External alternator regulator for 56 VDC output.

I am interested in charging four 12 volt batteries in series with an
engine driven automotive alternator.

A 12Volt ~100 Amp alternator should be able to give 20 amps or so at 56
volts.

Before I build one, does anyone know if they are manufactured?

If, not, a circuit diagram would be appreciated.


Has anyone outthere built a regulator for other than 12 vdc?
Thanks,

BoyntonStu

 

[Tony Williams]

In article <1105927514.769070.217400@f14g2000cwb.googlegroups.com>,
<stu@aaronj.com> wrote:

I am interested in charging four 12 volt batteries in series with
an engine driven automotive alternator.

If you are doing the mechanics yourself had you
thought of driving four smaller alternators off
the one shaft, and charging each battery separately.

Simpler and far more flexible than shoving the same
charging current down a stack of batteries (whatever
the state of each one).

A 56V battery pack is also a serious arc welder if
ever you have an accidental short.

--
Tony Williams.

 

Actually, many alternators will provide much higher voltages without
much in the way of modifications. This is because they are designed to
have a relatively high output at idling RPMs. At higher engine speeds,
the rotor input voltage is switched at a relatively low duty factor,
although some types of alternators also use inductance to limit the
increase in output voltage. Since output frequency is proportional to
RPMs, series inductance represents a rising inductance that can be used
to counteract rising output.
That said, I agree with the posters who argued against charging so many
cells in series.
Paul Mathews

 

[Ken Smith]

In article <v8GdnZGVhfIS2HHcRVn-tA@buckeye-express.com>,
Mark Jones <abuse@127.0.0.1> wrote:
[...]

Charging 4 12V lead-acid batteries in series is not a good idea.
Invariably this will lead to charge imbalance and one or more
batteries are going to die. Why not just charge all four seperately or
in parallel with barrier diodes? Should be enough room for a 2nd
alternator under the hood.

How about this:

If you build a voltage multiplier, every second tap has a capacitor to
ground. These points could be wired to the batteries to be charged. The
battery with the lowest voltage would get more current and thus the
balancing between batteries would happen with no extra work.

--
--
kensmith@rahul.net forging knowledge

 

[Sylvan Butler]

On Mon, 17 Jan 2005 18:09:03 -0500, Mark Jones <abuse@127.0.0.1> wrote:

Charging 4 12V lead-acid batteries in series is not a good idea.

It is if you have a 48v battery bank.

Invariably this will lead to charge imbalance and one or more
batteries are going to die.

That is why they invented an "equalizing" charge.

Why not just charge all four seperately or
in parallel with barrier diodes? Should be enough room for a 2nd

Barrier diodes, eh? I'd put those in series with my 250amp breaker
then?

sdb
--
Wanted: Omnibook 800 & accessories, cheap, working or not
sdbuse1 on mailhost bigfoot.com

 

[budgie]

On Mon, 17 Jan 2005 16:33:43 -0700, Sylvan Butler
<ZsdbUse1+noZs_0501@Zbigfoot.Zcom.invalid> wrote:

On Mon, 17 Jan 2005 18:09:03 -0500, Mark Jones <abuse@127.0.0.1> wrote:
Charging 4 12V lead-acid batteries in series is not a good idea.

It is if you have a 48v battery bank.

I would dispute that. It may well be the *most_logical*, or *simplest*,
approach - but there are sound arguments for not doing it.

Invariably this will lead to charge imbalance and one or more
batteries are going to die.

That is why they invented an "equalizing" charge.

Which unfortunately doesn't happen with simple automotive style regulators which
are really aimed at CV charging only.

Whwn you have a 400+ volt stack of 2V cells in a UPS, anything othert than
series charging is a nonsense. The result is a need to pay special attention to
equalisation. At 4x 12V I would look at charging them with four separate
chargers. If this needs to be fossil-fuel-driven, then I'd be contemplating an
AC output device to feed consumer market chargers x4.

Why not just charge all four seperately or
in parallel with barrier diodes? Should be enough room for a 2nd

Barrier diodes, eh? I'd put those in series with my 250amp breaker
then?

He lost me on that one too.

 

[Winfield Hill]

Mark Jones wrote...

Don't think they make big diodes? Check this out:
http://www.irf.com/product-info/datasheets/data/sd8500c-r.pdf

Yes, with a forward-voltage-drop tempco crossover at 25kA,
where it drops only 1.35V, indicating an ideal diode drop
plus 0.2V/25kA = 8 micro-ohms of internal resistance, and
a power dissipation of 34kW, which it can handle for one
pulse lasting for five milliseconds, raising the junction
temp from 25 to 200C, judging from the Thermal Impedance
Characteristic curves, IICC. Ahem.


--
Thanks,
- Win