Two nights, three day trip: what worked, what didn't

[RiversToTheSea]

Took the van out for two nights and three days camping. I thought all the electrical upgrades were sorted out and done. I was wrong.

I charged the 100 Ah battery using the shore power charger before leaving home. On the trip out I ran an electric cooler that draws 5A.

So 100 Ah divide by 5A means my electric cooler should have run for 20 hours. Call it 16 hours if I leave a 20% reserve.

About two thirds of the way to the destination the Victron DC/DC Charger started cycling off and on. Starter battery voltage <9A, charger off, DC charger shut down. Then starter battery voltage >12, DC charger back on.

Fine, I stopped the DC/DC charger using the app. At the campsite I start the gas engine to test things. The 40A Winnebago fuse in the 10 AWG wire from the battery isolator to the power panel blew and the Winnebago wire to the battery compartment was warm to the touch.

So my questions: obviously my DC-DC charger is drawing more current than the Winnebago wiring can deliver. For the AC/DC charger I can select 15A or 7.5A but I can't find in the Victron app where I can set a limit for the DC charger current. I saw another thread where someone replaced the 10 AWG Winnebago wiring with 4AWG. Is that what I have to do? What is the current output of the VW alternator? ,Is my alternator failing?

[kourt]

[xEVC]

Something doesn't seem right. Fortunately, you should have the tools to diagnose it.

Use VictronConnect app and open up your BMV 712 - click the Trends tab and you can see a historical graph of many parameters, including Current, Voltage, State of Charge, and possibly even the Starting battery voltage (if you wired that up).

From these data, you should be able to figure out what's happening.

* Eurovan alternators come in 90 amp versions (and higher) and even if your DCDC charger was drawing 40 amps, that leaves 50amps for the van. Even if you were using many electrical devices while driving (high beams, fan on high...) the alternator should have been able to keep up.

* For your starting battery to get under 9V, it really sounds like your alternator is not working properly (and/or your starting battery is dying. How old is the starting battery?)

* If the starting battery was at 9V, and your LFP house battery was at 13V, and you tried to start the van, the draw from the starter motor could easily pull more than 40A from the house battery and pop the fuse.
However, this would only happen using the stock wiring in which the House and Starting batteries are connected. With your rewired DC-DC charger, I think this is not possible. I wonder if your DC-DC charger is wired incorrectly (backwards?) or you still have the DC-DC charger in parallel with the original house wiring?[/i]
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[Stripped66]

[xEVC]

One of the great things about Victron is you can demo all the models using the app.

Open VictronConnect app, choose Demo Library, and then select your product. The app will give you a simulated unit to play with.

From this, I can see that Kourt's charger (Orion XS 12/50) does have both input and output amperage limits, but it looks like smaller versions (Orion Smart 12/30) does not have that feature.

It does have variable voltage output settings, so you might be able to do a reasonably good amperage control by simply limiting the charging voltage. A LFP battery charging at 14.6V will gobble up a ton of amps, but charging at 13.8V or even a bit lower will lower the amperage draw substantially.

If you've determined that everything is wired up correctly (which I'm still skeptical of) and don't want to upgrade to the Orion XS, this might be worth a try.
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[dsh1705]

Just an observation: the wire from the solenoid on the firewall of the EVC to the house battery is 8 gauge, with (for some reason) the wire from the battery to the 40 amp fuse before the solenoid being a 10 gauge. The Winnebago wiring diagram shows this.
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David
1705.net
95 EVC
ACU,098

[xEVC]

I've wondered about this myself.

Turns out there are different wire ratings for
* "chassis" wiring (a single wire suspended in air) - which is what that short piece of 10 ga wire qualifies as.
* "power" or "bundle" wiring (2 or more wires often run in a bundle or tight space) - the rest of the circuit made of 8 gauge.

The ampacity ratings for those situations are dramatically different.

See here for an example: https://electronics.stackexchange.com/questions/33...ansmission

... in that discussion a 10 gauge wire is good for 55 amps in "chassis" but only 15 amps in "bundle" configuration.
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[RiversToTheSea]

[quote="kourt"]

[RiversToTheSea]

[RiversToTheSea]

[dsh1705]

[xEVC]

I can think of two reasons you could have read 9v on the starting battery with the engine running:

1. Alternator is failing.
2. High resistance connections between the alternator and the Victron DC DC charger.

Can you do a quick sketch and or upload pictures showing the wiring?
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[xEVC]

> My wife was driving and I was adjusting the settings in the DC/DC charger to try to diagnose the problem.

This! This is the way

Funny story, but my partner got sick of the "let's diagnose as we drive" trips in our prior Westy Vanagon camper. So we sold that to a friend (long story) and bought a "new" Eurovan Camper.

That was 15 years ago, and it seems like we are getting to this point in the Eurovan.
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2000 Eurovan Camper (Winnebago)
Upgraded with 16" wheels

[RiversToTheSea]

[bigfoot_ev]

I think you have the Orion Tr Smart DC/DC charger. IIRC, as soon as that charger detects the engine is running it will go into bulk charge mode, since that is the first step in charge algorithm: bulk – absorption – float. If your battery was fully charged the algorithm will still go through the steps.

I could see with LFP batteries that it would take a bulk charge current long enough to cause issues if the rest of the circuit has problems.

I think xEVC is probably correct with either of the 2 issues. To test, draw down your battery just a bit. Enough so that it requires a bulk current longer than just briefly. Start your engine and check the Victron app. It will show what stage the charger is in and the BMV will show the current. If you get the same results, by that I mean, your alternator sagging to 9V, or some upstream resistance so high the Orion sees 9V, that would indicate something is wrong upstream of the Orion.

BTW, your wiring diagram looks good to me. Nothing jumps out.
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2003 Westfalia Weekender, AXK, 01P

[Stripped66]

[Abscate]

20% reserve is not a thing with a lead acid battery

A 5 Amp load constant will have a reserve load of 8 hours on a new battery and half that on an aged battery (over 3 years or more than 20 discharge cycles)
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[xEVC]

[xEVC]

[Stripped66]