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  #11  
Old 06-06-2012, 08:32 PM
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dtbaker dtbaker is offline
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Default Re: Dcdc fuse keeps blowing

Quote:
Originally Posted by skooler View Post
I tried running without the acc battery. The only thing the dcdc was powering was the soliton and it cut out with a 12v too low error every time I stamped on the pedal.

this is the big clue that the chennic unit nominal may be set higher than you think, and not handling the sag under load.... the chennics are not 'bullet proof' and do NOT like input voltage less than-10% of design nominal. review your chennic manual or plate on the side, what nominal input is your unit expecting?

second issue is if your dc-dc is not always on, and your aux battery is handling prarasitic loads until you turn the car on.... the dc-dc will be working VERY hard to top off the ux battery as soon as you turn on the car. I would suggest that you leave the dc-dc always on in this case so that the aux battery is basically always full and just handling the pull when the dc-dc struggles with mometary sag or spikes from sudden loads when turning on headlights, heaters, or vacuum pump.


ps. I am not impressed w/ the Chennic, and will try an ACME next I think. My first Curtis was faultless, but expensive. I tried the Chennic which was cheap, but the first one only lasted a year and then input side shorted out. I had a spare which I installed, but am not trusting it.... EvolveElectrics has a pretty good price on the ACMEs, and Justin is telling me that people have had good luck with them.
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Last edited by dtbaker; 06-06-2012 at 08:37 PM.
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  #12  
Old 06-07-2012, 09:26 AM
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skooler skooler is offline
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Default Re: Dcdc fuse keeps blowing

Thanks for all the help!

I'm going to follow the advice in this thread.

My todo lis is...
  • Install a Diode on the input side - to stop the input caps from being drained
  • Install a heatsink - to help with heat disipation (maybe an ali block underneath? its currently on a 2mm sheet)
  • Fully charge the acc battery and see if the DCDC remains hot while running
  • rewire so that it is 'always on'
I will update once I have done these on how things have gone.

I will put up with the chenic for now and upgrade as soon as evnetics release one... I'm sure that it would be bulletproof!

Cheers,

Mike
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  #13  
Old 06-07-2012, 09:43 AM
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Default Re: Dcdc fuse keeps blowing

Just had a look at the chennic site...

Im not onvinced that mine is the same model, look at the heatsink, I also have no plate whatsoever on mine...



http://www.chennic.com/up_files/file...0504521412.pdf

This is where I purchased it:

http://www.ebay.co.uk/itm/Isolated-D...item19cacd4e4d

Cheers

Mike
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  #14  
Old 06-07-2012, 10:08 AM
zsnemeth zsnemeth is offline
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Default Re: Dcdc fuse keeps blowing

I guess your's is the 144V version, not the 72V..
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  #15  
Old 06-07-2012, 10:11 AM
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Default Re: Dcdc fuse keeps blowing

yeah sorry,

its the 144v version.

same seller though
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  #16  
Old 06-07-2012, 12:09 PM
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Default Re: Dcdc fuse keeps blowing

Hi Mike

I've got quite a few universal-input 7.5V @ 30A output PSUs here (Meanwell 200W units), which should work fine with your pack voltage. A pair can be adjusted & wired with their outputs in series to make 14.4V

I've also got several other PSUs, including a Vicor battmod & large booster module (would be great with a liquid-cooled plate & waterproof box)
Send me a p.m. if you still have no luck with the Chennic unit.

P.S. any news on that Sinopoly cell?

Richard
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  #17  
Old 06-07-2012, 07:01 PM
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Default Re: Dcdc fuse keeps blowing

I would (and do) use an inductor on the input as Tesseract recommends, otherwise the ripple from the controller will kill the converter's input caps. The diode won't protect from the ripple.

I had the same fuse-blowing problem, solved it temporarily with a rectifier but ultimately ditched it, and I now use an inductor instead (http://parts.digikey.com/1/parts/659...2312-h-rc.html).

I have no problems with my Chennic... On my 205v nominal system it only really pulls a couple of amps. And I use an Odyssey 12v AGM as a buffer and failsafe.
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  #18  
Old 06-07-2012, 09:44 PM
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Exclamation Re: Dcdc fuse keeps blowing

I looked at the price and specs on the eBay site. $123 is not a bad price for a 400W DC-DC converter. But you can get a 300W switching supply for under $100, and a 500W unit for $200.
http://www.newark.com/xp-power/lcl50...ply/dp/52R2914
It provides a highly regulated 12VDC over a range of 127 to 370 VDC and its dimensions are 250x127x50 mm. It is 88% efficient at full output, so it will only dissipate about 48 watts with 400 watts output.

The Chennic needs to be specified for input voltage, and the output voltage seems to be 13.8V at 0 amps, and 12V at full output. There is no line or load regulation spec, so I think it may be essentially unregulated. Also I could not find the dimensions for the Chennic, but it looks like it is mostly a big heat sink. You don't need that for 48 watts at full output.

Mean-Well has a line of intelligent battery chargers and PSUs that might be better than the Chennic:
http://www.meanwelldirect.co.uk/prod...12/default.htm
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  #19  
Old 06-08-2012, 05:19 AM
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Default Re: Dcdc fuse keeps blowing

Hi Skooler,

You might want to check out my youtube video showing the fault on my brand new Chennic DC-DC.
http://youtu.be/8sEOQfKpfUk
I use a zilla and had blown a couple of fuses which were glass fast blow like the original I got with the Chennic.
I replaced it with a slow blow HRC style fuse and it's been fine ever since. I do believe the inductor is the right way to go, I've had one on the bench for months and never quite got round to fitting it

I trust you have the + and - connected permanently and are switching on and off with the other wire? If you are not doing this, you will have a huge inrush each time you switch on (built in protection is crap)and that will fatigue the fuse.

Derek

Last edited by dillond666; 06-08-2012 at 05:20 AM. Reason: forgot the link!
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  #20  
Old 06-09-2012, 05:25 AM
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Default Re: Dcdc fuse keeps blowing

Hi all,

Having a play with the dcdc at the moment.

It's also making a hissing sound after about 20 mins use.

At first I thought that it was the sinopoly cells venting but the sound is definitely the dcdc.

Does anybody else have this or have I got yet another problem with this unit!

I will try my luck with it over the next few weeks and decide whether or not to replace it!

I will have a read up properly later. On my helpers iPad ATM.

Richard,

The cell has been packaged up on the back seat of my car for the last couple of weeks! Apologies, I WILL post it on Monday!

P.s. my helper has suggested it could be damp / condensation boiling inside the unit? It's changed from an electrical hissing to a boiling sound while if written this post.

Cheers,

Mike
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