Does the Lambda relay always get hot?

[AugustneverEnds]

My D has been the recipient of a lot of electrical repairs in the past couple of days. Went out driving this morning and decided to stop and have a look around the relay compartment. The lambda relay was noticeably hot, hot to the touch not enough to burn my finger but hot nonetheless. Is this normal function?

(Some background: replaced the alternator last week because the PO installed the last one incorrectly and caused the positive terminal to break. Replaced all of the changeover relays with DMCH's kit. Running a new lamp delay module. The car didn't seem to like the new RPM relay so still using the old one. Also want to give a shout out to DMCMW for their sterling advice which saved me a considerable amount of money :thumbup:

[sdg3205]

Is the FV buzzing? I noticed the same on my new project car, but the FV is not buzzing. I haven't dug into that system yet. It got hot within about 20 seconds.

[Bitsyncmaster]

Yes it is normal for the Lambda relay to get hot. It's just that the coil current is higher than the other relays (except the RPM relay which is even higher). That was the second relay I made solid state because like you, I felt around for hot components.

[AugustneverEnds]

Yes it is normal for the Lambda relay to get hot. It's just that the coil current is higher than the other relays (except the RPM relay which is even higher). That was the second relay I made solid state because like you, I felt around for hot components.

Ohhh I see, thank you Mr. Dave. I might buy one of yours then since I'd like to keep the relay compartment as cool as possible.

[AugustneverEnds]

Is the FV buzzing? I noticed the same on my new project car, but the FV is not buzzing. I haven't dug into that system yet. It got hot within about 20 seconds.

Yep, FV is buzzing.

[Bitsyncmaster]

Ohhh I see, thank you Mr. Dave. I might buy one of yours then since I'd like to keep the relay compartment as cool as possible.

You can move one wire and use the standard relay in the Lambda location. I don't sell a solid state relay built for the stock wiring of the lambda socket.

[JohnZ]

Probably this question has been already put around here, but... are there some tips to actually cool down the entire relay compartment?

Maybe some different solution mixed together... replace wooden cover for example?

[Bitsyncmaster]

Probably this question has been already put around here, but... are there some tips to actually cool down the entire relay compartment?

Maybe some different solution mixed together... replace wooden cover for example?

There were a few people that were trying a fan about 7 years ago but I have not heard much about it since.

[dn010]

There were a few people that were trying a fan about 7 years ago but I have not heard much about it since.

I am running fans in my relay compartment; I put 2 small size computer fans in the compartment 8-10 years ago just to move the air around and I don't seem to have any heat issues. Prior to this, I had a melted headlight fuse but that could have been from the PO.

[DMC-81]

Resurrecting this thread to ask questions:

After I installed Bitsyncmaster's fused fan fail unit and the solid state cooling fan relay I went to a car show today and was monitoring the relay compartment throughout the day to make sure everything was good, as I always do after I make a change to the car.

The relays and wires underneath were great, being only warm after running the AC and sitting through Florida's 4-5 minute red lights on this gorgeous 85 degree day:

http://dmctalk.org/attachment.php?attachmentid=59283&d=1550439060

However I noticed (probably for the first time) that the lambda relay was hot. Like described above, not hot enough to burn my fingers, but hot. This is a 3 year old NOS lambda relay.

On the drive home, I had two thoughts:

1) I wonder if Bitsy makes an improved Lambda relay?

2) I thought of making a second wooden relay cover and replacing most of the inner area with wire mesh and installing 1-3 quiet computer fans in it to optionally use the cover to add more cooling to the relay compartment while driving, especially in the summer months.

I came home and looked here and lo and behold, both topics are discussed in the same thread. Apparently that's normal operation for the original lambda relay. So my questions:

1) Dave, do you still offer the solid state Lambda relay? Does it still require the wiring change?

2) Dan, can you post a picture of the fan solution that you made? Did it help in the temperature area?

I drive my car on most weekends and I'm trying to mitigate/ prevent any future problems.

Thanks,

[Bitsyncmaster]

Dave, do you still offer the solid state Lambda relay? Does it still require the wiring change?

