Leece neviille 4800 series j mount ?

[scottpeterd]

I have to say I've been very happy with the Sterling regulator. I'm using the PDAR with the 555, and I'm very satisfied with the results.  A lot cheaper than the Balmar.

As to the current sensor, have you seen the Pololu 30A sensor ( http://www.hacktronics.com/Sensors/Current-Sensor-30-Amp/flypage.tpl.html ?  It may be too small for your application, but they work very well with Arduino's and other pico-boards.

Pete

[vwbeamer]

I have see the pololu 30amp sensor.  I'm using an arduinio clone that is made to be inbedded, The ardunio is a great device, easy to program and work with.

I have to say I've been very happy with the Sterling regulator. I'm using the PDAR with the 555, and I'm very satisfied with the results.  A lot cheaper than the Balmar.

As to the current sensor, have you seen the Pololu 30A sensor ( http://www.hacktronics.com/Sensors/Current-Sensor-30-Amp/flypage.tpl.html ?  It may be too small for your application, but they work very well with Arduino's and other pico-boards.

Pete

[Mad_Labs]

If you are using a uC to control the RPM, why not just make your own field controller? Then it can behave however you like. That's what I do, mine can read volts, output amps and battery temp.. I am working on a new one that will also keep track of fuel volume consumed. I will eventually add rpm control as well, but that is more complex than field control and adds a new dimension to the field controller.

Jonathan

[Ronmar]

Ronmar,

That begs a question. The Balmar max charge has the ability to regulate the field of 2 alternators with separate fields and a 10 amp per field PWM . Why not use 1 for the alt and 2 for the throttle solenoid? As the field increases the rpm also increases, use time delay for short term transients that the battery can  handle.

Lloyd

Well I would guess that the controller you are talking about probably applies those 2 PWM channels based on feedback from 2 separate alternators.  IE, if it ups the duty cycle on alternator 1, it is expecting to increase or maintain the voltage output of alternator 1.  That might be usefull, but for engine control, I think you would need some voltage feedback from the engine that the controller could respond to and manage RPM... 

[vwbeamer]

I thought about it, but I'm not sure exactly how they limit voltage and current, kinda new to power generation. I get that they are PWM the excitation current, not sure how you can control voltage and current independently.

Can you help ?

If you are using a uC to control the RPM, why not just make your own field controller? Then it can behave however you like. That's what I do, mine can read volts, output amps and battery temp.. I am working on a new one that will also keep track of fuel volume consumed. I will eventually add rpm control as well, but that is more complex than field control and adds a new dimension to the field controller.

Jonathan

[Lloyd]

Ronmar,

That begs a question. The Balmar max charge has the ability to regulate the field of 2 alternators with separate fields and a 10 amp per field PWM . Why not use 1 for the alt and 2 for the throttle solenoid? As the field increases the rpm also increases, use time delay for short term transients that the battery can  handle.

Lloyd

Well I would guess that the controller you are talking about probably applies those 2 PWM channels based on feedback from 2 separate alternators.  IE, if it ups the duty cycle on alternator 1, it is expecting to increase or maintain the voltage output of alternator 1.  That might be usefull, but for engine control, I think you would need some voltage feedback from the engine that the controller could respond to and manage RPM... 

The Balmar unit use batter sensey to determine the voltage on the field. It a three stage charge bulk, asorb, float, in bulk the field is running between 75 and 85% on each channel. The idea is the one regulator controls 2 alternators on one engine. That being the case each field is powered the same so if one is connected to the alt and the other to a PWM acuator, as the battery sense request to increase the field on alt one, it would also increase the the field on channel 2 which if connected to the PWM throttle actuator then it would increase the speed.

The Balmer is rated at 10 amps per channel, and most PWM actuators are rated at 8 amps. I was just having a thought...don't know if it would work.

Lloyd

[Ronmar]

That is an interesting idea Lloyd.  For that matter, PW is PW and you could use a single channel charge controller.  A sensor looking at the field drive of an alternator could sense the duty cycle of the PWM driving the alternator and could drive a throttle servo that actuates the engine governed speed control lever.  A PWM servo may even be an off the shelf item, but there would be no delay between throttle and field control, so the linkage to the servo would have to be setup so the engine power curve is always ahead of the alternator load.  But you might be able to make it span a larger RPM range more easilly like the honda EU sets do, from high idle to full rpm based on load...  You might have difficulty configuring it for short transient loads, unless you can program a delay into the controller...  Interesting idea...

