Designing the ultimate heated undersuit

[RedSeaDiver2]

Not a scientific flex test, but 18gauge is probably double the durability of 20ga. The more strands in the wire bundle for a given gauge, the more flexible it will be, but thinner strands also break easier. So it's a bit of a balancing act.

Cheers - will stick with 18 gauge then all the way through.

I'm curious what you are using for heat now?

Heated undersuits haven't taken off here yet for a variety of reasons - but I really need one. The various reasons why they haven't yet taken off include -

• price - the poor Australian dollar exchange rate doesn't help, and the chain from manufacturer to consumer has a few steps and each one of those wants their profit margin so they are very pricey here
• lack of education/knowledge about heated undersuits - at both the diver and the retailer level
• the problems & expense of getting the lithium batteries to Australia - the fees for dangerous goods air freight are quite high, and the volume is too low to ship them by sea
• Santi for reasons that nobody fully understands can't send their batteries to Australia, so Santi in Australia try to convince people that it is OK to use them with the Halcyon batteries that they sell - but the Halcyon batteries don't have any form of output control - just on or off.

So if we can make a good heated undersuit, pair it with a battery canister that is designed for heated undersuit use so has a controller built in, and educate the stores and end users then we think we will do quite well. Winter in the best time to dive here, but winter water temps are about 46 degF and that isn't really pleasant in a wetsuit, and there is more and more technical diving taking place here now too.

Obviously we will want to sell it to overseas markets as well, and hopefully we will be able to if we have a superior product.

 

[RedSeaDiver2]

Down regulating a 4s pack is ideal. But a 200wh pack is pretty modest. I would go up to a 250-300wh pack if you're willing to put up with the bulk. Especially if you are looking at 140W of potential power draw on high.

The biggest pack that they sell currently is the 196wH pack, at this stage we will only be drawing 110 watts, I think the thing to do at this stage is get the suit made and get out and test it and then see if we need more or...

 

[Sascha314]

If go for Tec I would want to be able to use a bigger tank, say 400 to 700Wh. Miranda e.g. has such.
Remember you have a voltage drop, so there is less heating power if you use a lot of the battery capacity. Maybe some like a travel and local bigger option for later.

So make sure you have EO or better WAM cord conection. Then you could in an emergency use your tank as well for the light.

 

[RedSeaDiver2]

If go for Tec I would want to be able to use a bigger tank, say 400 to 700Wh. Miranda e.g. has such.
Remember you have a voltage drop, so there is less heating power if you use a lot of the battery capacity. Maybe some like a travel and local bigger option for later.

So make sure you have EO or better WAM cord conection. Then you could in an emergency use your tank as well for the light.

Once we have tested the suit and mad sure that everything works as it should then we will be able to look at even bigger batteries etc. These batteries are 14.4 volt but the maximum heat setting will run 12V so it won't be until the battery is pretty much drained before the voltage drops below that.

 

[RedSeaDiver2]

One other question - how hot is the maximum heat that each panel needs to reach? This is a little bit of a trade-off - the higher the heat that each panel needs to reach then the less heating panels / panel surface area that you can have for a given battery size.

 

[Whitrzac]

Once we have tested the suit and mad sure that everything works as it should then we will be able to look at even bigger batteries etc. These batteries are 14.4 volt but the maximum heat setting will run 12V so it won't be until the battery is pretty much drained before the voltage drops below that.

So it has built in compensation for the voltage dropping? The only one i know of so far is UWLD.

Carbon elements crack and will create hotspots. Fuses wont protect from this. The only way would be to have multiple zones to turn on/off.

That battery is tiny.

You could probably get away with using diy seat heating elemets for auto/motorcycles. Waterproof, multiple sizes, thermal fuse, adhesive(some), right resistance to run off 12v systems, etc.

 

[rjack321]

One other question - how hot is the maximum heat that each panel needs to reach? This is a little bit of a trade-off - the higher the heat that each panel needs to reach then the less heating panels / panel surface area that you can have for a given battery size.

Its surprisingly hard to feel when a pad or hotspot is "too hot" and many folks have been burnt by heater in the past. Usually from a broken nichrome wire or creased carbon fiber pad. That will create a spot of high resistance and excess heat over a tiny area. So that's a warning...

Otherwise keeping to 40-45C maximum would be wise.

 

[Sascha314]

Once we have tested the suit and mad sure that everything works as it should then we will be able to look at even bigger batteries etc. These batteries are 14.4 volt but the maximum heat setting will run 12V so it won't be until the battery is pretty much drained before the voltage drops below that

And what about the cable connection? EO compatible or some "proprietary"?

I would also suggest to think about a risk analysis fme(c)a.

 

[elvenhome21]

For inside the suit 2pin jst / servo connector is the smallest and thinnest i can think of that has good pull out resistance. As for thru suit use what ever the 2 connector types are on the drysuit valve you get.

 

[RedSeaDiver2]

So it has built in compensation for the voltage dropping? The only one i know of so far is UWLD.

It has built in compensation for voltage drop - the battery is 14.4v (I think UWLD is the same), it has four heat settings and the user can program the voltage for each setting - it is a well thought out system.

Carbon elements crack and will create hotspots. Fuses wont protect from this. The only way would be to have multiple zones to turn on/off.

OK it sounds like we need to put a backer on the carbon pads to allow them to flex with the user's movements but not flex to the point that they can crack. I will have a talk to the manufacturer about this.

That battery is tiny.

Yes - but it can be upscaled once we have tested and proven the undersuit.

You could probably get away with using diy seat heating elemets for auto/motorcycles. Waterproof, multiple sizes, thermal fuse, adhesive(some), right resistance to run off 12v systems, etc.

I had a look a some of these when I started looking at it, but we don't have much of a range here - if you are able to suggest some then that would be great!