I am ready to install new batteries. I have not found a reference for wire
size - between - batteries. I have six T105 six volt batteries. What size
wire should be used to series and parallel them? The boat has 2/0 with a
250amp fuse running to the battery selector switch. I am not sure how much
my started draws (Perkins 4-108) but I would like to size to start from
either the starting or house batteries or both. One more thing that does not
look right is that the Neg wire on the starting battery is size one or two
connected to the house bank Neg only. Shouldn't there be a jumbo size wire
directly to the engine block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

bushman wrote:
I am ready to install new batteries. I have not found a reference for wire
size - between - batteries. I have six T105 six volt batteries. What size
wire should be used to series and parallel them? The boat has 2/0 with a
250amp fuse running to the battery selector switch. I am not sure how much
my started draws (Perkins 4-108) but I would like to size to start from
either the starting or house batteries or both. One more thing that does not
look right is that the Neg wire on the starting battery is size one or two
connected to the house bank Neg only. Shouldn't there be a jumbo size wire
directly to the engine block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen



Hello Allen,

You could take the view that the interconnecting wires should be able to
handle either the maximum, short-circuit current of any of the
batteries, or the current rating of the main fuse, whichever is smaller.
There's a logic to that approach.

If the runs are on the order of just a few feet, I would say that 2/0
wire satisfies the rule nicely. You want your fuse to go before your
wires or your batteries.

Engine starting batteries are typically grounded directly to the engine
block near the starter as you indicated. But if the system you have has
been working OK, there's really no need to change it. I'd visit the
starting wiring only if you are having trouble starting in very cold
weather, etc.

Good luck,

Chuck

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Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form
damaging current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank on
a #2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of time
and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:
I am ready to install new batteries. I have not found a reference for wire
size - between - batteries. I have six T105 six volt batteries. What size
wire should be used to series and parallel them? The boat has 2/0 with a
250amp fuse running to the battery selector switch. I am not sure how much
my started draws (Perkins 4-108) but I would like to size to start from
either the starting or house batteries or both. One more thing that does not
look right is that the Neg wire on the starting battery is size one or two
connected to the house bank Neg only. Shouldn't there be a jumbo size wire
directly to the engine block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

Thanks Chuck and Matt
I think I am OK with the size wire from the batteries to the boat or engine
but what is the load on the wire that joins the two 6 volt batteries in a
pair in series? I have three pairs joined in parallel so I'm guessing that
each pair would have one third my max load and the wires joining them would
need to be sized for accordingly. I generally like to go a size larger. You
never know when I might get stranded somewhere and can sell the copper off
to get me to the next island. The 250 amp fuse on the starting battery has
never blown. The Perkins generally fires on the first revolution but one
time I lost prime and had to crank for half a minute or more at a time and
the fuse held.
- Allen

"witheld" wrote in message
...
Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form damaging
current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank on a
#2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of time
and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:
I am ready to install new batteries. I have not found a reference for
wire size - between - batteries. I have six T105 six volt batteries. What
size wire should be used to series and parallel them? The boat has 2/0
with a 250amp fuse running to the battery selector switch. I am not sure
how much my started draws (Perkins 4-108) but I would like to size to
start from either the starting or house batteries or both. One more thing
that does not look right is that the Neg wire on the starting battery is
size one or two connected to the house bank Neg only. Shouldn't there be
a jumbo size wire directly to the engine block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

Allen,
The strap between the two 6volt batteries should be the same as the
cable on both ends. More is no value(except as a cash reserve?) and
less is probably not much of and issue except as voltage drop. It will
be in -relatively- open air and if it gets hot enough to smoke it should
get your attention before it causes real trouble.

The fact that you are successful with three parallel pairs is quite
remarkable. The stacks (pairs) should not be counted on to share load
equally. It is actually very hard to make batteries do that.

I am surprized that a 250amp fuse will crank a 4-108. It must be a
better starter than the one I measured. Take good care of it.

