Review: Cozy Winters heated vest

[Charlie99]

There are a couple of practical impediments.

Some battery chemistries can offgas when recharged.

Inductive charging requires a coil in the battery case, inductive charging works by placing 1/2 of an "air coil" transformer in the charger and the other half in the battery case. Air coil transformers are not very efficient, requiring a fairly large coil if you want recharge times that are reasonably short. In addition some portion of the charge control electronics would need be in the battery canister. Adding a large, heavy copper coil, and charge control electronics to the canister poses obvious problems.

Inductive charging is practical when the batteries are small, and the duty cycle of the device is low, i.e. a shaver or toothbrush spends most of it's time in the charging cradle and not in use. If you had 2-3 days to recharge your light (or vest) and only wanted to use it for a few minutes per day inductive would work.

The statements above apply to 60Hz systems. If you drive the coils with high frequency, then inductive coupling at high power becomes feasible. For example, the SAE J1773 inductive coupling paddle for electric cars handles several kilowatts.

Power is transferred inductively. Control info comes back to the primary side either by RF or infrared. Most of the charge electronics are on the primary (the wall connected charger) side.

While the magnetics design are non-trivial, the electronics are pretty much the same as a regular isolated switchmode converter charger system. The only difference is that you took a bandsaw and cut the main transformer into two pieces and stuffed one inside the sealed battery case.

Doesn't solve any battery offgassing issues, though. It's a pity that simple real world issues like not blowing up the battery case interfere with dreams.

 

[TSandM]

So how do small batteries like my toothbrush deal with offgassing? Or are they just so small it's enough volume to cause major problems?

 

[cool_hardware52]

So how do small batteries like my toothbrush deal with offgassing? Or are they just so small it's enough volume to cause major problems?

If the charging remains within limits you won't have offgassing, it does remain a possibility however.

My guess is your toothbrush is not fully sealed, i.e. water resistant, but not intended to be submerged to 10 ATA.

Tobin

 

[cool_hardware52]

The statements above apply to 60Hz systems. If you drive the coils with high frequency, then inductive coupling at high power becomes feasible. For example, the SAE J1773 inductive coupling paddle for electric cars handles several kilowatts.

Power is transferred inductively. Control info comes back to the primary side either by RF or infrared. Most of the charge electronics are on the primary (the wall connected charger) side.

While the magnetics design are non-trivial, the electronics are pretty much the same as a regular isolated switchmode converter charger system. The only difference is that you took a bandsaw and cut the main transformer into two pieces and stuffed one inside the sealed battery case.

Doesn't solve any battery offgassing issues, though. It's a pity that simple real world issues like not blowing up the battery case interfere with dreams.

Sure,

I agree. Raise the switching speed and reduce the size of the inductors. Such an approach still adds cost. There still is a need for a coil in the battery case, and at least rectification.

I have a 5 kw induction welder, so I know you can move a LOT of power thru an "air core" transformer. I forget the operating Freq, ~20Khz IIRC. All solid state. Watercooled output Fets. Bigger than a bread box, more $$ than a Tootsie Roll. Works great. I can turn a fist sized hunk of steel red hot in about 5 seconds.

Tobin

 

[se2schul]

With the design mentionned in this thread, any type of short in the vest could result in burns to your body unless you can turn off your heat system. Also, if the short happens close to the battery terminals, where there would be considerably less resistence, you'd basically have an arc welding session inside your drysuit.


Here's a description of the heating system I'm using:
http://www.scubasteve.homeip.net/article.php?story=20070325162420111
I know several people who have been using a similar system successfully for some time now.

The advantage is that in the event of a malfunction, you can either flip the switch to turn off the heat, or even disconnect the battery from the suit.

 

[Steve R]

Ah Steve, ya beat me to it.

Here's my set-up, which is a copy-cat of Mr. Schultz's.

http://www.niagarascuba.ca/heated_vest.html

 

[cool_hardware52]

With the design mentionned in this thread, any type of short in the vest could result in burns to your body unless you can turn off your heat system. Also, if the short happens close to the battery terminals, where there would be considerably less resistence, you'd basically have an arc welding session inside your drysuit.

That's exactly why I suggested one make sure there is over current protection, i.e. a fuse, polyswitch, or Circuit Breaker. I'd likely use a polyswitch, ~with a trip point at ~150% of nominal current.

Tobin

 

[se2schul]

Leaving the battery pack outside of the drysuit provides other advantages as well.
If video lights are fit with the same impulse connector, you can film during the bottom portion of the dive, then during deco you can unplug a video light to power the suit heater.

This option isn't available with a battery pack inside the suit.

 

[cool_hardware52]

Leaving the battery pack outside of the drysuit provides other advantages as well.
If video lights are fit with the same impulse connector, you can film during the bottom portion of the dive, then during deco you can unplug a video light to power the suit heater.

This option isn't available with a battery pack inside the suit.

Nothing wrong with your approach, all designs have tradeoffs. Wherever the battery pack is located I'd encourage the use of overcurrent protection. I'd much rather have a polyswitch "trip" before I'm "grilled" than after. Might just save the vest, the undies, the Drysuit, the battery, and ME!

Tobin

 

[Venus]

I have had nothing but trouble from the heated vest. I have had four battery cans and none of them have worked properly:

Thinking that this was finally the answer to my getting so cold in the UK, I booked a one day trip to Swanage three UK trips liveaboards over the summer.

CAN 1) at Swanage the can leaked on dive one and I was freezing cold on dive two. I sent it back and it was agreed that the can was faulty.

CAN 2) + CAN 3) my replacement for can 1 had not arrived in time for my next trip. So I met the Typhoon rep at Winchester services on my way to the Scillies for a weeks liveaboard.

This was not on my way. I had to make a 40 mile detour to meet him. He gave me his demo bag which contained two cans. These cans were both faulty. Sometimes they worked and then stopped working after a few minutes. sometimes they did not work at all. An electrician on board tested them with his probes and deduced that the cables were broken and even though the batteries were fine the power was not getting through to the vest.

The following weekend I went to Lundy and took the same battery cans with me. Again they did not work for all the three days.

Then two weeks later a liveaboard to Plymouth. Again the same problems.

All this time I was calling Typhoon for my replacement battery cans.

Then I got a call from the rep who desperately required his demo kit back. I couriered then back to him.

CAN 4) my replacement had finally arrived. I noticed something different. The inside lid of the can had been potted. I thought great this is going to work. So I took it on my trip to the Galapagos last month. Same problem. It worked then went off after a few minutes. If I fiddled with the cable it came back on. Once again it seems that the cables are broken inside and no power is getting through to the vest.

I am so fed up with this now. I have been on four liveaboards where people have seen e suffer as a result of your product.

I don't like getting cold, that is why I spend £499 on this product. It is not fit for purpose because it does not work.

Within my club whenever we talk about keeping warm I tell them exactly what problems I have had with this product.