Dropping the LVC on a Crystalyte 7240 12-fet controller

[ryan]

I just heard back from Dave at ElectricRider.com about the LVC (low voltage cutoff) for the Crystalyte 7240 12-fet controller...

LVC for any controller should be a dead SLA, which is 10.2V times the number of cells, so 61.2V for a 72V controller.

I need to modify the LVC to closer to 36V. Can you help, or point me to a thread that can help?

I'm trying to allow two 36v20ah (5c) headways to be configured as series or parallel using the same controller.

Thanks!

 

[ryan]

The kind folks at ebikes.ca have this to say:

While the controllers can be ordered with these cutoff voltages hard-wired on the circuit board, it can lead to a needless confusion and incompatibility. Therefore, we have had the hard-wired low voltage cutoff on all of our Crystalyte controllers set to 19V (or 29V in the case of the v2 48A digital controllers), and then provided the option with the Direct Plug-in Cycle Analyst to set any custom value for a higher LVC in software. This gives maximum flexibility and allows you to re-program a new cutoff voltage tailored exactly to your battery pack with just a few button presses.

via http://www.ebikes.ca/store/store_controllers.php

So I know it's possible. (and I already have a note out to them to see if they still have their documentation for this mod)

 

[Kburn77]

Hey Ryan, there is absolutely no reason to need to be able to switch between series and parallel, you have the same power available in both scenarios, the only thing you would accomplish is reducing the watts and you could just as well reduce the amps with a throttle control in series configuration. Currently the cycle analyst isn't wired to cut-off the controller but it could be if you want to control amps, speed, and cut-off voltage.

 

[Affliction]

I just heard back from Dave at ElectricRider.com about the LVC (low voltage cutoff) for the Crystalyte 7240 12-fet controller...

LVC for any controller should be a dead SLA, which is 10.2V times the number of cells, so 61.2V for a 72V controller.

I need to modify the LVC to closer to 36V. Can you help, or point me to a thread that can help?

I'm trying to allow two 36v20ah (5c) headways to be configured as series or parallel using the same controller.

Thanks!

Why is this not allready set at 19 volts? I havn't seen a Chrystalite controller in quite a while with a higher lvc than 19 volts.
If it's got the plugin for the cycle analist then it's got to be allready at 19 volts.
Get a direct plugin cycle analist to control your lvc. Why the need for series/parrallel?
As said there really isn't a point or any gain from series/parralel swiching. If you want to limit your power output just let the cycle analist do it.
To keep your hub at 1000 watts at 72 volts just set your amp limit to 14 amps. You can limit the top speed as well.
With the setup you describe you should be in the range of 50mph top speed

 

[dogman dan]

Ryan's planning on a set of 36v 20 ah batteries, so he may not want to carry both at all times. Sometimes he'll need the power of 72v, and sometimes he'll only need 36v 20 ah.

If you plan on carrying one or both batteries on the trailer, mabye you could mount the 72v controller on the trailer, and have a second, much cheaper 48v controller on the bike.

Or, take a small loss on the controller, and sell it. Then buy one from Ebikes, or another source that has the lower lvc.

But, if you trailer all that battery, you might just be a happy camper all the time with 72v 20 ah. It's just carrying all that on the bike frame that I would have a problem with.