Why are extension cords hard to use?

[trader_4]

Why not fix the actual problem? As Bowman pointed out, the sun doesn't shine at night, so the solar panel is of very limited help. It would allow you to leave the car with the battery connected during the day, when it's sunny. That's about all I see it doing.

Put an ammeter on each fuse circuit. You can take a fuse, modify it to add wires, maybe solder them on, to have a test jig. Then find the offending circuit. Then get a circuit schematic and see what's on that circuit, disconnect components to narrow it down. Even if you can't find the actual problem, if you then take it to the dealer and say it's the climate control circuit or the locking system circuit, they can then focus in on that, swap parts, etc. It's also very possible if you tell them what circuit it is, they will have seen that before on other cars and know what it likely is. That's one big advantage to the dealer, they see the same models all the time. It's also possible something is draining it that's not on a fused circuit, but that's unlikely. When you do the testing, put the meter inside the car where you can see it, then close it up as you would normally and wait about

30 mins to see what it reads. Modern cars have all kinds of modules and some take 5, 10 15 mins to power down and go to sleep. You can keep an eye on it and if you see it only takes say 5 mins to go down to ~50ma or so and it doesn't go lower, then you know you can shorten your wait time down to just 10 mins or so. I'd much rather do that than fiddle around with kludges.

[trader_4]

That's true if you don't drive the car enough to recharge it. It shouldn't take much driving to take a battery from 90 back to 100. They have 90a, 120a alternators. If the parasitic current is 1A, with just 30A charging current, you could replace 12 hours of drain in 1/30th that time, ie ~24 minutes of driving time. Of course if the current is 3A, then it gets worse. But in my experience, they've typically not been very large.

But the right solution here is to find the fault. I gave him some tips on how to find it. It can be time consuming and if you have some basic skills, you can do the time consuming part, to find which fuse circuit it is, yourself. At that point, if you can't proceed yourself, the dealer should be able to find the fault without too much time. Could turn a long repair time into just an hour or two.

[Ralph Mowery]

I don't know who Steinmetz is. Quick search showed him to be a photographer.

Any diode worth uisng now has a reverse flow in the microamp range. Even sorry ones will be much less than a milliamp.

I don't know about the reverse of the selenium rectifiers, but they have not been used for very much of anything in the last 50 years or longer. Probably not even made in the last 25 or more years.

[Ralph Mowery]

It is good to run the AC once or twice a month even if you do not need it.

It is interisting how those mechanics can not seem to do basic trouble shooting before looking into something complicated. One would have thought like you did. Look at the compressor to see if it is turning. If not, check for voltage. If voltage, look compressor, if no voltage, look for something more compicated like a blown fuse, or a low pressure cut out switch indicatine most often low refregerent.

Always do the very basic simple tests first unless there is a known history of a certain failed part.

Where I worked it never faild to surprise me how many could not catch a blown fuse. They could not get it in their heads that in some circuits (mostly 3 phase) that you could have power on each side of a fuse and it still is bad. Some control circuits had low value capacitors across the switches. They would pass enough voltage to light up the simple neon testers many used.

I really loved the tester I used most often. It had two leads and a row of LEDs. YOu could put it across anything from about 20 volts to

600 vots. Look at the leds. If there was voltage above 20 volts a led or more would light up indicating if low voltage, 120, 240, 480 volts. Another for DC. and another is low resistance.

[Ralph Mowery]

Right. Fix the problem and quit screwing around with the external power.

Some cars draw a bit of current while cut off. I am not sure how long they would last, but should be good for a week before affecting the starting.

[trader_4]

BMW X5, the spec is 45ma. The one here draws 70ma,but close enough. Like I said though, you have to wait 5,10,15 mins maybe for it to go down to that after shutting it off. I also close all doors, hood, etc, lock it before measuring and look at the meter through the window. Leave a door open and who knows what happens. Maybe simple things like that are why the alleged mechanics can't figure it out.

[gfretwell]

Depending on your vehicle, it might be fairly easy to change the bus the "power port" connects to. On my Fords, it is simply moving the connector in the fuse block to an empty "always on" hole. It might be a good idea to mark the change on the fuse block and the owner book.

[gfretwell]

Some cars simply have a design problem. MY FIL's Cadillac used to kill the battery if he didn't drive it for a week or two. Cadillacs answer was a free trickle charger. They bought him several batteries on warranty and they had it in the shop for days each time. They tried playing with software changes and all sorts of load testing. Finally they just made him a deal on a trade.

[Clare Snyder]

In MOST cars today that is "programmable" on the fuse panel by simply moving the fuse - a 3 terminal fuse slot.

[Clare Snyder]

The old metal oxide diodes were even worse than the Seleniums - not made for several decades, thankdully. (think the old razor blade detector diodes on "trench radios")

[danny burstein]

[snippppp]

Big, make that BIG, mea culpa. I meant Charles Steinmetz...

Just like with polio, where everyone knows about Salk and Sabin, but hasn't/haven't heard of Hilary Koprowski [a],

or...

desegregation of bus lines, where everyone knows Rosa Parks but similarly never heard of Claudette Colvin [b] (not to be confused with the actress Claudette Colbert),

the early Electrical Genuises included the Very Well Known Edison, Tesla, and (older folk will recall Westinghouse...) there was also George Steinmetz [c]:

[a]

[Ralph Mowery]

Ok, Never heard of him either, or if I did, forgot him.

Looked him up and if he had a diode , it may have a lot of 'backflow'.

As mentioned , most any diode today will usually have micro amps reverse leakage at normal temperatures.

[M. L.]

I'd like a manufacturer to create a rechargeable trickle charger that could be easily removed for recharging a few hours at home, then reconnected to the car to last a week or month of trickling. Of course, the charger brick could be removed without disconnecting the alligator clips from the battery.

That sounds primitive and inconvenient, but that's exactly what I'm doing right now with my battery cutoff switch. The problem with using the battery cutoff switch to prevent overnight drain is that it resets the clock and the OBD computer at each morning startup.