Electrical Assistance

[dlochner]

In addition to what @LeslieTroyer pointed out:

The 2AWG cable is probably a little light. While the allowable max amperage out side an engine room is 210 amps and there is a 200 amp fuse and a 75 amp breaker, however between the batteries there is no over current protection and it could potentially draw 275 amps before over current protection interrupted the circuit. If one circuit drew 175 amps and one drew 50 the current draw would exceed the ampacity rating for the 2AWG wire without tripping any breaker or blowing a fuse.

Because of the size and lengths of the cables, between the first and last battery there could be a 1% voltage drop at a 75 amp draw. Here's a calculator that will help out: http://www.genuinedealz.com/voltage-drop-calculator There would be another 1% drop between the inverter and the battery bank.

All charging sources should go to the house bank. The temperature sensor should go to the bank being charged, i.e., the house bank.

I don't think you need both an ACR and an Echocharger, while different devices, I think they serve the same purpose. See this article: https://marinehowto.com/automatic-charging-relays/

The way the batteries are currently wired, they are only sort of in parallel. Think of the path an electron takes as it leaves the battery and travels through the system. As yours is currently wired, the electron only needs to leave Battery 1 go through the circuit and return to Battery 1, it never goes near the rest of the batteries. This means the batteries will become unbalanced as Battery 1 will be used more than the other batteries. The right way is for an electron to leave Battery 1 go through the circuit and return to Battery 4 and pass through Batteries 3 and 2 before entering Battery 1 and leaving the circuit again. In this way all the batteries are used evenly and they stay in balance.

 

[Davidasailor26]

I also agree with Leslie and dlochner. As for your ACR issue - I'd recommend a volt meter to help troubleshoot that. I don't know what voltage threshold the ACR should have and of it has any extra timeout, but my guess is that after you turned off your charger the batteries still had enough of a surface charge to stay above the ACR threshold. If you put a volt meter on one of the batteries and watch the voltage I'll bet that the ACR disconnects once the voltage falls below some predictable level.

 

[LeslieTroyer]

@Davidasailor26
Here are the voltages for the BS so-ACR

 

[Head Sail]

Mike:
Good diagram of what you currently have. Now with all the good inputs above, you need to decide what you want. Mainsail had great top level diagrams but I only have the one that I used. Here is the one I used...
http://c34.org/bbs/index.php/topic,8790.msg62933.html#msg62933

Looks like you don't have a 1-2-B switch in your system. I like it because it was already there. It allows me to set it to #1 battery (house) and leave it there 99% of the time.
As others have said, the Echo charger is redundant with the ACR. You shouldn't need both. Also, my ACR LED stay's on for longer than 10 minuets when engine turned off. Not an issue since it depends on the charge it sees, not time.

 

[LeslieTroyer]

I assumed the “echo” was a second output from the charger. As such it’s not necessary, but doesn’t hurt anything.

Les

 

[Davidasailor26]

@Davidasailor26
Here are the voltages for the BS so-ACR
View attachment 161973

Thanks Leslie. If I'm interpreting it right that means the ACR keeps combining until the voltage is below 12.75 for 30 seconds. If so then the behavior Mike saw makes sense to me. After being charged the batteries were probably still just sitting above 12.75 until the larger load of the inverter was added.

 

[LeslieTroyer]

Thanks Leslie. If I'm interpreting it right that means the ACR keeps combining until the voltage is below 12.75 for 30 seconds. If so then the behavior Mike saw makes sense to me. After being charged the batteries were probably still just sitting above 12.75 until the larger load of the inverter was added.

Yes - or below 12.35 for 10 seconds. Whichever happens first.

 

[MikeHoncho]

Thanks for clarifications

• 200 amp fuse at charger should be 7” to battery not at charger. You fusing the wire to the charger/inverter. Other direction is self limiting.

This is easily fixed and will do so.

• Alternator and charger to house not start

I'm going to add a on/off battery switch in the engine compartment and run the alt to it then to the house bank. Should there be a fuse on the alt side and the battery side of the circuit? If so what size of each?

• Hard to tell but should pull positive and negative from batteries at opposite ends of chain only. (Relocate house ground to engine to other battery)

Ok, I've been waiting for this one....So with any of the charge methods, should the + lead be on one side of the battery bank and the - lead be on the other?

• Alternator output blown diodes if crank disconnected while running.

The alternator is giving output when spinning. I can see it on my volt meters on the panel.

• No way to crank from house only or house+crank

I'm going to add a 12B switch near the SI ACR and run a circuit to bypass the SI ACR for emergency battery power to the starter from the house bank. I'll add a 300 amp fuse to the battery side of the circuit.

 

[MikeHoncho]

In addition to what @LeslieTroyer pointed out:

The 2AWG cable is probably a little light. While the allowable max amperage out side an engine room is 210 amps and there is a 200 amp fuse and a 75 amp breaker, however between the batteries there is no over current protection and it could potentially draw 275 amps before over current protection interrupted the circuit. If one circuit drew 175 amps and one drew 50 the current draw would exceed the ampacity rating for the 2AWG wire without tripping any breaker or blowing a fuse.

I need a little help understanding this. Would adding fused to each positive post fix this?

 

[Davidasailor26]

Should there be a fuse on the alt side and the battery side of the circuit?

Not critical to have one on the alternator side. Definitely fuse at the battery since it can provide much more current than your wire would handle. The alternator can only produce so much current, so it's not really necessary to fuse at that source. I think the fuse guidance on that would be about 1.5x the alternator's max output.

So with any of the charge methods, should the + lead be on one side of the battery bank and the - lead be on the other?

Yes, for both charging and load the + should be at one end of the parallel bank and the - at the other.

The alternator is giving output when spinning. I can see it on my volt meters on the panel.

What he means is that if you accidentally switch that "2 pole switch" to Off while the engine is running you will damage the alternator. Better to not have a switch between the alternator and battery bank for that reason. Some would recommend an alternator disconnect switch only for disconnecting the alternator when it's off and being serviced, but you don't want something that could be accidentally bumped when running.

I'm going to add a 12B switch near the SI ACR and run a circuit to bypass the SI ACR for emergency battery power to the starter from the house bank. I'll add a 300 amp fuse to the battery side of the circuit.

Makes sense. Also be sure to bypass the 125A fuses that are already there. The only downside of this approach is that if the Crank battery shorts internally and drops to a very low voltage you still don't have an easy way of taking it out of the circuit. For that reason it's a little better to jump from the output of the 2 pole switches that you show, but in your case that would introduce other problems with where your fuses are and maybe wire sizes. Given that trade-off what you suggest is probably the best way to go. In the unlikely event that your crank battery does short internally and you can't start the engine, just disconnect it at the terminal.

 

[MikeHoncho]

Not critical to have one on the alternator side. Definitely fuse at the battery since it can provide much more current than your wire would handle. The alternator can only produce so much current, so it's not really necessary to fuse at that source. I think the fuse guidance on that would be about 1.5x the alternator's max output.

Yes, for both charging and load the + should be at one end of the parallel bank and the - at the other.

What he means is that if you accidentally switch that "2 pole switch" to Off while the engine is running you will damage the alternator. Better to not have a switch between the alternator and battery bank for that reason. Some would recommend an alternator disconnect switch only for disconnecting the alternator when it's off and being serviced, but you don't want something that could be accidentally bumped when running.
Makes sense. Also be sure to bypass the 125A fuses that are already there. The only downside of this approach is that if the Crank battery shorts internally and drops to a very low voltage you still don't have an easy way of taking it out of the circuit. For that reason it's a little better to jump from the output of the 2 pole switches that you show, but in your case that would introduce other problems with where your fuses are and maybe wire sizes. Given that trade-off what you suggest is probably the best way to go. In the unlikely event that your crank battery does short internally and you can't start the engine, just disconnect it at the terminal.

Thank you sir!

 

[MikeHoncho]

Of the fuses out there I like MBRF but ANL are a close second. You need both the amp rating and a very high fusable rating (1000+ Amp). Both these fuses meet that spec

The 125 amp fuses are the Blue Sea MBRF's

 

[dlochner]

I need a little help understanding this. Would adding fused to each positive post fix this?

Increase the cable size to handle the load. The jumpers on my batteries are 2/0 cable.

As for fusing, always place the fuse close to the unregulated power source, i.e., the battery. Chargers, Alternators, Solar etc are all limited and regulated so you can't get a run away current.

 

[Maine Sail]

#1 Read the article below so you fully understand the ACR as it really should be set up on a cruising boat with disparate size banks:
Making Sense of Automatic Charging Relays (LINK)

#2 House bank, at a bare minimum because it is an ABYC requirement and may not pass an insurance survey, needs over current protection within 7" of bank positive. Contrary to popular misconception there is no such thing as being "grandfathered", because your boat is old, in an insurance survey. Unless your start cable is fully protected in a sheath it too should ideally be fused. 250A to 300A bare minimum for any bank that could ever be used for engine starting.

#3 You have isolated the house and start banks and the ACR has 125A fuses but you are not showing the Blue Sea "SI" or Start Isolation circuit being wired. Again, read the above article so you don't trip your 125A fuses during starting when the banks are combined. The fuses in the ACR wires are there to protect the wire not the ACR. If you install main bank fusing the ACR wires can share those fuses, saving fuse & holder money, if the wire is the same size. This stuff is in the article above.

#4 If you have an ACR there is no need for the Echo charger on your inverter/charger to be used and that wiring is redundant. The ACR works with any and all charge sources the in-built Echo charger, in the inverter/charger, only works with the inverter / charger.

#5 Inverter / charger temp sensor should be on house bank negative terminal on a battery with the highest chance of getting warmer than the others.

#6 Inverter positive should be on opposite end of bank. All negatives should come off one end of bank and all positives off the other.

#7 Alternator should be wired direct to house bank and have a fuse in that wire within 7" of the banks positive terminal. (in the article above) Feeding charging to the smaller bank is a less than ideal situation with an ACR on a cruising boat and it can actually become problematic. (all in the article above)

#8 You still have no emergency or redundancy provisions in your bank switching design. My friend who does marine towing and salvage loves switching/wiring like this, it earns him good money. Dead batteries are still one of his top service calls...

#9 Your alternator can still be toasted if someone flips the start battery switch off with the engine running.

#10 2AWG is a bit light by today's standards for bank wiring. Most builders today are using 1/0 or 2/0 as a bare minimum to comply with over-current protection requirements. 105C 2AWG can really only be fused, at 100% of ampacity tables, at 210A (not in an engine space) but this is 105C wire and many builders used 90C or 75C wire. In some instances it is allowable to go to 150% of ampacity tables which would mean you could use a 300A main bank fuse. This is less than ideal but, any fuse, provided it does not nuisance trip, is safer than no fuse at all.

#11 Because your house bank is split with a 3' length of cable that positive wire will crossing the green-dahs line will need protective sheathing eg: conduit or loom, or a fuse at either end of that one wire.. Keep all bank jumpers only as long as they need to be. This means just a slight curve in the wire between terminals.