Converting a 48V controller to 72?

[CGameProgrammer]

Is it possible to convert the Crystalyte 48V controller to a 72V? I know the low-voltage cut-off for the normal 36-72V controller is 29V; does anyone know if it's different for the 48V? I would assume not. Also I notice the 48V capacitors are 100V/220A. Is that too little? And obviously the FETs need to be replaced, but I have twelve 4310s ready for duty.

I actually have a 72V controller as well, but the connections are wrong and it'll take some time/effort getting the correct connectors on, particularly with the Hall Effect sensor cable. I'm not sure which task will be the easiest.

 

[fechter]

4310's should be good.
100v caps are probably OK for 72v, but the ones in my controller are 160v for some reason. Bigger capacitors can't hurt.

If you want to run 72v, the low voltage cutout won't matter much.
You can look at the resistors and possibly tell. The picture shows the resistor that gets bypassed by the voltage selector switch. The one just to the left of it is also part of the divider circuit. Increasing the resistance increases the LVC voltage.

 

[29a]

If i was you i would first fix the 72V controller so you have it to use if anything goes wrong with conversion, (once you open the 36V controller you will see most of the leads are just plug ins so just swap them with the 72V controller)once that is working convert the 36V.
I think the caps are 100V in that, just double them up in series to allow a max voltage of 200V

The cut off voltage is the same (29V for the 36V,48V,72V)
the rest of info is in these threads below

see here
http://endless-sphere.com/forums/viewtopic.php?t=750

and here
http://endless-sphere.com/forums/viewtopic.php?t=232

and here
http://endless-sphere.com/forums/viewtopic.php?t=444

IMHO if u can solder the miniXLR hall plug without damaging the connector you can easily do the controller conversion just takes a lot of time and patience

Good luck

 

[29a]

Fetcher or anyone else,
Is there a formula to get the LVC i want
For my 48V Nicd i am wanting a 44V cutoff how do i calculate the correct size resister

 

[xyster]

IMHO if u can solder the miniXLR hall plug without damaging the connector you can easily do the controller conversion just takes a lot of time and patience

Soldering that damn mini-XLR plug may be a telling prerequisite test prior to opening the controller. I couldn't do it. Frustrated, I finally cut the mini-XLR off and just individually soldered the hall-effect wires together. When the time comes, I'll try to bribe someone else here to upgrade my controller. My fine-hand dexterity is just not that good...so much for being a brain surgeon!

 

[29a]

Soldering that damn mini-XLR plug may be a telling prerequisite test prior to opening the controller. I couldn't do it. Frustrated, I finally cut the mini-XLR off

I cut it off allso
But i did put a mini screw terminal connector in series on the controller end so i could use the same controller with or without the XLRconnector for diferent wheels that don't have the connector.

 

[fechter]

If you look at my picture, the two resistors are labeled 104 and 304, which together is 400K ohms (=29v cutoff).

You'd want somewhere around 600K for a 44v cutoff.

I would suggest replacing the 104 resistor with a 500K or 1 Meg trimmer pot, then you could adjust the trimmer pot to get the desired LVC voltage.

 

[CGameProgrammer]

If i was you i would first fix the 72V controller so you have it to use if anything goes wrong with conversion, (once you open the 36V controller you will see most of the leads are just plug ins so just swap them with the 72V controller)once that is working convert the 36V.

Haha, somehow that never occurred to me. Yes, I can just swap the circuit boards so the 72V guts go into the 48V case, with its correct connectors. The cases and wires themselves are identical.

To fechter: You always seem to emphasize changing the low-voltage cutoff. Why? I'm not aware of 29V ever causing a problem. And if the controller is supposed to handle 36V, why bother making the LVC higher than that?

 

[29a]

I think fechter lets us know how to change the LVC because all the controllers have the same cut off voltage, but the cut off you need (so you don't damage your batts) depends on your voltage used and batt type. In my case Nicd which shouldn't go below 1.1V per cell so in a 36V Nicd batt pack (asuming 30cells) that would need a LVC of 33V.

 

[fechter]

Right, the LVC is put there for a reason. If you have a voltmeter or DrainBrain to keep track of your voltage, the LVC is optional.

I run 48 or 60v, but I never changed the LVC from 29v.

 

[Ypedal]

A 36v nicad pack ( 8ah from ebikes.ca ) will sag under load below 33v with plenty of charge left... 33v would be a tad high.. aim for 31v instead IMO.

 

[29a]

Thanks Ypedal
The 36Vnicd was just an example i actually use 48V Nicd so would i be correct to assume that the LVC for these to be 44V