Science (Car) battery issues

[Notebook]

Had a battery experience yesterday. Left the car for three month(airport long-stay, wasn't planned)...then tried to start it. Couldn't even get the door open.
Got the AA(UK automobile service organisation) out. Got a door and boot open with the mechanical key.
Paul(the AA man) hooked up his power-block, didn't even light the dashboard. Deeply discharged.
Got it started eventually, and on my way.

What I was surprised at was the current drain when the engine was off. 3 Amps at one point, "a bit high" said Paul! I was shocked 3 Amps, doing nothing?
It did drop to .3A after a bit more charge from the alternator. Still seems a lot to me.

Is this unusual, or am I out of touch with modern car electrics(yes)?

N.

 

[Fabri91]

It seems unusual indeed, since at the nominal 12V voltage that would equate to 36W.

With N_Molson's 44Ah battery such a current would discharge it in 13-14 hours, so even assuming your car has a 2x/3x bigger battery it would still be discharged in less than two days.

 

[Urwumpe]

What I was surprised at was the current drain when the engine was off. 3 Amps at one point, "a bit high" said Paul! I was shocked 3 Amps, doing nothing?
It did drop to .3A after a bit more charge from the alternator. Still seems a lot to me.

Is this unusual, or am I out of touch with modern car electrics(yes)?

What kind of car do you drive?

Actually 3 A is not even bad - in extreme summer or winter,electrical cars can consume much more doing nothing for you, just for protecting the battery from freezing or exploding.

3 A temporary is essentially normal, when the motor electronics are powered again. If it is completely blanked, it might do some self-tests, like driving the throttle valve to its limits.

0.3A is about 3.6 Watts - your TV might use more in standby.

 

[Notebook]

Its a 2009 Jaguar XF, hasn't got any extras, so just alarm, radio, sat-nav.
I have got previous, did a similar thing a few years ago, and that battery didn't survive the next winter, though that was the original.

I'm quite surprised by the reaction the car has to having a completely flat battery, alarm goes off, lights flash, every conceivable error message appears on the dashboard. Thought it was going to explode.

Still not happy about that quiescent current, but it stands outside for weeks and starts reliably. I'll see how it goes. My cousin has a BMW SUV thing and says he has to run it every few days, or it starts to crank slowly.

N.

 

[Urwumpe]

Its a 2009 Jaguar XF, hasn't got any extras, so just alarm, radio, sat-nav.

Yes, lots of luxury extras that consume power even if powered off, plus some devices around your engine that require constant attention, so you can directly start your engine and not need to go through a length "pre-launch checklist".

Sadly such cars still lack a ground power receptacle, so you can physically disconnect the battery after charging and survive longer stays in garage...

On my old car, the biggest joy after three weeks of -15°C or less was having a whole Christmas tree of warnings on starting the engine, most of them persisting after engine start. One of two CAN buses failed (possibly by changed impedance of a bus terminal), so half of the sensors in my car had been off-scale low. Including the speed display.

Had to drive slowly through my village initially until all sensors defrosted and the CAN bus came back. The first that reacted had been the brake fluid level sensor luckily, then cooling fluid level... last was the speed display...

 

[Notebook]

When I used to go on holiday, I would disconnect the car battery, and take it indoors. But that was a long time ago, and batteries weren't as good as they are now.

Modern cars, far too complex for me, going back to my Ford Popular...

https://en.wikipedia.org/wiki/Ford_Popular#Ford_Popular_100E

N.

 

[Urwumpe]

When I used to go on holiday, I would disconnect the car battery, and take it indoors. But that was a long time ago, and batteries weren't as good as they are now.

Modern cars, far too complex for me, going back to my Ford Popular...

https://en.wikipedia.org/wiki/Ford_Popular#Ford_Popular_100E

N.

