Electrical Engineering - battery wiring

Author

battery wiring

weebray@gmail.com

2008-02-09, 9:25 am

I am fitting an electric windlass on my Prout catamaran. I have
located a battery forward to be close to the windlass. The system is
a house bank and a starter battery separated by a battery isolator.
Power being supplied by the engine [30amp] alternator as well as 150
watts of solar. My plan is to use #8 awg wire from the battery
isolator starter battery terminal to the remote windlass battery (25
ft. away) and #6 awg for the short run from the battery to the
windlass (1000watts). I just realized that this may be a problem
because the starter and windlass batteries will try to equalize and
the #8 wire may not be of sufficient size. How do I deal with this
possible problem if there is one?

Tim Perry

2008-02-09, 9:25 am

<weebray@gmail.com> wrote in message
news:83cd63de-9ffb-45af-9baf-636bb2d873e6@e25g2000prg.googlegroups.com...
> I am fitting an electric windlass on my Prout catamaran. I have
> located a battery forward to be close to the windlass. The system is
> a house bank and a starter battery separated by a battery isolator.
> Power being supplied by the engine [30amp] alternator as well as 150
> watts of solar. My plan is to use #8 awg wire from the battery
> isolator starter battery terminal to the remote windlass battery (25
> ft. away) and #6 awg for the short run from the battery to the
> windlass (1000watts). I just realized that this may be a problem
> because the starter and windlass batteries will try to equalize and
> the #8 wire may not be of sufficient size. How do I deal with this
> possible problem if there is one?

If wired correctly a DBI (dual battery isolater) will prevent the batteries
from 'trying to equalize'.

A DBI unit is pretty rugged but like anything man makes it can sometimes
fail. Add a fuse or resetable breaker near the battery terminal. This will
provide some protection in case the wires get accidently pinched or shorted.

bobelon

2008-02-10, 9:25 am

On Feb 9, 10:00=A0am, "Tim Perry" <timpe...@nospammeadelphia.net> wrote:
> <weeb...@gmail.com> wrote in message
>
> news:83cd63de-9ffb-45af-9baf-636bb2d873e6@e25g2000prg.googlegroups.com...
>
>
> If wired correctly a DBI (dual battery isolater) will prevent the batterie=
s
> from 'trying to equalize'.
>
> A DBI unit is pretty rugged but like anything man makes it can sometimes
> fail. Add a fuse or resetable breaker near the battery terminal. This will=

> provide some protection in case the wires get accidently pinched or shorte=
d.

As set up the DBI splits the charge to the house bank on one side and
the starter battery and windlass battery on the other side. The
possible problem is these two are located 25 feet apart and connected
by an 8awg wire.

Palindrome

2008-02-10, 9:25 am

bobelon wrote:
> On Feb 9, 10:00 am, "Tim Perry" <timpe...@nospammeadelphia.net> wrote:
>
> As set up the DBI splits the charge to the house bank on one side and
> the starter battery and windlass battery on the other side. The
> possible problem is these two are located 25 feet apart and connected
> by an 8awg wire.

I'm assuming 12v..

If a "DBI" is what I would call a "split charge unit", that will prevent
the starter battery )or "house bank" powering the line to the windlass
battery. The maximum current that could flow under normal conditions
would be around 30A from the alternator. 8 gauge is around 0.6mohm per
ft - so 25ft at 30A is going to drop around 0.5v. Personally, I'd wire
it with something thicker, as those 15W come expensive in solar panels
and the OP may want to recharge the windlass battery faster or use shore
power to recharge it.. Whatever cable size is used, it should have a
thermal trip in circuit rated to protect the cable, just in case of fault.

The wire to the windlass is another matter. Rated at 1000W and 12v - its
stall current, should the anchor snag, could be several hundred amps.
Plus, a replacement windlass, one day, may be even thirstier.

Personally, if it were my boat, I'd be looking to run a really, really
heavy cable forward, so that, in an emergency, I could power the
windlass from the "house bank" and/or from the starter battery, in
addition to the windlass battery, if I fitted one. The engine will
usually already be running when the windlass is in use - so can be left
running until the starter battery has recovered. I hate losing anchors
(and cable) and have spent hours recovering one. A 1kW motor will
discharge a 100AH battery in a very few tens of minutes. The only thing
to be wary of is that the windlass motor probably has an intermittent
use rating - not much point melting the thing.. I'd rather spend the
money on a really heavy cable running the length of the hull than on a
windlass battery..

