If you have a 100 amp alternator - quite modest these days - the output cable will be capable of handling 100 amps. But that goes straight to the battery.
Other circuits in the car use the appropriate cable size.
I fitted an alternator to my Anglia - in which I took part in motor rallies The extra load on the driving belt broke the pressed metal take off pulley. Luckily Ford made a competition version which was a casting.
^^^^^^^^^^^^^^^^^^^^^
Presumably after the warranty period?
A drill bit would remove those in no time.
It can be any of the parts, including just a bad connection.
NT
Why?
But he's got a degree in this!
every cable in every car I've encountered has been thick enough to carry the current it carries.
it isn't
nonsense
alternator output cabling is also fairly thick.
FWIW starter motor cable thickness is as much due to voltage drop as ampacity.
NT
People forget about - or are unaware of - the importance of cable
*length* in this respect. You can get away with quite astonishing amperage levels with short runs of alarmingly thin cable, especially when the current is pulsed or of short duration. For example, there are some TO-220 packaged MOSFETs now which will handle close to 200A through their sub 1mm diameter leads provided those leads are cropped as short as possible.
Those A4 sized solar panels are great for keeping a car battery's charge topped-up if you make only infrequent short trips in the car. And with just a few cheap external components you can modify the charging current to prevent the battery getting cooked on very bright days. Add just a few more components on top and you can fit it and forget it - the car will always be 'on the button' no matter how long you leave it standing.
carries more than that a part of start up current. Voltage at alternator can go high enough at 150+ A to render extremely think cable not necessary.
Again simple minded armchair engineers confuse 'breaking' with 'becoming operationally unusable'. In things like sagging floors, and in terms of electrics.
A thick wire gives you two things: less power dissipation so it doesn't melt and less voltage drop so it doesn't affect operations
How dare I question the Bill,. He is plain right at all times eh?
No Bill. They dont have that. Wrong again.
Not in not reading questions no.
even if it's in the shade for most of the day?
my one does. It displays temperature along with battery voltage & charge current, If it thinks the temperature is too high, it turns on an internal fan.
Because if it breaks you won't be able to use it. Not even for regenerative braking.
That's not the only mechanism.
The transformer laminations are dipped in lacquer, then dried. Then the laminations are fastened together to make the core.
The purpose of the lacquer is to prevent eddy currents from forming. The assembly is clamped together to make a soft steel core with the desired magnetization behavior (B-H curve).
If the laminations happen to rust, it can cause the lacquer to be punctured. Then eddy electrical currents start to flow in a loop, between laminations. Perhaps a bit of a buzz is heard. The eddy currents heat up the laminations (which is why the lacquer was there in the first place).
This makes the transformer get hot, even at no load.
I had a RadioShack transformer fail this way. Sitting in the junk room for 20 years, dry conditions, and still it managed to have an eddy current problem. You couldn't leave it plugged in for an hour, as it would get scalding hot. When it gets hot, *then* there's some room for the other failure modes to happen. I had to buy another, and today they're not cheap (the cost spoils the fun of building your own gadgets).
The selenium rectifiers get pretty hot in those dumb chargers too. The reason selenium seems to be used, is the relatively high resistance in the conducting state. They're not efficient like a semiconductor diode. But the selenium rectifier also helps "tame" the output behavior, making for a better battery charger.
Selenium is a kind of impedance protection. Not perfect, but better. Semiconductor diodes are too "stiff" for this usage (making a dumb charger with a minimum of components).
If you were to replace the selenium rectifiers with a non-selenium solution, you would have to make sure the behavior of the output was modified with additional electronic components. Which kinda spoils the "I only paid £5 for this".
At 9V, maybe the dumb charger makes 6 amps. At 12V, maybe 2-3 amps. At 18V, about 0 amps (end of charging, when knackered battery is present. A good battery shouldn't rise to 18V.)
