I just bought a 900 cca battery at Costco to use as my starting battery
($58,100mo). My plan is to put that battery in bank 1 and to purchase
two Trojan T105s for bank 2 (hooked together in series of course). I
have the standard "1,2,both" switch. My motor is a Yanmar 2QM15.

I have an alternator which was recently rebuilt, supposedly to put out
60amps, and according to the ampmeter puts out about 35 amps at max. I
have a shore power West Marine 5 amp charger. I'm hoping to not have to
upgrade anything else due to low finances, especially not an expensive
new alternator!

Can someone show me the figures as to what problems I will have if I
stubbornly refuse to upgrade anything else? How long will it take to
charge them with the motor or with the shore power?

Last question, Do I have to do something unusual to hook everything back
up? Can I just charge both banks at the same time as I did before or do
I have to charge the banks separately?

Thanks so much for any help!!

--
Stephen

-------

For any proposition there is always some sufficiently narrow
interpretation of its terms, such that it turns out true, and
some sufficiently wide interpretation such that it turns out
false...concept stretching will refute *any* statement, and will
leave no true statement whatsoever.
-- Imre Lakatos

Stephen Trapani wrote:
I just bought a 900 cca battery at Costco to use as my starting battery
($58,100mo). My plan is to put that battery in bank 1 and to purchase
two Trojan T105s for bank 2 (hooked together in series of course). I
have the standard "1,2,both" switch. My motor is a Yanmar 2QM15.

I have an alternator which was recently rebuilt, supposedly to put out
60amps, and according to the ampmeter puts out about 35 amps at max. I
have a shore power West Marine 5 amp charger. I'm hoping to not have to
upgrade anything else due to low finances, especially not an expensive
new alternator!



Can someone show me the figures as to what problems I will have if I
stubbornly refuse to upgrade anything else? How long will it take to
charge them with the motor or with the shore power?

Last question, Do I have to do something unusual to hook everything back
up? Can I just charge both banks at the same time as I did before or do
I have to charge the banks separately?

Thanks so much for any help!!


You've asked a lot of questions but still have to give a few details.
For instance, will you daysail, overnight, or hang out at anchor for
a few weeks? Do you need the system to be failsafe and idiot proof,
or can you accept that a little forgetfulness can lead to a dead
battery and possibly a SeaTow call?

First, the charge rates:
The output of the alternator will be a function of the batteries,
charge state, and the regulator. The T105's will accept about 50 Amps
so the alternator is sized right, but if the regulator is not set to
the right voltage it will take too much time, or overcharge. With a
modern 3-stage, it should take about 90 to 120 minutes to go from 50%
charge to 85%. However, if you have the stock Hitachi alternator with
a dumb regulator, it will take longer. The shore charger, being
small, will take about 24 hours (or more) to top off the bank from the
50% state. (Hopefully, the starting battery should not be discharged
more than a few percent.)

Underway:
Ideally, the starting battery should be connected directly to the
starter, and the house bank to the other power sinks. This means that
there is no "big red switch" needed except for emergency situations,
such as using the house bank to start the engine. My last two boats
are wired this way.

The problem this creates is that you want to be able to charge both
from a single source. The best way is to have either dual output
alternator and chargers, or a combiner (an automatic relay), or an
Echo Charge, (a small changer for the starter battery slaved off of
the primary charger). Without one of these automatic systems, you
have to manually select "both" on the big switch for charging, and
then hopefully remember to disconnect when you're discharging. This
can cause another problem, which is that the alternator can cook a
diode if the batteries are disconnected even for a split second.
(Newer switches avoid this with "make before break".)

The easy solution, without spending (much) more money, is to hardwire
the two banks to their respective sinks, and use the "both" setting
only for emergencies. The starting battery should last for a number
of starts, so if you have it well charged when you leave the dock, it
should be good for an overnight. Even this is a bit of a problem,
since the alternator output on the Yanmar is probably fed directly to
the starter. It will need its own cable back to the house bank; this
annoyance is implied by the concept of having a dedicated starting
battery. And of course you'll want to have some way to disconnect the
batteries.

If this seems complicated, just imagine that electricity on boats, and
battery powered appliances are wholly unnatural concepts! And doing
anything cheaply on a boat is problematical.

Larry wrote:
Stephen Trapani wrote in news:nJrPf.263
:

Can I just charge both banks at the same time as I did before or do
I have to charge the banks separately?


I assume starting battery is on 1 and house batteries are on 2, right?

Any time there is a charging source, you may leave the switch in BOTH
to charge them all in parallel. The little battery will charge with
lots less current than the T-105s and when the voltage comes up to
14+, the currents will simply stop. The automatic charger will keep
pulsing the lot of them to keep them at full voltage, as will the
alternator. It'll work fine that way.

