I had to completely re-wire an Alfa because all the wires were melted. It's suspected that someone hooked the battery up backwards...
I saw a thread on here recently about someone hooking the battery up backwards and now they're suffering electrical gremlins...
My grandfather hooked a set of jumpers up backwards and now his Toyota Tundra's throttle wont work.
It's killing me. Can anyone think of any reason why manufacturers aren't installing diodes near the battery to prevent flow in the wrong direction?
I mean 2-seconds on flea-bay and I found a blocking diode that's way overkill for the application and it's a whoppin $10...
Thoughts?
I'm guessing the reasons are forward resistance and a lack of profit motive for doing so.
yeah. I was thinking the second one was probably the biggest factor.
Manufacturer's perspective:
1) Make sure every component, nut, and bolt is absolutely essential to the product.
Check.
2) Install a component that is useful only if a customer screws up and messes with something we don't want him to touch.
Um. NO.
T.J.
MegaDork
7/11/19 10:05 a.m.
How would this work? Batteries need to charge and discharge. The current is not always going the same way. You could install a diode on a dedicated jump starting post, but then it would only be good for getting a jump or giving a jump but not both. Seems easier to just put the positive to the positive and negative to the negative.
T.J. said:
How would this work? Batteries need to charge and discharge. The current is not always going the same way. You could install a diode on a dedicated jump starting post, but then it would only be good for getting a jump or giving a jump but not both. Seems easier to just put the positive to the positive and negative to the negative.
It should be possible to use a diode configuration that wouldn't prevent charging but would minimize reverse voltage if the battery was put in backwards.
Although I think that from a practical perspective, using mechanical lockout mechanisms (such as differently sized terminals, some cars do use this setup) and better visual indicators (many UPS & wheelchair batteries have the terminals set in red and black epoxy, why don't car batteries do something similar?) would be better solutions.
The smart way to do it is to design the cables so they only reach one way. I can think of one car like this - hooking up the cables backwards would require either the wrong battery with the terminals reversed or you'd probably have to unhook some cable anchors.
Keith Tanner said:
The smart way to do it is to design the cables so they only reach one way. I can think of one car like this - hooking up the cables backwards would require either the wrong battery with the terminals reversed or you'd probably have to unhook some cable anchors.
Wouldn't this limit your choice of batteries to those with a matching terminal location?
GameboyRMH said:
Keith Tanner said:
The smart way to do it is to design the cables so they only reach one way. I can think of one car like this - hooking up the cables backwards would require either the wrong battery with the terminals reversed or you'd probably have to unhook some cable anchors.
Wouldn't this limit your choice of batteries to those with a matching terminal location?
Yes, of course. The same way that a four bolt hub limits your choice of wheels. You would have to use the correct part for the car. This is a reasonable expectation.
If you want to use an incorrect part, then it's on you and you take responsiblity to understand how batteries work.
It's also a reasonable expectation to not connect the cables backwards.
You can also open the oil fill and top the crankcase off with water! Do we need to protect against that too?
1988RedT2 said:
Manufacturer's perspective:
1) Make sure every component, nut, and bolt is absolutely essential to the product.
Check.
2) Install a component that is useful only if a customer screws up and messes with something we don't want him to touch.
Um. NO.
It boggles my mind that they'll install complex computing systems to warn the driver about lane departure, or forward looking radar to automatically apply the brakes in the event of an imminent collision, or all sorts of "drivers aids" (so the driver can do everything but "drive"), but wont spend $10 or so to keep an absent minded mechanic (or good samaratan) from destroying all those systems by accidentally hooking up jumper cables backwards...
Keith Tanner said:
As for the jumper problem:
https://www.amazon.com/MYCHANIC-Smart-Cables-Polarity-Protection/dp/B076X7FGPW
Hey, now that's thinking with your dipstick!
mtn
MegaDork
7/11/19 12:25 p.m.
I know the correct way to hook up jumper cables. I have that memorized. I still look it up every time I jump a car out of fear of my doing it wrong.
Hungary Bill said:
1988RedT2 said:
Manufacturer's perspective:
1) Make sure every component, nut, and bolt is absolutely essential to the product.
