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Draft schematics for 12V and 300V circuits for my conversion

Posted: Thu Apr 16, 2009 7:49 pm
by audia2ev
Hi all,

I've made a first attempt at the schematics for the 12V and 300V wiring in my conversion. They are two PDFs, can be download from this page:

Any comments and advice appreciated before I blow anything up...

Posted: Thu Apr 16, 2009 9:43 pm
by retepsnikrep
Neither file works for me so can't comment :(

Posted: Thu Apr 16, 2009 10:44 pm
by Wilfried
The links are not working...

New links: 12V circuit and 300V circuit


Posted: Thu Apr 16, 2009 11:24 pm
by retepsnikrep
Be aware when connecting your charger to your HV battery that due to the output filter/smoothing capacitors in the charger there may be a big flash and spark as the caps suddenly see 300V appear with no current limit to control the charge speed.

The caps will look like a short to the battery pack/supply until they reach a reasonable voltage, you could burn out a pcb track in the charger and it will certainly make you jump.

I pre-charged my charger filter caps before making the final connections.

Your controller may also require some sort of capacitor precharge circuit.

Posted: Wed Apr 22, 2009 7:15 pm
by audia2ev
Sorry for the link c$%^-up and thanks for sorting it out...

I'm checking to see if my DMOC445 unit has a precharge function (seems some do, some don't).

Posted: Wed Apr 22, 2009 7:30 pm
by audia2ev
Azure Dynamics confirmed my DMOC445 has a precharger, so no problems on that front.

Fuse sizes.

Posted: Thu Apr 23, 2009 8:27 am
by GregsGarage
Hi Simon,

Had a quick look, you might want to have a look again at your fuse sizes. The 15 amp fuse for yuor DC-DC on the 300 volt side seems a bit high, that fuse will allow 4.5kw power to flow through it! :shock:

On the 12 volt side you show a 150 amp fuse on your 12 volt battery and a 20 amp fuse for the vacuum pump. Are you sure you can't size these smaller. Otherwise looks good.


Posted: Sat Apr 25, 2009 2:32 pm
by audia2ev
Thanks Greg for the look through.

On the 12V, the original battery has a 150A fuse sort of hard fixed into the connector, so I thought I would just keep it. However, I have since got another smaller gel battery (to fit in the cubby hole in the floor) which needs new connectors, so I will almost certainly change it. 100A sound about right?

The vacuum pump came with an in-line fuse and I think it is 20A (it draws around 8A). I'll double check it.

The DC-DC converter is indeed 55A at 12V output, so 660VA, let's say 80% efficient (pessimistic I think), so 825VA, less than 3A at 300V. Indeed can be much smaller, maybe I'll start with 5A.

Posted: Mon Apr 27, 2009 8:02 pm
by audia2ev
I've just had another exchange with Azure Dynamics (very fast reply again) and they say:

correct, please do not use the Kilovac. You will probably see abnormally long precharge times – minutes – if you were to use it. When the 12V supply is off, the DMOC is disabled, so we recommend leaving the high voltage connected all the time except for emergencies and maintenance. Many people use a E-stop for the latter situations.

So, the Kilovac's are out of my circuit. However, I don't like the idea of no way to isolate the batteries - but how do you achieve this without a relay? All the emergency switches I can find are pretty pathetic when it comes to 300V/100A circuits... like these.

Is there a switch that can handle that kind of circuit??

Posted: Wed Apr 29, 2009 7:19 pm
by jonathan jewkes
You could look at the "Emergency disconnect" switches made by Albright International. Should be able to handle 300A.