We have had reports of intermittent / bad connections when using certain Vmount batteries with the spectrum ST4 VMount. We have spoken with the professionals at IDX to get a better understanding of why this might be happening. We also spoke to industry professionals at Hot Rod Camera who have seen it all over the years.
Here's a quick overview:
1) Not all mounting plates are created the same. We source genuine, serialized P-V2 plates direct from IDX - http://www.idxtek.com/products/p-v2/ While not cheap, the quality is high and consistent and has the quality to last a long time. Sourcing $10-$30 plates is a recipe for failures and inconsistency that we just won't do.
2) Not all batteries are the same that claim VMount compatibility. There are a few issues which arise. Mechanically, the battery might not seat well or lock in consistently. Mechanically, the pins might not be centered on the right axis to make secure contact. Electrically, the pins might have low quality plating the wears quickly and can result in intermittent connections.
Our recommendation is to test the V Mount packs you want to use with the spectrum ST4 for a mechanically solid connection that latches in securely and keeps consistent electrical contact when wiggled on the mount.
At this time, we can recommend using major US brands with high quality control like IDX, Anton Bauer, CoreSWX, and Blue Shape. These aren't the only batteries that will work for sure, but we have feedback that these packs are mechanically and electrically consistent and reliable.
Here is a quick test we ran to figure out why certain packs don't work:
What batteries do we know have challenges? Packs from Amazon that aren't sold in the US through major retailers. There are many. The one we tested and saw mechanical challenges with the shape of the Vmount is MaxOak. The pack is also listed as incompatible with Wooden Camera, Blue Shape on the site. We aren't sure why the shape of their packs is different. This could be making things slightly different to get around patent issues or they build to different specs.
The difference between packs seems to come from being able to fully seat the battery, or having the battery not fully seat against the electrical contacts.
We did a couple measurements between our IDX batteries and the MaxOak we sourced. It was pretty stark. Our IDX batteries sat slightly more than 2.0 mm deeper into the mount than the MaxOak Pack. Basically the contacts weren't fully seating despite the mechanical lock engaging.
Once we swapped the plastic V out from the MaxOak pack with the metal V from and IDX pack, it was able to fully seat and make good connections and powered up the spectrum reliably.
I have a pack that won't work - how can I make it work?
Filing or replacing the V mount portion on the battery to allow it to seat lower and fully into the Plate, usually seems to be the ticket. Once we swapped the plastic V out from the MaxOak pack with the metal V from and IDX pack, it powered up the spectrum reliably. You might also note that it powered on our RED camera reliably too.
So if you have an issue with bad connections on some packs, start by looking around and trying to replace this VMount portion from your battery. Or if you don't want to fiddle, just start with highly controlled, but more expensive packs with a US warranty and safe yourself the trouble.