Solar Outback 80 programming Tips

[Pelagic]

This is my first solar experience which has been producing now for about 3 weeks.

Happy with the Output which is around 46amps at 24v during peak periods.

However, when my SOC reaches about 90‰ ...the Outback goes into absorbtion phase and I start lo loose SOC, even though my consumers stay the same

I'm getting the SOC from my Victron smart monitor which is synchronized with Victron Multiplus, but that shunt is not connected to Outback, as output cables go direct to batteries..

No shunt on solar so not sure how it is measuring SOC of large house bank ?

Are there any tips/tricks to allow the Solar to keep its output in bulk mode during prime energy periods?

[john61ct]

Nothing measures actual SoC directly, very rarely are such gadgets accurate unless you really know what you're doing in initial commissioning inputs and calibrate frequently.

Bulk vs Absorb, and then amps declining further as SoC climbs

are a function of the lead batts' chemistry, specifically climbing resistance.

Nothing to do with what the regulator controls, i.e. voltage only.

Your choices are

1. Find useful load dumps to use the "free" excess solar once amps decline a lot, e.g. making or heating water, charging eutectic fridge plates, washing clothes, hotpot cooking etc.

2. Add or switch to LFP, or

3. Accept lots of panel output gets "wasted"

[noelex 77]

Originally Posted by Pelagic

However, when my SOC reaches about 90‰ ...the Outback goes into absorbtion phase and I start lo loose SOC, even though my consumers stay the same

During the absorption phase the SOC cannot be going down unless the absorption voltage is set very, very low or the solar output is not enough to maintain the adsorption voltage.

It would be worth measuring the voltages at the battery to check there is not a bad connection causing a large voltage drop,but I think it is most likely the Victron is not reporting the SOC correctly.

[john61ct]

I assumed OP meant Amps output reading was dropping

[CatNewBee]

That is normal, this is what a charge controller is supposed to do. otherwise the voltage would continue to climb and may overcharge / destroy the battery.

You have to program the solar controller according to the specs of your battery. The controller cannot stay all the time to BULK, - if you want it that way, you would connect the panels directly to the battery without reducing amps / voltage when the battery voltage reaches full SOC..

[a64pilot]

All you need or do is set bulk and absorption voltage to the same value, so that when it drops into absorption, voltage remains unchanged.
I also based on Maine Sails recommendation set my float voltage to to absorption’s levels. In my case, bulk, absorption and float are all 14.4 V

Bulk means current limited, it means that your bank is accepting all that your panels can supply, if you had more power, it would take it.
Absorption is the point at which it becomes voltage limited, your bank can no longer accept 100% of the output of the panels.
Float of course is when the bank is 100% fully charged and is a maintenance voltage.
If Maine Sail is to be believed, its exceedingly unlikely you will ever get there on a cruising boat on Solar alone, it’s not a lack of power, it’s a lack of enough time to dribble in that last few percent of charge is all.

[a64pilot]

Your getting 46 amps at 24 V?
How much Solar do you have?

[Pelagic]

Originally Posted by a64pilot

Your getting 46 amps at 24 V?
How much Solar do you have?

Sorry, that I was not clear in my Original Post (I kept falling asleep!)

A64, sleepy typo, the max Output @ 24v I have seen is 36a not 46a

To clarify, the issue is that my Victron BMV 600 smart monitor does not recognize the output from the OutBack 80.

Perhaps related, I had started another thread about whether I needed to install a separate Shunt for the Outback, Consensus was NO so I connected and have been testing and Monitoring
http://www.cruisersforum.com/forums/...nt-201071.html

I just sketched this 24V DC main wiring diagram to help clarify

Test Steps:
1 Charged Battery with Victron Charger till on Float, then went thru Setup and synchronized the BMV 600 to show 100% SOC

2 Initialized and programmed Outback 80 with same battery parameters as BMV600 Monitor.

3 Switched from Shore Power to Invertor and turned on heavy consumers at SOC 100% (Outback initially showed “Charged”)

4 BMV600 Monitor SOC starts to drop over the next 2 days and I noted that its Current (I) screen always showed negative, even when I turned off all the consumers and the Solar Outback was in “Bulk mode”, and Outputting high Amps.

5 Leaving the large consumers off, except for a small drinks fridge, SOC continued to fall down to 65%, even though the Outback went back into ‘Absorb’ and then ‘Charged’ mode on screen.

6 Not knowing what to believe, I switched to Shore Power and charger. It would start on Bulk, then quickly to Absorb and eventually Float, confirming my House Bank was charged.

I’m just wondering if it is because I connected the MMPT directly to the House Bank and not the Neg and Pos Buss Bars.

The BMV600 Monitor is not getting the Output from the Outback and does not read accurate SOC condition until I go thru the Monitor Setup again.

