On Sunday, September 13, 2020 at 6:15:55 AM UTC-7, legg wrote:
> On Sat, 12 Sep 2020 20:05:52 -0700 (PDT), Edward Lee
> <edward....@gmail.com> wrote:
>
> >On Saturday, September 12, 2020 at 7:55:21 PM UTC-7, legg wrote:
> >> On Sat, 12 Sep 2020 18:43:18 -0700 (PDT), Edward Lee
> >> <edward....@gmail.com> wrote:
> >>
> >> >On Saturday, September 12, 2020 at 4:56:26 PM UTC-7, legg wrote:
> >> >> On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
> >> >> <edward....@gmail.com> wrote:
> >> >>
> >> >> >On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
> >> >> >> On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
> >> >> >> > On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
> >> >> >> > > On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
> >> >> >> > > <edward....@gmail.com> wrote:
> >> >> >> > > >I can't figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:
> >> >> >> > > >
> >> >> >> > > >> For isolated application, the feedback divider has to be secondary side only
> >> >> >> > > >> and a TL431 used for error amp, into an opto, in the usual way.
> >> >> >> > > >
> >> >> >> > > >I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7
> >> >> >> > > >
> >> >> >> > > >https://www.onsemi.com/pub/Collateral/TL431-D.PDF
> >> >> >> > > >
> >> >> >> > > >I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
> >> >> >> > > Seeing as how you're using this circuit for balancing (which it
> >> >> >> > > doesn't actually do - it's just overcharge limiting), you might
> >> >> >> > > be interested in the 'non-digital', 'non-comparator' balance
> >> >> >> > > method used here -
> >> >> >> > >
> >> >> >> > > http://ve3ute.ca/query/balance_analog_001.zip
> >> >> >> > >
> >> >> >> > Yes, that's pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
> >> >> >> The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.
> >> >> >
> >> >> >Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.
> >> >> Op amp is your choice.
> >> >>
> >> >> LT6000
> >> >> LT6001
> >> >> LT1672
> >> >> LT1494
> >> >> AD8657
> >> >> AD8659
> >> >> LT6023
> >> >>
> >> >> These have Iq of as low as 1.6uA, and run on voltages
> >> >> as high as 36V.
> >> >>
> >> >> The balance circuit, itself, is never meant to see
> >> >> 2 x cell voltages.
> >> >>
> >> >> Run the simulation.
> >> >>
> >> >> RL.
> >> >
> >> >OK, thanks. The LT17s and LT60s sound good, but a bit pricey. Is the circuit your own design, or pull from somewhere? Just wondering if there is pattern or copyright issue for production.
> >> This circuit is developed from conventional rail splitter
> >> balancing circuits by me in the refurb of a set of Owon
> >> oscilloscope batteries on my bench - these were not balanced
> >> as supplied, where failing cells produced early loss of
> >> capacity.
> >>
> >> The natural deadband is a 'defect' of any linear voltage
> >> follower, and is used to advantage here.
> >>
> >> The circuit, as published and maintained on VE3UTE service,
> >> is in the public domain. Note that the .plt file will not
> >> plot in LTspice installations that do not support unicode
> >> text. The OP amp used there has an Iq ~50uA, similar to
> >> TSX631 parts actually used in my battery refurbs.
> >>
> >> You will need to breadboard and test any circuit that you
> >> use in this or similar applications. Familiarity with the
> >> effect of gain, offsets, tolerances and noise should be
> >> examined. Ground plane layout is advisable.
> >>
> >> All measurements attempted on high-z nodes require care
> >> to take loading effects into account - best to avoid them
> >> where possible - there are plenty of low-z nodes or ~0V
> >> branches that are less succeptible to measurement error.
> >> It's slow DC, but scope it anyways to avoid surprises.
> >>
> >> Note that some of the ICs listeded are reverse polarity
> >> protected up to ~18V by their spec sheet. In applications
> >> where cells may be removed or inserted in a string, or
> >> where fault interruptors may function, the single-fault
> >> abnormal conditions must be examined carefully.
> >>
> >> A battery is always live and ready to screw you around.
> >> R5 is there for a reason - silicon shorts on a battery are
> >> no fun.
> >>
> >> RL
> >
> >OK, thanks. I'll quote you for credit. My version is almost identical, except for the opamp feedback. I just use open loop for now.
> >
> >You don't have to warn me about batteries. I already burn my fingers and BMS boards many time doing prototype.
> Open loop won't give you a uA drain window, around
> the balance condition..
>
> RL
Yes, this and the heavy duty lm358 is killing my batteries. I owe you the "legg resistor".