[SimonRafferty]

I need to make the Orion waterproof - more waterproof anyway.

A while back, I emailed Ewart asking about the thermal bonding inside the Orion - essentially asking if the components were thermally bonded to the casing, or if they rely on convection cooling to transfer heat to the casing. This determines how I approach the waterproofing.

Unfortunately, I didn't receive a reply and could not find any answers on line - so I decided to void my warranty and have a look! I figured that would be better than risk cooking it which would likely void the warranty anyway.

You can see they've used a (pink) thermal transfer pad to link the components on the bottom PCB to the face of the box where the heatsink attaches.

For me, that's good news because it means I can use something like Raytech Magic Gel to seal the whole thing, including connectors & wiring without it interrupting the heat flow to the casing.

It means also that just bolting it down to a cool surface via the flange with bolt holes will probably not provide sufficient cooling without the heatsink and airflow over it.

I wish someone made an IP rated BMS - but I cannot find anything other than Chinese ones on eBay - and I'm not going to trust the pack to one of them!

I hope this might be useful to some of you in future.

 

[SimonRafferty]

How much power dissipation do you expect from the BMS?

I don't have any specific data - but the heatsink is probably around 1°C/W based on it's size. Assuming it wants to stay below 100°C, say - that says the heat evolved by the BMS is in the 50 to 100W range.

This is just a guess though!

 

[SimonRafferty]

A Polaris General Side by Side - Electric 2021 Polaris General

Being a fairly open, fairly off-road vehicle, everything inside gets wet! Probably as bad as if it were a boat.

 

[SimonRafferty]

Does your battery not need to be sealed too?

The Battery is only 110V - and it will be protected with a conformal coating over the terminals, bus-bars etc. Much the same as Magic Gel but in a spray.

All the other components have ratings of either IP55 or IP54. While that's not a lot, compared to the IP69K required for most Automotive components, it's better than nothing. That plus conformal coating or Magic Gel will do the trick I think.

 

[SimonRafferty]

For what it's worth, voiding the warranty just from you opening the case may not actually be enforceable, depending where you live. We’re Afraid of Warranty Stickers, but Really, Manufacturers Should Be | iFixit News

I totally agree. I'm not sure how that will stack up now the UK has left the EU. It's probably not high on the politicians priority list.
However, it's never worried me! I disassemble most new things on principal!

 

[SimonRafferty]

I was considering building my Orion into my waterproof battery box, and replacing the heatsink with a chill plate. But I could be talked out of that.

If you have a waterproof battery box, and there's space for the BMS, that's by far the best option! I would stick with that.