intelligent alternators and solar panel

[everhopeful]

Has anyone experience of solar charging a vehicle battery on a Motorhome with an intelligent alternator?

 

2020 Peugeot Boxers and probably Fiat Ducatos now seem to have intelligent alternators, with a B2B for the hab charge etc. I guess this is part of achieving Euro 6D emissions and is probably a good move, but there are always drawbacks.

 

Would a normal solar controller survive if just connected to a vehicle battery that is intelligent alternator charged, or would some other arrangement be needed? Also would the alternator monitoring be upset by another charge source?

[spirou]

Typically on euro6 vehicles you have a dc-dc booster feeding your habitation/house battery supplied from the alternator/starter battery. Most commonly one of the schaudt WA boosters but there are a growing number of others such as victron orion range. These act just like any other intelligent charging source, either AC shore power, solar controller or anything else.

 

From the point of view of your hab battery these are all equivallent and will have various charging profiles based on whatever the manufacturer thinks works well for a given battery chemistry (unless you can custom modify parameters). How well each works in parallel with another charging source also depends on the logic contained within.

 

In practice, the difference will most likely be in when any of them switch between charging phases. Which usually isn't an issue to worry much about. I don't have enough experience with our new van to know if there is any really weird behaviour during certain scenarios. We have a CBE AC charger, Schaudt booster and Victron solar controller. So a mix of nearly everything where each has its own programmed mind.

 

That said, last weekend I did notice the booster had a bit of an issue deciding what exactly to do. I had the van plugged in for the day and 15min or so after setting off I noticed the voltage and current fluctuations seen in the attached chart below. At first I thought a wire might be loose between booster and battery (as the alternator voltage was very steady) but, as it didn't repeat the next day (bottom chart), I am assuming I happened to be looking at it while it was performing a diagnostic of the charge level of a full battery and simply didn't know what exactly to supply it with.

[everhopeful]

Thanks spirou.

The first graph looks like either a battle going on between the B2B and the solar controller, or, as you've had the van on charge the B2B was maybe thinking about winding down. The second graph looks like the B2B acting normally on it's own.

I'm assuming this relates to the Hab battery, and it seems to be accepted that the various controllers just work it out between them.

 

However, as the intelligent alternator system causes quite regular and violent voltage swings (12-15 volts), at the engine battery, I'm concerned as to wether a normal solar controller would be able to cope. Also, if a solar controller goes pop it's no big deal. But, if the solar controller upsets the alternator logic, or even kills the alternator, then big trouble!

 

I like your excellent graphs, but what have you obtained them from?

[spirou]

The entire point of the booster is to load the smart alternator with a demand thus preventing/smoothing voltage swings. On the output to the battery, the swinging in my case was limited to within 1V so no danger to the solar or any other charger or device. At least that's the theory, I will have more time to look at the behaviour in the next few weeks as we head to Scandinavia.

 

As far as the charts go, they are screen captures from a Victron app. I'm using their battery monitor BMV712 to track the state of the batteries. It has its own screen but also bluetooth to connect via phone or computer. If desired I could also set up online logging/monitoring. I had that working for a while with a Raspberry Pi on the previous van but it uses battery power constantly. Low demand like an alarm but still unnecessary beyond satisfying curiosity as a trial.

 

The first chart was on a drive at night so no solar going into the battery. But, as I just unplugged at home, the SOC was already high and the battery wasn't accepting much charge so it must have confused the booster for a while. Same would probably happen if the solar controller had been doing the initial charge. What I suspect would happen, if they were operating at the same time, is that either would switch to float mode earlier than usual, if it weren't there already. No big deal under most scenarios.

 

The second chart was the following morning after we used about 20Ah. I must point out that the solar panels were already up and producing a bit of power (about 1A current as you can see in the initial part of the chart) before I started the engine for a test. At engine shutdown there is seemingly no power for a while but I can tell you the solar charge picked right back up every time we stopped driving that day. What I didn't do at the time is look at the power out of the regulator (also bluetooth connected) with the engine running. I can do that in a few days.

 

All in all, I don't expect any major issues in charger interaction if you have a DC-DC booster between a smart alternator and the rest if the system. But also smoother alternator operation on the other end.

[everhopeful]

Thanks spirou.

That's a terrific bit of kit you've got there!

 

So, the hab charging is safe, but what about the vehicle battery with smart alternator and solar panel?

Most solar controllers have a second output for a vehicle battery, and with a conventional system this would be safe. The alternator only charges at 14.4V then drops to 13.6V, so the solar controller would probably just shut down when on the move.

 

With a smart alternator putting out high current 12-15 volts, frequently up and down, a directly connected solar contoller would be turning on and off regularly too. It doesn't seem like a healthy thing to do, and I wonder if this is what is planned to happen with a factory fitted twin solar charging arrangement.

 

spirou, Is your van wired for twin solar charging?

Does anyone have a van wired for twin solar charging with a smart alternator?

[spirou]

So, after the drive to Sweden (continuing to Finland) I'm quite certain that schaudt booster goes into the "swinging float" mode, as seen in chart 1 above, regardless of how it got there. While there were a few times when I checked, that the V/A lines were flat (during absorption phase), it seems to dissolve into a chaotic swing during float, with or without solar input to mess with it. I will likely email schaudt at some point about it. I wonder what they say.

 

Regarding engine battery, Victron does not do dual solar outputs. I find it largely unnecessary, as the engine battery is veeeery slow to self discharge. Things would be different if there was an alarm or something. But the base vehicle needs next to nothing on stand-by. Smaller models do have separate load outputs that could be used to deliver a limited current to engine battery but is not officially recognized or approved, as it has no charging logic. Just fixed voltage/current as long as there is sun.

 

What the regulator would do in such hypothetical case depends on the built in logic. Victrons can go back to bulk phase if voltage drops by x (user defined). Also user defined are tail current, absorption time and time averaged charged detection time. So quick swings probably wouldn't be great for its MPPT algorythm but likely wouldn't mess with the phase initation much.

[spirou]

Essentially the same question on victron forum on link below. But as said before, there is no dual charging.

 

https://community.victronenergy.com/questions/36890/victron-smart-solar-mppt-10050-and-orion-tri-smart.html