JW Marine Fridgemate

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Elemental

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Hi,

I have a JW Marine Fridgemate that came with my boat (it's a battery saving unit that detects charging voltages and runs the fridge, turning it off after about an hour after the charging stops).
The fridge has never worked since I had theboat so I unwired the Fridge mate and all is well. I like the idea of the Fridge mate so I investigated further and I can see that the BTS441R mosfet has blown. I've been unable to source one of these anywhere (and I've spent ages looking). However, all my attempts to contact JW Marine have failed. (their website lists unavailable numbers, no email etc.) Google hasn't helped either. Yet their products are still listed on various mail-order sites and shown as "In stock". So, I'm wondering if anyone here knows how I can get hold them (or even better the blown mosfet...)

Cheers

Mark
 
I had the same problem trying to contact them when I wanted to buy another one ......... I guess they are out of business!

I presume that you have tried Radio Spares for the MOSFET?

Alan.
 
If you want to start from scratch, there's a description here of a fridge controller/battery saver if you're happy with a soldering iron and are looking for a new hobby!
Derek
 
It's a FET with some logic added.
Infineon make it, it's listed as in production, but I can't find it in any of the popular distributors. RS stock a lower rated device in the same family. They are meant for automotive, so may not be easily obtained in small qty.
Are you sure its blown, these things are tough?
The data sheet is on the web, you could knock up a circuit equivalent to it.
Seems an ugly solution to switch the power to the fridge, why not switch it via the thermostat wiring? Then the logic input to the blown device would only have to be buffered to a small relay at worst.
 
It's definitely blown - it's burned and distorted and the case has some blackening on it. I found the data sheet already but creating a replica circuit is a bit beyond me (although I haven't looked yet really).

I hadn't thought about switching the thermostat circuit...

Mark
 
Dear Mark,

I was amazed to see this "pop up" when doing some work on my web site. I have not used this forum site before so not sure if you will get this but I would like to get in touch with you regarding the Fridge Mate. I realise it is a little after the event !! but am willing to replace the unit none the less.

Regards

Andy Johnson
JWMarine
 
Before fitting a new unit, don't forget to sort out why the old one blew.
 
Dear Mark / Lemain,

We have been making Fridge Mate since 2005 and had no failures at all up until early on last year. We suddenly got 5 failures on final test and had, to my knowledge, 7 returns from customers. To cut a long and somewhat panic stricken story short, the problem was with a new date code batch of the BTS 441 device. We had failure analysis done by Infineon and they isolated it to weak anti-static protection diodes on the input and status pins of the device from that batch. To be fair to Infineon, there is no specification on the data sheet for these internal diodes and, ironically, I don't use their status pin anyway. With the agreement of Infineon, we immediately included an extra resistor to limit the forward current that occurs with excessive "ground bounce" (usually due to very long wires) and we have not had another failure even with devices from that particular date code. We were as confident as we could be that the problem was identified and fixed and, most importantly, we understood why the fix worked.

Caravan and Leisure sold most of our units around that time (and still do) and they handled the replacements.

My contact details are on the web site (www.jwmarine.co.uk). Sorry to be thick here but what do you mean by PM sent ?

Regards,

Andy
 
HI Andy,

As you've already learned PM means Private Message (I wanted to give you my contact details but without the rest of the world finding out...)

I've sent the old unit back to you by post you should get it in a day or two.

It's really good to get an explanation of the problem - not least it gives some confidence the new one won't suffer the same fate.

Cheers

Mark
 
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