Ladegeräte (Englischssprachige Diskussion aus dem Odin Abgebrannt Thread)

[bob2.0]

Now you have me more worried, because I was already worried about this.

I have already installed a fuse in the charging lead.

This is because the weak point of many of these battery fires is the charger diode giving up, then the battery discharges into the charger. A fuse stops that.

I was thinking possibly to install a diode. The voltage drop would reduce the full charge strain on the battery, a bit more like the lower 100% voltages in cars. This should help lifetime a little.

A diode in the charger loop? What do people think to that idea?

Looking at that fire, I am thinking perhaps it is more to do with the 12V side. It is always on, and there are more 12V circuits to go wrong. No fuses, things get hot, things burn.

It is a motivation to throw the power breaker if you are not charging the bike?

Maybe some sort of way to cut the 72V circuit to the 12V DC DC converter?

If that can be done, the only thing left (in external circuits to the battery) is the 72V to the controller, which itself is the switch. That would need two transistors failing at the same time to accidentally create the short circuit Just one seems unlikely. Two would be unlikely squared. Is that a correct assessment?

So, a circuit to cut the 12V DC DC? Good idea?

[error]

I have already installed a fuse in the charging lead.

This is because the weak point of many of these battery fires is the charger diode giving up, then the battery discharges into the charger. A fuse stops that.

There is no way to "discharge a battery into a charger". Who made this up? If there is a diode on the output of the charger, it is used to prevent reverse polarity.

Funfact: in case of reversing polarity this diode shortens the battery and is tripping a fuse. So there will be no reverse polarity diode without some kind of fuse!

Sorry, but don`t you think someone could develop the schematics of a charger without knowing such simple facts?

[bob2.0]

There is no way to "discharge a battery into a charger". Who made this up? If there is a diode on the output of the charger, it is used to prevent reverse polarity.

Errrr .... ?

Basic electronics?

Look at the basic buck circuit you'll find in a charger.

Imagine there is huge 1000A 72V source sitting on the output, Vo.

Imagine it is 'OFF', that is, S is not running. It's powered down but plugged in.

Imagine diode, D, with Vo across it, failing closed. Or capacitor C failing, which is the other common failure.

What happens next?

THAT is why I have installed a fuse in the charging leads on the bike.

[error]

Errrr .... ?

Basic electronics?

Look at the basic buck circuit you'll find in a charger.

Let`s stop it. Simplified this is how the DC part on the primary side is working. But the battery is connected to the secondary side.

You are currently surrounded by millions of fine working SMPS (switched-mode power supplies). Please don`t make things up.


Very simplyfied schematics:

picture is stolen from:

https://www.circuitdiagram.co/switching ... planation/

[bob2.0]

Errrr .... ?

Basic electronics?

Look at the basic buck circuit you'll find in a charger.

Let`s stop it. Simplified this is how the DC part on the primary side is working. But the battery is connected to the secondary side.

You are currently surrounded by millions of fine working SMPS (switched-mode power supplies). Please don`t make things up.


Very simplyfied schematics:



Bildschirmfoto 2025-06-23 um 14.55.50.png

picture is stolen from:

https://www.circuitdiagram.co/switching ... planation/

You are misunderstanding.

There are various topologies, but the same situation in that circuit. If the diode goes pop, then it is exposed to a 72V high current battery.

Yes, we are surrounded by SMPS that are NOT connected to a power source. They are usually connected to a 'sink' not a 'source'.

The thing with a rechargeable vehicle pack is that it is both a sink and a source, depending on what voltage is present on that output.

If the output voltage is the battery voltage (because the right hand part of that circuit is unpowered by the left) then the 72V incoming from the battery can go via that diode in series with the 'low pass filter' and via the inductor.

Whatever topology you have in your charger, it is 'something like that' with a shunt capacitor stabilising the output and a diode blocking the reverse voltage (whether it is an output from a transformer, or from the switching part off of a DC link capacitor). If EITHER of the diode OR the capacitor give up, then the traction battery will flow around that circuit and 'big bang'.

[error]

Whatever topology you have in your charger, it is 'something like that' with a shunt capacitor stabilising the output and a diode blocking the reverse voltage (whether it is an output from a transformer, or from the switching part off of a DC link capacitor). If EITHER of the diode OR the capacitor give up, then the traction battery will flow around that circuit and 'big bang'.

Every time you are disconnecting the AC of your SMPS your battery will have a higher voltage than your charger. According to your theory it should start "acting as a source"? So what? This DC voltage is blocked by the rectifying diode(s) on the secondary side. So your charger is acting as an open cicuit.

Anyway, ou might see a short spark while connecting a switchted off charger first on the DC side (means to your battery). This is only because of some secondary smoothing capacitors charging up.

This is an open forum. Please stop confusing people with your wild theories. There is no need for addional diodes or stuff. This may only result in loosing your insurance coverage.

An EV Fire is a serious thing. But tinkering around based on what we in german calling "gefährliches Halbwissen" (dangerous superficial knowledge) is some serious stuff too.

Look at the basic buck circuit you'll find in a charger.

Please go to Youtube, there are tons of videos obout switched-mode power supplies. There is no buck ciruit! Every SMPS is based on boosting up the rectified AC in order to deal with lower currents.

[bob2.0]

Every time you are disconnecting the AC of your SMPS your battery will have a higher voltage than your charger. According to your theory it should start "acting as a source"? So what? This DC voltage is blocked by the rectifying diode(s) on the secondary side. So your charger is acting as an open cicuit.

I am a published author in electronics, issued patent holder of power supply designs, member of IEEE Reliability Society for many years.

