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Old 24-06-2017, 11:39   #1
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Explain positive and negative grounding for solar

I've just bought a new Phocos CIS 20 charge regulator for my existing panels. I went to install today and realised that it is a "positive ground" regulator.

I feeling admit I never knew that you could get positive ground regulators.

As I understand, all this means is that the switching, etc, happens on the negative side of the regulator?

I am replacing a Blue Sky 2512ix-HV regulator. I cannot find out if this was a positive or negative grounded regulator. But I'm assuming it was negative for now.

What I would like to know is can I install the new positive grounded regulator in place of the old one (assuming it was negative grounded) and be ok?

Some further info:
- My boat's ground is on the negative side.
- The panels do not have a separate ground (ie the +ve and -ve both go straight to the regulator
- The new regulator has a funny wiring setup whereby the positive from solar, battery, and regulator all join together at one connection

Any help on this would be great!
Cheers
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Old 24-06-2017, 12:32   #2
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Re: Explain positive and negative grounding for solar

I'd say return it, so unusual will be unfamiliar maybe cause a problem down the road.

Googling shows workarounds, but no explanation as to WHY anyone would want positive ground in a mobile context.
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Old 24-06-2017, 12:45   #3
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Re: Explain positive and negative grounding for solar

Quote:
Originally Posted by benzy View Post
I've just bought a new Phocos CIS 20 charge regulator for my existing panels. I went to install today and realised that it is a "positive ground" regulator.

I feeling admit I never knew that you could get positive ground regulators.

As I understand, all this means is that the switching, etc, happens on the negative side of the regulator?

I am replacing a Blue Sky 2512ix-HV regulator. I cannot find out if this was a positive or negative grounded regulator. But I'm assuming it was negative for now.

What I would like to know is can I install the new positive grounded regulator in place of the old one (assuming it was negative grounded) and be ok?

Some further info:
- My boat's ground is on the negative side.
- The panels do not have a separate ground (ie the +ve and -ve both go straight to the regulator
- The new regulator has a funny wiring setup whereby the positive from solar, battery, and regulator all join together at one connection

Any help on this would be great!
Cheers
I'm curious. Why are you replacing the Blue Sky controller?
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Old 24-06-2017, 13:51   #4
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Re: Explain positive and negative grounding for solar

I also have a BlueSky 2512iX.
The only thing I don't like about it is that it puts out a weak carrier on VHF 16 !
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Old 24-06-2017, 15:47   #5
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Re: Explain positive and negative grounding for solar

I am going to go out on a limb here and suggest that it "doesn't matter" at least in the sense that you can easily install the unit in your boat. Just make sure your boat's + wires go to the controller's + ground and your boat's - wires go to the controllers - terminals.

I believe + ground mainly means the controller's chassis is "grounded" to the + side. This would be an issue if you were installing it in a steel or aluminum boat or on a negatively grounded metal panel, but no worries on a fiberglass boat.

That was certainly the issue when I wanted to mount a negative ground radio on my positive ground MGA.
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Old 25-06-2017, 00:14   #6
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Re: Explain positive and negative grounding for solar

Thanks for the replies.

Yes I seem to finding a lot of info that says it doesn't matter. This is also accompanied by talk of it being a "floating" system. Again, slightly beyond me!

I would return it by due to cruising plans, I probably can't get back to the shop. We will see.

I'm replacing the Blue Sky as an experiment. After lots of chat about various elements of each controller, the guy in the shop convinced me that the phocos might perform better. The reason being that the charge voltage on the Blue Sky appears to be 14.2v, whereas the phocos is 14.4v. This, he reckons, will make some difference as it can drive more current into the battery. He might be having me on, but either way it is not an expensive experiment.
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Old 25-06-2017, 04:32   #7
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Re: Explain positive and negative grounding for solar

Absolutely last place to get advice on a technical product is from a retail clerk, nor from someone who stands to gain from you spending money.

Any good controller lets you customize the voltage setpoints, not so common on mains chargers but bog standard on solar.
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Old 25-06-2017, 04:50   #8
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Re: Explain positive and negative grounding for solar

Quote:
Originally Posted by benzy View Post
Thanks for the replies.

Yes I seem to finding a lot of info that says it doesn't matter. This is also accompanied by talk of it being a "floating" system. Again, slightly beyond me!

I would return it by due to cruising plans, I probably can't get back to the shop. We will see.

I'm replacing the Blue Sky as an experiment. After lots of chat about various elements of each controller, the guy in the shop convinced me that the phocos might perform better. The reason being that the charge voltage on the Blue Sky appears to be 14.2v, whereas the phocos is 14.4v. This, he reckons, will make some difference as it can drive more current into the battery. He might be having me on, but either way it is not an expensive experiment.
Here is the Blue Sky manual. It seems you can change the settings for charging.

http://www.blueskyenergyinc.com/uplo...X-HV_rev_b.pdf

I was curious why you'd change a Blue Sky controller, which is a top-quality product, for a second-tier charger like Phocos.
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Old 25-06-2017, 05:52   #9
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Re: Explain positive and negative grounding for solar

Hear what you're saying. Couple of questions to help me figure out what's going on:

In full sun when the Blue Sky says it is bulk charging, what should I expect to see voltage wise on a multimeter across the battery terminals?