What I would do is connect the AC charger to the house bank, directly,
not the switch common. Once charged, the starter battery doesn't
need to be connected all the time to the charger, just occasionally,
but the house batteries do because you keep switching on loads in the
boat. Having the AC charger hooked directly to the house batteries
also means no matter what you do with that switch, even OFF, the
charger will NEVER be connected to the loads without a battery to
sink its output to 14V. Chargers and alternators can blow electronics
if there's no battery attached to them..not good. So, when you want
the AC charger to boost up the starting battery, just flip to BOTH
for a day or while the wild party is going on to maintain its charge.
Don't leave it in BOTH all the while.

I'd like to also put a plug into making TWO connections to the
starting battery....one to the switch with a HEAVY cable capable of
cranking the Yanmar...including the house battery cables so the house
batteries can also crank the Yanmar if necessary in the BOTH
position. But, make the starter cable connect directly to the
starting battery as short as possible. Run the starter off the
starting battery, direct, not the house battery switch. If the
switch goes bad, you're not stranded. If there's a short in the
house, your not stranded. WHEN, not if, the big switch gets all
corroded up inside because it's cheap boat crap, cranking the engine
won't pulsate all the expensive electronics, possibly destroying it,
because the engine has a direct path around the corrosion to the
starting battery, directly. Starting in BOTH when the starting
battery is dead is the same circuit as using jumper cables (from the
house batteries) in your car. Works fine.

For years, the two paralleled AGM starting batteries in my diesel
stepvan have been charged in parallel with my L-16H monster house
battery bank from one 80A alternator. Don't be alarmed you only see
35A, by the way. Actually I think that's a little high for charging
such small batteries as T-105s. They must have been discharged quite
a ways. The BATTERY, not the capacity of the alternator, determines
how much charging current there is. The CHARGER/ALTERNATOR sets the
VOLTAGE LIMIT with its regulator and its CURRENT LIMIT with its
internal resistance in series. Too many think if they swap out the
80A alternator for a 300A alternator their going to charge the house
batteries in 5 minutes, not hours. That would be fine if it weren't
for the chemistry and physics of lead-acid batteries. The slower you
charge them, the better they charge. What the big alternator does is
give you OVERHEAD, allowing you to use the difference current between
the alternator's capacity and the charging current at the moment to
run other stuff like radars/radios/lights/pumps/inverters/etc.,
without discharging the batteries....same as your car.

This will all change shortly with Toshiba's invention of the
amazingly- fast-charging Ni-MH nanotube cell. It charges to 80% in
ONE minute and 100% in 3 minutes....at such huge current levels the
Yanmar won't be strong enough to pull in short order. Those cells
will be like a dream, charging at whatever capacity the alternators
can put out for very short times (more than 3 minutes, I'm sure)
until they are fully charged. With their introduction and after
their debugging, I'm going to go for an electric or hybrid car with
them powering it. To date, traction motor braking has only recharged
current technology batteries a few percent. The new batteries will
allow traction motor braking to put ALL the power they produce as
generators back into the battery bank as you brake... Big oil will be
trying to squash this introduction with big bribes and big offers to
buy it up and hide it. Let's all hope they don't succeed.

Let's hope all vehicles, including the boats, dump this stupid 12V
power system for much higher voltages to get the currents down using
more economical wiring systems. I'm for 220 or 440 VDC, myself.
Your starter cable would be #12 wire at 440VDC. Its solid state,
brushless motor would never need brushes, as its armature isn't would
with wire. Your outboard motor stator driving the ignition system is
already in this voltage range, now! Low voltage DC is stupid.

He says his house batteries are connected in series. Is this an error?

Dennis Pogson wrote:
Larry wrote:

Stephen Trapani wrote in news:nJrPf.263
:


Can I just charge both banks at the same time as I did before or do
I have to charge the banks separately?


I assume starting battery is on 1 and house batteries are on 2, right?

Any time there is a charging source, you may leave the switch in BOTH
to charge them all in parallel. The little battery will charge with
lots less current than the T-105s and when the voltage comes up to
14+, the currents will simply stop. The automatic charger will keep
pulsing the lot of them to keep them at full voltage, as will the
alternator. It'll work fine that way.

What I would do is connect the AC charger to the house bank, directly,
not the switch common. Once charged, the starter battery doesn't
need to be connected all the time to the charger, just occasionally,
but the house batteries do because you keep switching on loads in the
boat. Having the AC charger hooked directly to the house batteries
also means no matter what you do with that switch, even OFF, the
charger will NEVER be connected to the loads without a battery to
sink its output to 14V. Chargers and alternators can blow electronics
if there's no battery attached to them..not good. So, when you want
the AC charger to boost up the starting battery, just flip to BOTH
for a day or while the wild party is going on to maintain its charge.
Don't leave it in BOTH all the while.

