Battery Discharge Question C-28

[Bob/Bradenton]

Had the boat up for me installing the replacement bow thruster leg and the two trim tab actuators, for five days. I left the "House" switch ON for most of the time. No particular need to turn it OFF since I only ran a fan or two during the period. No heavy loads.

When the boat was put back in the water and I went to start the engine (260), the starter clicked but would not turn over.

The House side was completely dead, zero power to the lights, etc.

Turned the Crossover switch ON and it didn't do anything.

The yard put a charger on the House side and the Engine battery side for about 20 minutes, removed the charger, turned the key and the engine started right up. House and Engine batteries working fine. Charged the batteries back at the dock all night and they read this morning, 13.5 after turning the charger OFF for a couple minutes. Just did another voltage check (1 PM) and they are still at 13.5.

I am assuming that I left something ON somewhere in the boat while the House switch was ON and I'll check for that later (removing the positive cable from the battery and testing for mA discharge through the multimeter) but the question is why the House battery set would have an effect on the Engine battery, which I assume was still fully charged since there is nothing to discharge it while the boat was up. I did run the anchor chain out and back but I thought that the windlass got its power from the Thruster battery, not the Engine or House batteries. (The yard charger may not have been needed but they put one on the Engine battery anyway). But it seems as if the dead House batteries brought the Engine battery down to a level where it would not turn over the engine. Is this possible? (The Crossover switch is always OFF).

Just trying to figure out this rather complicated little boat. Comments/Thoughts? Thanks, Bob/Bradenton

 

[Someday*]

I hope you find the source of the problem Bob.

I don't think there as more discussed topic on this board than batteries...it seems to be an ever evolving enigma on the how's and whys of their behavior and their interactions with us humans. 😀

 

[marksandyham]

Was the refrigerator off? The auto bilge pumps in my R-27OB run briefly every few minutes (no float switch) unless you pull the fuses along with the CO and Propane alarms will kill my engine battery after a few days.

 

[Ralf H]

Hi Bob,

Mark has a good point. If leaving the boat for any appreciable amount of time, it's always best to make sure that everything is turned off, or if you need to keep certain things on, that you keep the boat plugged into shore power with the charger turned on. If you do not need to leave anything on, do as mark recommended and pull the fuses for the bilge pumps and any other items on the 24/7 panel so that there is no longer a draw. Just remember that you will not have the pumps available. Not a problem if you are on the hard and have the drain plug pulled, but make sure it meets your preferene when you have the boat in the water. Hope this helps a bit.

Cheers,

Ralf

 

[Bob/Bradenton]

A Followup:

As noted in my original post, upon relaunching the boat (2019 C-28) last week after a couple days up at the yard, the batteries were dead. Both the House and the Engine batteries. (Thruster battery was probably fine). Had them charged and the engine started/ran just fine, full amperage from the alternator.

(Note: Per my "guess" below, the Engine battery might not have actually been dead, just not connected to the engine).

Brought the boat back to my backyard dock but kept the shore power cable unplugged due to an zinc electrolysis issue that I will figure out. Kept the House battery switch OFF and no battery issues.

But for the past two days I kept the House battery switch ON. (Forgot to turn it OFF). Engine and Thruster battery switches were OFF.

This morning I went to test the batteries. Engine: 12.5. Thruster: 12.5. Engine: 7.0

Something discharged the House batteries and I've ordered a Fluke 107 multimeter to test for amperage discharge load, but that's not the immediate issue.

What is, is that it seems that the House batteries are somehow connected to the Engine battery. (I never use the Cross-Over switch so it's always OFF). The engine would not turn over. The House batteries are drawing the Engine battery down enough that it won't turn the engine over. I've got the on-board charger charging the set now.

But the question is: How could the House battery pair be connected somehow to the Engine battery?

Even if the House batteries were completely dead, my thought is that the Engine and Thruster batteries would still be fine and ready to work regardless of the House battery side.

(Need to dig out the old Columbo tapes and look for a clue).

If I were to guess, and since the Engine battery and the Thruster battery both read 12.5 volts this morning and only the House batteries read (dead) at 7.0 volts, it would seem that the engine is using the House battery side as its "starting" power source, not the Engine battery. Just a true guess on that.

Any thought/comments/clues/guesses?

Thanks, Bob/Bradenton

 

[Red Raven]

With the house fully charged try starting the boat with the engine switch off and house switch on. If it starts then somehow they are connected together or miswired.

Curt

 

[Automaticman865]

I would try shutting off all the battery switches then try bumping the engine only seeing if it starts to crank. Then again with each switch separately. Found out that my generator on my cw28 was wired directly to the thruster battery, switch on or off.
Stuart

 

[BB marine]

I have read this thread and tried to understand the issue.

When the engine battery switch is on only does the key fob activate the EVC panel? Yes? No?
If (Yes) what does it show for battery voltage? If (No) The engine battery is not wired to the engine.

