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Old 03-12-2013, 04:45 PM   #41
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How are they charged when underway?
130 amp alternator==> to an external voltage regulator==> to a batt isolator==> to any one, two or all 3 batts that might need a charge. Depending on the SOC of each batt, one, two or all three might be taking a charge simultaneously. (So says my ABYC Certified Electrican. )
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Old 03-12-2013, 05:32 PM   #42
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Even GB's big combiner relay that connects both main batteries (now banks) together when an engine start button is pushed was retained.
i believe the combiner separates the banks when start button is pushed, this helps to protect housebank and related electronics.
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Old 03-12-2013, 06:59 PM   #43
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i believe the combiner separates the banks when start button is pushed, this helps to protect housebank and related electronics.
A combiner would already have seperated the banks because the engine is not running and producing a charging current.

Simply put, a battery combiner (AKA voltage sensing relay) senses the voltage at the batteries and if it's high enough to indicate that the engine is producing a charging current, it connects them together. When the voltage drops (indicating that the engine is not running) the relay drops out and disconnects the batteries from each other. This keeps the house load from discharging the starting battery.
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Old 03-12-2013, 07:01 PM   #44
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130 amp alternator==> to an external voltage regulator==> to a batt isolator==> to any one, two or all 3 batts that might need a charge. Depending on the SOC of each batt, one, two or all three might be taking a charge simultaneously. (So says my ABYC Certified Electrican. )
A "battery isolator" is very different from a battery combiner. They attempt to do the same thing, but an isolator routes the charging current through diodes which causes a voltage drop. Unless the regulator can be and has been adjusted to compensate for this voltage drop, the batteries will never be fully charged. Close, but not fully.
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Old 03-12-2013, 07:04 PM   #45
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I had a group 31, 100ah AGM battery dedicated to my Freedom 30. It gave up the ghost after 25 months. I paid $250 for that battery. The local Batteries Plus store said the 24 month warranty had expired. I needed to decide what to do. Options were:
Direct replacement
2 12 volt batteries
2 6 volt batteries

My initial thought was to go with 6V flooded golf cart batteries - I'd get more capacity?

Then I thought if I had trouble with one of those 6 volt batteries, the other would be useless.

OK then, maybe 2 12volt flooded batteries? For ~$200 I could get my 100ah.

Trouble was, if I went with flooded, I'd have to relocate the battery from inside to the engine compartment.

I got 10' of 2 AWG cables and glassed a platform in the engine compartment for the two 12's. The 3000 Watt inverter specs say it is able to charge at 130 amps. 3000 watts and 130 amps are both above the capacity of 2 AWG, but I'm only powering the 1.2a 120 vac fridge with the inverter. If things don't work out, I'll run another pair of 2's alongside the ones I have.

Then my brother-in-law goes to his Batteries Plus store and they replace the battery because it's under a 3 year warranty. The list on the new battery is ~$400, but it shows a 5 year warranty of which they only offered me the remaining 11.

After figuring the platform size needed for the two 12's, I discovered that for 100ah, 2 6's or 2 12's would take up about the same space as the 31 and they are all about the same weight. I concluded that weight/size pretty much dictate capacity no matter which format you choose, so for me, next time, I will go with 2 flooded 12's.

I just checked the 8D specs. They fall pretty much in line with my weight/size assumption, but who wants to mess with a 140# battery?
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Old 03-12-2013, 08:20 PM   #46
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A combiner would already have seperated the banks because the engine is not running and producing a charging current.

Simply put, a battery combiner (AKA voltage sensing relay) senses the voltage at the batteries and if it's high enough to indicate that the engine is producing a charging current, it connects them together. When the voltage drops (indicating that the engine is not running) the relay drops out and disconnects the batteries from each other. This keeps the house load from discharging the starting battery.
there may be different types of combiners but mine works the way that batt banks are combined until the voltage drops below a certain threshold, i use an ACR from blue sea.
so in fact most times when the batts are somewhat recently charged the banks are combined until the start buttoned is pushed..
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Old 03-12-2013, 08:26 PM   #47
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I talked to Water Miser, we couldn`t work out if the caps fit my 200ah lead acids (= 8D?). I top up regularly, the monthly equalization phase of my solar regulators loses water.
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Old 03-12-2013, 08:55 PM   #48
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there may be different types of combiners but mine works the way that batt banks are combined until the voltage drops below a certain threshold,..
That's the same thing.
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Old 03-12-2013, 09:12 PM   #49
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i believe the combiner separates the banks when start button is pushed, this helps to protect housebank and related electronics.
The combiner relay I am talking about on our boat does not do this. It's sole purpose-- according to the manual and the way it is wired--- is to connect both the main batteries on the boat (originally two 8Ds but now two banks of 6vdc golf cart batteries) together for engine starting only. The relay connects the two batteries (or battery banks) together only as long as a start button is being pushed.

