Moving battery forward.

[Captain Steve]

thanks for the field work

 

[NorthernFocus]

Stuart, the system wired as you describe with the two ACRs functions as indicated in the schematic. There's nothing wrong with the ACRs wired that way. It's confusing to look at but it works. Hate to see you spend a lot of time/effort/dollars to fix something that's not broken. It is likely that your problems are related to the charging circuit. If I were you the first thing I would do is to remove the charger and solar power from the circuit, replace the dead thruster battery, and see if everything works as designed. It is also advisable to wire the positive leads from your charger/solar directly to the battery terminals when you hook them back up.

Aside from the power cables, there should only be one small "sensing wire" connected to the small spade connectors on each ACR. That is the ground reference. You can download the schematics for the ACRs on the BlueSea website. The terminals are physically labeled as well if your eyes are better than mine. The three spade connections are ground, LED, and start. The early boats came with an errant hot wire connection to the LED terminal. That one should be removed. There should be a small gauge wire from the ground buss to the ground terminal. Nothing connected to the start terminal unless the previous owner wired it up. If power is applied to the "start" terminal on the ACR it forces it open. You can use a jumper wire with alligator clips to force the ACRs open to test your system by using that terminal. When the ACR is open the LED will blink. When it is closed the LED is solid.

 

[BB marine]

From what you are explaining and experiencing I don't think it is the isolating relays it could be but.... What you are describing sounds like a battery lead might be in the wrong location. I would start at the battery and follow each lead to its source. I think if you trace all your leads where they are connected and where they go you will find your problem. I know on my boat there is a lot going on. If you look at the pictures I posted every lead I marked or labeled and every lead I confirmed that it was going to the right place from the battery post to the panel and everything in-between . I cut every tie strap and had every wire loose and followed them to the panel just to confirm. Possibly the previous owner of your boat added something or just hooked something up wrong and it worked but isn't working right.
Brian Brown
Cutwater26
PORT-A-GEE

 

[captstu]

Dan/Brian,

I traced every wire - either by physically running the wires with my hands or disconnecting one end and seeing which wire had an open circuit on the other end.

Other than the red wires on the ACRs (that I will disconnect as suggested), everything else now makes sense, including the failure of the thrusters to operate after a few days of no sun before using the boat.

There are no mystery any longer - you folks have enlightened me.

The thruster battery had died, partially of old age and partially because the bilge pumps were connected to that bettery. Once several days of no sun went by coupled with the load that was being carried by the thruster battery, it discharged enough to place the life in jeopardy.

Under normal conditions, the ACR combines all three banks as it is designed to do.

Everything is working as designed - not quite as drawn in the schematic - but substituting two ACRs for a 3-way isolation diode bank seems like a good idea.

Anyway, I moved the thruster battery up forward and replaced it with a new starting battery (1000 MCA) and the thrusters now run smoother and faster. The cable that used to control the front thruster now carries the battery circuit to the rear thruster instead. The ACR is still in place between the house and thruster busses, as installed by the factory. The net result is the thruster battery carries the load of the forward thruster and the rear thruster is fed by the cable from the bow and the ACR circuit. both show improved enough performance that I can now back into my slip against the current caused by the Corps of Engineers draining Lake Okeechobee through my slip.

And, my minimum planing speed dropped from about 12.8 knots to 10.6 knots - the bow dropped 2" so I can now drive sitting down because of the logintinual trim improvement. I was able to drip my cruising RPM about 500 rpm to maintain a cruise of 13.5 knots and my comfortable minimum cruise dropped to just under 12 knots.

I'm really pleased - the Admiral is pleased - the boat rides flat with minimum trim adjustments - and I have enough remaining trim range to trim flat after the generator is reinstalled.

Thanks for all the help!!

 

[NorthernFocus]

That's awesome, Stuart. Both figuring out what was going on with your system and the end result of the battery move. Nicely done.

But I hate that you posted this thread. Cause now I'll have to add this mod to my list 🙁

 

[captstu]

Sorry! It didn’t take long since I had to install a new battery anyway. About $30 with a new yellow wire and tie down strap. Rewarding.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[captstu]

Just a couple of remaining confusions, please:

1. When I disconnected the thruster battery to replace it with a new battery in the new location, the thrusters (and windless) worked better than before removing the battery. Part of this is easily explained, the thruster battery apparently dead and an internal cell short (a usual failure for an old battery), drawing down the system. Once removed, the other remaining batteries carried the load easily. Part is harder to explain.

I traced and removed every wire relating to the thruster until just the wire to the thruster switch and thruster bus remained. The thruster stopped. So, I believe, no magic was involved. When I replaced either wire from the thruster buss to either of the two ACRs, the thrusters operated - either on the house bank or the engine battery. I then tested the thrusters and found both closed.

