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Here's another thought, more geared towards the gentleman in .eu who was looking at running a bunch of 2 volt batteries in series, and home charging it.




I have done this in the past, and although it isn't the best method, since your going to use 2 volt batteries, you can still accomplish this and stay within the realm of 16 volts.


Take 2 of those 2 volt batteries and run them in series, creating 1X 4 volt cell.

Connect that in series, neg from the new bank to + on the car battery, and run your amp from the + side of the new battery bank. From vehicle ground to amplifier B+, you will see app 16 volts.

Now, the trick is here...


Take ONLY the B+ out from the ALTERNATOR (I always disconnect the vehicle CHARGE lead at the alternator, then run a dedicated lead from the alt to the battery stack), and connect it as well to the top of the battery stack (to the 16 volt side).

Since the cars electronics will all still see 12 volts, and the alternator will have to produce 18 volts to charge the 16 volt system, everything charges nicely.

I also think it is best to take and run a relay / solenoid setup to disconnect the extra 4 volt stack when not being used, to prevent overcharging. Usually 10 to 45 minutes of charging while driving around is sufficient. Just use a solenoid to disconnect the B+ from the alt to the top of the 16 volt stack to the + / - junction of the 12 and 4 volt batteries.

This works well in systems where you can't install a second alternator. Your car works fine, the amp works fine, everything charges nicely, BUT, you don't get something for nothing. Your alternator is usually running > manuf ratings, and you won't see rated Aout at 18 volts.... Expect about 20 percent less... Or even less efficiency. Still, makes it easy to run increased collector voltage cheaply.


--Toll_Free

That's an interstuing approch, thanks. I was not aware of the fact that a 12 V (or 14.4 Volt) alternator would supply 16 or even 18 VDC when connect to a 16 or 18 V battery stack.

In mmy case battery capacity is no issue, there is plenty of space to even fit 8 two volt cells. The point is the absolute lack of space for a second or larger frame alternator.

On second thought is might be an option to use an 18 V battery stack (with the stock alternator connected to the +18 VDC of the stack) and use a 18 => 12 V DC DC 30 amp converter to supply the needed charging current to the starter battery and the car electrical system.

Cheers, Dick
PA3DUV

On Thu, 11 Jan 2007 08:18:54 -0800, PA3DUV <pa3duv@...> wrote:

That's an interstuing approch, thanks. I was not aware of the fact that
a 12
V (or 14.4 Volt) alternator would supply 16 or even 18 VDC when connect
to a
16 or 18 V battery stack.

It only works because for the "sense" lead to see the "14.4" volts it
needs to, the alternator has to put out 18 volts... It has to make up
that 4 volt pad... It's the location of the sense lead and automotive
electronics that make this method work.

In mmy case battery capacity is no issue, there is plenty of space to even
fit 8 two volt cells. The point is the absolute lack of space for a
second
or larger frame alternator.

I'd go with the method your looking at, or another one we did in the
keydown circuit was a 12 volt and an 6 volt battery. Works just like
before, just more Vcc.

On second thought is might be an option to use an 18 V battery stack
(with
the stock alternator connected to the +18 VDC of the stack) and use a 18
=>
12 V DC DC 30 amp converter to supply the needed charging current to the
starter battery and the car electrical system.

If you do the 18 volt stack, using 12 and 6 volt batteries, you could pull
from the 12 volt side, use a steering diode (large current, stud mount) to
charge another 12 volt battery just for the car electric system. That
would give you isolation, and a psuedo dedicated circuit for your amp as
well.


--Toll_Free