Check.
2) Install a component that is useful only if a customer screws up and messes with something we don't want him to touch.
Um. NO.
It boggles my mind that they'll install complex computing systems to warn the driver about lane departure, or forward looking radar to automatically apply the brakes in the event of an imminent collision, or all sorts of "drivers aids" (so the driver can do everything but "drive"), but wont spend $10 or so to keep an absent minded mechanic (or good samaratan) from destroying all those systems by accidentally hooking up jumper cables backwards...
How do you propose the battery charges if there are diodes in the cables?
Knurled. said:
Hungary Bill said:
1988RedT2 said:
Manufacturer's perspective:
1) Make sure every component, nut, and bolt is absolutely essential to the product.
Check.
2) Install a component that is useful only if a customer screws up and messes with something we don't want him to touch.
Um. NO.
It boggles my mind that they'll install complex computing systems to warn the driver about lane departure, or forward looking radar to automatically apply the brakes in the event of an imminent collision, or all sorts of "drivers aids" (so the driver can do everything but "drive"), but wont spend $10 or so to keep an absent minded mechanic (or good samaratan) from destroying all those systems by accidentally hooking up jumper cables backwards...
How do you propose the battery charges if there are diodes in the cables?
I'm not that good with analog electronic design, but wouldn't an avalanche diode setup work for this?
In reply to GameboyRMH :
I don't know what that is, but do bear in mind that alternators can put out as much current as jumper cables can.
2025- After extensive internet research Acme Motors, the new North American arm of a Chinese auto manufacturer releases a lightweight, RWD, Diesel, manual transmission, brown, station wagon capable of towing 10k. It It is called the Coyote Smasher and costs under 20k fully loaded. It comes standard with next generation battery cables with proprietary diode protection.
2027- Acme goes bankrupt due to lack of new car sales as the entire internet is waiting for the used cars to hit the bottom of the depreciation curve.
Acme's assets are bought by a private equity firm that scraps all the service parts from inventory.
2040 - GRM member AcmeFAN22 buys a "Ran When Parked" Coyote Smasher from BBC Marketplace for 300 bucks. He finds it wont start because the smart cables have failed. NOS replacements are unobtainium so he makes a post complaining about how over engineered the car is. With the help of the board he makes replacement "dumb cables" from an old dryer and a broken vinyl cutter.
2041 - Car develops a parasitic draw because the Zune retrofit MP3 player doesn't always shut off. AcmeFAN22 has to jumpstart the car and accidentally hooks up the cables to the battery he borrowed from his buddies Miata backwards. This causes the wiring to ignite burning the car to the ground and ruins the meatball parm sandwich sitting on the front seat.
TLDR- Diodes will ruin a perfectly good sandwich.
In reply to logdog :
And I've got a pain in the diodes all down my left side. Brain the size of a planet, and they've got me protecting people from their own foolishness.
Some people should not attempt jump starting.
Many of this group should have their tool boxes welded shut.
logdog said:
2041 - Car develops a parasitic draw because the Zune retrofit MP3 player doesn't always shut off. AcmeFAN22 has to jumpstart the car and accidentally hooks up the cables to the battery he borrowed from his buddies Miata backwards. This causes the wiring to ignite burning the car to the ground and ruins the meatball parm sandwich sitting on the front seat.
Unrelated other than the "burn to the ground" comment - there was a fellow a few years back burned his NA to the ground while trying to set the timing. Anything is possible.
The alternator output and main power connection to the starter solenoid could go direct to the battery with every other system connected through a diode to protect them. That way the heavy current and charging stuff isn't affected but the vulnerable electronics are protected. It probably wouldn't be that hard to retrofit something like that into a current car if it is a concern.
Adam
Thinking about this a bit, if you wanted to use a diode to protect your electronics the easiest way would be to install it as a short circuit from negative to positive battery terminal and then add a fuse/breaker/fusible link between the positive diode connection and the battery. Normal operation would be reversed bias so no power through the diode, but reverse the polarity and there's a big enough short circuit to pop the protection.
Realistically, the top terminals are already different sizes. If you have to open the first clamp way up or clamp it way down to make it fit you're already wrong.
