Ovartech

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zeva   10 µW

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Ovartech

Post by zeva » Mar 30 2018 10:57pm

Hi all,

A quick community service announcement: Earlier this year I got contacted by a Chinese company called Ovartech, whose website lists a range of chargers and DC/DC converters for electric vehicles. I couldn't find any independent reviews of the company or their products on Google, but thought I'd risk it and ordered a sample of their 1kW DC/DC for evaluation.

I placed the order on 31st January, paid for it on 2nd February, and as of 31st March am yet to receive it. So I would advise against ordering from this company until we have more evidence of their legitimacy. Hopefully this forum page will show up if anyone else out there finds themselves looking for information on this company before committing to an order.

If I do eventually receive the order, I will be sure to update this thread and provide an honest product review.

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jonescg   1 GW

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Re: Ovartech

Post by jonescg » Apr 01 2018 12:23am

Hi Ian,

Rod Dilkes had exactly the same experience. Plus after I wrote to them asking for a price they said they generally won't sell one-offs, and if they do, it would be for twice the price I was quoted 6 months earlier.
I daresay TC might be a better place to go shopping.

Hope you get your money back!

Chris

zeva   10 µW

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Re: Ovartech

Post by zeva » Apr 02 2018 7:44am

Thanks. Getting money back from a Chinese vendor seems unlikely. I remain hopeful that they're not total vaporware, and will come through eventually and send the product. If not, at least this can be an expensive warning to others in the EV community.

zeva   10 µW

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Re: Ovartech

Post by zeva » Jun 29 2018 4:38am

A quick update - look what turned up today:

Image

Build quality seems good. I will put it through its paces over the coming weeks and report back.

Cheburator   1 µW

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Re: Ovartech

Post by Cheburator » Jun 29 2018 7:12am

So you waited 5 month for your order? :?

zeva   10 µW

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Re: Ovartech

Post by zeva » Jul 01 2018 8:01pm

Yes, about 5 months total - make of that what you will! In truth, I had given up on it after a few months. The most charitable explanation would be that the product was actually still in development, maybe took longer to finalise than they expected, and they had started drumming up presales well in advance.

It's certainly too long a lead time to be viable for most EV businesses / resellers / end users, but perhaps the situation will improve. In my experience there aren't a lot of good DC/DC converters on the market in this sort of size so it *could* be a useful product..

zeva   10 µW

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Re: Ovartech

Post by zeva » Oct 01 2018 11:12pm

Hi all,

I have some long overdue test results for the Ovartech DC/DC converter. The TLDR version is that it seems to work well, and if not for the long lead time (which the company is hopefully addressing) I would recommend them to others. I’d be interested to hear if anyone has bought more recently and can report on what their lead time was.

Quiescent current consumption
Some current values when its inputs and outputs are connected to things but turned off (i.e no 12V supplied to enable wires).

1.1mA backfeed on the 12V battery (i.e current flowing back into the DC/DC converter when off). Low enough that it’s safe to leave output side connected to a battery permanently.

37mA input current from the HV even when it is off (not enabled). So, it would be best not to have it permanently wired to your HV battery when not in use, or it could eventually flatten it. The HV input should be isolated by a contactor / relay when not in use.

Output regulation
Output voltage seems to be about 14.15V no load down to about 13.85V at 50A. About 50mV of this is probably due to drop in the 4AWG cables. 14.15V might be a bit high for some types of battery, e.g flooded lead acid? I use 4x Headway (LiFePO4) cells for my 12V battery so it charges them to about 3.55V each on average, which seems pretty safe.

Measuring efficiency under load
First test: 292V at 2.05A input (599W), 14.05V at 41.3A output (580W) = 97% efficient
Second test, slightly higher load: 291V at 2.51A input (730W), 13.85V at 50.1A out (694W) = 95% efficient

So, efficiency is good for an isolated converter, not too surprising to see reduced efficiency at higher loads, but also my measurement accuracy is probably ±1% anyway so take it with a pinch of salt.

Extended load test to check thermal performance
Continuous load of 45-50A (in my RX7 with power steering pump, high beams and fog lights on). Temperature measurements are approximate average around the heatsink (varies by a few degrees depending on where the temp gun is pointed). In still, open air.

T+0 21˚C (ambient)
T+10 m 27˚C
T+20 m 33˚C
T+30 m 36˚C
T+40m 39˚C
T+50m 41˚C

So, nothing I need to worry about with the 50A maximum load on the 12V in my EV. (Also it will be installed in a location that gets some airflow when driving.) But could possibly benefit from some added convection cooling if it were used near its maximum rating and in a confined space.

Test results seem good overall, and it has several advantages over my existing IOTA DLS-55 (primarily the weatherproof housing, but also higher current capability, slightly higher output voltage and with less sag under load), so my next step will be to install it permanently in my RX7 and see how it goes long term.

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jonescg   1 GW

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Re: Ovartech

Post by jonescg » Oct 02 2018 3:36am

Great to see you got some useful data from it Ian!
Is it like the TC converters which use a digital input to switch them on? Or are they fed by a PTC circuit so they always give a soft start?

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