Kurz vor Kabelbrand: Schaudt Elektrozentrale abgeraucht

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    From where do you take the 12V to measure it? The cable of the measuring device shouldt comes direct from the battery pole. If not - and if you connect the measuring device with the old or other cable - then you dont measure the voltage of the battery. Then you measure the lower voltage after the resistance of the cable where you lose some voltage in case of the electrical current flow over the resistance.

    If this error is the case, then you shouldt check the wire and the wire cross section and the connections of the wire to lower the potential difference.

    You find it out, if you measure direct at the batterie. If there also drop down the voltage, then your batterie has a problem.

    Jörg

    Uhm. Yes, of course I measure the battery voltage directly at the poles. And that seems double strange to me, because the fridge ought to be directly linked at the alternator (or to the engine battery). It looks like the fridge is pulling down the parallel between the two batteries. Maybe the internal circuit has some problems, too.

    I was thinking about the whole matter in the last days. Maybe the fridge connection has a problem, or: the alternator has a problem!

    In any case, I have finally decided to buy a clamping amperometer: I'm awaiting to have it, to make some measures, to understand in a better detail what's happening.

    I'll come back with more details in a few days.

    Meanwhile, I'm also thinking about a "new creation": my own version of the EZ90. Based on a Arduino-something nanocomputer, to overcome all these small problems. I don't know if I have enough time to project engineer and maufacture it, that's the key question!

    Zitat von Cordy

    I have finally decided to buy a clamping amperometer: I'm awaiting to have it, to make some measures, to understand in a better detail what's happening.

    I'll come back with more details in a few days.

    Thats a good idea.

    Zitat von Cordy

    I don't know if I have enough time to project engineer and maufacture it, that's the key question!

    In most cases, this tooks longer and it is more expensiv as an standard-solution. But you have more fun ...

    Best regards,

    This morning I had one spare hour to go to the van and start doing some checks. Unfortunately, very soon it was raining, so I couldn't make any test with engine on.

    But one thing is now evident: the fridge is directly connected to the second battery and not to the alternator, after a bypass relay managed by the "engine on" line.

    This simple fact explains all my problems, together with the broken parallelator relay.

    A few extra info for... well, anybody looking for information on this quite rare van (Carthago Malibu 31, year 1992):

    - the fridge, if the unit installed in my van is the original, is pumping away nearly 10 A DC.

    - the original charger/power supply is a 7 A unit.

    - The biggest AGM battery that can fit in that little space is, nowadays, a 70 Ah.

    I need to investigate further more, because:

    1. it looks like the two batteries are in parallel if the engine is on (and that's right) AND ALSO (with engine off, of course) if the external 230 V power line is on. And this, is strange, as a minimum. I need to better check this out, when it will be possible to stay outside the garage, measuring all the voltages with engine on and off. But it looks like the "emergency button" is always pressed. With "emergency button" I mean the "NOTSTART FUER LADER" button, that I presume, looking to the scheme, is performing that function, inside the EZ90.

    2. Considering point 1 and the quick check I did on parallel relay (with engine on, voltage goes up to 14.something volt... on battery 2), I'd like to understand if the alternator is supplying energy to bat2, with engine and fridge on. And, possibly, how much energy.

    In one word: I'm confused, even more than before... more to follow.

    A quick update. The van is now in a workshop, to professionally fix some bumps and scratches. I also asked to restore the base of the two rear seats, because it's very rusty. So, I could see the inside of the van without the two benches and... surprise! On the left side of the van, two red and a white wire are running from the front to the rear of the living compartment. They are short, with a system used to keep them in place that's... uhm... how can I politely say? To be changed. They are also quite thin, if I correctly understand the meaning: D+ (white?), Engine battery (on of the red lines) and van battery (the other red line). As a minimum, I'll add a double fuse (one on each side of the lines, because when the parallel is on the short circuit might happen in both ways) and thicken the wires; which is your suggestion? 16 mm2 ?

    Some more info and pictures. This is the inside of the van, with the two rear seats removed. I must partly correct myself: the wires are:

    two, red, two lines each, for the rear cabinet loudspeakers

    one, white, that carries the engine battery voltage to the EZ90 and

    one, yellow, that is the "D+", or the alternator charger line.

    As you can see in the picture, they are kept in place with the wrong tool: a metal, blade-sharp edges, fixing object. I have removed it from and added a lot of isolation in that place to the wires. As you can see, the wires are of the exact length, non a mm more, so, they could easily short. Moreover, the black pipe is the exit of water, to the waste water compartment: there could be some water, there.20220305_092706.jpg

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    This is the space behind the fridge. My plan, now, is to add a relays, activated by the yellow line (D+), to interrupt the direct connection to the van battery.

    I could connect the fridge to the engine battery, instead. Or, add a new D+ line, with a large wire, to feed directly the fridge. But, with this kind of connection the fridge works very well also with 12 V power supply, so my plan is to avoid accidental discharge of the van battery and use for a while the van with this modification. If everything is OK, or if not, I'll come back with the results of my test and measures.

