[skooler]

Hi Jeffrey,

What kind of size charger are you thinking of (in kw)? Or will you have more than 1 option?

Will it be possible to parallel them?

Either way... Put me down for the one!

Cheers,

Mike

[Tesseract]

Originally Posted by skooler

..
What kind of size charger are you thinking of (in kw)? Or will you have more than 1 option?

Will it be possible to parallel them?
...

I just started on the design so can't answer any questions yet. It will be isolated, it will be at least 8kW, and it will be programmable. That's about all I've nailed down right now.

[Woodsmith]

Originally Posted by Tesseract

Lately we've been kicking around the idea of combining the dc/dc and charger in one box... It seems like a good idea to me, and eliminates some of the cost concerns with a custom enclosure, etc., since the charger would require one anyway.

I like this idea.

The more I read about your products the more I feel I should be saving for and planning around using them.

It may mean I can't afford a battery pack but I can cross the bridge then.

[Yukon_Shane]

Originally Posted by Tesseract

Lately we've been kicking around the idea of combining the dc/dc and charger in one box... It seems like a good idea to me, and eliminates some of the cost concerns with a custom enclosure, etc., since the charger would require one anyway.

I think this is a great idea. The more integration the better; plus you're killing two problem areas with one stone.

Glad to see the evnetics charger is still on the table.

[Emd]

Originally Posted by Tesseract

Lately we've been kicking around the idea of combining the dc/dc and charger in one box...

Not in favor because
-I already have a charger (although if I needed one, I'd probably buy one from Evnetics )
-I need more than 50A from the DC-DC... I don't think I'd buy two DC-DC + Charger combos to get there...
-If something fails (DC-DC or charger), I like to return only the affected item for service.

So please count my vote for keeping components separate.

Cheers!

[PStechPaul]

Just to enhance my own understanding, I had thought that the DC/DC converter and charger, for 12V accessories, was a single unit, and would always be used with a regular lead-acid battery as may have been in the vehicle. And I had assumed that the charger would just keep that battery topped off from the main battery pack. Of course a separate AC-DC charger could be used to keep the accessory system charged up during extended storage.

Then there would need to be the main battery charger, which would need to be powered by AC mains of 120 or 240 VAC. And as long as that power was charging the main battery pack, the DC/DC charger would also be charging the accessory battery.

If the accessories battery was a LiPo type, then the charging profile would need to adjusted for that chemistry, but otherwise the design and construction would be about the same. And since well-designed battery chargers have an output current limit of perhaps 13.8 or 14.4V, they could also be used without a battery in case it fails and needs to be disconnected. In such cases it would be good to have a decent size capacitor in the charger to keep the voltage steady under momentary current surges, and to limit ripple and noise.

Is this correct, or am I missing something?

[Tesseract]

Originally Posted by PStechPaul

If you can accept an input voltage range of 127 to 373 VDC, you can get 16 amp switching chargers for about $80 each:
http://www.mouser.com/ProductDetail/...%2f5DIEw%3d%3d

Yes, most people are aware of the MeanWell switchers. We even use them as individual chargers for the 12V AGM batteries for our dyno. They do have a disturbing tendency to blow up every now and then, so not the greatest quality, but at $30 each (for the 150W version) it's a tolerable failure rate.

That said, we mounted them in a NEMA enclosure with multiple fans for cooling and inside said box they aren't subjected to vibration, impact, temperature extremes, or high humidity. They get none of these benefits when installed in a car.

It's admirable to try to find a less expensive product, but at some point you go too far down the price vs. quality vs. performance scale. The MeanWell switchers are well past that point in my professional opinion.

Originally Posted by PStechPaul

Maybe I can collaborate with you on this design. ...

Thanks for the offer, but the dc/dc converter won't be too much of a challenge for me. I've more or less designed it already, anyway, I just need to lay out the board, build a prototype, etc...

[Tesseract]

Originally Posted by Woodsmith

I like this idea.

The more I read about your products the more I feel I should be saving for and planning around using them.

Come to the dark side, Woody... We have cookies...

[Tesseract]

Originally Posted by Yukon_Shane

I think this is a great idea. The more integration the better; plus you're killing two problem areas with one stone.

Ok, that's two votes for integrating the charger and dc/dc converter and...

Originally Posted by Emd

Not in favor because
-I already have a charger (although if I needed one, I'd probably buy one from Evnetics )
-I need more than 50A from the DC-DC... I don't think I'd buy two DC-DC + Charger combos to get there...
-If something fails (DC-DC or charger), I like to return only the affected item for service.
...

...one vote against.

However, these reasons may not apply to the integrated charger + dc/dc.

1. Can't argue with that, though I have to point out that the same rationale could be used to argue against the development of any new product.
2. If I integrate the dc/dc into the charger I won't have the same constraints w/r/t the maximum practical output current, so I'd probably aim for 70A instead.
3. The dc/dc would be an almost totally separate "module" inside the charger box. The only component it would share with the charger would be the ripple-blocking inductor. The main reason to put it in the same box is to save the cost of the enclosure (~$40-$50).

Otherwise, I happen to agree with on your 3rd point - I'm not a big fan of highly integrating multiple functions in one box (e.g. - charger and motor controller) precisely because it increases the likelihood of failure (mainly because there is an inevitable compromise in the shared components to allow them to do double duty).

Nothing's etched in stone at this point.

[lowcrawler]

Throw a in a 120V AC plug for those of us that like to plug things in in the car or use the car as a mobile power source?