VW, you basically control amperage with voltage and I guess vis versa.  When charging a battery, the greater the alternator voltage in relation to the battery voltage, the greater the current flow into the battery.  So a typical auto alternator control looks at the battery voltage and adjusts the field to deliver a particular output voltage at the battery.  If the battery is discharged, it's voltage will be low and the controller will boost output to deliver the current necessary to maintain it's regulated voltage.  As the battery becomes charged, this becomes easier and easier for the alternator to accomplish so the field decreases as state of charge increases, untill the alternator is delivering just a trickle of current to maintain it's commanded voltage and float the battery at full charge.  Switch on the headlights the alternator sees the voltage drop from the applied load and boosts field and current output to maintain voltage.  The extra current this delivers powers the load while still floating the battery at full charge...  The electrical system dosn't monitor current, but it delivers varying ammounts of it to maintain a set voltage. 

A controller that senses current could vary the voltage output of the alternator to deliver a particular current. 

A programmable controller basically has several voltages it can switch between depending upon the need.  A high voltage to bulk charge a really dead battery and get the charge process started.  A slightly lower voltage for absorption charging which delivers current for the middle/majority of a charge cycle at a more efficient and less harmfull level for the battery. Once the battery approaches full charge, then it switches to a lower regulated voltage for floating the cells at full charge.  This is known as 3 stage charging.  There are other methods as well. A fancy controller may also have a very high voltage for cell equalization and mixing the electrolyte...

[Mad_Labs]

Beamer,

So, that alt has a field coil. The harder you drive the field coil, the more the alt puts out. I drive the field coil with the uC's PWM and a NPN Darlignton transistor. So the uC reads the amps and the volts and in my case the battery temp. In my case, the uC drives the field coil until A: I reach 14.4 volts or B: the current from the alt is more than 150 amps.  Once it reaches 14.4V it lowers the PWM on the field coil, maintaining 14.4 volts, until my current drops below 20 amps. Then it shuts itself off. So, if you can control RPM (much trickier than alt output) you can easily make your own charge controller.

HTH,

Jonathan

[Mad_Labs]

I realized I didn't quite answer your question, how do control BOTH volts and amps.

Actually, you can't control them seperately, they are ALWAYS tied together. Let's take a battery at 50% charge for an example. You start the engine and engage the alt. The controller/alt will try to raise the voltage to 14.4V. But it can't because the battery is so discharged. So the controller runs the alt as hard as it can, or if a smart controller, as hard as is safe for the alt. The alt continues to dump as much as it can and the battery voltage starts to rise. When it reaches 14.4V, the controller starts to back off the PWM on the field coil and the amps start to drop. When the amps drop low enough (how low depends on the size of the battery bank) the charge is complete. In my case with my controller, it then politely shuts the engine off. 

So, amps and volts are always inextricably tied together and adjusting the field coil PWM duty controls both at the same time.

HTH and doesn't make it more confusing. 

Jonathan

[BruceM]

Interesting project, Jonathan.  You might be at liberty to get even better fuel efficiency by tailoring your controller software to match your power usage- such as no point in starting the engine for a tiny load and battery fully charged.  Perhaps a basic state of charge calculation would help do that, and isn't too tough if you know amps in, amps out, and adjust for Peukert effect and your batteries relative charge efficiency at various state of charge.  I do this for my 120V battery bank but it's all fixed point, table look up, specific for my Walmart/Johnson Controls 110AH marine batteries.

Wet lead acid batteries are more like 50-60% efficient in charge acceptance for the last 10% of charge, though of course for long life you'd like to keep them fully charged most of the time. This is based on pretty reliable Sandia Labs data which I posted here before.  It's a design conflict that has to be worked out depending on your application and usage pattern.  Topping off the batteries at least once a day might be a good compromise.  AGM's should have less of this effect, and Lithium batteries likely the best regarding this effect.  Both AGM and Lithium batteries cost compared to wet lead acid rules them out for many practical applications.

BobG has posted some efficiency strategy ideas for off grid generator charging of wet lead batteries which I thought were promising, too.

Best Wishes,
Bruce

[vwbeamer]

Thnaks, that helps. 

