Time for new batts, should i go 12v or 6v?

[O C Diver]

I was thinking the same...yet not sure about the probability of one belt taking out the other..I only really need one alt... and if that one craps out...having a new, vacuum packed spare would solve the bad alt picture and a genset takes care of the temp no alt situation...hmmmmm

Just can't seem to decide...

What's anyone's experience with broken belts and a setup like Larry's??? Paired belts have a high likelyhood of taking each other out...but not sure about this setup.

The primary belt on my Cummins is an 8 grove serpentine. The mechanic asked what I wanted on the 2nd alternator. I said, "the same". He said, "that's way over kill". I said, "yes".

Regarding belts:
My boat burns 12 gallons per hour. Losing the belt which drives the fresh water pump, almost instantly will over heat the engine. On a "C" Cummins, there is a good chance that you won't get it shut down before damaging the head. At $40, replacing the primary yearly is cheap insurance. I remove and inspect the second alternator belt yearly (it come off to change the primary). Keep new spares of each on the boat. As a result, I have never had a belt problem on a boat.

Ted

 

[Codger2]

In my experience, all but the simplest (entrry level) boats have two battery banks even if each consists of only one battery. These are either arranged with a 1/2/both/off switch or wired as a starting bank and a house bank with a voltage sensitive relay to keep both banks charged.

I have 3-8Ds...2 for the house and 1 for starting. All are charged by a smart charger with the volt meter reading each independently. ( A 3 position switch at the panel.) The start battery is separate from the house bank. A combiner is available should the start battery be low.

 

[LaBomba]

On a "C" Cummins, there is a good chance that you won't get it shut down before damaging the head.

Ted

Ted, I know this is off topic but does your engine not have an automatic shutdown for overheating?? Maybe this is a new thread? Mine does and it happens quickly.

 

[psneeld]

It's a rare main engine that has auto shutdown unless conncted to a fire supression system.

 

[LaBomba]

It's a rare main engine that has auto shutdown unless conncted to a fire supression system.

Your right, after I thought about it, it doesn't shut the engine off just makes this horn go off, scares the crap out of you and "I" shut it down quick or open the sea cock I forgot to open. Gettin' old.

 

[O C Diver]

Ted, I know this is off topic but does your engine not have an automatic shutdown for overheating?? Maybe this is a new thread? Mine does and it happens quickly.

No auto shutdown on my boat, only alarms.

While auto shutdown sounds good, coming back through a stone jetty inlet in heavy seas is not where I need automation making choices for me.

Ted

 

[CaptTom]

coming back through a stone jetty inlet in heavy seas is not where I need automation making choices for me.

I had a bilge high-water alarm go off at just such a moment once. Surfing down the back sides of some heavy seas had driven a small amount of water where it doesn't usually go, which lit up the alarm. I'm sure glad it didn't shut down the engine!

I was reading somewhere about a sensor that goes on the exhaust hose to give early warning of overheating. Seemed like pretty cheap insurance, I was thinking of getting a pair of those.

Not really sure what that all has to do with batteries, sorry for prolonging the hijack.

 

[rwidman]

I have 3-8Ds...2 for the house and 1 for starting. All are charged by a smart charger with the volt meter reading each independently. ( A 3 position switch at the panel.) The start battery is separate from the house bank. A combiner is available should the start battery be low.

How are they charged when underway?

 

[Chrisjs]

We have a "smart" regulator set to AGM parameters to charge our battery banks from the main engine alternator. For historical reasons (I screwed up!!) we have 2 banks of 2 8D's each, one is Fullriver AGMs (hard to access), the other bank is Rolls lead/acid. Both banks are charged by the same alternator/regulator. When I charge from the gen. or shore I usually set the charge parameters to AGM, then if on shore power, occasionally top off the Rolls on the wet batt. parameter. Both banks continue to perform well after 5 years. I have been impressed by the FR batts. and will probably replace all batts with AGM's next time around. Interestingly, after hanging on the hook for a few months in the Bahamas, the FR's did begin to seem a bit "tired". Contrary to my previous understanding of AGMs, I was instructed to equalize these batts along with the wet batts. They came back really strong and are fine 2 years later. One significant advantagde of the AGMs is their significantly faster charge rate - a real consideration when relying on the generator at anchor.

 

[Marin]

I assume there was some change to the boat's wiring to wire the 6 volt batteries in series to create twelve volt banks.

There was no change to the boat's wiring itself. Four of the six 6vdc batteries were connected together and the other two were connected together. The boat's leads that had been connected to the starboard 8D were connected to the four-battery bank (normally used as house) and the boat's leads that had connected to the port 8D were connected to the two-battery bank (normally designated as start).

So the only new wiring consists of the short connection cables the shop made up to connect the 6vdc batteries together. These cables are all in the battery boxes themselves.

But downstream (or is it upstream?) of the boat's two sets of battery connectors no change was needed or made to the boat's wiring. Even GB's big combiner relay that connects both main batteries (now banks) together when an engine start button is pushed was retained.

 

[Codger2]

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. )

 

[Per]

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.

 

[rwidman]

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.

 

[rwidman]

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.

 

[jeffnick]

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?

 

[Per]

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..

 

[BruceK]

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.

 

[rwidman]

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.

 

[Marin]

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.

 

[FlyWright]

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.

 

[psneeld]

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.

 

[Keith]

And they saved my a-s a couple of times on my '85 Sea Ray.

 

[Codger2]

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.

 

[rwidman]

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.

 

[rwidman]

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.

 

[psneeld]

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....
​

 

[Marin]

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.

 

[rwidman]

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.

 

[Per]

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?

 

[psneeld]

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.