This is to ensure that there is plenty of battery power available to start the engines. It also ensures that even if a battery fails due to a bad cell or whatever, there will be sufficient power to start the engines. This relay has gotten us going once when we did, in fact, develop a failed cell in the "start" battery.

It is a very simple device and was used on all the early GBs. At some point they stopped using it, I suspect when the battery capacity on boats began getting greater and greater with multiple banks and so forth.

But the ealier GBs simply had two batteries, both 8Ds, and either battery could be designated "house." The "start" battery was "start" only by virtue of it not being used for house loads because of the position of the battery selector switch.

It was a very simple system and we've retained it desipite the upgrade to our actual batteries.

There are "combiners" that are used as part of the battery charging system. The "combiner relay" on our boat is not one of these. It is simply there to connect all the boat's batteries together to start the engines whenever a start button is pushed.
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Old 03-12-2013, 09:13 PM   #50
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Quote:
Originally Posted by Per View Post
there may be different types of combiners but mine works the way that batt banks are combined until the voltage drops below a certain threshold, i use an ACR from blue sea.
so in fact most times when the batts are somewhat recently charged the banks are combined until the start buttoned is pushed..

Per, I don't know if this is the same as your model, but here are some specs on a BlueSea ACR.

It ties and opens at various voltages depending on the charging or depletion state. The idea is to tie together during charging when the primary battery reaches a high enough voltage to allow charge current sharing, then open when charging stops. If tied together and the battery depletes to a low voltage, the lockout logic opens the circuit, preventing further discharge from the secondary battery.
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Old 03-12-2013, 09:22 PM   #51
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Long before fancy electronic sensing relays came into the small rec boating world...."combiner" relays were just dumb relays that did the same as a 1/2/all/off switch.

You pushed the button to parallel up the start and/or house bank to get an engine started...nothing fancy...just a momentary switch and a heavy duty relay to combine/parallel the banks....let the button go and the banks are separated. No voltage sensing involved.

Just about every 30 foot plus 2002-2005 Sea Ray had them as welll as a host of other boats I have run from that time frame.
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Old 03-13-2013, 08:26 AM   #52
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And they saved my a-s a couple of times on my '85 Sea Ray.
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Old 03-13-2013, 10:32 AM   #53
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A "battery isolator" is very different from a battery combiner. They attempt to do the same thing, but an isolator routes the charging current through diodes which causes a voltage drop. Unless the regulator can be and has been adjusted to compensate for this voltage drop, the batteries will never be fully charged. Close, but not fully.
I sent a copy of this post to my electrician and here is his response.
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Old 03-13-2013, 10:45 AM   #54
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I sent a copy of this post to my electrician and here is his response.
You are fine then. Battery isolators seem to be going out of fashion since the proliferation of combiners on the market. Installation is just three wires so it's a simple DIY project for many folks and they accomplish the same thing.
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Old 03-13-2013, 10:49 AM   #55
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The combiner relay I am talking about on our boat does not do this. It's sole purpose-- according to the manual and the way it is wired--- is to connect both the main batteries on the boat (originally two 8Ds but now two banks of 6vdc golf cart batteries) together for engine starting only. The relay connects the two batteries (or battery banks) together only as long as a start button is being pushed.

This is to ensure that there is plenty of battery power available to start the engines. It also ensures that even if a battery fails due to a bad cell or whatever, there will be sufficient power to start the engines. This relay has gotten us going once when we did, in fact, develop a failed cell in the "start" battery.

It is a very simple device and was used on all the early GBs. At some point they stopped using it, I suspect when the battery capacity on boats began getting greater and greater with multiple banks and so forth.

But the ealier GBs simply had two batteries, both 8Ds, and either battery could be designated "house." The "start" battery was "start" only by virtue of it not being used for house loads because of the position of the battery selector switch.

It was a very simple system and we've retained it desipite the upgrade to our actual batteries.

