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

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audia2ev
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Draft schematics for 12V and 300V circuits for my conversion

Postby audia2ev » Thu Apr 16, 2009 7:49 pm

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:
http://groups.google.com/group/audia2ev/web/design-new-electrical-systems

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

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retepsnikrep
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Postby retepsnikrep » Thu Apr 16, 2009 9:43 pm

Neither file works for me so can't comment :(
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

Wilfried
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Postby Wilfried » Thu Apr 16, 2009 10:44 pm

The links are not working...

New links: 12V circuit and 300V circuit

Wilfried

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retepsnikrep
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Postby retepsnikrep » Thu Apr 16, 2009 11:24 pm

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.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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audia2ev
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Postby audia2ev » Wed Apr 22, 2009 7:15 pm

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).
Simon

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audia2ev
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Postby audia2ev » Wed Apr 22, 2009 7:30 pm

Azure Dynamics confirmed my DMOC445 has a precharger, so no problems on that front.
Simon

GregsGarage
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Fuse sizes.

Postby GregsGarage » Thu Apr 23, 2009 8:27 am

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.

Greg
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

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audia2ev
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Postby audia2ev » Sat Apr 25, 2009 2:32 pm

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.
Simon

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audia2ev
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Postby audia2ev » Mon Apr 27, 2009 8:02 pm

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??
Simon

jonathan jewkes
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Postby jonathan jewkes » Wed Apr 29, 2009 7:19 pm

You could look at the "Emergency disconnect" switches made by Albright International. Should be able to handle 300A.
Jonathan Jewkes
Daily EV user for 10years - an enthusiast and also a realist


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