If you used semiconductor diodes in place of the selenium ones, at 9V you might get 20 amps and a fuse blows or smoke comes out or... Some additional resistance to current flow is needed, somehow, but without eroding the good characteristics as the charge operation continues and the battery fills up.
You paid £5 40 years ago. If the inflation rate caused a doubling of the value every 10 years, your "budget" today would be £80. Since the new chargers don't use nearly as much copper wire inside (SMPS, high frequencies, small transformer), they can do considerably better than £80 a unit.
The device also has to be selected for the task. The lawnmower battery isn't a lot of amp-hours. Maybe even the cheap 1 ampere charger would work (charger is switchable between 6V and 12V battery types). But to do a good job of charging the car battery, you would probably enjoy using more current than that. I have a 3 amp one, which is sufficient for car battery top-up. It would take a whole day if the battery was flat (run-down by inattention during COVID).
The Lidl one is probably a bit more current than that.
The car battery type matters to. There are regular batteries, and there are "start/stop" batteries. Cars that stop the engine at intersections are the "start/stop" case. Older cars left the engine running all the time until you got home and removed the key. The older cars are easier on their battery, calling for bulk current less often. The advert for the charger may mention whether it's compatible with "start/stop". I saw one float charger, that said it was not intended for start/stop battery types. That suggests you'd also want to monitor *any* charger, for aberrant behavior when the main charging sequence is complete.
In the graph here, phase 2 (topping charge) is CV (constant volts) at 14.4V.
Phase 3 (float charge) is supposed to be CV 13.5V. Some of the chargers you buy today, don't do phase 3 quite correctly, and some batteries are "resting" at 15V with the charger connected. I checked mine, and I did see it float-charging at 13.5V.
You would not leave the smart charger connected forever, unless you'd verified (somehow), that it wasn't abusing the battery (wrong float charge behavior).
Phase 1 CC (bulk charge, 9V rising slowly towards 14.4V) (if the battery is full, it gets to 14.4V within the first five minutes or so) Phase 2 CV (topping charge, 14.4V in a CV mode) Phase 3 CV (float charge, 13.5V) Phase 4 (some chargers switch off, leaving battery at 12.8V if it's in good shape) (when the battery self-discharges to 11.8V, some chargers automatically start Phase 1 again, others need the user to press the button)
The purpose of these user manuals, is to check and see what ampere-hour size of battery they charge with each. The 5 amp one, handles a battery up to 120 amp-hours. The 2 amp one is shown charging a 40 amp-hour battery. You'd check your car battery rating on the label, to see what ballpark it's in, like 60Ah. If it was 60Ah, you'd likely want a bit more than a 2 amp charger.
Since for the cheap ones, AldiLidl buys them in "lots" and how they work could change from lot to lot, you want to find a discussion thread for the "current" one, to see whether it's a good deal or a dud in terms of the whole charge sequence. I've been paying more attention to mine, and notice it's not as "saintly" as I thought. The "full" light comes on, while it's still pumping current. It shouldn't do that. I ended up disconnecting it while it was doing "verification phase". No idea what would have flashed if it wasn't holding well. Mine could use a LED that says it's stopped faffing about. But at least so far, I've not caught it using a wrong voltage.
The dumb chargers, the human operator had to guess at the fullness, and disconnect the alligator clips before it was too late. That's why we have smart chargers - in theory, to do the job well enough, they can be ignored once connected. You want to be able to walk away for a year, and come back to a properly charged battery, and no battery damage.
Paul
It doesn't matter if the car's parked in the shade - it's where the solar panel is mounted that counts! :-D
Mine do. I'm not saying you can't have an intelligent charger without that (in fact it's an option with most) but it is a system that works well.
Bill
After a working lifetime of dealing with people who have degrees, I've concluded that they are just as capable of talking bollocks as the rest of us. Furthermore the ones who mention their degree in an attempt to provide verification for the bollocks they are coming out with are usually spouting absolute total bollocks.
Bill
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