Same about my old Polo 86C ... It was easy to fix even for a software developer, its suspension was great after some modding, and what the 45 hp lacked for top speed, got compensated by low weight and huge agility. With a larger engine, it would have been the perfect FWD Rallye car. But before I could have bought the Polo G40 of another soldier, it was turned into expensive scrap metal by overtaking a tractor with some trailers the wrong way... (Of course, driving a G40 meant paying the insurance fees for a Porsche car - those had been hugely overpowered for their weight)

 

[N_Molson]

I totally agree, modern cars are a near-infinite source of problems. You now have all kind of electronic stuff and even multimedia equipement that heats up and eat tremendous amount of power. If they were honest, they should put a truck battery in the trunk. And erase the "SuddenDeath in 600 days" instruction from the fuel injector and other critical stuff memory.

Everything is running nominal here. I'll have to get new forward tires some day but oh well, too much grip is no fun !

Oh and I still have the old battery. Is it possible to charge it with the car engine alternator through the new battery ? I'm sure it is, but there's no point if I have to let the engine burn fuel for 12 hours or more at idle.

It's still the original battery, now six years old.

I'd definitively say you are entering the "danger" zone.

 

[MaverickSawyer]

I will be driving my 1990 Honda Civic until it dies and I can't repair it any more. I flat out refuse to drive a modern "nannymobile"unless given no other options. They're excessively complicated and try to do too much for the driver. :dry:

 

[Artlav]

Oh and I still have the old battery. Is it possible to charge it with the car engine alternator through the new battery?

WARNING!

Do not ever connect two car batteries in parallel to charge one from the other.

If you do that, the good one would send all the current through the discharged one. All of it.
Within a second the latter would start producing hydrogen by electrolysis, venting it out, acid would start to boil heated by all the current going through it, whole thing would shake from the boiling, something touches inside from the shaking to make a spark, and BOOM.

In other words that's an easy way to get a face full of boiling acid, which is a little bit unhealthy.

If you want to charge it with your car, then start the car, swap the batteries, keep the new one in the trunk just in case, then drive around as usual. Once full, swap them back.

 

[Urwumpe]

I will be driving my 1990 Honda Civic until it dies and I can't repair it any more. I flat out refuse to drive a modern "nannymobile"unless given no other options. They're excessively complicated and try to do too much for the driver. :dry:

I won't complain there. If you drive a few hours on a Autobahn, a cruise control is very relaxing... And being able to halt on a steep grade without rolling back is also not the worst feature.

But what really impressed me so far about having a recent car: About the same size, about the same mass.... 30% less fuel consumption at the fuel station.

 

[N_Molson]

Within a second the latter would start producing hydrogen by electrolysis, venting it out, acid would start to boil heated by all the current going through it, whole thing would shake from the boiling, something touches inside from the shaking to make a spark, and BOOM.

Wow :blink:

If you want to charge it with your car, then start the car, swap the batteries, keep the new one in the trunk just in case, then drive around as usual. Once full, swap them back.

But I think the car will dead stop once you disconnect the battery. It happened to me when the alternator died, two years ago. There's absolutely no backup to the battery, and its a part of the electrical loop. If you remove it, you open the circuit, just like with a switch. Then the fuel injector chip gets no power, and the engine stops, out of fuel to burn. In fact it happened to me when I stopped in front of a gate, waiting for it to open. I think there is also an antique electronic circuit that regulates the idle RPM in function of temperature and some other parameters. Previous batch of my car had a manual starter, a lever you had to pull when starting the engine. It made the air/fuel mixture rich, easing cold starts. Problem was, it wasn't a good idea at all to forget it on. I have to admit that the electronic injector is very handy for that, and it helps a bit with fuel consumption (but remember, that's quite a crude system, it doesn't recalculate 100 times per second the exact optimal amount of fuel to burn).

I'll just wait to get a decent charger then

I won't complain there. If you drive a few hours on a Autobahn, a cruise control is very relaxing... And being able to halt on a steep grade without rolling back is also not the worst feature.

