Two chargers blow simultaneously.

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Paul9
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Two chargers blow simultaneously.

Post by Paul9 » Wed, 23 Jan 2019, 10:52

G'day people,

I am not having much luck with chargers!

About 18 months ago I decided to fit two chargers to my car. Use one by itself for 10 amp circuits, use the second one for 15 amp circuits and use both together when charging from 32 amp public charging stations. I bought 2 of the new small TC Chargers and fitted them. I managed to destroy one and the other would simply not work.

I decided to replace them with the old version of TC Chargers. I bought a 2.5kw TC Charger and a 2kw KPES charger and fitted both those about 15 months ago. I have been using them quite successfully for the last 15 months both individually and simultaneously.

The other day I had them both plugged into a Chargepoint public charging station at a shopping centre. Before I left the car I checked to ensure both chargers were working and they were. I wandered off to do my shopping and came back half an hour later and found that neither charger was working. I disconnected them and reconnected them and no charge. I drove to a different shopping centre and tried again and still no charging happened.

Both chargers appear dead and both appear to have "died" at the same time. I do have an old 48 v charger which I hooked up to 16 cells and its works fine regardless of whether I connect the 48v charger directly to the wall socket or charge through the car. (I thought the wiring in the car may have caused the problem but that does not seem to be the case)

I am guessing that I will have to buy two new chargers but I am wondering what may have caused both chargers to "blow" simultaneously? I would obviously prefer the two new chargers don't "blow" for the same reason?

Any guesses?

Thanks in advance
Paul

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Re: Two chargers blow simultaneously.

Post by antiscab » Wed, 23 Jan 2019, 11:03

How hot do they get in their present location?
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Re: Two chargers blow simultaneously.

Post by jonescg » Wed, 23 Jan 2019, 11:55

Are their AC inputs properly isolated?
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Re: Two chargers blow simultaneously.

Post by coulomb » Wed, 23 Jan 2019, 14:10

Paul9 wrote:
Wed, 23 Jan 2019, 10:52

Both chargers appear dead and both appear to have "died" at the same time. ... I am wondering what may have caused both chargers to "blow" simultaneously?
I don't know the KPES chargers, but I know the older Elcon/TC chargers reasonably well. They have a PFC (Power Factor Correction) front end with a large inductor. If you ever disconnect them from the mains while they are running near full output, the arc is spectacular as the PFC inductor attempts to keep the current moving. There are parts to suppress this, but they are too small for the job, and often wear out, but this doesn't cause the charger to stop working immediately.

The main switching MOSFETs in these chargers are protected mostly by an aluminium capacitor of moderate but not the best specifications. It's been hot recently, and when these capacitors get hot, they dry out and increase in ESR (Effective Series Resistance), allowing larger and larger voltage spikes across the MOSFETs, which eventually blow. They often fail short circuited, so suddenly there is nowhere for the PFC inductor's energy to go, and the energy has to go somewhere. If these overworked suppression parts are worn out, there is nowhere for this energy to go other than back into the mains. There will be a short, sharp, but intense voltage pulse, which will cause problems mainly for nearby mains connected devices, in this case your other charger. Hopefully, the EVSE equipment (that your car would have been plugged into) had enough protection to handle this.

The best way to avoid this problem is to use quality chargers that don't have this problem, and to keep them cool. Unfortunately, this information (which ones are the good ones) is really hard to come by. It took years of work on these chargers to figure out the above, and I might still have it wrong. Something like a water cooled Brusa charger would be ideal, but it costs many times the price of the cheaper chargers.

This is becoming an increasing problem in today's throw-away society, with cheap electrical goods of dubious quality and little to no market history flooding the market.
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Re: Two chargers blow simultaneously.

Post by bladecar » Wed, 23 Jan 2019, 18:19

This is part of the reason I decided to abandon the Blade cars. The TC chargers blew too often and at $1300 is it a time?
This is why I am a little anxious with any modern ev, what with the imiev costing $4500 if the charger blows, it really plays havoc with the low cost potential of good technology which could be durable.
I would like to read some ideas on what the key points are for the construction of truly robust chargers. EV's deserve better :)
'

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Re: Two chargers blow simultaneously.

