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Failed project / eBay TEC1-12706 fail

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Sulaiman

Sat Nov 24 2018, 06:29PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

For my chemistry hobby I want a recirculating water cooler/chiller to cool condensers.
I'd previously experimented with a dual TEC1-12706 @ 12V cooler,
but the performance was inadequate,
so I built a new water cooler using four TEC1-12706 @ 6V each for better efficiency hence performance,
(I assumed that the performance of the heatsinks (AK-786) would be the limiting factor)

At 6V per TEC I was getting 6.24 Watts total effective cooling power.
I was expecting more like 100 Watts.
So I rewired the module with all TECs in parallel connected to 12.0V,
the module performed even more poorly.
(I've requested a refund from the eBay seller)

Here is the module just after I tested it.

(Testing was at 10.5 Celcius ambient, water was at 10.0 Celcius, water flow was adequate, HY810 heatsink compound)

I damaged my 'old' TECs removing them so I can't do a comparison now)

Two questions ;

1) Is it 'normal' to get seriously sub-standard TECs if from China via eeBay ?

2) Could anyone point me (in UK) to a reasonably priced supplier for genuine/original 40mm x 40mm TECs ?

Plasma

Sat Nov 24 2018, 10:39PM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
Location:
Posts: 268

Alexnld.com
Tegmart is only questable based on max tempture, I buy off alexnld ,with heatsink compounds and All or copper they will probably reach specs

iJim

Sat Dec 01 2018, 07:58PM

Registered Member #2662 Joined: Fri Jan 29 2010, 10:14AM
Location:
Posts: 36

Sulaiman, exactly the same thing happened to me. Picked up 5x 50W TECs from EBay for about Â£10, wired two in series and had terrible performance. Annoyingly I used thermal epoxy to secure on the heatsink so that will also probably go in the bin. Ended up buying 2x TECs from RS for Â£35 each and they work fine.

klugesmith

Sun Dec 02 2018, 01:18AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

At my workplace, thermally-epoxied heatsinks are routinely taken off in the course of equipment repair.
You soften it by getting it plenty hot.
I bet that with heat applied from the heatsink side, there's a point where you can separate TEC ceramic from the heatsink with a thin knife, and not melt soldered joints inside the no-good TEC. Heat pumped toward heatsink by energizing the no-good TEC probably wouldn't hurt.

Plasma

Mon Dec 03 2018, 02:44AM

Registered Member #61406 Joined: Thu Jan 05 2017, 11:31PM
Location:
Posts: 268

I changed the heatsink ability, but I brought 3 different batch, two matach with on 0.3volt with five ,five times as much, they also have refreagtion tec, the spelling mistice with MA is a launwage barrier, I don't want to add heat sink but it changed from 50*50mm block of steel to a transformer core.
Alexnld.com for 6 times as cheap you have to budget for the quality, but it might make sense

Sulaiman

Mon Dec 03 2018, 09:48AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I just asked eBay resolution centre to step in.

I can see that buying from RS would give me a working solution,
but 4x TEC at RS prices make the project more expensive than using conventional refrigeration.

For my first prototype I used epoxy to glue Tank:TEC and TEC:Heatsink rather than using mechanical clamping,
a very poor choice because;

Force on the heatsinks will tear the TECs apart, damaging ingot:pad connections

There is negligible clamping force on the TECs, which should be under compression

Epoxy resin adhesive has poor thermal conductivity compared to decent heatsink compound, 10x poorer

Replacement of a faulty TEC is difficult.

EDIT: In the time that it took to write this post, eBay have refunded my payment in full.
Now that I'm in a better mood I'll start looking for cheap genuine TECs.

Shrad

Wed Dec 05 2018, 08:01AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

For small prices on electronics I would have a look at banggood or similar sites, for all the items I bought from them I have never really had any issue knowing the quality of what I bought

I think the main difference with random ebay sellers is that at least china is trying to raise the bar on expectations via official channels, and for what I saw it seems to be OK.. just maybe delivery delays and politics for US guys

I'll try alibaba as soon as they will have their new delivery centre in Belgium, waiting time should be way less

Inducktion

Wed Dec 05 2018, 08:15PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

Yeah, honestly based off what I've been hearing about more and more lately, Chinese sourced semiconductor goods are very suspect and ... it'd probably be a better idea to just go with a reputable supplier in the first place, so you don't

1. Waste time trying to diagnose the problem

2. Waste money on something counterfeit in the first place.

Especially, since a lot of semiconductor goods are hard to verify as legit in the first place too. Unless you have specialized equipment.

It's just hard to justify saving a few dollars when you might end up getting something that's ...basically not what you ordered.

teravolt

Thu Dec 06 2018, 08:40PM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

usaly those pelter devices are power hungry. did the heat sinks get warm and hiw many amps did you supply when I tried this I need a 12v 10amp supply

Sulaiman

Mon Dec 31 2018, 03:02PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Good News :
I bought four TEC1-12715 for Â£12.68 total from here

and they perform close to specifications.

I tried 2x TEC1-12715 per heatsink
(AK-786 cpu heatsink/fan assemblies, 0.25 C/W per heatsink, measured)
... fail

With One TEC1-12715 per heatsink performance is tolerable;
2x TEC wired in series, 15Vdc @ 6.3 Adc,
Tmin= -10 C, about 40W heat pumping power at 20 C.

0.25 C/W is too great, something more like 0.1 C/W is required ... per TEC1-12715

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