--
Sue

Tim Perry

2008-02-10, 1:25 pm

"bobelon" <ebobbyray@gmail.com> wrote in message
news:7a8960c7-f68e-46b0-adc0-df58143249d1@s37g2000prg.googlegroups.com...
On Feb 9, 10:00 am, "Tim Perry" <timpe...@nospammeadelphia.net> wrote:
> <weeb...@gmail.com> wrote in message
>
> news:83cd63de-9ffb-45af-9baf-636bb2d873e6@e25g2000prg.googlegroups.com...
>
>
> If wired correctly a DBI (dual battery isolater) will prevent the
batteries
> from 'trying to equalize'.
>
> A DBI unit is pretty rugged but like anything man makes it can sometimes
> fail. Add a fuse or resetable breaker near the battery terminal. This will
> provide some protection in case the wires get accidently pinched or
shorted.

As set up the DBI splits the charge to the house bank on one side and
the starter battery and windlass battery on the other side. The
possible problem is these two are located 25 feet apart and connected
by an 8awg wire.

Another reason for thicker wire is termianl corrosion. Bigger wires just
last longer in harsh conditions.

Assuming a solar panal that 'trickle charges' the battery at an amp or so
under bright sunlight I wouldnt think a large wire is indicated for that...
however: the sad fact is batterys go bad, often enough when you least want
them to be bad.
I guess the windlass has an "armstrong' backup system but being able to
quickly jump batterys is a big plus in my book. you may even want to use
that battery to start the engine sometime.

Are you familier with the 4 position dual battery switch? if not search for
'marine battery switch'.

phil-news-nospam@ipal.net

2008-02-10, 1:25 pm

On Sun, 10 Feb 2008 11:32:51 -0500 Tim Perry <timperry@nospammeadelphia.net> wrote:

| Another reason for thicker wire is termianl corrosion. Bigger wires just
| last longer in harsh conditions.

Is that due to the larger contact area of the terminal? If so, why not
large stranded wire (e.g. where the strands themselves are at least 14 AWG)
fan out into multiple individual contact points? Or if not that, then at
least taper the bundle of strands and have decreasing widths in a longer
terminal to make better overall contact.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2008-02-10-1234@ipal.net |
|------------------------------------/-------------------------------------|

Palindrome

2008-02-10, 1:25 pm

phil-news-nospam@ipal.net wrote:
> On Sun, 10 Feb 2008 11:32:51 -0500 Tim Perry <timperry@nospammeadelphia.net> wrote:
>
> | Another reason for thicker wire is termianl corrosion. Bigger wires just
> | last longer in harsh conditions.
>
> Is that due to the larger contact area of the terminal? If so, why not
> large stranded wire (e.g. where the strands themselves are at least 14 AWG)
> fan out into multiple individual contact points? Or if not that, then at
> least taper the bundle of strands and have decreasing widths in a longer
> terminal to make better overall contact.
>
There are so many mechanisms at work, eg surface corrosion, crevice
corrosion, akin effect, vibration, work-hardening, etc, etc, etc.

However, I'd suggest that the most important thing is to use a terminal
designed for the cable being used, or vice versa.

This particular application is "only" a few hundred amps. It gets more
interesting once another zero or two is added..

--
Sue

Stuart

2008-02-10, 5:25 pm

In article <47af27e9$0$4939$4c368faf@roadrunner.com>,
Tim Perry <timperry@nospammeadelphia.net> wrote:
> Another reason for thicker wire is termianl corrosion. Bigger wires just
> last longer in harsh conditions.

I presume you coat everything well with petroleum jelly or something
similar.

--
Stuart Winsor

From is valid but subject to change without notice if it gets spammed.

For Barn dances and folk evenings in the Coventry and Warwickshire area
See: http://www.barndance.org.uk

phil-news-nospam@ipal.net

2008-02-10, 5:25 pm

On Sun, 10 Feb 2008 18:54:58 GMT Palindrome <me9@privacy.net> wrote:
| phil-news-nospam@ipal.net wrote:
|> On Sun, 10 Feb 2008 11:32:51 -0500 Tim Perry <timperry@nospammeadelphia.net> wrote:
|>
|> | Another reason for thicker wire is termianl corrosion. Bigger wires just
|> | last longer in harsh conditions.
|>
|> Is that due to the larger contact area of the terminal? If so, why not
|> large stranded wire (e.g. where the strands themselves are at least 14 AWG)
|> fan out into multiple individual contact points? Or if not that, then at
|> least taper the bundle of strands and have decreasing widths in a longer
|> terminal to make better overall contact.
|>
| There are so many mechanisms at work, eg surface corrosion, crevice
| corrosion, akin effect, vibration, work-hardening, etc, etc, etc.
|
| However, I'd suggest that the most important thing is to use a terminal
| designed for the cable being used, or vice versa.
|
| This particular application is "only" a few hundred amps. It gets more
| interesting once another zero or two is added..