I never made a Lambda relay for plug and play. It just takes one wire change to use the standard relay or one of my solid state standard relays.

Yes the Lambda relay gets hot. Never knew why the design used a relay with two common output pins. I guess they were trying to fix an electrical noise problem. This was the second relay I replaced after the RPM relay because of the heating and the fact it is always on with the engine running.

All you need to do is pull the center pin (red/purple wire) from the socket and connect that wire to the green/yellow wire on the pin above the center.

[bytes311]

Would the standard relay (with the wiring change) get just as hot as the Lambda relay?

[Bitsyncmaster]

Would the standard relay (with the wiring change) get just as hot as the Lambda relay?

No. The heat is caused by the coil current in that relay. The standard relays use less current. I will look if I still have the OEM lambda relay and measure it.

Edit:
I found the OEM lambda relay. Tested and not as bad as I thought. I guess the smaller case makes it get hotter.
61 ohms = 221 ma at 13.5 volts = 2.98 watts

Standard relay
86 ohms = 157 ma at 13.5 volts = 2.11 watts

[bytes311]

Interesting! Thanks.

[Chris 16409]

I rewired my Lambda relay socket according to Dave's directions and am using one of his standard solid state relays. I think it's a no brainer. The other plus is you eliminate the need to have a specialty Lambda relay. Any standard Bosch type relays will work to keep as spare.

[bytes311]

I rewired my Lambda relay socket according to Dave's directions and am using one of his standard solid state relays. I think it's a no brainer. The other plus is you eliminate the need to have a specialty Lambda relay. Any standard Bosch type relays will work to keep as spare.

I agree, and it sounds simple enough.

[Bitsyncmaster]

The second producer of heat in relays is the voltage drop due to the contact resistance and internal wiring of the load current. In the case of the lambda circuit I don't think there is much current and the OEM relay is rated at 15 amps on each output pin. Where that voltage drop is important is the higher current circuits like the fan relay. The fan relay load of 30 to 40 amps (OEM fans) can add another 5 watts or more of heating in the relay.

[DMC-81]

I never made a Lambda relay for plug and play. It just takes one wire change to use the standard relay or one of my solid state standard relays.

Yes the Lambda relay gets hot. Never knew why the design used a relay with two common output pins. I guess they were trying to fix an electrical noise problem. This was the second relay I replaced after the RPM relay because of the heating and the fact it is always on with the engine running.

All you need to do is pull the center pin (red/purple wire) from the socket and connect that wire to the green/yellow wire on the pin above the center.

OK, cool. (Pun intended). I may do the simple wiring change and use a spare purple Bosch relay and see what kind of heating difference it makes. Then, I'll definitely opt for your solid state standard relays and keep my spare as the intended spare.

I'm guessing that after the wiring change and by using the solid state relay the heating problem is mostly addressed?

I just want to avoid cooking the plastic receptical and/or the wiring in the long term because of usage and warmer climate.

Maybe then, I won't need an auxiliary fan to cool that area. The lambda relay got hot enough to heat the adjacent relays. Certainly not ideal.


I rewired my Lambda relay socket according to Dave's directions and am using one of his standard solid state relays. I think it's a no brainer. The other plus is you eliminate the need to have a specialty Lambda relay. Any standard Bosch type relays will work to keep as spare.

Great! Thanks for the review Chris.

[Bitsyncmaster]

OK, cool. (Pun intended)I'm guessing that after the wiring change and by using the solid state relay the heating problem is mostly addressed?

My standard solid state relay draws 5 ma. so only 0.07 watts of power. And the voltage drop on the load is far less than any mechanical relays so it will stay at ambient temps for the lambda loads.

I don't keep a lot of inventory of the headlight and standard (blower) relays because not many people get those. They use the same circuit boards as my fan relay with some component changes so there is no delayed operation. Headlight relays run the same power and load pins as the fan relay. The standard relays reverse the power and load pins internally in the relay. I wish all the relays would have used the same power and load pins.