I realized I didn't quite answer your question, how do control BOTH volts and amps.

Actually, you can't control them seperately, they are ALWAYS tied together. Let's take a battery at 50% charge for an example. You start the engine and engage the alt. The controller/alt will try to raise the voltage to 14.4V. But it can't because the battery is so discharged. So the controller runs the alt as hard as it can, or if a smart controller, as hard as is safe for the alt. The alt continues to dump as much as it can and the battery voltage starts to rise. When it reaches 14.4V, the controller starts to back off the PWM on the field coil and the amps start to drop. When the amps drop low enough (how low depends on the size of the battery bank) the charge is complete. In my case with my controller, it then politely shuts the engine off. 

So, amps and volts are always inextricably tied together and adjusting the field coil PWM duty controls both at the same time.

HTH and doesn't make it more confusing. 

Jonathan

[vwbeamer]

Thanks to all

That is an interesting idea Lloyd.  For that matter, PW is PW and you could use a single channel charge controller.  A sensor looking at the field drive of an alternator could sense the duty cycle of the PWM driving the alternator and could drive a throttle servo that actuates the engine governed speed control lever.  A PWM servo may even be an off the shelf item, but there would be no delay between throttle and field control, so the linkage to the servo would have to be setup so the engine power curve is always ahead of the alternator load.  But you might be able to make it span a larger RPM range more easilly like the honda EU sets do, from high idle to full rpm based on load...  You might have difficulty configuring it for short transient loads, unless you can program a delay into the controller...  Interesting idea...

VW, you basically control amperage with voltage and I guess vis versa.  When charging a battery, the greater the alternator voltage in relation to the battery voltage, the greater the current flow into the battery.  So a typical auto alternator control looks at the battery voltage and adjusts the field to deliver a particular output voltage at the battery.  If the battery is discharged, it's voltage will be low and the controller will boost output to deliver the current necessary to maintain it's regulated voltage.  As the battery becomes charged, this becomes easier and easier for the alternator to accomplish so the field decreases as state of charge increases, untill the alternator is delivering just a trickle of current to maintain it's commanded voltage and float the battery at full charge.  Switch on the headlights the alternator sees the voltage drop from the applied load and boosts field and current output to maintain voltage.  The extra current this delivers powers the load while still floating the battery at full charge...  The electrical system dosn't monitor current, but it delivers varying ammounts of it to maintain a set voltage. 

A controller that senses current could vary the voltage output of the alternator to deliver a particular current. 

A programmable controller basically has several voltages it can switch between depending upon the need.  A high voltage to bulk charge a really dead battery and get the charge process started.  A slightly lower voltage for absorption charging which delivers current for the middle/majority of a charge cycle at a more efficient and less harmfull level for the battery. Once the battery approaches full charge, then it switches to a lower regulated voltage for floating the cells at full charge.  This is known as 3 stage charging.  There are other methods as well. A fancy controller may also have a very high voltage for cell equalization and mixing the electrolyte...

[mobile_bob]

it took me a long time to figure out how to control both amps and volts with a controller
balmar does it in a fashion as do others

from what i have learned from them, this is what i have in mind for a custom built controller

i would sense both current and voltage, current going from the alternator to the battery
and by extension the load, and voltage at the battery.

then i would set the microcontroller to upon startup do the following

1. give me a delay before energizing the field, 60 seconds or so, programmable of course so it could be anything

2. ramp up slowly the field current, while monitoring the current leaving the alternator to the battery/load, ramp it up to whatever i program the amps to max out at
this might be limited by size of battery bank, or the max i want to load the alternator or both.  while also monitoring the voltage as a second control handle, making sure the voltage stays below my maximum setpoint for whatever part of the charging i have in place (bulk, absorption or float)

3. have the micro periodically recalculate the voltage/amps etc to reset max amperage and voltage, based on what inputs are reading and also what my code lookup table parameters might be.

4. complete bulk, move to absorption, and finally float

5. have the capability to switch to a manual equalization, or a programmed equalization.

i think we can do both volts and amps, although it is difficult to do charging a battery, it is easier to do when the system is also providing power to a load.

bob g

[Lloyd]

reays in a can.

if anybody is interested.

http://www.kussmaul.com/control%20relays%20index.html

lloyd