Battery completely dead - no prior symptoms

[emax]

I didn't know this a few days before. But then on youtube I became aware of "charging boosters", "D+ simulators" and camper problems with batteries and delved a bit into it. In some videos they explained the background.

I think it is mainly a European matter, but likely, England is involved as well. And I think that similar concepts apply in the RoW.

If you can detect and reproduce a decreasing charge current when you press the accelerator pedal or a higher charge current when you release the accelerator pedal, it is almost certain that you have the same technology installed. The effect is most visible when the battery is a bit low, as a fully charged battery cannot withstand high currents.

 

[ADVAW8S]

I wonder if I could get a battery isolator as I live in a ski resort and don’t intent to use it much in the winter. My 4x4 Panda has one as standard.

Why not disconnect the battery? We have a Yukon that gets driven once every 3 months during the summer. Gets more usage in winter for hauling the family skiing. I disconnect the battery and have no issues reconnecting it when it's time to go. I also replaced the factory battery with a AGM battery.

 

[OGrid]

I’m learning on the go here about smart alternators like others. I already don’t like them (finally get to pickup my vehicle tomorrow).

I saw this DC-DC converter for vehicle auxiliary batteries which I found interesting due to it referencing specifically its awareness of smart alternators in the design.

What caught my eye also was the brochure’s comment - “ ‘Engine running’ detection system: Deep discharge of the vehicle's starting battery is avoided by a built-in ‘engine running detection”.

https://www.victronenergy.com/upload/documents/Datasheet-Buck-Boost-DC-DC-converter-25A-50A-100A-EN.pdf

Thought it might be of interest to the ongoing discussions.

 

[emax]

Yes, that's such a "D+ simulator".

Background: There is an electric signal called the "D+" signal (according to German nomenclature). To be precise: there once was such a signal but it seems to have disappeared in newer cars.

This signal (only a signal, not for power provision) was "high" (i.e. 12V) when the motor was running and the generator produced current. It was used to switch a relay to provide power to loads like a fridge or a battery charger.

This signal doesn't officially exist any more for "smart" generators. To avoid drained batteries, some companies have therefore developed so called D+ simulators. They exists, to my knowledge, in two different variants. 1st - a voltage driven version, 2nd - a vibration driven version.

The voltage driven simulator delivers a "D+ high" signal if the system voltage climbs over a programmable limit, for example 13.7 Volts. This voltage indicates that the generator is currently delivering power because otherwise the system voltage would be below the threshold which you have programmed or configured in the simulator.

The vibration driven version does so by detecting motor vibrations.

This is indeed a way to half way reliably control your extra loads like a fridge or to charge a second battery from the main battery with a chargeing booster.

BUT: this only fights the symptoms. And it doesn't IMO help to have a fridge which only runs if the engine is on. The "smart" Generator is still there, and I don't know at which low-voltage level of a main battery it jumps in.

If at all, I would use such a simulator to charge my second battery with a charging-booster and then I would connect my fridge to the second battery, and secure it with a voltage monitor to switch of the fridge below some voltage.

With that scenario, the hope is, that the second battery gets always charged (from the main battery) as long as the engine is running. The main battery will then be drained every time the generator has "decided" not to deliver power. But with the then continuously decreasing voltage of the main battery, such a generator should be triggered earlier to start charging the main battery again.

The entire concept is a workaround. It may work or not. My personal assessment is that this is all crap which came out of the heads of planet-rescuers which have absolutely no clue about technology and electronics. It's like switching of nuclear power plants. The are not switched off because we don't need their electricity, but because they are evil.

I have attached a PDF of such a simulator. I personally would prefer a voltage controlled version, but this vibration detecting version does conceptually do the same. Sadly, I haven't found an English version.

PS: to me, it's still unclear what the D+ signal originally was supposed to control in a traditional car. I think that it controlled the dashboard light for "charging". But it was there and is still used by many campers (in Europe) to improve the broken concept of smart generators.

 

[emax]

I found this (originally German) posting which provides some background to the D+ thing:

"Until around 2004, alternators were installed which, when they rotated at around 900 rpm, generated a signal with +12V. This "original D+ signal" was used to control the display in the dashboard (battery charging, alternator). When it was generated, the warning light went off!

From around 2005, this signal was no longer issued by the generator but rather a signal that was easier to use for the electric engine control, namely the DFM signal, which shows how busy the alternator is. But since the "original D+ signal" was still needed, it was generated by the the ECU. Sometimes this signal was also routed to the outside in the wiring harness as D+ 12V (original), such as at Ford.

However, the signal was changed. Previously there was +12V on the line at D+ (originally), it has now been reversed. The new D+ is now output as 0V ground. Many new battery chargers now have a switch, because this D+ signal is now available in different forms: for older vehicles as conventional D+ (with engine operation +12V) or for Fiat X250 290and Transit MK7 as D+ active ground (when the engine is running, D+ is at ground, otherwise it is high impedance).

Since it is no longer easy to find the original D+ signal in the car, the accessories industry became inventive and looked for a way out. We know that the voltage on the starter battery increases when the alternator is running (at least before Euro 6). So they said: If the voltage rises above 13.6V, the alternator must be running, so we generate an "artificial (or voltage-controlled) D+ signal" with +12V (!) via the voltage increase for controlling isolating/coupling relays, fridges coolers and B2B (battery to battery) charging boosters. But it is a very inaccurate signal to ensure that the generator is charging!

Another control signal is "ignition plus". It is generated when the ignition key is in position II, ignition. At Fiat it's called ACC. However, no engine is running in this position. It first starts at position III and then jumps back to II. So also an uncertain signal on the subject of "generator is charging"!!

In connection with the fuel/emission-saving "intelligent generator control", which regulates the generator power (voltage), this "voltage-controlled D+ signal" is becoming increasingly problematic in use.

That's why some manufacturers try to get around this dilemma by mixing the "ignition +" signal with a shake sensor and deducing from this that the engine shakes when it rotates. Not unproblematic either!"

Source: https://www.wohnmobilforum.de/w-t133031.html