# [EVDL] Alternator Charge Controller



## EVDL List (Jul 27, 2007)

> martin emde wrote:
> > I'm looking for an easy and efficient way to control/limit the
> > current from an alternator into a battery. I know the alternator has
> > a regulator that limits the voltage to ~14V yet the current output
> ...


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## EVDL List (Jul 27, 2007)

Hello Martin,

This is easy to do with a two wire alternator, which is really a 4 wire 
type. One wire is the 12 V- ground conductor that bolts to the alternator 
housing, one wire is the 12 V+ output, one wire is also a 12 V+ that's 
jumper from the 12 V+ that is plug into the regulator and the last one is 
the ON-OFF control circuit which is call the R-circuit that comes from the 
ignition switch through indicator lamp that also put a set amount of 
resistance that limits the 12 V+ output which is control by regulator.

It is more difficult to do this with the one wire alternators. You have to 
jumper and switch the internal regulator leads around and developed two more 
input terminals.

You will notice that when you turn on the ignition switch only on to the 
ignition on position, a alternator indicator light will come on in some 
cars. At this point the alternator is not turning, but the ignition switch 
is sending the battery voltage through this resistance circuit to the 
internal regulator. A transistor in the regulator switches this 12 volts to 
12 V- at this time and the alternator indicator lights up, showing the 
alternator is not running.

Now when you turn the ignition switch to the start position, the ignition 
switch turns off the R-circuit to the regulator in the alternator and the 
alternator indicator light will now go off. This is done, so when the 
starter is on, we do not want the alternator on at the same time because the 
alternator may have a lower ampere rating then what it takes to start the 
starter.

As the alternator rpm gets up to about 1100 to 1200 rpm which may be only 
350 to 400 engine or motor rpm because most alternators have a pulley ratio 
of about 3 to 1 between the motor drive and alternator.

At about 1100 to 1200 rpm the alternator will excited it self and you see 
the alternator voltage come up higher then the standing voltage of the 12 
volt battery.

Lets say the 12 volt battery is below 80% State of Charge (SOC) which is 
about 12.5 volts at 1.238 SG, the voltage R-circuit is drop below this 
voltage through R-circuit resistance and thus the regulator will ramp up to 
charge the battery.

I have experiment with this R-circuit by installing a 1 to 2 watt rheostat 
in parallel with the alternator indicator circuit. I then could raise the 
charge voltage from 13.3 to 16 volts as require. The resistance is set at 
about 10 ohms for about 14.8 volts. I normally using a large 12 volt deep 
cycle battery that I can allow it to discharge it to about 70% SOC before 
the alternator starts to charge it.

I use a single pole three position rocker switch on this R-circuit where I 
can either select the manual control resistance circuit or select the normal 
operation or turn the R-circuit off completely so the alternator is just 
free wheeling with no output.

Today I using a Delco 6 wire commercial alternator that is design to use 
with a DC-DC-DC-AC inverter which both controls the 12 volt output to any 
voltage you want and at the same time provides 120 VAC 60 hz 6KW which is 
use for my heaters and pumps.

You can test out this R-wire circuit by bench testing a alternator which is 
turn by a electric motor. Install the standard 12 volt and amp auto meters. 
Instead of turning a starter with a selector switch to duplicated the 
ignition switch, just use a start indicator light and some 12 volt load 
which will cause the battery voltage to drop. t As you come back to the 
ignition on position, you could have that also light up a ignition 
indicator. Also test the voltage indicators on the R-circuit before and 
after the R-circuit resistance.

Roland








----- Original Message ----- 
From: "martin emde" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, March 15, 2009 1:23 PM
Subject: [EVDL] Alternator Charge Controller


> Greetings,
>
> I'm looking for an easy and efficient way to control/limit the current 
> from
> an alternator into a battery. I know the alternator has a regulator that
> limits the voltage to ~14V yet the current output seems only limited by 
> the
> load impedance up to the max output current rating of the alternator. Are
> there any off-the-shelf charge controllers or DC/DC converters that will
> allow me to "dial-in" (maybe via a pot) the amount of current delivered to
> the load? I have two applications. The first is to use an alternator to
> 'regeneratively' charge an auxiliary battery in an EV. The second is a
> stationary bicycle power plant for my classroom (so that students with
> excess energy can generate power).
> Thanks for any help you can provide.
>
> Martin
>
> www.seaburyhall.org/engineering
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> 