According the the ACR manual for SI-ACR Automatic Charging Relay - 12/24V DC 120A, the under voltage lockout is activated at 9.5 volts for either battery. I'm struggling to understand why did neither ACR open when the thruster battery had been disconnected for several hours?

2. My R25 is wired so the windless comes directly off the positive terminal on the bow thruster. This is what the schematic shows. My R25 also has a windlass circuit breaker in the bow compartment under the bunk (a place I've never looked before since it is not on the schematic). The schematic shows a 200 A fuse for the combined windlass and bow thruster load. When I moved the battery forward, I also relocated the power source for the windless and its circuit breaker on the battery side of the bow thruster fuse. Anyone see any problem with that?

3. Finally, since there is no common point of power for the two thrusters, I removed the on/off thruster switch in the generator compartment and intend to replace both thruster fuses with new 150 amp circuit breakers. See any problem with this?

Thanks for the extended help.

 

[NorthernFocus]

1. ...When I replaced either wire from the thruster buss to either of the two ACRs, the thrusters operated - either on the house bank or the engine battery. I then tested the thrusters and found both closed.

According the the ACR manual for SI-ACR Automatic Charging Relay - 12/24V DC 120A, the under voltage lockout is activated at 9.5 volts for either battery. I'm struggling to understand why did neither ACR open when the thruster battery had been disconnected for several hours?

Is your solar power or charger connected to the thruster buss? That would cause what you describe as both ACRs would see charging voltage on that side.

2. Can't see an issue with it. The protecting breaker is still in the circuit.

3. Conceptually sounds like a good idea. But why 150A vs the 200A as-built fuse? Is 150A what the thuster specs call for?

 

[BB marine]

Just a couple of remaining confusions, please:

1. When I disconnected the thruster battery to replace it with a new battery in the new location, the thrusters (and windless) worked better than before removing the battery. Part of this is easily explained, the thruster battery apparently dead and an internal cell short (a usual failure for an old battery), drawing down the system. Once removed, the other remaining batteries carried the load easily. Part is harder to explain.

I traced and removed every wire relating to the thruster until just the wire to the thruster switch and thruster bus remained. The thruster stopped. So, I believe, no magic was involved. When I replaced either wire from the thruster buss to either of the two ACRs, the thrusters operated - either on the house bank or the engine battery. I then tested the thrusters and found both closed.

According the the ACR manual for SI-ACR Automatic Charging Relay - 12/24V DC 120A, the under voltage lockout is activated at 9.5 volts for either battery. I'm struggling to understand why did neither ACR open when the thruster battery had been disconnected for several hours?

If your thruster buss has power going to it with the thruster battery disconnected you need to find that power source. With the thruster battery disconnected there should be no power to the buss the isolating relay should sense the no voltage.



The engine battery is the only battery to feed the charging source to the thruster battery.
The engine battery is the only battery to feed the charging source to the house battery.
The house battery and thruster battery should never provide power to each other.
The engine battery has to be at 12.75 V in order for it to combine to either the house or the thruster battery.
When the engine is not running and the house battery circuit is used and the relay is combined to the engine battery there will be a voltage drop. As soon as(30seconds) the engine battery voltage drops below 12.75V the relay opens and now the engine will not be combined to the house battery or thruster battery.
After the relay opens and the engine battery as no load it may return to 12.75V and then combine back with the thruster battery if it has a full charge. If the thruster battery does not have a full charge in your case it didn't because it was bad this should put a equalizing load on the engine battery and drop the voltage below 12.75 and the thruster relay should go open.
When the engine is running the alternator charges the engine battery and raises the battery voltage as high as 14.7 V.
Now if there is a load coming from the house battery it will not drop the engine battery below 12.75 and relay stays closed and house battery gets charged and the same for the thruster battery.
If you have a battery below 10volts the relay will not sense a battery and the relay will stay open. In order to get it to close you need to excite the battery with another source for the relay to close( engine as to be running).

If you have power at the Thruster buss something is feeding it power from either the engine battery or house. if the power is coming from the relay the relay is bad. The system is designed so that you can not discharge the other battery banks.

2. My R25 is wired so the windless comes directly off the positive terminal on the bow thruster. This is what the schematic shows. My R25 also has a windlass circuit breaker in the bow compartment under the bunk (a place I've never looked before since it is not on the schematic). The schematic shows a 200 A fuse for the combined windlass and bow thruster load. When I moved the battery forward, I also relocated the power source for the windless and its circuit breaker on the battery side of the bow thruster fuse. Anyone see any problem with that?


