[18650] Re: BMS Controller
- From: "Edward Ang" <EdAng@xxxxxxxxxxxxxx>
- To: <18650@xxxxxxxxxxxxx>
- Date: Tue, 12 Oct 2004 23:16:55 -0700
I had some success controlling my PFC-30 with a PIC18F258 and a digipot. I
am testing my circuit by paralleling the 10k digipot with the current POT in
the charger. This allows me to control charging current both manually and
also using a RS-232 serial port.
I was having a lot of problem with electrical noise in the charger. First,
I tested everything without any opto's for isolation since the digipot does
provide some type of isolation between the POT and the control circuit. It
did not work out well despite a few days of testing. The electrical noise
affected the charger's current control circuit. The moment I set it to more
than 2A charging current, the control would blow up to full current mode. I
had to isolate the digipot with opto's from the PIC and the MAX232 chip.
This helps to stabilize the charger's current control loop.
However, since I also had to relocate the digipot inside the charger with
close proximity with the existing POT, I am now having some intermittent
problem communicating with the digipot. I sometimes have to send the SPI
commands 2 or 3 times for the digipot to change its value. A quick look at
the scope shows a lot of noise on all SPI lines even though their are all
less about 2 cm long. I have not had success filtering out the noise with
caps and resistors yet.
I have a new scope on order with 2 channels so that I could do a more
detailed investigation. Any suggestions? The current scopemeter I have is
really not adequate for the job.
I am off building more regulators for now.
Ed Ang
AIR Lab
(510)673-7602
> -----Original Message-----
> From: 18650-bounce@xxxxxxxxxxxxx [mailto:18650-bounce@xxxxxxxxxxxxx]On
> Behalf Of Davide Andrea
> Sent: Thursday, October 07, 2004 9:24 AM
> To: 18650@xxxxxxxxxxxxx
> Subject: [18650] Re: BMS Controller
>
>
> I'm buried in work. I'm off to Germany. Please be patient.
> Thanks
> Davide
>
> ----- Original Message -----
> From: "Edward Ang" <EdAng@xxxxxxxxxxxxxx>
> To: <18650@xxxxxxxxxxxxx>
> Sent: Friday, October 01, 2004 6:02 PM
> Subject: [18650] BMS Controller
>
>
> > Davide,
> >
> > I think we missed an important component of our system. On your block
> > diagram, you drew a "Pack V and I Sensor Addr:0" block. But, we do not
> have
> > any details on this module. Are you envision this to be another BMS
> module
> > with special features or are you envision this to be part of the BMS
> > controller function? Or, it is a PIC reading measurement from
> the Emeter?
> >
> > On my side, I have gotten my new PFC-30 charger and a few 10k
> digipots. I
> > am starting to play around with them using a PIC18F258. This PIC has
> USART,
> > SPI, and also CAN that could be used at the same time. We might have to
> use
> > PIC18F458 which also have parallel port features later.
> >
> > For now, I plan to modify my PFC-30 to be RS-232 controlled with the
> > following features:
> > 1) Increase/reduce charging voltage
> > 2) Increase/reduce charging current
> >
> > Future features:
> > 3) Accept calibration data
> > 4) Control charger with several different charging curves
> > 5) Record # of completed charge cycles
> > 6) Decide to use a different curve upon completion of a
> certain number of
> > cycles
> >
> > I have also decided to build a lead acid BMS based on what we
> have so far.
> > Since it is so similar, it would not need a lot of effort. It is like
> > killing 2 birds with one stone. And, current EVs with lead
> acid batteries
> > do need a complete BMS system. There isn't a complete system available.
> > Any LiIon system is not going to be available for at least a
> year or 2 or
> > more. And, EV owners might not decide to switch to LiIon later. This
> would
> > allow us to put more "beta" units out there to fully debug the
> high level
> > control algorithm and GUI.
> >
> > Ed Ang
> > AIR Lab
> > (510)673-7602
> >
> >
> >
>
>
>
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