[DMC-81]

My standard solid state relay draws 5 ma. so only 0.07 watts of power. And the voltage drop on the load is far less than any mechanical relays so it will stay at ambient temps for the lambda loads.

I don't keep a lot of inventory of the headlight and standard (blower) relays because not many people get those. They use the same circuit boards as my fan relay with some component changes so there is no delayed operation. Headlight relays run the same power and load pins as the fan relay. The standard relays reverse the power and load pins internally in the relay. I wish all the relays would have used the same power and load pins.

Ok, perfect. I'll PM you when I'm ready for the relay.

[BABIS]

I never made a Lambda relay for plug and play. It just takes one wire change to use the standard relay or one of my solid state standard relays.

Yes the Lambda relay gets hot. Never knew why the design used a relay with two common output pins. I guess they were trying to fix an electrical noise problem. This was the second relay I replaced after the RPM relay because of the heating and the fact it is always on with the engine running.

All you need to do is pull the center pin (red/purple wire) from the socket and connect that wire to the green/yellow wire on the pin above the center.

I've always found odd that fuse #7 wires have 2 different gauges (obviously smaller toward the lambda relay); in my car I kept the smaller wire going to the the lambda relay socket, but I have added a new bigger wire going from the fuse to the rpm relay connector, and I removed the original brown wire going from the lambda relay socket to the rpm relay connector

[DMC-Ron]

I never made a Lambda relay for plug and play. It just takes one wire change to use the standard relay or one of my solid state standard relays.

Yes the Lambda relay gets hot. Never knew why the design used a relay with two common output pins. I guess they were trying to fix an electrical noise problem. This was the second relay I replaced after the RPM relay because of the heating and the fact it is always on with the engine running.

All you need to do is pull the center pin (red/purple wire) from the socket and connect that wire to the green/yellow wire on the pin above the center.

Dave,
It seems like it would be handy to have an electronic Lambda relay direct replacement. I know it seems simple to change one wire but it's a pain to monkey around with the relay sockets. Does your electronic relay have the additional pin and could it be opened up and altered with a jumper so it has two output pins?

Ron

[Bitsyncmaster]

Dave,
It seems like it would be handy to have an electronic Lambda relay direct replacement. I know it seems simple to change one wire but it's a pain to monkey around with the relay sockets. Does your electronic relay have the additional pin and could it be opened up and altered with a jumper so it has two output pins?

Ron

My standard relays don't have the center pin. I guess I could make a Lambda relay (plug and play) but not sure I could sell enough of them to break even.

[DMC-81]

My standard relays don't have the center pin. I guess I could make a Lambda relay (plug and play) but not sure I could sell enough of them to break even.

I would definitely line up for a specific plug-and-play solid state Lambda relay. Given how hot the OEM one gets, there is a very real benefit to a no-modification upgrade product. Maybe the idea just needs promotion?

[iflights]

My standard relays don't have the center pin. I guess I could make a Lambda relay (plug and play) but not sure I could sell enough of them to break even.

I'll take one as well. How many would it take to get a plug-n-play version produced?

[bytes311]

I'm interested.

[CFI]

I'd buy one.

[dmcnc]

I'd buy a solid state Lambda relay from you if available!

[Bitsyncmaster]

My cost is about $500 to get 100 blank circuit boards. I may do an order when I get time.

[DMC-81]

My cost is about $500 to get 100 blank circuit boards. I may do an order when I get time.

Cool! In the meantime, I'll defer the wiring modification.

If you make them, perhaps you could paint the case silver or gray like the original and to differentiate it from the other relays (since it has a different pin setup). .... Just an idea.

And, if you make them, I'll take one right away.

Thanks for all the work you do to make our cars even better. As I said multiple times on the weekend to people inquiring about choosing one as a classic car....with the variety of part choices, it is an exciting time to own a Delorean.

[Bitsyncmaster]

Cool! In the meantime, I'll defer the wiring modification.

If you make them, perhaps you could paint the case silver or gray like the original and to differentiate it from the other relays (since it has a different pin setup). .... Just an idea.

And, if you make them, I'll take one right away.