When the engine battery switch is off and house bank is on does the key fob activate the EVC Panel Yes? No?
If yes what does it show for battery voltage? If no the house bank is not wired to the house bank.

My gut feeling is you have two things going on. (1) you left your house bank on with the refrigerator on and over a few days the house bank discharged.(2) you have an engine battery that is in marginal condition or a bad connection loose or corroded causing an increase in resistance and requiring more start amps which the battery does not have.

Inspect all battery connections. Put a full charge on all battery banks. Let the batteries set idle for a few hours then load test the batteries to check the battery condition. With limited information about your issue my first conclusion is bad batteries or loose or corroded connections. The fact that your house bank has had full discharge a few times if it is an AGM I would keep a close watch on its condition. AGM batteries perform most reliably when their use is limited to the discharge of no more than 50% of battery capacity. your batteries have been at 100% a few times.

 

[Bob/Bradenton]

Group:
Thanks for all the trouble-shooting comments. Tried them all, lots of switches ON/OFF and cables ON/OFF.

I could not replicate the House batteries having some connection to the Engine battery.

As noted, the issue was that the House batteries were dead, 7 volts. Twice, But the engine battery read 12.5. Tried to start the engine, barely clicked. House battery switch OFF/Engine battery switch ON to try to isolate the Engine battery from the House battery. Seemed to be connected somehow, the House drawing down the Engine battery, for some reason, connected in parallel.

But none of the tests recreated the connection.

Had a very good marine tech guy by this morning to change out the Garmin autopilot pump (warranty) that causes the boat to veer to the Port. A common issue with these. Chatted about the House/Engine battery connection problem.

He asked me if I had an ACR on the boat, yes, there are two. And that was the answer (please correct if this is wrong) to why the charged Engine battery connected to the House battery when the House battery was low. That's the purpose of the ACR, to allow engine charging on all three batteries. Engine first but if the others are low, the ACR closes and allows charging to the other two batteries.

BUT, you are asking, the ACR only closes when there is engine alternator power to the ACR, and when you are trying to start the engine the alternator is not putting out enough electrical charge power to energize the ACR. Yup, you are correct.

But, what if there is another charging source that during the day is constantly pushing power to the batteries without the engine/alternator running? The solar panel on the roof. Regardless of whether the engine alternator is providing power to the ACR, the solar panel is always doing that during the day, therefore, energizing the ACR, if needed.

That's what is causing the connection between the dead House and the charged Engine battery set. The solar panel energizes the ACR.

So, please comment and feel free to shoot holes through this.

If this is the way that all these gizmos are working, a simple battery ON/OFF switch to keep the ACR from transferring power from the Engine battery to the House battery might keep a dead House battery set from drawing down the Engine battery. (Or other suggestions?)

Bob/Bradenton

PS: This is my 55 hour 2019 C-28. Both House AGM batteries are toast. Load tested and they will only hold a 50% charge. Thruster/Engine batteries checked out just fine. My plan is to remove all the AGM's and replace them with normal wet-cell batteries. Easy to monitor over-charging.

 

[Gypsy]

Well, I solved my dead starting battery problem. First, the batteries all checked out fine. From there, we traced the positive and negative cables from the battery to the engine. The positive cable was fine, but the negative cable was loose. The cable ground was fastened tightly to the cable lug, but the cable lug was not tight to the engine. So far, the engine starts each time.

 

[BB marine]

If this is the way that all these gizmos are working, a simple battery ON/OFF switch to keep the ACR from transferring power from the Engine battery to the House battery might keep a dead House battery set from drawing down the Engine battery. (Or other suggestions?)

Sort of!!!

The ACR's will close as soon as one battery reaches 13V for 90 seconds or 13.6 V for 30 seconds at this point any batteries that are wired to the battery banks through a ACR will now be wired in Parallel. As long as the other battery banks are at 11 volts or higher. If a battery bank falls below 11Volts it will no longer be able to link through a ACR because the relay will lock out that battery bank. When all battery banks are at or below 12.7 Volts the ACR open and are not wired in parallel in the circuit. If there is a charging source that brings the batteries up to 13V which in most cases the house bank would be the battery bank that is wired to the solar and the engine secondary. The house bank would need to be at a 13V or higher charge in order to be paralleled to the engine battery. So the chances of the ACR staying closed at 12.5V is not possible unless the ACR is faulty which is a very easy check. Green light on? (closed) Green light off (Open) quick flashing light the ACR is in lockout. If the ACR was failed in the closed position the engine battery would read the same voltage as the house battery bank they would be wire in parallel so consider the house and engine as one battery and the voltage would be the same.In your case 7 volts. You have a reading of 7 volts house and 12.5 engine I find it hard to reason that they are connected through a ACR .The voltages should be the same if that was the case.

If your engine battery is fully charged when you tested it what was the battery voltage? I would assume it would read 12.7 V If it is about 80 percent that would read about 12.5 volts. A 80 % charged battery is marginal to start a D4 Volvo. The battery that is installed is marginal to start the engine when it is at 100%. This has been discussed many times on TugNuts.

