GBM wrote:
"Jeff" wrote

My personal preference is for an EchoCharge, which is only a few
dollars more. In fact, I was willing to buy one even though I already
had a combiner similar to the ACR. My issue is that I frequently
discharge my house bank and then spend an hour or more charging at
fairly high voltage. A combiner would be overcharging the starting
batteries during these times. The EchoCharge allows the starting
batteries to trickle charge, while the house bank getting 90 Amps.


Jeff,
If the combiner is set to close the contact at say 13.5v, my concern is that
with House at low level, this might not happen before I want to turn the
engine off, so the starting battery gets no charge at all! This would
presumably be true for Echo-Charge too.

I don't follow. Unless you have a real dead battery, which can screw
up all the readings, the alternator will put out 14+ Volts right from
the beginning. The contacts will close and both will be charged. The
starting battery should never be less than 90% so it should get close
to fully charged while you're warming up the engine.

There are cases (hopefully rare) when you'll have to do some charging
just to get the house bank up to a reasonable state, but you don't
want to combine a dead house bank with the starting bank anyways.

A trickier issue might be charging from a weak source, such as a solar
panel.



Regarding the Echo-Charge vs ACR. In the case of the combiner, once the
contact closes, the alternator "sees" both batteries. Wouldn't the current
flow distribute itself where needed?

The current will "distribute itself" but there will be one voltage,
and that may be too high. In my case I use AGM starting batteries
which can be killed by overcharging.

But you do raise a question: if the regulator is instructing the
alternator based on its perception of the battery state, how does it
tell the difference between the house bank and the starter bank? You
must make sure that everything is sensing at the correct point. For
instance, I had to disconnect the alternator from the starter and
starting battery since the primary recipient of the juice was to be
the house bank.

These issues convinced me that the EchoCharge was the way to go: the
output of the alternator went to the house bank, so the regulator's
sense was driven by that. The EchoCharge acts as a second regulator,
doing the proper thing for the starting bank. The only bad scenario
is a dead starting bank and a full house bank - this requires some
special jumpering, either a switch (as I had in my previous boat) or a
jumper wire (which I have provision for in my current boat).

I have read that the current to the
starting battery should be limited by the wire gauge used.

Dangerous thinking there - small wires limit current with a voltage
drop. The reduced voltage may prevent the battery from overcharging
but the wires will be heating up! Also, it means that what the
regulator thinks is a trickle charge will be no charge at all at the
end of the voltage drop.

I think I read
that oversizing the connections can cause problems such as too high a
current flow through the combiner. In the case of the Echo-Charge, how does
it "control" the current flow? Is it just a resistor?

I don't know the internals, but I'm sure its not a resistive load -
that would generate heat, which it doesn't do. There are lots of ways
to do it with modern components. If you buy a 15 Amp battery charger
how does it control the flow when the socket you plug into can deliver
200 amps? It certainly isn't by wire size!

Perhaps someone with a deeper understanding of electronics will
correct me, but I've never heard that "oversized" wires cause a
problem by passing too much current. On the contrary, the voltage
drop can really mess up any attempt to regulate the charge voltage.

"Jeff" wrote in

I have read that the current to the
starting battery should be limited by the wire gauge used.

Dangerous thinking there - small wires limit current with a voltage
drop. The reduced voltage may prevent the battery from overcharging
but the wires will be heating up! Also, it means that what the
regulator thinks is a trickle charge will be no charge at all at the
end of the voltage drop.

I think I read that oversizing the connections can cause problems such
as too high a
current flow through the combiner. In the case of the Echo-Charge, how
does
it "control" the current flow? Is it just a resistor?

Perhaps someone with a deeper understanding of electronics will
correct me, but I've never heard that "oversized" wires cause a
problem by passing too much current. On the contrary, the voltage
drop can really mess up any attempt to regulate the charge voltage.

Jeff - I read about this in this link:
http://www.yandina.com/acrobats/C150Data.pdf
that was posted here by Andina Marie Foster. This is what is says:

3. Connect one high current terminal to the positive terminal of each
battery bank.
Secure the ring terminals tightly under the flat washer and lock washer
supplied on each Combiner 150 power terminal. A 7/16" socket wrench will be
required to access these connections in the insulated cavities. No other
cables should be on these terminals at the combiner end.
IMPORTANT:- Use only 6 gauge cable. Use a minimum of 6 feet of wire total
between the positive battery terminals to connect the combiner.
DO NOT use a heavier gauge (lower gauge #) wire. Do not coil excess wire
which can confine heating or
create magnetic fields and upset your compass. The insignificant resistance
in these leads will result in no voltage
loss at end of charge but it is enough to protect the Combiner 150 from
excessive currents which can flow when
the batteries are first connected in parallel.