Post by Paul9 » Thu, 24 Jan 2019, 07:24

Thanks guys, your replies are appreciated.

As far as I am aware both chargers are AC isolated and I have used this particular Chargepoint station with the current set up many times in the past. Excessive heat seems to be a common thread in some of your replies. I don't know how hot the chargers become while charging, and I realise we have had some very hot weather recently, but this particular day's max temp was only 27C. And the charging station is in an undercover carpark so no direct sunlight hits the car.

On the other hand I recently added two more cells (CALB 100AH) to the car. While I can't see this making any difference to the chargers electrically, it did require me to close off some space through which air may have been circulating around the chargers. While the possibility of reduced circulation struck me at the time, I assumed (probably incorrectly!) that as both chargers had fans, that this would not be a problem.

I may fit my new chargers with heat sinks and extra fans to hopefully reduce the possibility of this happening again. And I will just have to wear the fact that you get what you pay for! I assume there is nothing else I can do to further reduce the possibility of this happening again (while realising that nothing is guaranteed)?

One other thought has just struck me. This particular day was the first time I had ever used a Chargepoint station while someone else was charging their car at the same station. When I returned to my car the other vehicle had left. I assume that him disconnecting his car from the power could not have caused a problem with mine?

Thanks again
Paul

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Re: Two chargers blow simultaneously.

Post by coulomb » Thu, 24 Jan 2019, 07:57

Paul9 wrote:
Thu, 24 Jan 2019, 07:24
This particular day was the first time I had ever used a Chargepoint station while someone else was charging their car at the same station. When I returned to my car the other vehicle had left. I assume that him disconnecting his car from the power could not have caused a problem with mine?
Presuming that the other car was a production model, then no. Stopping the charge would involve a CAN message to the charger, which allows the charger to ramp down the current, preventing the problem of the PFC inductor with nowhere to dump the energy. Even ramping down to zero current in a tenth of a second is a lot better than disconnecting instantly, as might happen with your Elcon/TC and probably the other one. By the way, most of the older Elcon/TC chargers have an "enable" input so that you can turn the charger off electronically; this is much better than disconnecting the mains input with a relay, for example. But this is presumably too late for you; those Elcon/TC chargers stopped being made in late 2013, as the processor that they were using reached its end of life (no longer made).

So I suppose that's something to look out for with your replacement chargers: either a CAN bus control so that the charge current can be turned off electronically, or some analogue equivalent to the Elcon/TC "enable" input. But with a CAN bus charger, you need some small computer to supply it with the required CAN messages; some BMS can do this.

Yes, the fans on your chargers would have helped, but if they can't get the hot air out very well, then eventually the temperature builds up anyway. Perhaps some tubes to the outside air would help, if they are now somewhat trapped behind recently added cells. I think you'd need a small fan to encourage air flow as well as the tube(s).
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Re: Two chargers blow simultaneously.

Post by jonescg » Thu, 24 Jan 2019, 08:28

Interesting coulomb - are you suggesting that TC chargers don't come with the Enable / voltage divider option any more? Do you know of any cheap or easy CAN Bus communication devices which can interact with the TC charger and change their settings? I just find that CAN Bus is not the easiest thing for the DIY community to work with. A simple TC charger GUI would be ideal...
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Re: Two chargers blow simultaneously.

Post by coulomb » Thu, 24 Jan 2019, 09:36

jonescg wrote:
Thu, 24 Jan 2019, 08:28
are you suggesting that TC chargers don't come with the Enable / voltage divider option any more?
Sorry, I lost track of what happened after the late 2013 change (took a while for that change to filter through the market). So I don't know.
Do you know of any cheap or easy CAN Bus communication devices which can interact with the TC charger and change their settings? I just find that CAN Bus is not the easiest thing for the DIY community to work with.
Yes, that's true.
A simple TC charger GUI would be ideal...
Like the one that used to be available from the EVTV Motor Verks store? My recollection is that it was never cheap.
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Re: Two chargers blow simultaneously.

