Ovartech

A quick update - look what turned up today:



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

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+10m 27˚C
T+20m 33˚C
T+30m 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.

I have the aircooled version, the 1kW one without a cooling fan on the heatsink, i.e passive air cooling only. Luckily it seems like it won't get particularly warm in my EV.

I've been in the EV conversion game for about 10 years now and it has always been hard to find good DC/DC converters. Lots of them proved to be unreliable, or weren't really designed for the job. Most EV I've built personally have used IOTA DLS55s, which are technically an AC/DC power supply and are not weatherproof (open housing), but they worked fine with DC input and were quite reliable. But AFAIK they're no longer available, and the open housings make me nervous (just waiting for the day that dirt or water ingress kills it). So finding a better option was my original motivation for trying out one of the Ovartechs. The lead time was worrying, but I think if the company can address this and improve availability, they could do well.

It would also be good to see 100-200V versions of their DC/DC converters, since probably the majority of EV conversions are in that range.