Blue Sea ACR Wiring Question

[Tiktaalik]

Very helpful. Thank you! I will certainly test and report back. It may take a little while as I have been having alternator issues and my alternator just died. I had the stock alternator rebuild 13 months ago to 80A. The regulator died in July and about a week ago it started flickering and last week the alternator died. It's currently not charging at all so I ordered a remanufactured Bosch replacement (55A) which is stock. It arrives tomorrow. I plan to pull the rebuilt one and install the new one and see how that goes. Next Sunday I leave on a 1-week, 1000 mile road trip to some pretty remote parts, so hopefully I get it all sorted before then.

 

[Scott B.]

Bringing this thread back! So I never installed the dual battery system in my Defender but I am getting close to installing it in my Mercedes 300GD with two Odyssey 34-PC1500 batteries. My question to the experts out there is related to the alternator. I just ordered a remanufactured stock alternator rated at 55A. This is less amps than what is common today. Will the 55A alternator be up for the task in properly charging these two batteries?

Look on the battery label - it will say what the recommending charging voltage is. I believe it is 14.5v or so.

Your alternator, at 13.9v, will never charge the Odyssey to full charge.

Search for "schottky diode". There are various ways to use one of these (depending on your vehicle's electrical design) to increase your charge voltage.

 

[Tiktaalik]

Thanks Scott!

The Odyssey 34-PC1500 label says:
Cyclic Charge Voltage: 14.4 - 14.8v @25C
Float Charge Voltage: 13.4 - 13.8v @25C

Apparently there are adjustable regulators that allows you to set the voltage output you want. I'm just going to take my rebuilt alternator in for repair and add an adjustable regulator to it that is set to 14.8v.

Look on the battery label - it will say what the recommending charging voltage is. I believe it is 14.5v or so.

Your alternator, at 13.9v, will never charge the Odyssey to full charge.

Search for "schottky diode". There are various ways to use one of these (depending on your vehicle's electrical design) to increase your charge voltage.

 

[Scott B.]

Thanks Scott!

The Odyssey 34-PC1500 label says:
Cyclic Charge Voltage: 14.4 - 14.8v @25C
Float Charge Voltage: 13.4 - 13.8v @25C

Apparently there are adjustable regulators that allows you to set the voltage output you want. I'm just going to take my rebuilt alternator in for repair and add an adjustable regulator to it that is set to 14.8v.

Using an adjustable regulator should work for you just fine.

BTW, I am running 2 of those Odysseys in my Tacoma.

 

[Tiktaalik]

I thought I'd share my little rainy sunday project from last week. I designed a dual battery tray insert that mounts in to the existing holes of the Mercedes W460 battery tray. The sides will act as a heat shield as well as mounting point for my Blue Sea Systems Automatic Charging Relay, fuses and power posts. Looks like two Optima 34-PC1500 will fit fine and allow clearance for my air cleaner.

I also have a novice wiring question for you all.

I am planning to install a digital dual battery monitor gauge that I bought. I have heard you'd want to wire the gauge directly to the batteries for the most accurate reading so I was going to run the three wires (two positives and a ground) directly to the batteries. However, I don't want the gauge to be on all the time, only when ignition is on. Whats the best way to go about this? I was thinking of running them to a dedicated (ignition circuit) on my new aux fuse panel that I am installing but then I would need to take up two circuits (one for each battery), right? Am I overthinking something that in the end is really simple?

 

[Tiktaalik]

I don't know if they need a dedicated fuse. What say the experts? An inline fuse is a another option. As I understand it, each battery will need to be connected to a circuit specific to each battery in order to monitor that battery correctly. If a bunch of other appliances are on that circuit, how accurate will that voltage reading be?

 

[DaveInDenver]

I don't know if they need a dedicated fuse. What say the experts? An inline fuse is a another option. As I understand it, each battery will need to be connected to a circuit specific to each battery in order to monitor that battery correctly. If a bunch of other appliances are on that circuit, how accurate will that voltage reading be?

It'll indicate voltage at the appliance. There's value to making the measurement at either end. There is no right or wrong since it depends on why you want to know the voltage and what you intend to do with it.

 

[Tiktaalik]

I want to know the most accurate voltage reading at the point of each of the two batteries without interference of other appliances, losses or draws.

I don’t know if standard practice is to have a gauge of this type to be fused. If its advised then I will. I’m leaning towards an in-line fuse for each positive wire going to each battery instead of using my shiny new aux fuse panel.

What throws me off is having each of the two circuits (to each of the two batteries) only turn on when the ignition is on. How does one go about doing that without tapping into an existing circuit or adding two new circuits to my new aux fuse panel. Is there a third way? What’s the cleanest and most simple way to do it?

It will be as accurate as the voltage available to that circuit when its under load.
If you want to know precise voltage at the battery, Maybe its best to connect directly to the battery, nevermind losses downstream.
Btw, If you do connect your voltage measuring circuit to a shared fuse at your loadcenter, Be sure OCPD of the shared circuit is not oversize for the voltage measuring conductor.

 

[Tiktaalik]

It’s a simple and cheap, Chinese digital dual battery volt meter that I bought off of eBay. I bought so I can monitor the voltage of each battery in real time. Just curious if anyone else have installed a dual battery voltmeter gauge and how they went about doing it.

It'll indicate voltage at the appliance. There's value to making the measurement at either end. There is no right or wrong since it depends on why you want to know the voltage and what you intend to do with it.

 

[Tiktaalik]

What’s the alternative? Why would you want the gauge lit up all the time, even when the engine is off? My plan was to have the gauge turn on at position 1 on the ignition so the motor wouldn’t be running but all dash accessories turn on. Position 2 is motor running and Position 0 is off.

Has anyone else here installed a dual battery volt gauge? If so, how did you wire it up? Why do I feel like I am the first person to ever do this?

Btw, it seems odd wanting the battery monitor controlled by ignition.
If motor is running, presumably the system is charging from alternator. You wont get accurate battery voltage / state of charge readings.

 

[luthj]

I generally would wire the gauge so that a momentary push button supplies power. If the ignition power is desired that can be wired up as well depending.

Does the gauge have separate power and sense wires? If so run the sense wires directly to the batteries, and don't worry about where the power wires go, just use a convenient source.

 

[dwh]

Have whatever ign position you want operate a relay. Have the relay switch the common ground of the gauge. Turn on key, both batts' voltage displays.

Connect the gauge hots to the batts. Use a 1a or 3a fuse on each hot. Measuring the voltage doesn't use much amperage at all.

 

[Tiktaalik]

That’s it!

That’s my preferred option!

Thank you!

The digital dual volt gauge I have has two hot (+) and one shared ground (-) contact on the back of it.

Have whatever ign position you want operate a relay. Have the relay switch the common ground of the gauge. Turn on key, both batts' voltage displays.

Connect the gauge hots to the batts. Use a 1a or 3a fuse on each hot. Measuring the voltage doesn't use much amperage at all.

 

[Tiktaalik]

What kind of relay would you recommend for something like this?

Preferred brand and rating?

What is your preferred online source for electric supplies?

 

[luthj]

Standard ISO relays work fine for applications with engine power. They pull 200-600mA, but thats not a problem with the engine running. They are a decent type to standardize around.

https://www.amazon.com/Nilight-Automotive-Harness-Interlocking-Socket/dp/B0748F1JK4/ref=sr_1_1?keywords=iso+relay&qid=1570199376&sr=8-1