I'm not suggesting, I am telling you that there exists a problem with many chargers offered for charging electric motorcycles in general.

The problem is that 'the same sorts of SMPS' that drive devices (like, in the back of your computer, TV, whathaveyou) have been (IMHO) neglectfully re-used for charging batteries.

The diode is a single point failure mode.

If the SMPS is supplying a TV screen and the diode breaks, then, oh well, you don't get to watch TV. But the benign part is that the screen does NOT generate a current back into the diode.

But in a battery charger that is connected to its battery, the diode is now a single point failure mode.

That is Not Good.

Simply using the same sort of SMPS topology and not redesigning it with a further blocking diode, or other mechanism, leads to there existing a non-benign single point failure mode.

The failure is not merely needing a repair, the outcome is the battery may dump its current into the charger until something melts.

That is the problem.

It would be better if the thing that melts is 'a fuse' than things that can catch fire.

If you have never seen a diode failure, then don't speak to me about it being impossible to happen. I have investigated many equipment failures from diode and capacitor failures.

The diode and capacitor in a buck circuit, boost circuit, rectified circuit, whatever you think is in your charger, as I have shown, or as you have shown, it doesn't matter, are single point failure modes and the failure risk is a fire if it is connected to a charged battery, because the battery current is dumped into the charger if one of those fails closed.

Whilst the charger is plugged into the battery, both the diode and the capacitor in that secondary output stage are holding off the whole battery voltage. Those components have the full battery voltage held across them, for all the time it is plugged in.

There is (often) no secondary safety device or mechanism for either of those (none I saw in the supplied charger). So I fitted a fuse as the secondary safety device, mitigating the failure mode.

It is a standard requirement in all current functional safety standards that any single point failure modes must have benign consequences. The single point failure of the diode or the capacitor in the buck/boost circuit output stage of a switched mode supply that is plugged into a battery carries a very high, non-benign, risk of a 'thermal event'.

[error]

I'm not suggesting, I am telling you that there exists a problem with many chargers offered for charging electric motorcycles in general.

The problem is that 'the same sorts of SMPS' that drive devices (like, in the back of your computer, TV, whathaveyou) have been (IMHO) neglectfully re-used for charging batteries.

The diode is a single point failure mode.

Primay and secondary are coupled inductive? Right? So which diode do you mean? The secondary rectifiing Diode? If this diode goes OL nothing happens, if it shortens a "a proper calibrated fuse on the output" is blown. It is all about designing something the right way.

But I see your your Point: If there is a common port BMS involved, the battery is able to deliver large currents. But this is also about designing a charger the right way.

Modern Chargers are communicating with the BMS. During the charging process some kind of handshake is preventing such failures.

[bob2.0]

Primay and secondary are coupled inductive? Right? So which diode do you mean? The secondary rectifiing Diode? If this diode goes OL nothing happens, if it shortens a "a proper calibrated fuse on the output" is blown. It is all about designing something the right way.

If there is a fuse on the output, then all is well. That is what is needed.

I totally agree designing it the right way is to have a suitable output fuse.

I did not see one on the charger supplied.

To answer your question, I am not sure if you do, but I will answer and put this to bed.

No, modern supplies don't always work inductively like your diagram. In fact, it can present problems that are avoided by a more modern topology.

What I work with, and what I design, has been with a 'DC link capacitor' sitting between a 'primary' source side and then the secondary voltage conditioning side.

The primary input is a basic circuit that puts DC voltage on to the DC link capacitor. It does not have to be a traditional rectified transformer, there are other ways to put a DC voltage on to the DC link capacitor.

It could, for example be a simple rectified mains putting ~315V on to the capacitor. Not usually, but it could. Isolation could be a simple 1:1 (or applicable) transformer on the mains input before the rectifier.

The DC link capacitor's voltage will fluctuate around from mains ripple and power drawn.

If the output voltage is to be above this voltage, you then install a boost converter on the DC capacitor, and if it is to be lower then you use a buck converter.

It would therefore look like this;-

Depending on the accuracy of voltage and stability required, there are sometimes 3 stages, these two stages producing a stable DC voltage to a second DC link capacitor.

Or a neater way for better control is to have active transistors in the rectifier bridge which can be controlled to regulate the rectified voltage to the link capacitor directly. Switched (MOSFET) rectifiers are also more efficient than diode rectifiers as they have very low voltage drop across them.

(FWIW, my first power supply invention is a way to accomplish capacitive galvanic isolation from the source supply, without inductive isolation.)

The problem I am pointing out with our motorcycles is D1 or C1 failing short.

As you rightly say, if there is an appropriate fuse on the output to the battery, this is fine.

I am saying there is no such fuse on the charger supplied with my motorcycle that I saw. Therefore, I added a fuse on the bike itself in the charging leads. This also ensures if the charging port is damaged in a bizarre way while out on the road, it will fuse if it is shorted somehow.

I am not saying anyone has to do anything, but the electrical design is flawed in several safety aspects, and I think we know this?

[error]

I totally agree designing it the right way is to have a suitable output fuse.

Ok, we could settle this? I am for shure not a pro, but what whould you think if someone is presenting a diagram of an unisolated DC-Buckconverter atttached directly to the mains via a simple bridge rectifier in an open electromobility forum???

You are (and of course me too) confusing the other users. This is no electronic engeneering forum.

Reverse picture search took me to the source: https://www.learnabout-electronics.org/PSU/psu31.php

This is the beginning, the missing part, the whole story: https://www.learnabout-electronics.org/PSU/psu30.php

The important difference is the isolation from mains! There is a Control Circuit for trouble-free and safe operation.


So please kids, don`t try this at home!