Post by Paul9 » Thu, 24 Jan 2019, 10:14

Thanks for the replies.

Looks like plenty of space and more fans is the go.

Regards
Paul

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Re: Two chargers blow simultaneously.

Post by 4Springs » Thu, 24 Jan 2019, 17:23

jonescg wrote:
Thu, 24 Jan 2019, 08:28
Interesting coulomb - are you suggesting that TC chargers don't come with the Enable / voltage divider option any more?
This seems to be the case, yes.
I left room in my vehicle for a third(!) charger, with the idea that I could hook up to 10, 15 or 30A supplies like Paul has done. The new chargers though only seem to have CAN interfaces. One reason why I haven't done it - I'd need to figure out CAN and reprogram my BMS to use it...

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Re: Two chargers blow simultaneously.

Post by antiscab » Thu, 24 Jan 2019, 21:31

You can still order Tc chargers with the enable option. I ordered a 1800w unit with it last year
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Re: Two chargers blow simultaneously.

Post by brendon_m » Fri, 25 Jan 2019, 06:24

I didn't buy it but the tc charger in my car is new and has the enable/voltage divider stuff, so they are available. Pretty sure it came from ev works

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Re: Two chargers blow simultaneously.

Post by brendon_m » Fri, 25 Jan 2019, 06:26

Also on the reliability side, it's the 3rd tc charger since 2012 to be fitted to the car since it was converted. I don't know what happened to the old ones

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Re: Two chargers blow simultaneously.

Post by Paul9 » Fri, 25 Jan 2019, 07:18

I just checked the evcomponents.com website where both the old TC models and the new HK models of the TC Chargers are both listed as having either the enable option or the CAN interface at the purchaser's discretion. I have always bought the enable option to keep things simple.

I did purchase two of the new HK models about 2 years ago and had nothing but trouble. I had to replace them with the old TC model and the KPES charger which have now blown as per my posts above.

The old TC charger is twice the size and weight of the KPES charger (and twice the price) so I am going to buy two of the KPES chargers.

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Re: Two chargers blow simultaneously.

Post by coulomb » Fri, 25 Jan 2019, 07:48

Paul9 wrote:
Fri, 25 Jan 2019, 07:18
I just checked the evcomponents.com website where both the old TC models ...
Actually, these are branded Elcon [ edit: I just checked, and the photos show a combination of TC and Elcon branding, but I think all of these are supplied and programmed through Elcon in California ] ; I don't think you'll find an older model TC charger that is branded as TC [well, available from any source independent of Elcon USA ]. It seems to me that Elcon have some sort of agreement with TC to keep manufacturing these older models, even though TC themselves no longer sell them.

I don't understand how this is possible, unless they are all old stock, or Elcon or TC bought up a lot of the now obsolete processors, or these use a different processor with much the same firmware recompiled for the new processor.
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Re: Two chargers blow simultaneously.

Post by T1 Terry » Fri, 25 Jan 2019, 15:11

Would powering the 2 chargers off separate phases from the 3 phase charging stations help against the spikes from a charger suddenly shutting down? I'm guessing the over temp protection doesn't gradually wind back the charge rate but rather cuts the input with the resulting problem you explained earlier with the power correction circuitry.

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Re: Two chargers blow simultaneously.

Post by coulomb » Fri, 25 Jan 2019, 16:40

T1 Terry wrote:
Fri, 25 Jan 2019, 15:11
Would powering the 2 chargers off separate phases from the 3 phase charging stations help against the spikes from a charger suddenly shutting down?

I guess so, but I'd prefer to have the problem fixed at the source.

I'm guessing the over temp protection doesn't gradually wind back the charge rate but rather cuts the input with the resulting problem you explained earlier with the power correction circuitry.
Actually, it does cut back gradually, so that part is fine. The ridiculous problem is that they use a surface mount sensor on the main PCB, which is facing the metal case. So the high temperature has to conduct through the air to the sensor, and I strongly suspect that the message ("it's too hot!") arrives far too late.
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1.4 kW solar with 1.2 kW Latronics inverter and FIT.
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Patching PIP-4048/5048 inverter-chargers.

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