Hot start relay

It's been so long that my original post for this unit must have been before the site crash. So here is an update on my hot start relay.

When I'm building more boards for my inventory, I make notes on my schematic of improvements to make on the next PCB board order. Some of these are just moving components around to make assembly better. So are to try a new component to give my circuit better specifications or more reliability.

I've been very busy building hot start relays to keep up with demand. I always wondered if my one second delay before firing the CSV should be longer. I've been happy with how my car instantly starts unless it has been sitting for 6 days or more and then I notice that it does take more than one second of cranking (so it needs the CSV).

I would like my unit to delay for two seconds so I really know when it needs the CSV. I did some testing of the timing of the control signal to my hot start relay. This is the signal of how long you turn the key to start so some people may have slower or faster reaction times to letting the key off.

My car has sat for 5 days and that start time was 1.17 seconds.
Test 2 right after was 0.635 seconds
Test 3 was 0.620 seconds
Test 4 was 0.560 seconds

It does look if the car sat longer, it would in fact need the CSV.

Anyway, I came up with a software change that lets the user solder a little jumper between two adjacent pins on the programing pads to make the delay two seconds instead of one second.

I think one or two owners have had problems with that one second time being too short on a hot engine. I've sold over 500 of these units so maybe their reaction time is slow or their engines just take longer to start the hot engine.

I've ordered some spring-loaded pins to see if I can reprogram the software on finished units. Since I had to solder fill those holes used for programming because of potting the units, the surface is not even enough to make contact of the 5 pins.

I got those spring loaded pins to reprogram any older hot start relays. They work better than I expected. I reprogrammed 10 older inventory and only had to do one of them twice. The pins are soldered on a blank board to hold the 5 pins spaced correctly. Then I hold that setup on the exposed solder filled holes and hit the program button. The hot start relay is the only relay with the programming pads on the bottom. You can't fit that on the other relays.

I'm marking the units as "C2" to show you it will delay 2 seconds rather than one second if you jumper pads 3 to 4 of those programming pads. Leaving the jumper off makes it delay one second. Note the square pad is #1 so count from that.

I still have a lot of REV C boards but if I ever use them up, a new board will have separate solder pads for the jumper. I don't have any improvements planned for new boards other then replacing the TO-220 MOSFET with a surface mount component. If I had a major improvement I would scrap the boards and get new ones. That same reasoning goes for all my products.