe here...
Rather than buying a new 12V battery for my 48V controller, it would be nice to use my two 36V batteries.
But 72V (84V full) would be too much for the 48V controller. It seems that 60V is the max it can admit.
I can't find a dc/dc converter with enough power. Is there really no solution ?

I wrote my previous post forgetting you had a lithium pack.

Assuming this is your kit,
http://www.goldenmotor.com/
since it's a brushless hubmotor, it *might* work with a 72 volt crystalyte controller.
DC/DC converters in oddball voltages are expensive, difficult to find, and you'd lose a fair bit of efficiency in the conversion. I'd first try to find out if your brushless motor will work with a common, brushless 72v crystalyte controller (which I'd think would be available in France), like one these 20, 35, or 40 amp 72 volt models:
http://www.poweridestore.com/Brushless-Controllers/Series-500-Controllers

 

[tifalou]

Yes it is the brushless Goldenmotor kit.
According to french forumers, a Crystalyte controller will not work with it, because of the number and position of the hall sensors.
And then, I was looking to a Golden one, because their new controller has a regenerative function, and I have a credit to spend with them.
So, I think I will be limited to 48V...
Never heard of a 12V lithium battery, so I will be obliged to buy a heavy SLA one

 

[Ypedal]

SolarBBQ in Australia spoke of something similar with motor phase timing and hall sensors.... to try and make crystalyte controllers work with GM motors...

I'll try to find the link..

Edit :

http://endless-sphere.com/forums/viewtopic.php?t=957&start=0

 

[xyster]

Never heard of a 12V lithium battery, so I will be obliged to buy a heavy SLA one

Well, a 12 volt SLA isn't really 12 volts either (but for maybe a fraction of its discharge).

There's many 11.1 V and 14.8 volt lithium packs from many different vendors, probably some in France too. Most of these packs have less than your main pack's 15ah capacity. But you could parallel a couple, or use your original plan of a switch or a relay.
http://www.all-battery.com/index.asp?PageAction=VIEWCATS&Category=245

12 volt 10+ ah NiMH packs are also very common, and would work well in series if on a switch or relay.

 

[Mark_A_W]

Brett (solarbbq) adds diodes when putting packs in series.

What are the diodes for? Isolation during charging?

Or preventing one pack from "charging" or reversing the other if they get way out of whack?

 

[pdonahue]

Did you ever figure out where the low voltage cutoff is on the goldenmotor controller?
I just put a 48V battery on my 36V controller and it works find while running (battery dragged down below 48.5V), but triggers the high voltage cutout when you stop (battery > 48.5V).

Pete

 

[pdonahue]

The golden motor 36V controller uses a PIC16F72.

The pins are (as far as I can tell):

1: not MCLR (drag low to reset the processor)
2: ???
3: Measure input voltage for low voltage cutout
4: ???
5: Throttle input
6: Brake input
7: ???
8: GND
9: Oscillator
10: Oscillator
11: ???
12: ???
13: ???
14: ???

15, 16, 17: Hall sensor inputs
18: Green LED
19: GND
20: +5V
21: ???
22: ??? (connected to the LM358 op-amp chip)
23, 24, 25, 26, 27, 28: Outputs to the FET gate drivers.

If anyone has more info please share.

You can ping with an ohmmeter from pin 3 to find the location of the resistor you need to change to affect the low voltage cutoff.

Pete

 

[TylerDurden]

I just put a 48V battery on my 36V controller and it works find while running (battery dragged down below 48.5V), but triggers the high voltage cutout when you stop (battery > 48.5V).

You were riding... or on the test-stand?

:lol:

 

[pdonahue]

Riding... I can watch the battery voltage as I ride on the DrainBrain (now Cycle Analyst).

I ride the bike about 15km to work. I hit about 5 red lights along the way and I have to disconnect the power and wait for the controller to reset at each one. I'm slowly tracking down what each pin on the controller does in the hope that I can either:
- Find a fast way to reset the high voltage cutout.
or
- Find a way to increase the voltage for the high voltage cutout.

Pete

 

[TylerDurden]

some folks hack in to drive the controller with the primary battery only, sending the full pack voltage just to the FETs...

You still gotta watch the LV and cut manually.

:wink: