PG 20 Wiring Critique

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fallguy1000
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Re: PG 20 Wiring Critique

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Looks good to me then.
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APLJaK
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Re: PG 20 Wiring Critique

Post by APLJaK »

FluidDynamic wrote: Tue Jan 19, 2021 5:27 pm But you also need to fuse the connections from each battery positive to the ACR which is missing in FluidDynamics diagram. Those fuses are larger because it's much larger wire.
Thanks for ponting this out. I didnt see it.

I'm trying to figure our what size fuse now.
ACR fuse is based on engine charging amps. A #6 fused at 75-90 amps will cover all but the largest engines (60 amps charging).
Blue Sea provides details:

Blue Sea ACR wiring

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Re: PG 20 Wiring Critique

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FluidDynamic wrote: Tue Jan 19, 2021 5:20 pm
fallguy1000 wrote: Tue Jan 19, 2021 5:02 pm Okay, take me with a grain of salt.

But y fuse on the ground side of the acr?

Okay. It looks right based on a review of a couple googles. Ain't sayin I understand fusing it.
I thought the same thing about the fuse.
Blue sea answers this as well. I had a similar question so went looking

https://www.bluesea.com/resources/540/A ... Connectionwhy fuse ground on ACR?

"Automatic Charging Relays (ACRs) are connected to engine and house battery banks through large conductors. In the unlikely event that there is a fault in the ACR internal circuitry that allows fault current to flow from the high powered positive leads to the negative reference wire, the negative reference wire may have to carry more current than it is capable of and can overheat. The wire is typically rated for 20A; the normal current in this wire is less than 1 ampere.

A 10-15A fuse in the negative wire can prevent excessive current from flowing in the wire leading to overheating or possible fire. In-line AGC or Blade fuses are suitable. Place the fuse in a location not subject to flammable gas and use a sealed fuseholder.

All ACRs are vulnerable to ground faults flowing through the negative connection. This includes ACRs from other manufacturers. Refer to the wiring diagram for the location of the negative wire and install an in-line fuse in it.

Follow these specific instructions for each Blue Sea Systems' ACR:

7610/7650
Connect the quick connect terminal marked GND (ground) through a 10-15A in-line fuse to the main negative bus or negative terminal of the nearest battery."

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BarraMan
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Re: PG 20 Wiring Critique

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Personally I wouldn't use an ACR! I know of two boats that have almost been lost when an ACR burnt! I use DC - DC chargers only in my boat.

fallguy1000
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Re: PG 20 Wiring Critique

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APLJaK wrote: Wed Jan 05, 2022 7:56 pm
FluidDynamic wrote: Tue Jan 19, 2021 5:20 pm
fallguy1000 wrote: Tue Jan 19, 2021 5:02 pm Okay, take me with a grain of salt.

But y fuse on the ground side of the acr?

Okay. It looks right based on a review of a couple googles. Ain't sayin I understand fusing it.
I thought the same thing about the fuse.
Blue sea answers this as well. I had a similar question so went looking

https://www.bluesea.com/resources/540/A ... Connectionwhy fuse ground on ACR?

"Automatic Charging Relays (ACRs) are connected to engine and house battery banks through large conductors. In the unlikely event that there is a fault in the ACR internal circuitry that allows fault current to flow from the high powered positive leads to the negative reference wire, the negative reference wire may have to carry more current than it is capable of and can overheat. The wire is typically rated for 20A; the normal current in this wire is less than 1 ampere.

A 10-15A fuse in the negative wire can prevent excessive current from flowing in the wire leading to overheating or possible fire. In-line AGC or Blade fuses are suitable. Place the fuse in a location not subject to flammable gas and use a sealed fuseholder.

All ACRs are vulnerable to ground faults flowing through the negative connection. This includes ACRs from other manufacturers. Refer to the wiring diagram for the location of the negative wire and install an in-line fuse in it.

Follow these specific instructions for each Blue Sea Systems' ACR:

7610/7650
Connect the quick connect terminal marked GND (ground) through a 10-15A in-line fuse to the main negative bus or negative terminal of the nearest battery."
Where did you find that? I installed the acr to blueseas installation and it never said to use a fuse in the ground side...I'm gonna pour back over my install manual..
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fallguy1000
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Re: PG 20 Wiring Critique

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BarraMan wrote: Wed Jan 05, 2022 8:32 pm Personally I wouldn't use an ACR! I know of two boats that have almost been lost when an ACR burnt! I use DC - DC chargers only in my boat.
I already have dc-dc chargers to run power from the engines to the house and an acr to help one engine start the other if one battery is low. It is switched at the helm. Not really sure the acr is not a charger if it it switched by me...all I am saying
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fallguy1000
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Re: PG 20 Wiring Critique

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https://d2pyqm2yd3fw2i.cloudfront.net/f ... 80-005.pdf

Here is my bluesea install manual. Never whispers a word about fusing the ground.
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Re: PG 20 Wiring Critique

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BarraMan wrote: Wed Jan 05, 2022 8:32 pm Personally I wouldn't use an ACR! I know of two boats that have almost been lost when an ACR burnt! I use DC - DC chargers only in my boat.
That's interesting (and scary). An ACR is a pretty simple device. I've never heard of one burning. Do you have any more details?
How do you wire for two batteries charging from the motor? I know some outboards have two DC outputs, but not all.

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BarraMan
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Re: PG 20 Wiring Critique

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APLJaK wrote: Thu Jan 06, 2022 2:47 pm
BarraMan wrote: Wed Jan 05, 2022 8:32 pm Personally I wouldn't use an ACR! I know of two boats that have almost been lost when an ACR burnt! I use DC - DC chargers only in my boat.
That's interesting (and scary). An ACR is a pretty simple device. I've never heard of one burning. Do you have any more details?
How do you wire for two batteries charging from the motor? I know some outboards have two DC outputs, but not all.
1) I have my Start and House batteries connected to a master switch unit (Blueseas, I think) - Start on one master, House on the other, with an interconnect switch which allows both to be connected in parallel so that you can get a start if the Start battery goes flat or fails (I have only ever had to use that once).

2) I have a 12v DC - 12v DC smart charger between the Start battery and the House battery. When the OB is running it charges the Start battery and once the smart charger detects the Start battery is above a certain charge it switches on an directs charge to the House battery. It protects the Start battery by turning off if the Start battery gets below a safe charge.

3) I run a 36v Minn Kota Trolling motor, so I also have a 12v DC - 36v DC smart charger between the House battery and the trolling motor batteries.

So when the OB is running it charges 1) the Start battery, then 2) the House battery, then 3) the Trolling motor batteries.

I run a lead acid Start battery and AGM batteries for the House and the Trolling motor batteries. I have been told that ACRs don't like mixed battery types and smart DC - DC chargers are better between unlike battery types. That is in agreement with my experience.

I don't have much detail on the ACR fires. One was on a mates boat and was a very close call. He discraged his fire extinguisher but it didn't put it out. Buckets of sea water saved the day. The second was one I heard about from a pro fishing guide mate. On boar fires scare me - so I carry 3x extinguishers, two small and one large! :lol:
Last edited by BarraMan on Thu Jan 06, 2022 5:36 pm, edited 1 time in total.

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Re: PG 20 Wiring Critique

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The black ground wire is never fused, it comes from its block strait to the starting battery. All red wires must be fuzed at some point to prevent a surge over electrifiying what they are powering. As far as powering 2 batterie you use a 2 way battery switch. There is a second switch available that will detct when the first battery reaches a full charge and switches to the second battery.

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