I'd like to also put a plug into making TWO connections to the
starting battery....one to the switch with a HEAVY cable capable of
cranking the Yanmar...including the house battery cables so the house
batteries can also crank the Yanmar if necessary in the BOTH
position. But, make the starter cable connect directly to the
starting battery as short as possible. Run the starter off the
starting battery, direct, not the house battery switch. If the
switch goes bad, you're not stranded. If there's a short in the
house, your not stranded. WHEN, not if, the big switch gets all
corroded up inside because it's cheap boat crap, cranking the engine
won't pulsate all the expensive electronics, possibly destroying it,
because the engine has a direct path around the corrosion to the
starting battery, directly. Starting in BOTH when the starting
battery is dead is the same circuit as using jumper cables (from the
house batteries) in your car. Works fine.

For years, the two paralleled AGM starting batteries in my diesel
stepvan have been charged in parallel with my L-16H monster house
battery bank from one 80A alternator. Don't be alarmed you only see
35A, by the way. Actually I think that's a little high for charging
such small batteries as T-105s. They must have been discharged quite
a ways. The BATTERY, not the capacity of the alternator, determines
how much charging current there is. The CHARGER/ALTERNATOR sets the
VOLTAGE LIMIT with its regulator and its CURRENT LIMIT with its
internal resistance in series. Too many think if they swap out the
80A alternator for a 300A alternator their going to charge the house
batteries in 5 minutes, not hours. That would be fine if it weren't
for the chemistry and physics of lead-acid batteries. The slower you
charge them, the better they charge. What the big alternator does is
give you OVERHEAD, allowing you to use the difference current between
the alternator's capacity and the charging current at the moment to
run other stuff like radars/radios/lights/pumps/inverters/etc.,
without discharging the batteries....same as your car.

This will all change shortly with Toshiba's invention of the
amazingly- fast-charging Ni-MH nanotube cell. It charges to 80% in
ONE minute and 100% in 3 minutes....at such huge current levels the
Yanmar won't be strong enough to pull in short order. Those cells
will be like a dream, charging at whatever capacity the alternators
can put out for very short times (more than 3 minutes, I'm sure)
until they are fully charged. With their introduction and after
their debugging, I'm going to go for an electric or hybrid car with
them powering it. To date, traction motor braking has only recharged
current technology batteries a few percent. The new batteries will
allow traction motor braking to put ALL the power they produce as
generators back into the battery bank as you brake... Big oil will be
trying to squash this introduction with big bribes and big offers to
buy it up and hide it. Let's all hope they don't succeed.

Let's hope all vehicles, including the boats, dump this stupid 12V
power system for much higher voltages to get the currents down using
more economical wiring systems. I'm for 220 or 440 VDC, myself.
Your starter cable would be #12 wire at 440VDC. Its solid state,
brushless motor would never need brushes, as its armature isn't would
with wire. Your outboard motor stator driving the ignition system is
already in this voltage range, now! Low voltage DC is stupid.


He says his house batteries are connected in series. Is this an error?


Not if they are T-105s - they are 6V batteries

Larry wrote:

Stephen Trapani wrote in news:nJrPf.263
:


Can I just charge both banks at the same time as I did before or do
I have to charge the banks separately?



I assume starting battery is on 1 and house batteries are on 2, right?

Right.

Any time there is a charging source, you may leave the switch in BOTH to
charge them all in parallel. The little battery will charge with lots
less current than the T-105s and when the voltage comes up to 14+, the
currents will simply stop. The automatic charger will keep pulsing the
lot of them to keep them at full voltage, as will the alternator. It'll
work fine that way.

What I would do is connect the AC charger to the house bank, directly,
not the switch common.

So you mean to *not* hook the AC charger to bank 2 in the switch, but
directly to the house batteries?

Once charged, the starter battery doesn't need to
be connected all the time to the charger, just occasionally, but the
house batteries do because you keep switching on loads in the boat.
Having the AC charger hooked directly to the house batteries also means
no matter what you do with that switch, even OFF, the charger will NEVER
be connected to the loads without a battery to sink its output to 14V.
Chargers and alternators can blow electronics if there's no battery
attached to them..not good. So, when you want the AC charger to boost up
the starting battery, just flip to BOTH for a day or while the wild party
is going on to maintain its charge. Don't leave it in BOTH all the
while.

So when you switch the switch to BOTH, the AC charger charges through
the house batteries, back through the switch and into the starting
battery even though the charger is not connected to the switch? or did I
misunderstand?

Thanks!

--
Stephen

-------

For any proposition there is always some sufficiently narrow
interpretation of its terms, such that it turns out true, and
some sufficiently wide interpretation such that it turns out
false...concept stretching will refute *any* statement, and will
leave no true statement whatsoever.
-- Imre Lakatos

"Dennis Pogson" wrote in
:

He says his house batteries are connected in series. Is this an error?



I'd think they were 6V house batteries in series for 12V....

There should be a 250A fuse in the link, in the middle between the
batteries, to protect them from a short....