Fair Wind and Smooth Sea
Matt Colie

bushman wrote:
Thanks Chuck and Matt
I think I am OK with the size wire from the batteries to the boat or engine
but what is the load on the wire that joins the two 6 volt batteries in a
pair in series? I have three pairs joined in parallel so I'm guessing that
each pair would have one third my max load and the wires joining them would
need to be sized for accordingly. I generally like to go a size larger. You
never know when I might get stranded somewhere and can sell the copper off
to get me to the next island. The 250 amp fuse on the starting battery has
never blown. The Perkins generally fires on the first revolution but one
time I lost prime and had to crank for half a minute or more at a time and
the fuse held.
- Allen

"witheld" wrote in message
...

Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form damaging
current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank on a
#2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of time
and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:

I am ready to install new batteries. I have not found a reference for
wire size - between - batteries. I have six T105 six volt batteries. What
size wire should be used to series and parallel them? The boat has 2/0
with a 250amp fuse running to the battery selector switch. I am not sure
how much my started draws (Perkins 4-108) but I would like to size to
start from either the starting or house batteries or both. One more thing
that does not look right is that the Neg wire on the starting battery is
size one or two connected to the house bank Neg only. Shouldn't there be
a jumbo size wire directly to the engine block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

Thanks again Matt
I will upgrade wire and fuse with the new starting battery and take it off
the battery selector switch. That will shorten the run from 10 feet to less
than 3. I think I will buy 2 more 6 volts and have second house bank on the
selector switch. I will leave the wire from the switch to the starter in
place with a disconnect so that I can still crank from the house bank if
needed.

Looks like we will miss our Christmas Day sailing this year. We have made it
a tradition to go for a sail each year. However this year we are working.
- Allen

"Matt Colie" wrote in message
...
Allen,
The strap between the two 6volt batteries should be the same as the cable
on both ends. More is no value(except as a cash reserve?) and less is
probably not much of and issue except as voltage drop. It will be
in -relatively- open air and if it gets hot enough to smoke it should get
your attention before it causes real trouble.

The fact that you are successful with three parallel pairs is quite
remarkable. The stacks (pairs) should not be counted on to share load
equally. It is actually very hard to make batteries do that.

I am surprized that a 250amp fuse will crank a 4-108. It must be a better
starter than the one I measured. Take good care of it.

Fair Wind and Smooth Sea
Matt Colie

bushman wrote:
Thanks Chuck and Matt
I think I am OK with the size wire from the batteries to the boat or
engine
but what is the load on the wire that joins the two 6 volt batteries in a
pair in series? I have three pairs joined in parallel so I'm guessing
that
each pair would have one third my max load and the wires joining them
would
need to be sized for accordingly. I generally like to go a size larger.
You
never know when I might get stranded somewhere and can sell the copper
off
to get me to the next island. The 250 amp fuse on the starting battery
has
never blown. The Perkins generally fires on the first revolution but one
time I lost prime and had to crank for half a minute or more at a time
and
the fuse held.
- Allen

"witheld" wrote in message
...

Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form
damaging current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank on
a #2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of time
and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:

I am ready to install new batteries. I have not found a reference for
wire size - between - batteries. I have six T105 six volt batteries.
What size wire should be used to series and parallel them? The boat has
2/0 with a 250amp fuse running to the battery selector switch. I am not
sure how much my started draws (Perkins 4-108) but I would like to size
to start from either the starting or house batteries or both. One more
thing that does not look right is that the Neg wire on the starting
battery is size one or two connected to the house bank Neg only.
Shouldn't there be a jumbo size wire directly to the engine block at the
starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

Allen,

It sounds like your plan is:
Have a dedicated starting battery,
have two banks of house battery on a selector switch and
an available cross-connect from house to start.

If I have that right, you have a good plan.
The cross connect switch should be the kind of Bosch switch you can take
the key out of and never close (but it is nice to know it is there).

Do you have a plan to charge all three banks?

I bet you can figure out how to push off and go out for at least a
little while.

We often use to sail Christmas Day. Even along the upper east coast, it
wa seldom too cold to sail and way too early to be frozen. I am on the
Great lakes now and the boats come out in October (fresh water freezes
too easily).