What I have seen in applications of several hundred or more amps is multiple
wires and very large terminal blocks with multiple lugs. But those are
wires that stay separate all the way. The following I recall was 4200 amps
at 416 or 480 volts (based on the colors):

http://phil.ipal.org/usenet/aee/200...rator-wires.jpg

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2008-02-10-1607@ipal.net |
|------------------------------------/-------------------------------------|

bobelon

2008-02-11, 9:25 am

On Feb 10, 6:40=A0pm, phil-news-nos...@ipal.net wrote:
> On Sun, 10 Feb 2008 18:54:58 GMT Palindrome <m...@privacy.net> wrote:| phi=
l-news-nos...@ipal.net wrote:
>
> |> On Sun, 10 Feb 2008 11:32:51 -0500 Tim Perry <timpe...@nospammeadelphia=
..net> wrote:
> |>
> |> | Another reason for thicker wire is termianl corrosion. Bigger wires j=
ust
> |> | last longer in harsh conditions.
> |>
> |> Is that due to the larger contact area of the terminal? =A0If so, why n=
ot
> |> large stranded wire (e.g. where the strands themselves are at least 14 =
AWG)
> |> fan out into multiple individual contact points? =A0Or if not that, the=
n at
> |> least taper the bundle of strands and have decreasing widths in a longe=
r
> |> terminal to make better overall contact.
> |>
> | There are so many mechanisms at work, eg surface corrosion, crevice
> | corrosion, akin effect, vibration, work-hardening, etc, etc, etc.
> |
> | However, I'd suggest that the most important thing is to use a terminal
> | designed for the cable being used, or vice versa.
> |
> | This particular application is "only" a few hundred amps. It gets more
> | interesting once another zero or two is added..
>
> What I have seen in applications of several hundred or more amps is multip=
le
> wires and very large terminal blocks with multiple lugs. =A0But those are
> wires that stay separate all the way. =A0The following I recall was 4200 a=
mps
> at 416 or 480 volts (based on the colors):
>
> http://phil.ipal.org/usenet/aee/200...rator-wires.jpg
>
> --
> |---------------------------------------/---------------------------------=
-=AD|
> | Phil Howard KA9WGN (ka9wgn.ham.org) =A0/ =A0Do not send to the address b=
elow |
> | first name lower case at ipal.net =A0 / =A0spamtrap-2008-02-10-1...@ipal=
..net |
> |------------------------------------/------------------------------------=
-=AD|

Point taken. Looks like bigger is better Will wire accordingly. BR

Tim Perry

2008-02-11, 1:25 pm

"Stuart" <SW_NOSPAM@dsl.pipex.com> wrote in message
news:4f6f16ea4aSW_NOSPAM@dsl.pipex.com...
> In article <47af27e9$0$4939$4c368faf@roadrunner.com>,
> Tim Perry <timperry@nospammeadelphia.net> wrote:
>
> I presume you coat everything well with petroleum jelly or something
> similar.
>
> --
> Stuart Winsor
>

Pic of corrosion http://focus.noegruts.com/battery/battery.htm

The red stuff that the Interstate Battery pros use seems to work best for
me.

Having spent several years at one point doing 2-way mobile service I feel I
have gained some insight on problems involved in attaching wire to
care/marine batteries.

My suggestion: use the largest practical connector that will fit on the
terminal lug.
Crimp and solder the connection (depending on type of connector). On
occasion I have brazed larger conductors with copper phosphorous.
Replenish the corrosion preventive goo annually (more or less depending on
local conditions)
Secure wire in such a manner as to minimize the effects of vibration.
The mass of large inline fuse and holder assembly can vibrate the connection
apart over time, especially when the connection point is weakened by
corrosion. Secure it in some manner such as tape, wire ties, or clamps.

Stuart

2008-02-11, 5:25 pm

In article <47b09992$0$8655$4c368faf@roadrunner.com>,
Tim Perry <timperry@nospammeadelphia.net> wrote:
> Pic of corrosion http://focus.noegruts.com/battery/battery.htm

Strewth! Never have I seen anything /that/ bad

--
Stuart Winsor

From is valid but subject to change without notice if it gets spammed.

For Barn dances and folk evenings in the Coventry and Warwickshire area
See: http://www.barndance.org.uk

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