Heated undergarments

[_Ralph]

Quite a bit here ....

The DUI wasn't cutting the mustard. A barely 200g undergarment in most sections with a (felt like) small heated area on the upper back..... Faith and all the rest at DUI were great at selling its features off, but would be ok for the 'warm water' Cali diving I guess. Only tried it as they were offering.

I should have mentioned, a vest under what I currently dive is what I'm after I believe, else a nicely heated 400g. Biggest issue is the battery. I do see LM and a few others are approaching that issue with dual inline batteries (2x 10A in a 20A package) to get around the Airlines Li amounts ... The 160wh can fly, but needs to be cleared before getting to the airport (if they know what it is when the see it ..). 100wh is the limit for no questions asked (unless again, they don't know what it is).

On the 4C/49F dives, I'm comfy, but would definitely benefit from some heat (especially on scooter dives). 1C/34F, well it's cold and I'm usually getting cold after 40min and frozen around 70min.

The 2.5hr battery, is for a day of diving (2 dives) ... ideally not changing out a battery on a wet boat is the goal. Two smaller (~100 minute) batteries are definitely an option as well.

I've been hearing a bit about the thermulation as well, but haven't looked to closely at them yet.

_R

 

[tbone1004]

@_Ralph thermolution is definitely not going to cut it unfortunately. The DUI pulls 80 watts, at least according to maths on the website. 160wh battery, 2 hours burn at 100%=80 watt consumption
Wattage doesn't always equal efficiency though, so 80w out of the DUI may not=110w out of the Santi, which may not=35w out of the Exo2. It all depends on where the heat is, and what the temperature output is. 35w on the Exo2 is concentrated in high efficiency panels that are close to the skin. If the others have lower efficiency panels, have thicker layers of material between the skin, or are too large, the temps may not feel warm. I.e. if the Exo2 is 35w and ~.5sqm of material, and the DUI is 80w, but is 2sqm of material, the DUI may only feel "warm" instead of hot. Not ideal.
Heating Vest
that guy creates more heat than you can really deal with right at the skin for extended periods of time *similar to a heating pad on high*.
DUI doesn't give any useful information on the blueheat, so I really don't consider it a real product to look at.
The Santi has a consumption of 55w, and produces 45C. That's a pretty big difference in consumption when you look at it, especially when it consumes 1.5x the power, and especially at $420 vs $200

 

[Patoux01]

"high efficiency panels", "lower efficiency panels". Please explain this, what would the efficiency of a panel be, and what would the losses be? There's a reason we say birds keep their feet warm on high power lines.

 

[Patoux01]

Here around we get mainly Santi and some SF-techs. Thermalution as well.

I'd say the Santi should do the job for you...

I also suspect you don't necessarily need to have it turned on during the whole dive.

 

[tbone1004]

"high efficiency panels", "lower efficiency panels". Please explain this, what would the efficiency of a panel be, and what would the losses be? There's a reason we say birds keep their feet warm on high power lines.

ironically, efficiency for this is backwards of what we use for most electronics. In most electronics you try to minimize heat which is a waste product, and by doing that you increase efficiency. In heated panels, you want to minimize the power consumed without sacrificing the heat produced.
In this case, the Santi takes 55w to produce 45C of heat over a similar surface area to the Exo2 that takes 35w to produce 50C of heat

Part of the issue with the santi's, sftechs etc and basically everything outside of Exo2 *they own the patents to the technology* is that they use carbon fiber or metal wires that are coated in something like silicone to protect them since they are incredibly brittle on their own *this is what causes shorts and people to get zapped*. Every time a strand breaks, depending on the weave, that whole thread is no longer going to create a circuit so it can't produce heat. The consequence here is that when they get close enough, the electricity will arc which causes the short. This is bad, but it also reduces the heat production of the vest.

The Exo2 technology uses carbon impregnated panels which means you can stab it as much as you like and no matter how many holes you poke in it, it won't short. The whole panel is also conductive which means that holes like that don't create cold spots in the vest so you don't lose any heat production

 

[Patoux01]

You cannot make losses in a resistor when you're trying to heat something up.
You can make losses in the cable that connects the battery to the heatpad if it's been very poorly engineered.
You can make losses in the current sense circuitry if you are using one and it's been poorly designed.

You can have poor heat conduction, or large thermal capacity, or placed the pads on the outside of the suit against the water, but this is not efficiency.

 

[tbone1004]

You cannot make losses in a resistor when you're trying to heat something up.
You can make losses in the cable that connects the battery to the heatpad if it's been very poorly engineered.
You can make losses in the current sense circuitry if you are using one and it's been poorly designed.

You can have poor heat conduction, or large thermal capacity, or placed the pads on the outside of the suit against the water, but this is not efficiency.

how is poor heat conduction not efficiency? I'm measuring temperature as a function of power consumption. Higher temperature with less power consumption is more efficient.... That can be a function of heat conduction, or full suit design, but it's still efficiency of the product as a whole since it is the power required to do some sort of function. In this case that function is to transmit heat from the heating panel into the body of the user.

regarding the electrical function, you are correct that electrical resistance heating is always 100% efficient in terms of turning all of the power into heat, however the efficiency of the panels in conducting that heat into the body is what is important, and the panels used by many manufacturers aren't designed well enough to do this. Typically due to poor vest design as well as the unfortunate protective measures required to make the yarns durable

 

[Patoux01]

Because you mention the efficiency of the panels, which stops at the moment it dissipates the energy.

 

[stuartv]

What exactly does "50C of heat" mean?

Also, the UWLD page about the EXO vest says it "can be damaged if used in a wet environment." So, if you're drysuit leaks, it can damage the vest??

 

[tbone1004]

What exactly does "50C of heat" mean?

Also, the UWLD page about the EXO vest says it "can be damaged if used in a wet environment." So, if you're drysuit leaks, it can damage the vest??

at design voltage, the pads get up to 50*c.

all vests can be damaged if used in a wet environment. I.e. the connectors inside of the vest aren't fully waterproofed, so while it will work just fine in a flooded suit, you probably shouldn't dive with it in a wetsuit... This is true of all of the commercial vests, so is nothing different with this one. The two exceptions are the thermolutions that are designed for wetsuit use, and the UTD solar wrap that is an EXO2 product that is designed for wetsuit use. These still need fresh water rinsing and proper drying though.