This is good.You want to have the thruster fused independently of the Windless .
you should have four fuses coming off the battery in the bow 1. Windlass
2. bow thruster
3. Stern thruster
4.The battery terminal that you have going back to the thruster Buss needs to be fused too. This lead needs to be independent of the stern thruster power lead.


3. Finally, since there is no common point of power for the two thrusters, I removed the on/off thruster switch in the generator compartment and intend to replace both thruster fuses with new 150 amp circuit breakers. See any problem with this?


You should have a battery switch in the bow to turn the thruster battery off to thrusters. The switch should contain the Battery lead going to the switch, Bow thruster lead ,stern thruster lead, and the Windless lead with the fuses attached to leads . The battery lead going Back to the thruster buss should not be switched and be sized for the length of the run from Buss to bow and capable of handling the amperage output of alternator . It needs to be live so the battery can be charged.

Thanks for the extended help.[/quote


These are suggestions as how I think the system works and how I would troubleshoot and wire it. I consider myself a jack of all trades and a Master of nothing! So I would research it further.
Brian Brown
Cutwater26
PORT-A-GEE

 

[NorthernFocus]

...
The engine battery is the only battery to feed the charging source to the thruster battery.
The engine battery is the only battery to feed the charging source to the house battery...

That's not necessarily so on the older boats. This was discussed in another thread a while back. On the shop floor there was apparently some confusion about whether house or engine batt was no.1. My boat came with the alternator cable landed on the house buss.

...The engine battery has to be at 12.75 V in order for it to combine to either the house or the thruster battery.
When the engine is not running and the house battery circuit is used and the relay is combined to the engine battery there will be a voltage drop. As soon as(30seconds) the engine battery voltage drops below 12.75V the relay opens and now the engine will not be combined to the house battery or thruster battery.
After the relay opens and the engine battery as no load it may return to 12.75V and then combine back with the thruster battery

Not quite so. Once the ACR opens it will not close again until it sees at least 13.0V for 2 min. or 13.6 for 30 sec.

Bottom line is this, unless there is a charging source being applied somewhere (or unless you have AGM batteries?) even with all three batteries installed both ACRs should open after a short time and batteries have had time to reach "resting" voltage of 12.7V.

 

[BB marine]

How do AGM batteries differ in the operation of the isolation relays ? I know there is a different charge rate or setting on the Battery charger but do the isolating relays work differently? I do not have AGM batteries ,I have wet maintenance free now. But when I replace them I thought I would replace them with AGM.

Bottom line is this, unless there is a charging source being applied somewhere (or unless you have AGM batteries?

No offense to Ranger but I don't think that is the best way to have it set up. And they changed it I would assume after learning that. If I was changing the wiring I would make a point to make sure each system is isolated. I actually think that is the problem Stuart is having circuits leaking voltage to other circuits . Engine, house and thruster circuits should be 100% isolated from each other except thru isolation devises and manual battery switch for emergencies.

That's not necessarily so on the older boats. This was discussed in another thread a while back. On the shop floor there was apparently some confusion about whether house or engine batt was no.1. My boat came with the alternator cable landed on the house buss.

Exactly right, I didn't get into exact specs , I was trying to just give a generalized explanation of how the system works and that Stuart should not have voltage at the buss without the battery connected.

Not quite so. Once the ACR opens it will not close again until it sees at least 13.0V for 2 min. or 13.6 for 30 sec.


Thanks for you responses NorthernFocus, and Stuart. This is Stuart's post but I have been interested in it too ! Thru out this discussion I have thought about and researched the subject.That's what I like about Tugnuts learn more about our boats.
Brian Brown
Cutwater26
PORT-A-GEE

 

[NorthernFocus]

How do AGM batteries differ in the operation of the isolation relays ?...

I don't use AGMs. But I've looked into them for various reasons in the past and some manufacturers claim FSOC voltage as high as 12.85. If that's in fact true then in a no load state the ACRs would stay closed. From a practical standpoint it's probably not an issue as suggested by the fact that many Ranger/Cutwaters are fitted with AGMs and ACRs. I only mentioned it because we were down in the weeds of detail and when troubleshooting etc. it might be relevant.

 

[captstu]

The ACR manual from Blue Sea says the ACRs open at 9.75 volts. How does this specification relate to the observations above?

My batteries only disconnect when one or more are very low due to no sun and no battery charger for several days. Then, no amount of charging of the house and engine batteries brings the thruster batter back into the overall buss. Once the thruster disconnects because it drops below 9.75 volts for a while, it is a goner until I bridge the thruster to the house with a wire for a few seconds. Then the ACR cuts in and charges the thruster.