Where are You?

Matt


bushman wrote:
Thanks again Matt
I will upgrade wire and fuse with the new starting battery and take it off
the battery selector switch. That will shorten the run from 10 feet to less
than 3. I think I will buy 2 more 6 volts and have second house bank on the
selector switch. I will leave the wire from the switch to the starter in
place with a disconnect so that I can still crank from the house bank if
needed.

Looks like we will miss our Christmas Day sailing this year. We have made it
a tradition to go for a sail each year. However this year we are working.
- Allen

"Matt Colie" wrote in message
...

Allen,
The strap between the two 6volt batteries should be the same as the cable
on both ends. More is no value(except as a cash reserve?) and less is
probably not much of and issue except as voltage drop. It will be
in -relatively- open air and if it gets hot enough to smoke it should get
your attention before it causes real trouble.

The fact that you are successful with three parallel pairs is quite
remarkable. The stacks (pairs) should not be counted on to share load
equally. It is actually very hard to make batteries do that.

I am surprized that a 250amp fuse will crank a 4-108. It must be a better
starter than the one I measured. Take good care of it.

Fair Wind and Smooth Sea
Matt Colie

bushman wrote:

Thanks Chuck and Matt
I think I am OK with the size wire from the batteries to the boat or
engine
but what is the load on the wire that joins the two 6 volt batteries in a
pair in series? I have three pairs joined in parallel so I'm guessing
that
each pair would have one third my max load and the wires joining them
would
need to be sized for accordingly. I generally like to go a size larger.
You
never know when I might get stranded somewhere and can sell the copper
off
to get me to the next island. The 250 amp fuse on the starting battery
has
never blown. The Perkins generally fires on the first revolution but one
time I lost prime and had to crank for half a minute or more at a time
and
the fuse held.
- Allen

"witheld" wrote in message
...


Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form
damaging current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank on
a #2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of time
and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:


I am ready to install new batteries. I have not found a reference for
wire size - between - batteries. I have six T105 six volt batteries.
What size wire should be used to series and parallel them? The boat has
2/0 with a 250amp fuse running to the battery selector switch. I am not
sure how much my started draws (Perkins 4-108) but I would like to size
to start from either the starting or house batteries or both. One more
thing that does not look right is that the Neg wire on the starting
battery is size one or two connected to the house bank Neg only.
Shouldn't there be a jumbo size wire directly to the engine block at the
starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

Yes that describes what I have in mind. I like that switch. I have a
xantrex?? 40 charger that will do 3 banks. I am not sure how the solar is
wired but it needs improving. I left the switch on the starting battery and
it killed it in 24 hours. Solar charges it when on the house. I believe I
have some current flowing with all the breakers off. This is just going to
take time to get it all mapped out.
As for Christmas sailing. I just finished 48 hours at work and Jackie is
doing 16. No big loss as we seem to see bad things on Christmas day. Dead
manatee, Fuel Spill, Sunk boat, Dead newborn dolphin with mother holding
its head up out of the water, Uncle got sick and had D-day flashback when a
stinky diesel went by. He spent 6 hours circling in a small landing craft in
diesel smog. He said he was so happy to get on the beach?????
Oh I did find a reference to fuse size for the starter from Casey. He says
to match the fuse to the wire size, looks like 0000 with a 400amp fuse. (if
I remember right.)
Thanks again - Allen


"Matt Colie" wrote in message
...
Allen,

It sounds like your plan is:
Have a dedicated starting battery,
have two banks of house battery on a selector switch and
an available cross-connect from house to start.

If I have that right, you have a good plan.
The cross connect switch should be the kind of Bosch switch you can take
the key out of and never close (but it is nice to know it is there).

Do you have a plan to charge all three banks?

I bet you can figure out how to push off and go out for at least a little
while.

We often use to sail Christmas Day. Even along the upper east coast, it
wa seldom too cold to sail and way too early to be frozen. I am on the
Great lakes now and the boats come out in October (fresh water freezes too
easily).

Where are You?

