Questions and answers about the remote control panel.
Joe Smalley
4/26/2002

These are excepts from email traffic regarding interfacing to the remote control port.
 
> There are some things that are not necessary to make it work. The meter is
> easily deleted. The warning lights are easily deleted. Making a single
> current control and a single voltage control is easy to do also.
> 
> > Am I correct in concluding that to equalize, I would first need to run a
> > regular cycle and only after that cycle has completed then switch to the
> > higher voltage/lower current and then run the equalize phase?
> 
> Correct.
> 
> > In order to equalize, you had previously said that the regs need to be
> > turned off via a dip switch on the front panel - is this controllable
> > via the remote somehow? Or since I don't have regs (yet) may not be an
> > issue?
> 
> No. That was not included. It should be included but it wasn't. That was an
> oversight on my part.
> 
> > It would appear that I could use a multi-position switch and extra 10K
> > pots to have other current set points? I'm thinking of 3 cases:
> > "high"=regular charge from dedicated 20A outlet, "medium"=regular charge
> > from small/shared outlet (say 10A 120V available), and "low"=equalize
> > charge.
> 
> Good choices.
> 
> > It appears that the *output* current is what is controlled, so that as
> > the pack voltage rises during the bulk charge, the total power consumed
> > will increase?
> 
> Actually, it controls the current at the lower voltage. If you are charging a
> 240 volt pack from 110, it will control the input. If you are charging a 120
> volt pack from 240 it controls the output. The power peaks when the line
> voltage equals the pack voltage. The power goes down on either side of this
> peak.
> 
> > Is there some way to instead set the *input* current
> > limit?
> 
> This requires another $40 current sensor and would raise the price of the
> charger $125. We are considering doing this on the PFC50 but have not
> committed to it yet.
> 
> > This would make it easier to set to match a given AC outlet - of
> > course this would be more of a constant power than constant current
> > mode, but would get every available drop of power out of the outlet
> > during the entire bulk phase.
> 
> Concur. You can get almost anything you want if you are willing to pay for
> it.
> 
> > "You may use digipots, trim pots or control pots to control it."
> > What is the difference between these? Are these just all names for a
> > multi-turn pot?
> 
> Digipots are digital potentiometers that come in two types: push button and
> rotary.
> Trim pots the little ones you turn with a jewelers screwdriver.
> Control pots are the ones that take a knob like the volume control on old
> radios.
> They all can be single or multi turn types.
> 
> > On sheet 3, U3a shows pin 11 of the LM324 going to ground, but U3b shows
> > pin 11 going to MINUS 15? (It appears that 7.5V, 2.5V, and 0V references
> > are needed, but as I'm not good with op-amps I can't figure out how this
> > circuit is supposed to work)
> 
> There are two LM324 quad op amps in the circuit. U1 goes from ground to +15
> and U3 goes from -15 to +15.
> 
> U3B is a voltage follower that generates a local ground that is unaffected
> by voltage drops in the wires between the remote and the charger. This way,
> the remote can be run on small gauge wire without a large ground conductor.
> 
> > On sheet 2, U1b/c/d turn on the respective LED's when the signal goes
> > above 2.5 Volts, but... what do the different colors indicate? From the
> > directions on the web site, blue is the timer, and red & yellow somehow
> > are current limit, voltage limit, and error warnings?
> 
> This is from the short version of the instructions.
> 
> Green LED (Power indicator)
> OFF- Charger has no power or is turned off.
> ON- Charger is plugged in and turned on.
> 
> Yellow LED (Cutback indicator)
> OFF- The charger is current limited either by the control knob or the
> internal current limit (AKA bulk stage)
> BLINKING- Charger is in thermal cutback. Cooler air will make more power
> (AKA bulk stage)
> ON- Charger is in voltage cutback (AKA acceptance stage)
> 
> Blue LED (timer function)
> OFF- Timer is not running (timer criteria not met)
> BLINKING- Timer is running (timer criteria met but not timed out)
> ON- Timer has timed out and the charger is in stand by mode.
> 
> Red LED (fault condition)
> OFF- Charger is operating properly.
> BLINKING- Output fuse is blown or charger is disconnected from battery
> ON- ambient temperature is over 170F
> 
> > How is the value for R7 calculated? I assume there is some formula based
> > on the full scale current of the meter used?
> 
> R7= (5 volts-meter full scale voltage)/(meter full scale current)
> 
> > On sheet 1, U1a shows pin 11 of the LM324 going to MINUS 15, but sheet 2
> > had U1b/c/d with pin 11 going to ground? Maybe the op-amps should be
> > grouped differently for the power supplies to work out right?
> 
> Good catch. When I automatically reannotated the schematic it swapped U1A
> and U3A. They need to be swapped back.
> 
> > For the voltage set points, how does the temperature compensation come
> > in? I think you said the charger uses one BatReg as a temperature
> > sensor even if I'm not using a full set of regs. Do I just need to set
> > the voltage correctly for the battery temperature at the time of the
> > setting?
> 
> Correct.
> 
> > The PLUS 15 power supply is well filtered (sheet 3); does the MINUS 15
> > supply need any filter caps?
> 
> Another good catch. Use the same caps as the Plus 15.
> 
> > Are the resistors just ordinary 10% 1/4W types?
> 
> They would work but I would use 5% 1/8 watt resistors.
> 
> > Does the "small wire" cable from the remote to the PFC20 need to be
> > shielded, twisted pair, or anything else special?
> 
> I have not built one yet. It should have 600 volt insulation from bundle to
> exterior since there will be 120 VAC plus pack volt on the conductors
> relative to ground.
> 
> > What type of connector is used for the remote to plug into the PFC20?
> > (The picture on the web site shows an RJ45 (??) for the BatRegs but I
> > didn't see a port for the remote)
> 
> The connector is a single row 10 pin Molex vertical header located about 4
> inches behind the Regbus connector.
> 
> > How crucial is the component layout and assembly? Is it likely to work
> > with basic wire wrap and hand solder techniques?
> 
> It should work fine. There is no AC signal present. It just needs to be
> insulated from the outside world since any voltage error or noise will be
> amplified 100x through the charger.