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Blue Seas ACR "pulsing" ?

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Old 09-14-2018, 10:32 AM
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Default Blue Seas ACR "pulsing" ?

I know there are a number of ACR threads already, so sorry for the duplication. I installed the ACR about 2 months ago, per the manufacturer's diagram, between my port engine alternator and the house batteries. Seems like everything lights up OK when the engine is running and it's been keeping the house batteries at about 12.5 volts while we're running (off the plug, inverter running the house loads). However, while the engine is running (i.e., supposed to be charging the house batteries thru the ACR), the port volt meter pulses between 12.5 and 13.2 volts about every 1-2 seconds. Is that the ACR opening and closing ? I thought it would close when the alternator output voltage was greater than the house batteries, and it would stay closed. Is this normal operation or is something amiss ? Thank you !
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Old 09-14-2018, 11:16 AM
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Some chatter is normal as the voltages equalize, but the timers in the ACR should eliminate most of it. If you see it a few times when first started then it stops, I would say it sounds normal. If it does it the whole time, something is wrong - bad connection, etc.
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Old 09-14-2018, 12:30 PM
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OK, thanks Paul--it goes on the whole time we're running, so I'll check it ASAP. Didn't think it was normal.
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Old 09-14-2018, 12:41 PM
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Originally Posted by geomike View Post
OK, thanks Paul--it goes on the whole time we're running, so I'll check it ASAP. Didn't think it was normal.
Iíd call Blue Seas, because as stated, I think there should be an internal timer that would keep it from pulsing that quickly even if it did have an issue where the house bank charging load was able to drop the voltage low enough for it to close the ACR.

If itís not an ACR problem, then the opening and closing would mean (I believe) that the load on the house bank is higher than your alternator output, which seems unlikely.
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Old 09-14-2018, 01:37 PM
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Something seems wrong with the voltages you are seeing. They seem too low. I think the ACR is simply reacting to what it sees.

The output of the engine generator, or a battery charger, is nominally 14.5 volts. A fully charged battery is nominally 12.7 volts. As soon as the battery starts the motor the generator should bring the voltage at the starting battery up to ~14.5 volts. At which time the ACR will parallel the batteries. If the voltage drops below the set point of the ACR then the ACR will disconnect the batteries. The voltage will then come up on the start battery and when the set point is reached the two batteries will again be paralleled.

If the house battery is mostly discharged the ACR may cycle for a brief period of time but normally after a few cycles the batteries will remain paralleled in which case each will be getting charged based on what each battery needs.

You should be seeing engine driven generator voltage output of about 14.5 volts on the starting battery at all times. If not, something is amiss. The low voltage is causing the ACR to do exactly what it is supposed to be doing.
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Old 09-14-2018, 03:00 PM
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Maybe draw us a diagram of your setup. The way you describe how it is connected makes me wonder if it is connected properly.
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Old 09-14-2018, 03:10 PM
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I'm with Basketcase, it doesn't sound like you're wired correctly.
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Old 09-14-2018, 03:18 PM
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Are you sure itís not a problem with the engine? Your symptoms pretty much match what my engine was doing when the rectifier went.
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Old 09-14-2018, 03:25 PM
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I think it's going to come down to how it's wired, what size batteries are on the house system and what kind of load are you trying to run off of the inverter? It could very well be that you are trying to run more of a load then the batteries and alternator can handle.
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Old 09-14-2018, 03:48 PM
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Originally Posted by Clinker View Post
Are you sure itís not a problem with the engine? Your symptoms pretty much match what my engine was doing when the rectifier went.
Yep, sounds like the electrical system cannot keep up with the demands of the batteries when they are paralleled by the ACR.
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Old 09-14-2018, 04:33 PM
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What size engines? Some smaller engines don't have enough alternator output to quickly stop the chattering if the house batt is low..
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Old 09-14-2018, 04:56 PM
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What size WIRES are going to your ACR? If they are too small and you have a big load on the house battery, then this can happen due to voltage drop. Even though the alternator is putting out >13.6VDC, by the time it gets to the ACR and then to the battery, it sounds like it's at 12.5VDC, WHICH IS ACTUALLY NOT CHARGING THE HOUSE BATTERY. You need to be at least at 12.6 at the battery. Where are you measuring the 12.5? If it's somewhere 'downstream', then that might be OK, but my guess is if you measure the voltage RIGHT AT the ACR, then you're not going to be seeing >13.6 because you're drawing a big load.

FIRST, make sure that your alternator CAN handle the big loads on your house side. Then, check what gauge wires you're using and perhaps go up to a #6 or larger, depending on length.
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Old 09-15-2018, 03:20 PM
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I spent some time on this today, with a couple of voltmeters to watch the input and output sides. Here is a drawing of the current wiring setup....