Thanks for all the work you do to make our cars even better. As I said multiple times on the weekend to people inquiring about choosing one as a classic car....with the variety of part choices, it is an exciting time to own a Delorean.

I have been painting the relays black (head light and blower) and then label the headlight relays "HEADLIGHT". One advantage to doing the wiring change is you can swap "blower" relays with lambda so you have spares for troubleshooting.

[iflights]

[QUOTE=DMC-81;243612

Thanks for all the work you do to make our cars even better. As I said multiple times on the weekend to people inquiring about choosing one as a classic car....with the variety of part choices, it is an exciting time to own a Delorean.[/QUOTE]

I want to expand on these thoughts... My first work was proactively getting the electrical system to be reliable to prevent pesky gremlins later. I have such improved confidence in the electrical system now after I've installed your upgraded components. Electrical is one thing that can be checked off as being solid in my car.

Thanks for all you do.

[Bitsyncmaster]

I'm wrapping up some inventory builds. Boy I thought the RPM relay would start slowing down because most users have already bought one. But I'm still selling 5 or 6 a month. Also ran low on hot start and fan fail units.

Anyway I laid out a new circuit board for the lambda relay. This will be a 30 amp rated relay with the output drive to both output pins. I may also sell this unit without the center pin installed as my standard relay (blower and other relays that use the same power and load pins). I still don't recommend using it for the starter relay even though it does have a TVS suppressor diode. There is just nothing to gain with the starter relay since it only runs when cranking the starter.

So my plan is to paint the lambda relay yellow since I think most of our cars do have a yellow relay socket for the lambda relay. I will paint the 4 pin standard relays black.

Still need to order the boards and build them up so it will be about one to two months to be ready to sell.

[iflights]

Still need to order the boards and build them up so it will be about one to two months to be ready to sell.

I'm ready to buy the instant you are! And let me be the first one to say Thank You.

[DMC-81]

Anyway I laid out a new circuit board for the lambda relay. This will be a 30 amp rated relay with the output drive to both output pins. I may also sell this unit without the center pin installed as my standard relay (blower and other relays that use the same power and load pins). I still don't recommend using it for the starter relay even though it does have a TVS suppressor diode. There is just nothing to gain with the starter relay since it only runs when cranking the starter.

So my plan is to paint the lambda relay yellow since I think most of our cars do have a yellow relay socket for the lambda relay. I will paint the 4 pin standard relays black.

Still need to order the boards and build them up so it will be about one to two months to be ready to sell.

Sweet! Yellow is great for color. As mentioned above, I'm ready to buy as soon as they are done. :thumbup:

[DMC-Ron]

Same!

[Bitsyncmaster]

Well I got the 100 circuit boards and built up 10 but then I was testing one with a 30 amp load and found my new boards must have been made with 1 oz. copper and I ordered 2 oz. copper. So at 30 amps the relay does get hot because of the higher voltage drop with that high load. I'm contacting my PCB manufacture to see if I can get new boards made with my needed 2 oz. copper.

These would probably be fine for the lambda relay since I think the current is below 5 amps but I always try to keep things as cool as possible. So this project gets delayed.

FYI:

PCB copper is the weight of one square foot of copper. So 1 oz. copper is 0.0014" inch thick. Outside layers get plated so holes get a plated through connection and prevent the copper from oxidation so you can solder good connections. So normally the outside copper is less weight and the plating builds up the thickness to your specification. Thicker copper (higher weight) cost more and requires more space and thicker traces because the copper etching has to remain longer and it eats some of the sides of your traces.

[Bitsyncmaster]

Well my circuit board house did a cut of a board I sent back and they measured the copper and said they are 2 oz. copper.

So if I want to run these as the blower relays I would need to order boards with 4 oz. copper.

I measured the current the lambda relay conducts and it is about 2 amps. So I'm going to build these boards I have as originally interned as lambda only relays. You won't get any measurable heating from only a 2 amp load. The control current is 4.62 ma with 13.5 volts on the control pin.

[iflights]

Thank you for the update. Looking forward to having one in my car.

[DMC-81]

Thank you for the update. Looking forward to having one in my car.

