Battery cable selection

"oilsardine" wrote in message
...
not sooo fast, Mr.L'ectrzity!

supposed this guy got some bargain instuments (or radios, or starter or
whatever else) BUT these are 24 volt units then you could come to this
conclusion to join two batteries. In this case you will have half of the
current flow compared to a 12V system. So you can use half the cross
section of your cabling. Basic electics.

That is not in dispute.

Look back to my answer. I said to use the same size as the main cable. It
(the jumper) would see the same amperage.

If the main cable is sized to carry the 24 volt load, it would indeed be
half the amps of the same 12 volt system.

The jumper would need to be the same size as the properly sized main cable.

THAT is basic "electics."
--
Jim in NC

wrote:

I am putting two 12V batteries together
http://www.batterymart.com/p-hawker-...t-battery.html
to make a 24V battery.

What size cable should I use to make the serial connection?

Longer the cable, bigger the cable...
connect two batteries with a 1"cable: a 6AWG cable will work

flat copper bar will be better (less losses):
http://www.aircraftspruce.com/catalo...ges/busbar.php

by
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬
** Posted from http://www.teranews.com **

"Philippe" wrote in message
news:1770438.ul5SB0L1ai@GastonCoute...
wrote:

I am putting two 12V batteries together
http://www.batterymart.com/p-hawker-...t-battery.html
to make a 24V battery.

What size cable should I use to make the serial connection?

Longer the cable, bigger the cable...
connect two batteries with a 1"cable: a 6AWG cable will work

flat copper bar will be better (less losses):
http://www.aircraftspruce.com/catalo...ges/busbar.php

by
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬
** Posted from http://www.teranews.com **

A copper bar would indeed work much better than a short cable. If you plan
to join two standard aircraft batteries sharing the same battery box, a
well-fitted copper bar is easier to install than a cable.

You can make a bar by flattening a short section of 1/2" thick-wall copper
tubing (as used for refrigeration lines) in a vise and drilling two 5/16"
holes the correct distance apart (about two inches I think, but you should
measure). Coat it with grease each time it's installed or it will corrode
rapidly.

Beech Barons use a similar copper bar, tin-plated as I recall. You could
buy one.

Dale Scroggins wrote:

"Philippe" wrote in message
news:1770438.ul5SB0L1ai@GastonCoute...
wrote:

I am putting two 12V batteries together
http://www.batterymart.com/p-hawker-...t-battery.html
to make a 24V battery.

What size cable should I use to make the serial connection?

Longer the cable, bigger the cable...
connect two batteries with a 1"cable: a 6AWG cable will work

flat copper bar will be better (less losses):
http://www.aircraftspruce.com/catalo...ges/busbar.php

by
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬
** Posted from http://www.teranews.com **

A copper bar would indeed work much better than a short cable. If you
plan to join two standard aircraft batteries sharing the same battery
box, a well-fitted copper bar is easier to install than a cable.

You can make a bar by flattening a short section of 1/2" thick-wall
copper tubing (as used for refrigeration lines) in a vise and drilling
two 5/16" holes the correct distance apart (about two inches I think,
but you should measure). Coat it with grease each time it's installed
or it will corrode rapidly.

Beech Barons use a similar copper bar, tin-plated as I recall. You
could buy one.




The truly energetic could tin the bar with solder or, wait for it, tin.

Dan, U.S. Air Force, retired

Gee, this discussion became convoluted. Your maximum draw on the circuit
would be when starting. Your battery may be rated in peak starting amps
capacity. One of the advantages of 24 volts over 12 is the ability to
use smaller diameter wires (weight savings). So, using the same diameter
for interconnection as was used for the 12 primary connection is
overkill. Low of mentioning of twice the voltage then half the wire
diameter...but I thought it was 1/4, but I am not an EE and it has a
loooong time since I have played with those calculations.{no, I don't
want to do the calculations right now! ;-) }

wrote:

I am putting two 12V batteries together
http://www.batterymart.com/p-hawker-...t-battery.html
to make a 24V battery.

What size cable should I use to make the serial connection?
http://shop.genuinedealz.com/Marine%...ttery%20Cable/

Thanks,
Karl

Bruce A. Frank wrote:
Gee, this discussion became convoluted. Your maximum draw on the circuit
would be when starting. Your battery may be rated in peak starting amps
capacity. One of the advantages of 24 volts over 12 is the ability to
use smaller diameter wires (weight savings). So, using the same diameter
for interconnection as was used for the 12 primary connection is
overkill. Low of mentioning of twice the voltage then half the wire
diameter...but I thought it was 1/4, but I am not an EE and it has a
loooong time since I have played with those calculations.{no, I don't
want to do the calculations right now! ;-) }


I don't blame you. Such calculations require higher levels math where
one leaves off counting on one's fingers and starts using one's toes.
This is called "algebra." Now, if one wants to use calculus...well,
calculus is found on one's teeth.

Dan, U.S. Air Force, retired

Or you can simply go to www.rstengineering.com and then to Jim's Engineering
page and then open up the spreadsheet "wiretable.xls", put in the wire size
and length that you want and let the magic of rather complex algebra (for
the temperature rise) be invisible in the answers.

Jim
I *am* an EE and I play one at the college every day {;-)



but I thought it was 1/4, but I am not an EE and it has a
loooong time since I have played with those calculations.{no, I don't
want to do the calculations right now! ;-) }

Bruce A. Frank wrote:

Gee, this discussion became convoluted. Your maximum draw on the
circuit would be when starting. Your battery may be rated in peak
starting amps capacity. One of the advantages of 24 volts over 12 is
the ability to use smaller diameter wires (weight savings). So, using
the same diameter for interconnection as was used for the 12 primary
connection is overkill. Low of mentioning of twice the voltage then
half the wire diameter...but I thought it was 1/4, but I am not an EE
and it has a loooong time since I have played with those
calculations.{no, I don't want to do the calculations right now! ;-) }

battery is heavier... are you sure you gain weight?

For wi section would be 1/2 as the amperage, diameter would be reduce
by 0,707.


--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬
** Posted from http://www.teranews.com **