Sorry for the quick drawing--I don't think I'm going to spend a lot more time on this (explained below). This is a 350 Crusader engine with the stock 65-amp alternator (I think)...nothin' special; it's on a 1976 Silverton 31.

I measured voltage between engine ground and alternator (+) at the starter/battery connection, with engine running -- 14.46 volts. I measured voltage between engine ground and the ACR "out" with an actual voltmeter (not a digital) -- 13.3 volts, STEADY. Meanwhile, the instrument-panel voltmeter is still showing the 1-second "pulse". I made these measurements with hardly any house load (a fan) and with a heavier load (coffee pot).

So based on the measurements directly at the alternator and ACR, the voltages in and out are steady and appear to be sufficient to charge the house batteries while underway. I still have no clue what the pulsing is from but it seems to me that it's unrelated to the alternator/ACR setup. Aside from installing some heavier-gauge wires all around (I think the current ones are 10 or 12-gauge), I think I will leave it as-is. Thanks to everyone for your input.
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Old 09-15-2018, 03:59 PM
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You could run the ACR wire to the starboard engine and see if you get the same result. Maybe your port voltmeter is screwy. I'm going to assume you have 3 batteries on your house bank, wired correctly in parallel, and that they are all good.
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Old 09-15-2018, 06:27 PM
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Couple of observations -
1) If you are measuring 14.46v at one point and 13.3v at another and there is only wire plus the ACR between those two points then you do have a problem and it is seriously affecting how your house batts charge. 13.3V will charge the batteries incredibly slowly. 13.2V is the 'float' or 'sustain' voltage for lead acid batts if you leave them on a charger long term. I would do a bit more digging about where you are losing that voltage. With no significant loads turned on, with the house batteries already charged, engine running and ACR activated you should see very little voltage difference between the +ve terminal of the start batt and the +ve terminal of the house batt. A difference of over 1V is not right.
2) I guess your drawing is wrong but it shows a 3A fuse between the ACR and the House Batts? That fuse needs to be somewhere near the amp rating of your alternator with matching wire size. If the ACR is working and that is a 3A fuse then it should blow every time you turn the engine on.
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Old 09-15-2018, 07:57 PM
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Aliboy has a valid point. It doesn't seem right that the ACR is consuming 1.1 volts to close. I'd double check the ground wire going to the ACR and make sure the wire and both end connectors are good. Blue Seas seems to be a good company to deal with, I would certainly give them a call if you can't locate the problem.
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Old 09-15-2018, 11:38 PM
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10/12 gauge wire is to small for battery charging, I would recommend a minimum of 6 gauge. And as posted above 3 amp fuse is not right, maybe you meant 30 amp? Which is still to small but may work.. if that fuse is actually an auto circuit breaker that could be the problem.
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Old 09-16-2018, 06:28 AM
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Maybe your alternator amps cant keep up with the battery, so when ACR clicks on, it creates a volt drop and it clicks off, then when off volts rise again, and it clicks on again, over and over.
Perhaps check alternator ground to block and all wiring and verify alternator and batteries are ok.

And if wire gauge is too small, that will cause a big voltage drop for a battery charging, which could click off the ACR.

Last edited by sdowney717; 09-16-2018 at 08:51 AM.
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Old 09-16-2018, 09:11 AM
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I have an inverter, a huge house battery, four motors and currently ACR's installed. I am pulling the ACR system off the boat this week as they can not handle the load. If I shut down two motors my breakers start flipping and it takes hours to get them to stick again. I am installing four of these -
https://www.victronenergy.com/batter...tery-isolators
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Old 09-16-2018, 12:43 PM
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Originally Posted by Sarasota Line X View Post
I have an inverter, a huge house battery, four motors and currently ACR's installed. I am pulling the ACR system off the boat this week as they can not handle the load. If I shut down two motors my breakers start flipping and it takes hours to get them to stick again. I am installing four of these -
https://www.victronenergy.com/batter...tery-isolators
This doesn't make a whole lot of sense to me. When the engines are shut down, what do the ACRs have to do with anything? Which breakers start flipping?

I'm also curious how you're going to wire one of the victron isolators to four different motors. Did you have four ACRs (one from each motor)?

You want the wire size from the 'source' to the ACR to be rated at least as large as the ACR can handle. On the output of the ACR, you can use a smaller gauge, knowing there will be some voltage drop. Sounds weird, but sometimes this is an advantage. If you want to limit the current draw on the source, the smaller gauge wire will create enough voltage drop to limit the total current it can draw... thereby protecing your alternator(s) from excessive draw. Once the draw is diminished, then the full voltage will be available to fully charge the battery. This will also allow the ACR to work correctly sensing the voltage and properly switching 'on' when it's supposed to.

Last edited by km1125; 09-16-2018 at 12:54 PM.
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