This does not seem right, so I am wondering what I have done wrong and what the solution is?

[Dsanduril]

The diagram isn't clear where the shunt is physically located in the power wiring (it shows a separate connection to the inverter and the neg. bus). In order to see everything the shunt should be connected between the negative battery post and every other negative connection. That way it will see everything going in and everything coming out. It could be you can just move the Outback negative cable to the bus, but since the diagram isn't clear as to actual shunt location can't say for sure.

[a64pilot]

Originally Posted by Dsanduril

The diagram isn't clear where the shunt is physically located in the power wiring (it shows a separate connection to the inverter and the neg. bus). In order to see everything the shunt should be connected between the negative battery post and every other negative connection. That way it will see everything going in and everything coming out. It could be you can just move the Outback negative cable to the bus, but since the diagram isn't clear as to actual shunt location can't say for sure.

This, I made a bus bar myself out of a copper bar about six inches long to keep it from being a mess as I had so many grounds, but every ground must go through the shunt, any that don’t are not seen of course.

[a64pilot]

Originally Posted by Pelagic

I’m just wondering if it is because I connected the MMPT directly to the House Bank and not the Neg and Pos Buss Bars.

is?

Yes assuming of course that your shunt is between the neg bus bar and the bank, connecting directly to the bank, your shunt and therefore your battery monitor doesn’t see the current going into the bank, it however will see all other current flowing into or out of the bank, obviously this considerable power going into the bank that isn’t known about will really mess up any attempt at SOC by amp counting.

[Pelagic]

Originally Posted by a64pilot

Yes assuming of course that your shunt is between the neg bus bar and the bank, connecting directly to the bank, your shunt and therefore your battery monitor doesn’t see the current going into the bank, it however will see all other current flowing into or out of the bank, obviously this considerable power going into the bank that isn’t known about will really mess up any attempt at SOC by amp counting.

I think this is where my problem lies.
The Victron Multi and Monitor was "professionally" installed at a shipyard in 2013
If I remember correctly, the Electrical Supervisor connected:
Battery side of the Shunt to the Neg Battery of the Multiplus Charger/Inverter
LOAD side of the Shunt to the Neg Buss Bar (system Ground).
I will confirm tomorrow.

[Pelagic]

Originally Posted by a64pilot

This, I made a bus bar myself out of a copper bar about six inches long to keep it from being a mess as I had so many grounds, but every ground must go through the shunt, any that don’t are not seen of course.

OK, I have better pictures labeled now of how it was wired pre-Solar in 2013 and as you can see, I added similar Bus bars in 2016 and connected the same way.

This Tutorial Video shows the Victron P600 Shunt Connections at around minite 4:12
https://www.youtube.com/watch?reload=9&v=JO8AGV4Z7K0

I see 2 differences and I think 2 Options to get the shunt to see the Solar Output

1) Move the small Voltage Sense Wire of the P600 from Pos Bus Bar to Pos Battery Terminal (It is about a 4.5m run to Battery Bank, so I would need to extend this small red cable...not sure how that would affect measuring performance?

2) Move Pos and Neg Solar Output terminals to Pos and Neg Bus Bars, so that all loads are seen at Bus Bar. (does that then give a false reading to state of Batteries?

From my sketch I wanted the Solar to go direct to Batteries bypassing the 4-Pole On/Off switch, so that I could turn off all non essential 24v Breakers if away from the boat, but still have Batteries charged by Solar.

What would you guys try first?

[Dsanduril]

I see your problem in the dual main switch. To get the SOC reading properly you only need to move the negative solar cable to the neg. bus, the positive can stay where it is. That would allow the current from the solar to be measured by the Victron.

However, if you want the solar to be on the battery side of the main switch (and I understand your reason for that) then you need to move the shunt so that it is in the cable from the negative post to the switch. That way the shunt can see everything that is happening regardless of switch position.

Another option is to forget about switching the negative side (just move both cables to the same stud on the switch) - most American boats didn't used to do this, it is a requirement in European builds. There could be an entire thread of discussion about which approach is 'right' so I won't offer an opinion, just state that it is a possible solution.

Moving the sense wire won't do anything for you. One way or another the current that is flowing through the solar negative lead has to make its way through the shunt in order for your SOC monitor to show you what is going on.

[Pelagic]

Thanks greatly Dsanduril.
I will start now by moving Neg Solar to Neg Bus and live with it until I get around to my own wiring clean-up and proper labeling

When I first bought boat in 2004, she did not have a house bank On/Off switch or proper fuse.
So the back of the distribution panel was always live unless you disconnected batteries

I guess they were depending on all the 24v distribution breakers to keep her safe...which probably is ok, but I saw a lot of items behind there that needed proper cleanup but without easy on/off, inconvenient!