There are "combiners" that are used as part of the battery charging system. The "combiner relay" on our boat is not one of these. It is simply there to connect all the boat's batteries together to start the engines whenever a start button is pushed.
Having the ability to connect both banks together for greater capacity is a good thing.

Having it happen automatically is not, because if one of the batteries is really discharged or has a shorted cell, it will draw power from the other and actually reduce the available power for starting the engine.

Good design would have a starting battery capable of starting the engine without help.
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Old 03-13-2013, 11:42 AM   #56
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Lifted this from another site....

Smoking voltage regulator!
Here we go again....
The boat is on the hard and plugged into AC power, AC panel is on and the Xantrex/Statpower Truecharge 20 is on charging the batteries. No different than I have done many times before....

Working on wiring in new instruments I noticed that the battery combiner solenoid was quite hot. I removed the cover on the Ample Power NS2 voltage regulator and the error LED was lit solid indicating battery over-voltage condition, the combiner LED was lit indicating that the solenoid was indeed latched, and the status LED was flashing the system OFF message. A thin plume of smoke was emanating from the circuit board on the NS2. I pulled the fuse and shut it down. I did check the charging voltage and it was 14.2volts.

The Xantrex charger has the ability to charge two banks independently and is wired like that, one leg to the house and the other to the start batteries.

Apparently the NS2 combiner function is always on and it senses charging voltage from ANY source and then latches the solenoid tying the start battery to the house bank.

I spoke to Ample about the problem and they would have liked me to run diagnostics but that would require running the engine, which I can't do right now. They were unable to tell me if the problem was caused by the charger trying to charge two banks and the combiner kicking in and possibly screwing things up. I have sent the unit to them so they can check it.


Exactly why some of us like to design and use neanderthal systems that aren't right or wrong...good or bad...it's just what we like.

No system is foolproof....
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Old 03-13-2013, 01:43 PM   #57
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Having it happen automatically is not, because if one of the batteries is really discharged or has a shorted cell, it will draw power from the other and actually reduce the available power for starting the engine.
Doesn't seem to work that way in reality. The relay allowed us to get our engines started when the "start" battery had lost a cell, and we know other GB owners who were "saved" on a cruise in the same way. Our marine electric shop says it's a great feature to have-- simple, 100% reliable, and effective. This is why they recommended we keep it when we changed our battery system.
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Old 03-13-2013, 02:33 PM   #58
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Doesn't seem to work that way in reality. The relay allowed us to get our engines started when the "start" battery had lost a cell, and we know other GB owners who were "saved" on a cruise in the same way. Our marine electric shop says it's a great feature to have-- simple, 100% reliable, and effective. This is why they recommended we keep it when we changed our battery system.
If your battery "loses a cell" because the cell is open, it's effectively no battery at all and you are using the other battery alone. If it "loses a cell" because the cell is shorted (and I've had this happen to me in the past), it becomes essentially a 10 volt battery and will seriously load the good battery, often to the point where there is not enough current available to start the engine.

Example:

I stopped my car on the way to the marina to get ice. I got the ice and got back in the car and the engine would not turn over. Even the electric door locks wouldn't work.

A good samaritan offered to jump start the car. No dice. I called AAA and they attempted to jump start the car. Again, no dice (this is using his battery and mine in parallel just like the relay on your boat). They loaded the car on a truck and took it to my home.

At home, I disconnected the car's battery and using jumper cables, connected the car to my truck's battery. It started right up.

Believe me or not, it realy happened and I know (technically) why.

A manual swith or a relay with a manual control would be much better.
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Old 03-13-2013, 02:34 PM   #59
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it sounds as if there are different types of isolators and combiners and also combinations of both, i think as long as we know how these switches work then we are all the better off.

so i speak to my mechanic, he has I should consider one of two options:
1. switching all batteries over to regular lead acid (not agm)
2. install external regulators on my alts.. reason for this he says you cannot set up regular alt's with internal regulator to charge AGM batts properly.

your thoughts?
my alts are self exciting internal adjustable regulator leece neville marine alts.
yes, i would get better charging with an external regulator, but is it correct that these alts are not suited for AGM batts?
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Old 03-13-2013, 03:08 PM   #60
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Where's RickB when you need him to get to the basics?

Per...it's really only a question you can answer. Some eople are sold on AGMs and other batts for many reasons. For me and my boat...lead acid wet cells are the ticket.

If you feel AGMs are the ticket for you...get them and set up accordingly.
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