+1

[Bitsyncmaster]

No. The heat is caused by the coil current in that relay. The standard relays use less current. I will look if I still have the OEM lambda relay and measure it.

Edit:
I found the OEM lambda relay. Tested and not as bad as I thought. I guess the smaller case makes it get hotter.
61 ohms = 221 ma at 13.5 volts = 2.98 watts

Standard relay
86 ohms = 157 ma at 13.5 volts = 2.11 watts

Just finished painting the first 10 lambda relays. I tested with a 4 amp load (I tested lambda current a bout 2 amps) so power (heat produced) is 0.10 watts. So basically my lambda relay will run at ambient temperature. This is plug and play but only to be used for the lambda relay socket (yellow socket). I'm pricing the lambda relay at $69 shipped to US locations.

Now the relays always on, RPM, lambda and AUX relays are the ones producing the most heat in the relay compartment. I run my standard solid state relays for the AUX relays but they do no have the large power and ground pins.

[DMC-81]

Just finished painting the first 10 lambda relays. I tested with a 4 amp load (I tested lambda current a bout 2 amps) so power (heat produced) is 0.10 watts. So basically my lambda relay will run at ambient temperature. This is plug and play but only to be used for the lambda relay socket (yellow socket). I'm pricing the lambda relay at $69 shipped to US locations.

Now the relays always on, RPM, lambda and AUX relays are the ones producing the most heat in the relay compartment. I run my standard solid state relays for the AUX relays but they do no have the large power and ground pins.

Excellent Dave! I'll take one.... funds sent.

From "almost too hot to touch" to ambient temperature is quite an improvement! :thumbup:

[iflights]

Beat me to it!!!


Payment sent as well.

Thanks, Dave.

[CFI]

I’ll take one Dave. Payment sent.

[dmcnc]

Payment sent!

[DMC-81]

I received my Lambda Relay today. As usual it looks like a quality unit. I'll take before and after temperature measurements on the old and the new relay when I install it. Can't wait!

http://dmctalk.org/attachment.php?attachmentid=59844&d=1556147090

http://dmctalk.org/attachment.php?attachmentid=59845&d=1556147170

Thanks very much Dave!

[CFI]

Installed mine today. Will take the car for a spin tomorrow. Thanks Dave!

[DMC-81]

Well, I went to a Caffeine and Coffee event on this beautiful morning, and took a measurement of the old Lambda relay. The temperature after driving for an hour in 81 degrees F weather was 57 degrees C, or 134.6 degrees F. Definitely hot, but I have seen it hotter.


http://dmctalk.org/attachment.php?attachmentid=59877&d=1556386891

I'll change the relay and do the same thing.

[DMC-81]

I changed the relay, and took a measurement.

As Dave mentioned earlier, most cars have a yellow relay holder/socket, but where my car is a fairly early VIN, I have a black socket but with 2 yellow stickers on the front side of it.

http://dmctalk.org/attachment.php?attachmentid=59883&d=1556397610

New relay installed:
http://dmctalk.org/attachment.php?attachmentid=59884&d=1556397698

So, the new Lambda relay temperature after driving for an hour in a slightly warmer 85 degrees F, measured 28 degrees C, or 82.4 degrees F. Cool as a cucumber!! :cool:

http://dmctalk.org/attachment.php?attachmentid=59886&d=1556398705

That's another fantastic product! Thanks again Dave!

[iflights]

Installed my new lambda relay. Couldn't have been easier. Love the plug-n-play feature which really made it all worth it for me.

Thanks Dave.

[Domi]

I just bought one of these too, can't wait to install it :)
62725

[CFI]

I’ve had Dave’s Lambda relay installed for almost 1 year now with zero issues. Actually, all of my relays made by Dave have been flawless. Solid state is the way to go!

[Riley88]

Dave I want to buy one, do I need to pm you? it is on your website but there is no checkout option!

[WHO1DMC]

Dave I want to buy one, do I need to pm you? it is on your website but there is no checkout option!

Go to his website and click on his email. He will get back to you.


Dave B.