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Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 06:11
by goingbush
Anybody used one of these, cant find any info on them, the fact that its fully sealed appeals to me, I just placed an order for my EV LandRover conversion , cheap enough & 50Amps is plenty as the ICE Alternator was only 35Amp :)

https://wholesaler.alibaba.com/product- ... 33459.html

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 12:27
by Richo
There is no spec on the isolation.
This IS a requirement for compliance in Australia.

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 14:26
by goingbush
OK thanks, where would I find the Australian requirements, other than NCOP14 ?

I cant find anything in there about isolation where it mentions auxilliary ELV , obviosly when I turn the car off the DC-DC converter will be isolated by a seperate relay , or am I missing something. ?

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 14:37
by 4Springs
Size: 30*19*15mm - seems a tad small! The photo looks more like 100mm long which would be more like it.
Max output current 32A. You'd need two I think, but still good for the price.

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 14:42
by 4Springs
goingbush wrote:
Tue, 17 Oct 2017, 14:26
OK thanks, where would I find the Australian requirements, other than NCOP14 ?

I cant find anything in there about isolation where it mentions auxilliary ELV , obviosly when I turn the car off the DC-DC converter will be isolated by a seperate relay , or am I missing something. ?
The requirements are in NCOP 14 section 2.9. It says that there must be less than 20mA leakage between the HAZV and the chassis. Since the chassis is normally 0V on the auxiliary ELV, that means that you need to have less than 20mA leakage between HAZV and auxiliary ELV.
This is a requirement of NCOP 14, but the specs on the DC/DC converter don't say if it is isolated at all. It quite possibly meets the specs but we can't tell until we buy one and test it.

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 15:14
by goingbush
Heres the same one in a different listing.

It does say 'isolated' on the label of the one that I purchased , but this one has it in the actual heading , and on the label of the converter.
https://wholesaler.alibaba.com/product- ... 96583.html

I think even 32Amps will be plenty, all I'll be running apart from the normal lights / indicators etc is a VW 12v vacuum pump for the brakes.

physical size is 204*127*48mm

So to be legal do I need to send it off to a lab for Australian certification , or just get the seller to certify it , or can I just test it with my DMM ?

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 15:52
by 4Springs
goingbush wrote:
Tue, 17 Oct 2017, 15:14
So to be legal do I need to send it off to a lab for Australian certification , or just get the seller to certify it , or can I just test it with my DMM ?
Can't test it with a DMM as it won't generate a high enough voltage. I think you'd need a megger? Electricians have them. I'd ask advice from someone more knowledgeable than me though, I wouldn't want you to blow it up!

You need to test the leakage on your completed vehicle. NCOP 14 states that it must be checked before working on the electrical system of the vehicle. I have a method that uses the traction pack voltage to do the test. So if it was me, I'd connect the DC/DC converter to my car, then run my test (on the whole car) and see if it passed.
The way I do this test is from E/ECE/324, regulation N. 100. It involves manually inserting resistors between the the chassis and each of the Traction Pack terminals (+ve and -ve). You measure the voltage across the resistors with a multimeter, do a calculation and work out the leakage current.

Re: Chinese DC-DC converter

Posted: Tue, 17 Oct 2017, 19:29
by goingbush
Awesome, thanks 45springs

I have a megger buried in the shed somewhere , ( courtesy of my old job ), but the resistor test sounds easy . I'll do same with car completed.

Re: Chinese DC-DC converter

Posted: Thu, 19 Oct 2017, 12:31
by Richo
One of the pictures does have a couple of wound parts on it which would imply isolation - but you can never be sure unless it's written.
Normally the manufacturer would know what the isolation is rated to.

It's more for your safety.
Nothing worse than laying on the floor unconscious because you touched your car.
Oh wait there is - being dead on the floor - but usually you don't care after that point :shock:
:lol:

Weather you test it or not I'd still be asking the supplier or manufacturer what the isolation is "rated" to or what conditions the isolation was "tested" to.

Other than that is looks pretty good.

Re: Chinese DC-DC converter

Posted: Wed, 01 Nov 2017, 12:11
by goingbush
I got a reply from the Manufacturer , the leakage between High Voltage and chassis is less than 20mA
FWIW have asked for certificate to be included.

Re: Chinese DC-DC converter

Posted: Wed, 01 Nov 2017, 15:01
by jonescg
20 mA at 300+ VDC is not good. Should be well less than that.

Re: Chinese DC-DC converter

Posted: Wed, 01 Nov 2017, 19:15
by goingbush
Well yes Chris, it should be zero leakage as far as Im concerned, but I just wanted assurance that it complied with NCOP14 which stipulates less than 20mA

Re: Chinese DC-DC converter

Posted: Thu, 07 Jun 2018, 15:03
by poprock
Hi goin bush. How has the chinese DC..DCperformed? I saw the same one on alibaba but 72v. At present I am using two 12v in parrallel and have not flattened them yet ( my pack is only 6.72 kwh). The electrician and engineer both passed this
arrangement, the only test was operating emergency flashers as per NCOP. Is it worth the effort for the small weight and distance gain with such a small AGM pack? Thoughts?