This is not only counterintuitive, it isn't what we would want. Once low, always low. The only way to get it back is to plug into a/c power or start the generator and run the battery charger to bring the thruster above 9.75 - then the engine generator does the rest.

Clearly, the isolator in the Ranger-supplied schematic does a far better job of recovering if a battery becomes low for some reason. On the other hand, my boat, with two factory ACRs wired, it seas, as Blue Sea suggest, does a better job of splitting the thruster load among the banks.

 

[NorthernFocus]

The ACR manual from Blue Sea says the ACRs open at 9.75 volts...

Stuart, presumably the 9.75 above is a typo? The current BlueSeas literature lists the Low Lockout voltage as 9.5V. However the vintage that you have in your boat(assuming they haven't been replaced with a post 2012 model) lock out at 10.8V. This low voltage lock out is to protect the rest of your system from a bad battery. 10.8 is considered zero charge on a 12V lead/acid battery. Blue seas lowered the floor to 9.5 presumably due to customer feedback. If you've been routinely seeing your thruster batt drop that low, then it's pretty much DOA.

...My batteries only disconnect when one or more are very low due to no sun and no battery charger for several days....

Maybe it's just the use of terminology. But strictly speaking this is not correct. Consider:

When the relay is closed the two connected batteries are effectively on the same buss and therefore at the same voltage. The relay opens(i.e disconnects) when voltage(on both) drops below 12.75V. Once the relay opens the two batteries are functioning independently and only then can the voltage levels begin to vary from one another. The relay will not close again to join the batteries unless the relay senses greater than 13V on one of the terminals. Which can only occur if there is a source of charge on one of the batteries, ergo the name Automatic Charging Relay.

... Then, no amount of charging of the house and engine batteries brings the thruster batter back into the overall buss. Once the thruster disconnects because it drops below 9.75 volts for a while, it is a goner until I bridge the thruster to the house with a wire for a few seconds. Then the ACR cuts in and charges the thruster.

This is not only counterintuitive, it isn't what we would want. Once low, always low....

One challenge designing any type of automated system is to build in fail safe features. Pulling a lead acid battery below 10V is not "normal". It is good design to protect the system from sensing voltage that is that low. That is way too low for a healthy/useful battery and would typically indicate a problem. The relays are designed to protect the rest of the system from a dead short or other problem that might be pulling things that low. The point that BlueSeas chose for the fail safe point is 9.5V(10.8 on the older ones). If your battery has been pulled that low and stayed there for any period of time it is pretty much history. Sounds like your solar charger is not adequate to routinely get above 13V to close the relay and charge the thruster before it drops below the lockout threshold.

...Clearly, the isolator in the Ranger-supplied schematic does a far better job of recovering if a battery becomes low for some reason...

That presupposes the isolator is not a simple switching type. Each supply cable would have to run through a diode. But in any case there would likely be some sort of fail safe circuit for extreme low voltage/high load.

... On the other hand, my boat, with two factory ACRs wired, it seas, as Blue Sea suggest, does a better job of splitting the thruster load among the banks.

True.

The system works as designed assuming there is an adequate charge source available. No matter how you design a system the available source of charge has to exceed the demand or the system will eventually crash. As this system is designed, once you tip over the edge the system simply can't recover. If it is a matter of not having enough battery to support the loads during low periods of solar power, then the loads may need to be shifted to the house bank so there is more capacity to last until the sun comes out...

 

[NorthernFocus]

Stuart, on first read I didn't get your point on the schematic vs installed "isolator". Now I think I understand and edited my prior post accordingly. Sorry... :?

 

[captstu]

No problem, Dan. After rereading much of the thread, I see how it is easy for my confusion to become general confusion.

Since I was on a/c power when I ran the tests, the ACRs remained engaged since after I removed the battery, the ACR still saw the charger voltage.

I can see how the engaged ACR provided thruster power even when the thruster battery was not installed.

I can also see how the entire bank of batteries was drawn below the engage voltage (9.75 was not a typo - it is what the manual I read said) when sun was not present for several days.

Finally, since there was load on the thruster battery and it was in the process of old age failing, I can see why the ACRs did not re-engage when the sun came out - the house and engine battery ACR engaged, the solar cells (attached to the house) charged everything but the thruster up and the load on the thruster drew it down further, probably killing the already weak battery.

All works for me.

Now I'm thinking of installing a push button that bridges the ACR so it will re-engage when the same thing happens the next time.

/Stu

 

[captstu]

Here are the photos of the completed project to relocate the thruster battery forward. Unfortunately, I can't figure out how to post them inline.

After years of rocket science, this is beyond me.

So, you can go to the Shearwateer IV photos, look up Battery Relocation and the pictures are there.