And also from Yandina site:

Q Is the 6 gauge wire recommended for the 150 amp combiner heavy enough?
A Yes, in fact this is a MAXIMUM size, using a heavier gauge can damage
the combiner. Increasing the length above the minimum recommended can
actually prolong the contact life with virtually no reduction in charging
efficiency. See the following question for more information.

Q I installed a 50 amp combiner on my boat which has a 90 amp alternator.
Last year the contacts welded shut so I replaced it but now it has happened
again. Should I have used a 150 amp combiner?
A No, the 50 amp combiner is probably adequate. Typically only a portion
of the current flows through the combiner because the charging source is
connected directly to one of the banks. Your problem is most likely that the
installer did too good a job and did not follow the installation
instructions. The intuition that bigger is better applies to most
installations, however it can kill a combiner. The instructions for the 150
amp combiner recommend a minimum wire run from the battery of 3 feet to each
combiner terminal and recommend a wire size no heavier than 6 gauge. The
leads come already attached with the 50 and 100 amp combiner which must not
be shortened. This wire has a negligible resistance to the normal charging
current and has zero voltage drop as the batteries reach full charge but it
does have enough resistance and inductance to prevent the contacts welding
when the batteries being combined are at different voltages and one battery
is supplying high power to the other for a few seconds.

This kind of thing makes me wonder if I am adding yet another item that
might give me trouble!

GBM

GBM wrote:
"Jeff" wrote in

I have read that the current to the
starting battery should be limited by the wire gauge used.

Dangerous thinking there - small wires limit current with a voltage
drop. The reduced voltage may prevent the battery from overcharging
but the wires will be heating up! Also, it means that what the
regulator thinks is a trickle charge will be no charge at all at the
end of the voltage drop.


I think I read that oversizing the connections can cause problems such

as too high a

current flow through the combiner. In the case of the Echo-Charge, how

does

it "control" the current flow? Is it just a resistor?

Perhaps someone with a deeper understanding of electronics will
correct me, but I've never heard that "oversized" wires cause a
problem by passing too much current. On the contrary, the voltage
drop can really mess up any attempt to regulate the charge voltage.


Jeff - I read about this in this link:
http://www.yandina.com/acrobats/C150Data.pdf
that was posted here by Andina Marie Foster. This is what is says:

3. Connect one high current terminal to the positive terminal of each
battery bank.
Secure the ring terminals tightly under the flat washer and lock washer
supplied on each Combiner 150 power terminal. A 7/16" socket wrench will be
required to access these connections in the insulated cavities. No other
cables should be on these terminals at the combiner end.
IMPORTANT:- Use only 6 gauge cable. Use a minimum of 6 feet of wire total
between the positive battery terminals to connect the combiner.
DO NOT use a heavier gauge (lower gauge #) wire. Do not coil excess wire
which can confine heating or
create magnetic fields and upset your compass. The insignificant resistance
in these leads will result in no voltage
loss at end of charge but it is enough to protect the Combiner 150 from
excessive currents which can flow when
the batteries are first connected in parallel.


OK. But what's really going on here is that the normal high current
path is from the alternator (or large charger) directly to the large
house bank. It would be foolish to use 6 gauge for this because when
passing 100 Amps the Voltage drop could be 10% (check out the chart in
the West Catalog). This can have a HUGE affect on the charging if
14.4 Volts is dropped to 13! (People don't always consider that if
the alternator is 12 feet from the battery, the run is 24 feet, and
even 1 gauge will have 3% drop, or 0.4 Volts, enough to greatly affect
performance.)

The wire they are talking about is tapping off that to feed the
combiner which feeds the starting battery. For the primary purpose of
keeping that battery charged, the current flow is probably under 15
Amps so there is no issue at all with Voltage drops. In the rare case
where the charging current is high enough to cause a drop, the
situation would resolve itself fairly quickly. Thus, they can use
smaller relays with the reduced current.