Yeah, my father has a Land Rover with cruise control and an automatic gearbox. I admit it makes life easier. Though cruise control can be a trap if you don't know how it works. But automatic gearbox yes. Now I really enjoy driving and having a manual one on my car, but when you want some comfort yes, the auto-gearbox is a pleasure. Now it depends. If I have to drive 600 kilometers on the highway, the Land Rover, though not designed for that, is clearly much better. If I have to brawl crossing the lanes into the rush hour or to find a parking slot in downtown, yes, the sturdy small car is perfect.

 

[Urwumpe]

Yeah, my father has a Land Rover with cruise control and an automatic gearbox. I admit it makes life easier. Though cruise control can be a trap if you don't know how it works. But automatic gearbox yes. Now I really enjoy driving and having a manual one on my car, but when you want some comfort yes, the auto-gearbox is a pleasure. Now it depends. If I have to drive 600 kilometers on the highway, the Land Rover, though not designed for that, is clearly much better. If I have to brawl crossing the lanes into the rush hour or to find a parking slot in downtown, yes, the sturdy small car is perfect.

Same here. I am usually prefering manual over automatic, because it gives me more control over the car. Even with modern automatic boxes that allow a semi-automatic mode (dual clutch).

But then... considering a future where my car has to drive slowly and without even the slightest hint of drifting around a curve because my passengers might get upset again, I think automatic is suitably boring for a boring future. Maybe I can buy some old RWD car one day for the fun.

The same BTW with parking sensors. While you can generally be sure on a small car, that your car ends right where you can't see it anymore. its pretty useful to know how close you can exactly get, when moving in constricted places like a small underground garage. But you should trust your eyes more than this anyway.

 

[Fabri91]

Well, so I got around to replace the battery in our 6-year old Ford Ka.

Due to it having a start-stop system, the required battery rating was higher, and so was the price (135€, hah). But now when said system engages the car won't automatically start again after just 5 seconds, so most likely the older battery was indeed going the way of the dodo.

In any case, I at least got to learn how to replace a battery, which won't hurt.

The old battery:

The new one:

The motor bay with the newly installed battery and the fearsome Fiat 1.2L engine:

 

[Urwumpe]

Your engine looks way less confusing than mine. :lol: (And I also have 1.2l with turbocharger and start-stop system)

 

[Fabri91]

See, that's due to there not being any turbocharger. It's the "standard" Fiat 1.2L Fire engine, used in the Panda, Punto, 500, Lancia Ypsilon where it's still sold and so on. As far as I know it's also an 8 valve engine. Simple but can't complain about it, really.

The intake of our 1.0 Ecoboost Focus, which indeed is turbocharged, is quite a labyrinth, what with intake butterfly valve, turbocharger and intercooler.

Now, having a car as light as the Ka with the Focus' engine would be quite something. I once test drove an Abarth 500 of a friend, which had a 1.4L turbocharged four-cylinder, and no small car has business sounding that good and being that properly fun, too (keep in mind that the Ka is a badge-engineered Fiat 500).

 

[Urwumpe]

See, that's due to there not being any turbocharger. It's the "standard" Fiat 1.2L Fire engine, used in the Panda, Punto, 500, Lancia Ypsilon where it's still sold and so on. As far as I know it's also an 8 valve engine. Simple but can't complain about it, really.

Oh I thought you had a turbocharger there because of the large duct from the engine cover to the front. Looks like the connection from turbocharger to intercooler here.

 

[Fabri91]

As far as I know, so take this with a decent grain of salt, the duct you see comes directly from the intake proper and the engine cover is not so much a removable plastic cover as instead the housing of the air filter and intake manifold.

 

[Urwumpe]

As far as I know, so take this with a decent grain of salt, the duct you see comes directly from the intake proper and the engine cover is not so much a removable plastic cover as instead the housing of the air filter and intake manifold.

Yeah... and when you think all cars look nearly the same inside, there can be other solutions. :lol:

The intake box is on the top, at the front of the hood here.