Matt


bushman wrote:
Thanks again Matt
I will upgrade wire and fuse with the new starting battery and take it
off the battery selector switch. That will shorten the run from 10 feet
to less than 3. I think I will buy 2 more 6 volts and have second house
bank on the selector switch. I will leave the wire from the switch to the
starter in place with a disconnect so that I can still crank from the
house bank if needed.

Looks like we will miss our Christmas Day sailing this year. We have made
it a tradition to go for a sail each year. However this year we are
working.
- Allen

"Matt Colie" wrote in message
...

Allen,
The strap between the two 6volt batteries should be the same as the cable
on both ends. More is no value(except as a cash reserve?) and less is
probably not much of and issue except as voltage drop. It will be
in -relatively- open air and if it gets hot enough to smoke it should get
your attention before it causes real trouble.

The fact that you are successful with three parallel pairs is quite
remarkable. The stacks (pairs) should not be counted on to share load
equally. It is actually very hard to make batteries do that.

I am surprized that a 250amp fuse will crank a 4-108. It must be a
better starter than the one I measured. Take good care of it.

Fair Wind and Smooth Sea
Matt Colie

bushman wrote:

Thanks Chuck and Matt
I think I am OK with the size wire from the batteries to the boat or
engine
but what is the load on the wire that joins the two 6 volt batteries in
a
pair in series? I have three pairs joined in parallel so I'm guessing
that
each pair would have one third my max load and the wires joining them
would
need to be sized for accordingly. I generally like to go a size larger.
You
never know when I might get stranded somewhere and can sell the copper
off
to get me to the next island. The 250 amp fuse on the starting battery
has
never blown. The Perkins generally fires on the first revolution but one
time I lost prime and had to crank for half a minute or more at a time
and
the fuse held.
- Allen

"witheld" wrote in message
...


Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form
damaging current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank
on a #2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of
time and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the
world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:


I am ready to install new batteries. I have not found a reference for
wire size - between - batteries. I have six T105 six volt batteries.
What size wire should be used to series and parallel them? The boat
has 2/0 with a 250amp fuse running to the battery selector switch. I
am not sure how much my started draws (Perkins 4-108) but I would like
to size to start from either the starting or house batteries or both.
One more thing that does not look right is that the Neg wire on the
starting battery is size one or two connected to the house bank Neg
only. Shouldn't there be a jumbo size wire directly to the engine
block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen

Allen,
Well, at least it sounds like you missed the Christmas sail for a good
cause.

It sounds like you have a good shore charger.

If by left the start battery switched on, you mean the engine power was
left on, I am surprised that the engine support killed the start battery
.. The engine instruments should not draw that much power.

If you think you have a drain with all breakers open, I suggest you
locate it.
Expensive way - pull a battery terminal from a battery in the active
bank and put a millammeter in line. If it shows current when there
should be none, start detaching things until it goes away. Watch out
for automatic bilge pumps - if one switches on while the meter is inline
, it may smoke the meter.
Cheap way - come up with a small light bulb that you can clip into the
circuit. It will no give you a value, but if it lights, start
disconnecting things until it goes out.

A solar panel needs to have a charge isolator (a set of diodes) to keep
one bank from ble3eding back into the others. This device might be in
place if the alternator is charging three banks. If you have the
isolator, you do not need the blocking diode in the panel and that diode
will cost you charging voltage.

Fair Wind and Smooth Sea
Matt Colie


bushman wrote:
Yes that describes what I have in mind. I like that switch. I have a
xantrex?? 40 charger that will do 3 banks. I am not sure how the solar is
wired but it needs improving. I left the switch on the starting battery and
it killed it in 24 hours. Solar charges it when on the house. I believe I
have some current flowing with all the breakers off. This is just going to
take time to get it all mapped out.
As for Christmas sailing. I just finished 48 hours at work and Jackie is
doing 16. No big loss as we seem to see bad things on Christmas day. Dead
manatee, Fuel Spill, Sunk boat, Dead newborn dolphin with mother holding
its head up out of the water, Uncle got sick and had D-day flashback when a
stinky diesel went by. He spent 6 hours circling in a small landing craft in
diesel smog. He said he was so happy to get on the beach?????
Oh I did find a reference to fuse size for the starter from Casey. He says
to match the fuse to the wire size, looks like 0000 with a 400amp fuse. (if
I remember right.)
Thanks again - Allen


"Matt Colie" wrote in message
...