Make sure all battery connections are clean and tight. Fully charge the batteries and let them sit as you did when you had your issue. over night with no charge. Then test the battery banks.

If all connections are clean and tight and you install all new batteries I believe your issues will be gone.

Test the ACR easy to do.

 

[Bob/Bradenton]

Brian, Great explanation of how the ACR's work in these boats, thanks. That really helped. When we built our former 40' trawler, everything was manual, nothing automatic, to keep it simple. These are very complicated and complex boats. Perhaps "overly".

As noted, the two House AGM batteries were bad. Tested at 50% capacity. The AGM Thruster and Engine batteries were fine. I suspect that the former owner put the boat up on the trailer for storage and left something ON. Can't drain these very delicate batteries all the way.

So yesterday I replaced all four AGM's with Interstate G-31 wet-cell batteries. Much more forgiving than the AGM's and it's easy to check for overcharging by popping the tops off and if needed, adding some more distilled water. Can't do that with the AGM's.

Had to move the Kisae battery charger from next to the water heater. Very stupid place to put it since you can't ready the display, but now by extending the AC wires, it's next to the Garmin autopilot pump. The specs had to be changed to account for the AGM to Wet-Cell change, and now it's easy to do.

According to the C-28 schematic one ACR takes the power from the Engine battery and connects to the House battery set. The other ACR takes power from the Engine battery and connects to the Thruster battery.

The Engine battery is charged through the Engine DC Switch that connects to the + at the Starter which is also connected to the + at the Alternator.

Blue Seas also has a good explanation of their ACR's:

https://www.bluesea.com/resources/1366

I still don't know why the dead House batteries would pull the Engine battery down unless the ACR engaged just for enough time to kill it. As you noted, that Engine battery needs a lot of current to turn that 260 over so maybe it was down just enough.

The Interstate G-31's were two Deep Cycle ($159/ea) for the House side and a Starting type ($169/ea) for both the Thruster and the Engine start. I wanted the automotive post for these batteries since the threaded stud type was not long enough for all the various cable connections. To adapt the automotive post, I bought "Military" style terminals which has a side area that has a longer threaded bolt for the cables. The standard threaded bolt on these is 2". I used a SS 2 1/2" x 3/8" bolt to allow for more cable connections.

Thanks again...Bob/Bradenton

 

[Alpina]

Group:
Thanks for all the trouble-shooting comments. Tried them all, lots of switches ON/OFF and cables ON/OFF.

I could not replicate the House batteries having some connection to the Engine battery.

As noted, the issue was that the House batteries were dead, 7 volts. Twice, But the engine battery read 12.5. Tried to start the engine, barely clicked. House battery switch OFF/Engine battery switch ON to try to isolate the Engine battery from the House battery. Seemed to be connected somehow, the House drawing down the Engine battery, for some reason, connected in parallel.

But none of the tests recreated the connection.

Had a very good marine tech guy by this morning to change out the Garmin autopilot pump (warranty) that causes the boat to veer to the Port. A common issue with these. Chatted about the House/Engine battery connection problem.

He asked me if I had an ACR on the boat, yes, there are two. And that was the answer (please correct if this is wrong) to why the charged Engine battery connected to the House battery when the House battery was low. That's the purpose of the ACR, to allow engine charging on all three batteries. Engine first but if the others are low, the ACR closes and allows charging to the other two batteries.

BUT, you are asking, the ACR only closes when there is engine alternator power to the ACR, and when you are trying to start the engine the alternator is not putting out enough electrical charge power to energize the ACR. Yup, you are correct.

But, what if there is another charging source that during the day is constantly pushing power to the batteries without the engine/alternator running? The solar panel on the roof. Regardless of whether the engine alternator is providing power to the ACR, the solar panel is always doing that during the day, therefore, energizing the ACR, if needed.

That's what is causing the connection between the dead House and the charged Engine battery set. The solar panel energizes the ACR.

So, please comment and feel free to shoot holes through this.

If this is the way that all these gizmos are working, a simple battery ON/OFF switch to keep the ACR from transferring power from the Engine battery to the House battery might keep a dead House battery set from drawing down the Engine battery. (Or other suggestions?)

Bob/Bradenton

PS: This is my 55 hour 2019 C-28. Both House AGM batteries are toast. Load tested and they will only hold a 50% charge. Thruster/Engine batteries checked out just fine. My plan is to remove all the AGM's and replace them with normal wet-cell batteries. Easy to monitor over-charging.

I had a different but similar issue. House and Thruster batteries where low. Engine fine. I couldn’t understand why. I suspected that it had to do with the solar panel providing sufficient voltage during the day to keep the ACR engaged but not enough amps to keep the batteries from being drained through use of the fridge, etc. It was a cloudy day. That’s my theory at least. I plan on testing that tomorrow. Will report back.


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