In the Blue Sky manual, I can't find anywhere what voltage it is putting in during bulk charge? Or any way manually set this (it says maximum charge set point is 15.5v, but surely it's not actually ever putting in that much?)

Cheers
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Old 25-06-2017, 06:01   #10
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Re: Explain positive and negative grounding for solar

Bulk is CC, constant current, seeking to get to Absorb voltage, actual V at any time is rising with SoC.

Absorb stage is CV constant voltage, declining Amps (supposed to be) until battery is full.

Most charge sources there is just a set Absorb target V, and then a lower Float for after the bank is full.

Monthly or so, depends on the battery, an Equalization, higher voltage routine, should be run manually as per mfg spec protocol.

Most AGM no longer do this last.
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Old 25-06-2017, 06:11   #11
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Re: Explain positive and negative grounding for solar

Quote:
Originally Posted by benzy View Post
Hear what you're saying. Couple of questions to help me figure out what's going on:

In full sun when the Blue Sky says it is bulk charging, what should I expect to see voltage wise on a multimeter across the battery terminals?

In the Blue Sky manual, I can't find anywhere what voltage it is putting in during bulk charge? Or any way manually set this (it says maximum charge set point is 15.5v, but surely it's not actually ever putting in that much?)

Cheers
The bulk charge is not really determined by the controller, but by the battery bank size, state of charge (or discharge really) and the solar panel output. In bulk the controller sends as much current (amps) that the batteries will accept until they get to a certain charge (SOC), then it goes into absorption.

From the manual:

"Bulk Charge
The 2512 will be in Bulk charge when battery voltage is below the Absorption Charge Voltage setpoint. During Bulk the 2512 delivers as much charge current as possible to rapidly recharge the battery and drive battery voltage up to the Absorption Charge Voltage setpoint."

Looking again at the manual, your controller is not like mine (the newer 3000i), which is easily programmable from the display front via a button. You may have to buy an interface for your controller to change the charge settings. Again, from the manual:

"The 2512 contains various user configurable settings all of which are preconfigured at the factory. Most installations require no changes to these settings which are typically suitable for most lead-acid batteries including sealed lead-acid batteries such as Gel and AGM. All software programmable settings require an IPN-ProRemote or UCM to change and are retained if power is lost or the IPN-ProRemote or UCM are used as setup tools only and removed."

Personally, I'd contact Blue Sky (they were prompt with all answers to my questions when I was choosing a controller) and ask them about changing the charge settings. Then I'd take the Phocos back and use the money to buy the Blue sky interface (if indeed you need to change the settings and can't do this without the interface- Blue Sky will inform you). Are you certain the current charge settings are wrong for your batteries? What are the settings recommended by the battery manufacturer?
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Old 25-06-2017, 08:25   #12
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Re: Explain positive and negative grounding for solar

If you add (as I did) the remote, you can program the 2512iX to whatever you want.
I set mine for LiFePo4. 13.8 absorb and 13.2 "float" which is in effect disconnected.
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Old 25-06-2017, 11:53   #13
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Re: Explain positive and negative grounding for solar

Hear what you're saying. Couple of questions to help me figure out what's going on:

In full sun when the Blue Sky says it is bulk charging, what should I expect to see voltage wise on a multimeter across the battery terminals?

In the Blue Sky manual, I can't find anywhere what voltage it is putting in during bulk charge? Or any way manually set this (it says maximum charge set point is 15.5v, but surely it's not actually ever putting in that much?)

Cheers
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Old 25-06-2017, 12:00   #14
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Re: Explain positive and negative grounding for solar

Quote:
Originally Posted by benzy View Post
Hear what you're saying. Couple of questions to help me figure out what's going on:

In full sun when the Blue Sky says it is bulk charging, what should I expect to see voltage wise on a multimeter across the battery terminals?

In the Blue Sky manual, I can't find anywhere what voltage it is putting in during bulk charge? Or any way manually set this (it says maximum charge set point is 15.5v, but surely it's not actually ever putting in that much?)

Cheers
I think it will depend on the state of charge when in bulk. You should see the voltage rising and then the controller should go into absorption when they reach 14.2v. You might no see much in the way of voltage at the terminals until then. Do you suspect the controller isn't charging properly?

I'm really not an expert (hopefully Maine Sail will chime in!), but I went through a few controllers (cheap Chinese and then an Outback PWM) on my original setup, all the while wondering why I didn't see higher voltage. I now know the Outback controller is charging fine, and I see 13.2v (the float charge) as the sun goes down.

How many watts are your panels and what size is your bank (in AH)? Do you run them down overnight?
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Old 25-06-2017, 12:00   #15
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Re: Explain positive and negative grounding for solar

Hmmm I understood that the controller does determine the charge mode based on sensing the voltage on the battery, just like a smart regulator does off an alternator.

Following from this, I thought that when charging, a battery will accept as much current as it can, however the clincher is that a high enough voltage needs to be delivered in order to "push" the current in. The Blue Sky doesn't specify what voltage it uses during bulk charging. As you suggest, I'll contact them and ask.
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