Allen,

It sounds like your plan is:
Have a dedicated starting battery,
have two banks of house battery on a selector switch and
an available cross-connect from house to start.

If I have that right, you have a good plan.
The cross connect switch should be the kind of Bosch switch you can take
the key out of and never close (but it is nice to know it is there).

Do you have a plan to charge all three banks?

I bet you can figure out how to push off and go out for at least a little
while.

We often use to sail Christmas Day. Even along the upper east coast, it
wa seldom too cold to sail and way too early to be frozen. I am on the
Great lakes now and the boats come out in October (fresh water freezes too
easily).

Where are You?

Matt


bushman wrote:

Thanks again Matt
I will upgrade wire and fuse with the new starting battery and take it
off the battery selector switch. That will shorten the run from 10 feet
to less than 3. I think I will buy 2 more 6 volts and have second house
bank on the selector switch. I will leave the wire from the switch to the
starter in place with a disconnect so that I can still crank from the
house bank if needed.

Looks like we will miss our Christmas Day sailing this year. We have made
it a tradition to go for a sail each year. However this year we are
working.
- Allen

"Matt Colie" wrote in message
...


Allen,
The strap between the two 6volt batteries should be the same as the cable
on both ends. More is no value(except as a cash reserve?) and less is
probably not much of and issue except as voltage drop. It will be
in -relatively- open air and if it gets hot enough to smoke it should get
your attention before it causes real trouble.

The fact that you are successful with three parallel pairs is quite
remarkable. The stacks (pairs) should not be counted on to share load
equally. It is actually very hard to make batteries do that.

I am surprized that a 250amp fuse will crank a 4-108. It must be a
better starter than the one I measured. Take good care of it.

Fair Wind and Smooth Sea
Matt Colie

bushman wrote:


Thanks Chuck and Matt
I think I am OK with the size wire from the batteries to the boat or
engine
but what is the load on the wire that joins the two 6 volt batteries in
a
pair in series? I have three pairs joined in parallel so I'm guessing
that
each pair would have one third my max load and the wires joining them
would
need to be sized for accordingly. I generally like to go a size larger.
You
never know when I might get stranded somewhere and can sell the copper
off
to get me to the next island. The 250 amp fuse on the starting battery
has
never blown. The Perkins generally fires on the first revolution but one
time I lost prime and had to crank for half a minute or more at a time
and
the fuse held.
- Allen

"witheld" wrote in message
...



Allen,

Wire must be sized for the expected load.

It should be fused to protect it and the connected equipment form
damaging current in the case of failure.

The cranking current of a 4-108 at shirtsleeve temperature is hard to
measure, but the peaks are around 500-600 ampere for 70-100 miliseconds
then dropping to 300-400 between peaks. If the fuse is in the cranking
circuit, I'm surprised it is still intact.

Stater motors are not very voltage sensitive. Most engines can crank
on a #2AWG wire and not have a problem.

Do not try to set up to crank from the house battery, just be sure that
the only load on the start battery is the engine. It is a waste of
time and effort and will only cause you problems.

This is what I do www.southpointechandler.com, in my area of the
world.

If you want to discuss this more, I'm here alot.

Matt Colie


bushman wrote:



I am ready to install new batteries. I have not found a reference for
wire size - between - batteries. I have six T105 six volt batteries.
What size wire should be used to series and parallel them? The boat
has 2/0 with a 250amp fuse running to the battery selector switch. I
am not sure how much my started draws (Perkins 4-108) but I would like
to size to start from either the starting or house batteries or both.
One more thing that does not look right is that the Neg wire on the
starting battery is size one or two connected to the house bank Neg
only. Shouldn't there be a jumbo size wire directly to the engine
block at the starter?

Thanks as always. I couldn't have come this far without you folks.
- Allen