    Another thing I'll add are fuses: one in the engine compartment, near the engine battery, to protect the white line that goes to the EZ-90. In case of crash or any other kind of problem, it is a good protection. Based on the actual size of the wire, I presume a 10 A fuse ought to be OK. I'm going to make some measures, to check if there are some spikes of current that might blow a 10 A fuse. Again, I'll keep you informed.

    A similar, 20 A fuse will be installed on the yellow line, that's starting from the fuse compartment, on the left side of the steering wheel.

    An identical fuse protection will be installed before the EZ-90 on the two above mentioned lines. I presume that EZ-90 has fuse protection inside, but I want to be sure that the fuse is working before the plugs and prongs shown in these 3 pages may melt.

    Is there something wrong in my "project"?

    20220409_085927.jpg

    This is the diagram of the inner circuit of the fridge. It was hard to believe, but it works exactly as I have supposed to: it is directly connecting to the service battery. I have installed a fuse that disconnects the resistance once the engine is off. I.e. I modified the inner circuit.

    But I didn't solve the problem, apparently: the battery is not being charged if the fridge is on 12 V. I presume the line is not enough strong to support a 10 A consumption from the fridge AND to charge the second battery.

    Moreover the EZ90 does not provide a reliable connection. I am now thinking whether I ought to send it to Schaudt (long time and presumably a significant cost) or I ought to change the whole circuit of the van, installing a new fuse box, dc-dc charger, earth bar, and eventually a BMS (with a lythium battery?).

    Did anybody do this?

    A radically new and more up-to-date wiring is more expensive. And, what's the most to me, not respecting the originality of the vehicle. It's a 30-years old van, only 4 of them are still alive, in Italy, so it also has a collector's value, not to be underestimated. I don't know... what would you do?

    This is it, after restoration:

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    I have finished the job: now, it works fine, for my need. What I did is... well, totally redesign the electrical system of the van. Scrapped (as I have already mentioned) the original battery charger, because it was melted. Now, I have scrapped also the EZ 90. Because it's made in iron and I don't like the idea of 230 V in a metal box, together with the 12 V connections.

    So: totally rewired the 230 V part of the system, installing the original safety switch (10 mA ABB differential and thermal-magnetic 6 A automatic switch) in a plastic box (IP44).

    A new (Victron) battery charger, which is also perfect the keep the battery in a good shape when the van is left unused for a long time in the garage. It can be left on, since it's a good iUO battery charger, but works fine as a battery maintainer (IP67).

    I have scrapped all the plugs that connect to the original EZ90, switching to a different approach. A multi-pole connection system, coupled with a 6 places fuse box. On these two components I have re-wired and re-coupled with faston plugs all the users: pump, pump switch, 3 neon lights, Truma heater, fridge ventilator, the panel that shows water levels as well as battery levels.

    Moreover, I have modified the fridge, to get it on only when the engine is on, adding a parallelator relais.

    The battery charger and the inverter (yes, I added a 600 W inverter...) are directly connected to the battery, with a dedicated fuse on each line.

    The final touch, is a Victron parallelator relais, that is microprocessor controlled, to connect engine and service batteries. The fridge is connected to the engine battery.

    I need to add some order now, because the wiring is still in a provisional situation, to check if it works fine (yes, it does!!!).

    I also want to add a midi fuse box at the beginning and at the end of the wire that parallels the two batteries, but I'll ask a workshop to do it: the wire is too thick, for my tools, to have a good mechanical connection: it's better to use an hydraulic clamp and it's too expensive, to buy it for 4 connections...

    One extra bonus: the Victron parallelator works both ways. I.e.: when I switch the engine on, if the service battery is substantially less charge than the engine battery, it goes on. But, also, when I connect the Van to the electricity in the garage or in a camping, if the engine battery has less charge than the service battery, it goes on as well.

    I'm still wondering if I ought to add a battery protect, but I didn't find the right spot to place it. It must be in a very well ventilated area, not hot, not on top of the battery, not beyond 50 cm from the positive pole of the battery. There's no space conforming to all these requirements, in the van, unfortunately...

    If you have any hint or questions, feel free to ask. Bye Bye. Stefano

    Just the final info: I have finished all the activities. And used the van for summer holidays: 9 days and 2.200 km (approximately), without any single problem. I did not need to charge the batteries. I love the very basic concepts that has been used by Carthago.

    Gas: two very simple, very easy to find Campingaz gas bottles. It's expensive, nowadays, but I hope it will be better soon. I found spares in Bad Toelz, in Stuttgart, but it's easily available nearly anywhere in Europe. And the gas connection is standard, so you can simply leave the empty and take away the full bottle.

    Water: two plastic bottles, each approximately 20 l. You can fill them anywhere there's a tap. No need for pipelines, adapters...

    Electricity: there's nearly no power consumption in the van. So, a 70 Ah is still full after 3 days steady somewhere. And in a few kilometers (now...) it's fully charged.

    On a single phrase: easy, lightweight, with days of self-sustainable storage of everything you may need.