However, if you want to use the house bank for starting the engine (by
forcing the combiner) then you're getting back into a high current
range where the will be a drop, something you might not want in this
situation! Consider that your house bank could be down to 12 Volts,
then you find your starting battery is dead. Forcing the combiner
seems like the right thing, but the starter load (plus the load of the
dead battery) means that the current in the 6 gauge forces a 10%
voltage drop, and now you trying to start the engine with under 11
Volts! This is why I have shutoff switches on each battery and can
quickly rewire any battery to either starter.



And also from Yandina site:

Q Is the 6 gauge wire recommended for the 150 amp combiner heavy enough?
A Yes, in fact this is a MAXIMUM size, using a heavier gauge can damage
the combiner. Increasing the length above the minimum recommended can
actually prolong the contact life with virtually no reduction in charging
efficiency. See the following question for more information.

Q I installed a 50 amp combiner on my boat which has a 90 amp alternator.
Last year the contacts welded shut so I replaced it but now it has happened
again. Should I have used a 150 amp combiner?
A No, the 50 amp combiner is probably adequate. Typically only a portion
of the current flows through the combiner because the charging source is
connected directly to one of the banks. Your problem is most likely that the
installer did too good a job and did not follow the installation
instructions. The intuition that bigger is better applies to most
installations, however it can kill a combiner. The instructions for the 150
amp combiner recommend a minimum wire run from the battery of 3 feet to each
combiner terminal and recommend a wire size no heavier than 6 gauge. The
leads come already attached with the 50 and 100 amp combiner which must not
be shortened. This wire has a negligible resistance to the normal charging
current and has zero voltage drop as the batteries reach full charge but it
does have enough resistance and inductance to prevent the contacts welding
when the batteries being combined are at different voltages and one battery
is supplying high power to the other for a few seconds.

This doesn't make me happy. Or perhaps I should say I feel justified
in switching to the EchoCharge. It also might explain why I've seen
a few combiners fail when the relay are "certified for millions of
cycles"!



This kind of thing makes me wonder if I am adding yet another item that
might give me trouble!

GBM

"Jeff" wrote

OK. But what's really going on here is that the normal high current
path is from the alternator (or large charger) directly to the large
house bank. It would be foolish to use 6 gauge for this because when
passing 100 Amps the Voltage drop could be 10% (check out the chart in
the West Catalog).

The articles were talking about teh actual combiner leads, not the lead from
the alternator. But, seeing you brought it up , in my case I will actually
use 6 ga. But, I only have a 55A alternator and the return trip run is only
about 10ft. But, do see your point. At present, my alternator feed is via
the 2 ga starter cable but this will change when I go to the House bank.


However, if you want to use the house bank for starting the engine (by
forcing the combiner) then you're getting back into a high current
range where the will be a drop, something you might not want in this
situation!

The Blue Seas two circuit switch I referenced earlier has a manual combine
position - We would use that as we do now with the old switch in the Both
position.


This doesn't make me happy. Or perhaps I should say I feel justified
in switching to the EchoCharge. It also might explain why I've seen
a few combiners fail when the relay are "certified for millions of
cycles"!

True - It seems like there can be problems, but many boats have combiners
and most seem to be happy with them.

Thanks for your input - It is useful!

GBM

Batteries are charged with current - ie. amps, not volts. You measure
charge in amp-hours, not volts. So a low battery will drop the charger
voltage to the battery voltage. If there is 10% voltage drop in the
cable (which it isn't!) then that is because ALL the current the
charging source can supply is being absorbed by the battery. As the
battery reaches full charge the regulator will reduce the current to
stop the voltage getting too high. As the current is reduced, the
voltage drop along the protection cables will also drop so finally at
end of charge there is no voltage drop in the cable. ALL the current
going through the cable is going into the battery!

All our combiners include a manual combine. Adjustable threshold
settings are not necessary and we eliminated them in 1995 because the
potentiometer was a maintenance item. All our combiners include an
optional 14.2 volt cut-off that you can use to protect a gel type
battery from the high voltages often found on lead acid batteries.

The blue seas unit is just a battery combiner copy of ours. We
invented the combiner in 1993. We are the cheapest. Ours are the only
ones carrying an UNLIMITED warranty. We have sold over 26,000 of them
all on unlimited warranty! We get about 20 returns per year of which
about 15 have nothing wrong with them.

There is an extensive FAQ on battery combiners at
http://www.yandina.com/combInfo.htm

Regards,

Andina Marie Foster,

wrote in message
oups.com...
I use something similar to the Bluesea - Smartbank split charge
controller - www.smartgauge.co.uk


That site has some very interesting technical info - Well worth a read!

GBM