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## EVDL List (Jul 27, 2007)

Lee,
Thanks for the help. Actually it's on the bike setup that I need the
current to be regulated just for the reason you mentioned. If the load
(battery) is drawing too much current then it's impossible to pedal. I
would like to charge the battery at 10 amps or less so that the kids don't
burn out too fast. I would like for them to pedal for maybe 10 to 20
minutes at a time to slowly charge a couple of deep cycle marine batteries
that I may connect to a small ( 500 watt) inverter and then ultimately power
some of the loads in the classroom. Yes it does make for a good experiment
to demonstrate how much power is required for some of our everyday
electrical appliances including lights. As for as the regen idea I'm not
too concerned with the current limit as I'll only energize it when there is
adequate kinetic energy available.

I'll do a bit more research and try to understand your idea of modifying the
built in regulator to to be able to variably decrease the output voltage.
BTW it's a two-wire (bat and field) Bosch alternator (from an old VW Golf)
with what I think is an externally mounted regulator. I'll have to
disassemble and take a closer look. I also plan to program a PIC with LCD
to monitor and display voltage, amps, power (watts and hp), energy, rpm,
etc.

Martin

www.seaburyhall.org/engineering



> > The second is a stationary bicycle power plant for my classroom (so
> > that students with excess energy can generate power).
>
> That's a good example. It makes is clear just how much work it takes to
> generate the electricity to run a TV or computer.
>
> The alternator won't need any form of current limiting. It just gets
> harder to pedal as it generates more current. It will limit itself
> (becomes impossible to pedal too fast).
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in -- Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
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>
>
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## EVDL List (Jul 27, 2007)

Using alternators with small (3 to 8 HP) engines coupled with an amperage
and voltage controller (instead of only voltage like a standard car voltage
regulator) was a common thing for winter backup with the smaller off-grid PV
systems in the past. They've kind of fallen out of favor as people have
bought bigger and more extravagant houses, but Backwoodssolar still sells
the basic rheostat controller for it (has to be an alternator with a
separate field excitation terminal, not the one wire ones with the internal
regulator). Home Power also had several articles on how to build your own
electronic controller for it that would let you dial in the current and max
voltage independently -- I can't find the article on the web anywhere, but I
believe it is the Mark 8 controller, in issue 42 for the most recent
version. Also useful for microhydropower, and bicycles, and other input
horsepower limited applications.

Z



> martin emde <[email protected]> wrote:
> 
> > Lee,
> > Thanks for the help. Actually it's on the bike setup that I need the
> ...


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## EVDL List (Jul 27, 2007)

> martin emde wrote:
> > Lee,
> > Thanks for the help. Actually it's on the bike setup that I need the
> > current to be regulated just for the reason you mentioned. If the load
> ...


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## EVDL List (Jul 27, 2007)

Martin
For my bicycle generator I use a permanent mag motor. Its a salvaged 
radiator fan motor (the biggest one I could find). I don't use any regulation since 
the load will be nil until the motor rpm causes it to generate more than the 
battery voltage. I can easily get above 10A but because of mechanical losses 
I cant hold it there for very long. I can use the gearset to regulate pedal 
speed and effort. I normally can draw off some power with 12V lights when I am 
doing a sprint. Remember to use an appropriately rated Diode to prevent the 
battery from spinning the motor.
Rick




In a message dated 3/15/2009 3:26:59 P.M. Central Daylight Time, 
[email protected] writes:
Greetings,

I'm looking for an easy and efficient way to control/limit the current from
an alternator into a battery. I know the alternator has a regulator that
limits the voltage to ~14V yet the current output seems only limited by the
load impedance up to the max output current rating of the alternator. Are
there any off-the-shelf charge controllers or DC/DC converters that will
allow me to "dial-in" (maybe via a pot) the amount of current delivered to
the load? I have two applications. The first is to use an alternator to
'regeneratively' charge an auxiliary battery in an EV. The second is a
stationary bicycle power plant for my classroom (so that students with
excess energy can generate power).
Thanks for any help you can provide.

Martin

www.seaburyhall.org/engineering
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