Olympus OM-D E-M1 MkII external power supply (AC-5 alternative)

This article is for information only. Any mistakes in providing power to your camera can cause irreparable damage to it. In particular, incorrect voltage and/or polarity are critical errors that are highly likely to destroy your camera. If you decide to make your own power supply for your camera, it is at your own risk.

While I don’t need to make use of them often, I like to get external power supplies (PSUs) for my cameras to cope with extended shoots such as timelapse sequences. Unfortunately, all camera manufacturers seem to like to charge a premium for what is, essentially, a simple piece of equipment and the PSU for the OM-D E-M1 MkII is no exception. Olympus appear to have reached new heights with the AC-5, however – a cool £150 is required to buy it from the Olympus store. Oh – and you need the HLD-9 battery grip to use it, of course, which costs another £280. The grip is useful in its own right, and maybe its price isn’t too bad as they’ve added the direction pad buttons to it – these were missing on the HLD-7 for the original E-M1. I did wince at the price of the AC-5 though.

The AC-5 is rated at 9V, delivering up to 5A. Similarly spec’d power supplies typically cost less than £20 on eBay and Amazon, so I decided to investigate going down the third-party route. There are plenty of third-party PSUs advertised for various cameras, but I suppose the Mk II is too new at the moment – I certainly didn’t find any on sale. The only recourse was to repurpose an existing supply. One of the difficulties you generally encounter with this approach is that camera vendors typically employ proprietary connectors for their accessories (take a look at the AC-3 connector, as used on the original E-M1, for an example). These are often close to impossible to buy, so the usual solution is to sacrifice something else that uses the same connector. This is only feasible if the sacrificed part is relatively low in cost, such as a third-party remote.

Refreshingly, on the E-M1 MkII, Olympus are using standard connectors for functions that were accessed via proprietary connectors on earlier bodies:

  • The remote release uses a simple 3-pole 2.5mm jack
  • Video out is now through an HDMI micro connector (type D)
  • USB access is via a USB Type-C connector
  • The external PSU connector is a standard barrel connector (5.5mm external diameter, 2.5mm internal diameter). The outer sleeve is negative, the inner terminal is positive, but please don’t take my word for it – check the diagram on the rubber flap covering the connector on the HLD-9 for yourself.
5.5mm/2.5mm barrel connector

This makes it simple to repurpose a suitable supply. A quick search on Amazon found several supplies (mainly by ExPro) claiming to be 9V 5A and equivalent to a Nikon EH-5A so I ordered one. The EH-5A has four pins in its connector, two are not connected (NC) and the other two are the 9V supply pins, so it seemed ideal for the MkII. I’ve bought several items from ExPro over the years and found them to be a reliable source for compatible equipment, such as batteries. Sadly, when the PSU arrived it was actually rated at 9V 4.5A. This may well have worked, but I wanted to have a PSU rated the same as the AC-5 to be sure I wouldn’t run into problems – accordingly, the ExPro PSU went back to Amazon for a refund.

Completed PSU

Searching further, I found a Nikon EH-4 equivalent (also on Amazon), again rated at 9V 5A.  A quick question to the vendor confirmed that the unit was really rated at 5A so another order went in. It arrived within a few days and was indeed rated for 5A.

Thirty minutes or so later, I had chopped off the Nikon connector and soldered on a suitable barrel connector. This is not for the faint-hearted! If you get the voltage or the polarity wrong, you could cause irreparable damage to your E-M1 MkII. My background is in electronics, so I was confident in my abilities and I also double- and triple-checked everything before trying the PSU on the camera.

It was still with some trepidation that the moment arrived to switch it on connected to the camera. Thankfully, it all worked fine. I tried some quick tests of shooting at 60fps, assuming this would probably be one of the biggest loads the camera would place on the PSU and it went without a hitch. Total cost for the PSU was about £20 – quite a nice saving compared to £150!

7 thoughts to “Olympus OM-D E-M1 MkII external power supply (AC-5 alternative)”

  1. The connector is on the HLD-9 and has positive centre, negative sleeve – check the diagram on the HLD-9 connector cover.

    Thanks for pointing out that omission – I’ve added something about this to the text above.

  2. Great idea thanks!

    I’m half way there. Bought a suitable barrel connector, bought a power supply compatible with the Nikon (EH-4 – 9V & 5A) & even have my soldering iron. But … (and yes, I know, you can’t take any responsibility for me frying my EM-1 Mk II & HLD-9), but how do I know which of the THREE wires leaving the power supply I should use? Which is +ve, which is -ve, and which can I ignore (as I guess it’s an unused earth)? One has long white bars along it. The middle one is blank. The other one has writing on. I can’t open up the AC adapter block.

    Many thanks for any guidance you can give!

    1. Let me first say that I wouldn’t recommend just going by the markings – who knows whether the markings are consistent from one supply to the next? One would hope that they are, but one can never be sure with cheap electrical equipment. The only way to be certain is to measure the voltages using a multimeter or similar.

      Unfortunately, I didn’t make notes about the wire markings when I did the work. I have, however, found the original discarded Nikon plug and some scribbled notes I made about the voltages on the connector pins. If the notes are correct, on my particular PSU the wires are as follows:

      long white bars: 0V
      no markings: +9V
      writing: N.C. (not connected – there is a wire there, but it doesn’t appear to be connected to either of the others in any way)

      Be aware that the NC wire is potentially a sense wire of some sort, providing feedback to the supply from the camera. My limited testing, however, suggested that this isn’t the case (at least for my particular supply) and just connecting the +9V and 0V wires using the barrel connector powers my EM-1 MkII without any problems.

      I do urge you to measure the voltages yourself though. Even though you’re doing it at your own risk, I’d hate for you to let the magic smoke out of your camera!

      Hope this helps.

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