Battery problems

WTFH

Strider590 wrote: »

2.4w = 200mA (in the brightest of sun), that's not enough to even float charge a car battery. At best it'll compensate for stuff like the alarm and the ECU in standby, but as a car battery ages, the internal loss increases, that solar charger is nothing more than a placebo.

There was someone who had one of these and made all sorts of claim about it, until someone else pointed out that on his car the lighter socket didn't work if the ignition wasn't turned on.

Strangely enough, it plugs into the EOBD port.

Also, I have used it to get a battery from "unable to turn over the engine" to started car in 15 minutes.

AdrianC

WTFH wrote: »

Strangely enough, it plugs into the EOBD port.

Which does contain a permanent live, but with minimal current-carrying capacity and fairly high potential to cause issues if overloaded.

Also, I have used it to get a battery from "unable to turn over the engine" to started car in 15 minutes.

<sigh> A basic understanding of physics is all that's needed to call bull here...

200mA max charger, 15 min = 50mAh. Sufficient to illuminate a single 5w bulb for about 5min.

And that's going into a ~70Ah battery. The average starter motor pulls somewhere around 100A+.

TrickyWicky

WTFH wrote: »

Strangely enough, it plugs into the EOBD port.

Also, I have used it to get a battery from "unable to turn over the engine" to started car in 15 minutes.

I find that hard to believe.

WTFH

Well, you can call me a liar if you want, but it was a honda crv this summer on the day that England won the ashes.

kingstreet

[quote=[Deleted User];64325857]Merc A170 2001. Battery less than year old.[/QUOTE]
You use Lofty's pages on the A Class?

http://www.aclassinfo.co.uk/a1.htm

I know his is a petrol, but I've solved so many problems on my wife's 2000 A160 using this, it's incredible.

We found a seizing pulley which was destroying the auxiliary belt and causing charging problems on hers. The starter motor went on it too. Bloody engine is canted over at an angle and a right pain to replace parts like that.

Richard53

TrickyWicky wrote: »

I find that hard to believe.

Remember that all batteries have a certain amount of self-recovery. You can churn an engine until the battery is flat, and then if you wait half an hour it's able to turn the engine over again, although feebly and not for long. Perhaps that's what happened here.

Joe_Horner

Richard53 wrote: »

Remember that all batteries have a certain amount of self-recovery. You can churn an engine until the battery is flat, and then if you wait half an hour it's able to turn the engine over again, although feebly and not for long. Perhaps that's what happened here.

That 50mAh or so is also enough to turn a starter motor for about 2 seconds, on top of any recovery. Plus, starter load drops significatly (by up to about half) once the motor's actually turning, so in practice it might even give you 3 seconds.

With a car that normally starts instantly, and has had (say) lights left on rather than having the battery hammered by unsuccessful starts, that could be just enough to get a start.

But it'd be a very unusual set of circumstances to pull it off!

WTFH

Joe_Horner wrote: »

That 50mAh or so is also enough to turn a starter motor for about 2 seconds, on top of any recovery. Plus, starter load drops significatly (by up to about half) once the motor's actually turning, so in practice it might even give you 3 seconds.

With a car that normally starts instantly, and has had (say) lights left on rather than having the battery hammered by unsuccessful starts, that could be just enough to get a start.

But it'd be a very unusual set of circumstances to pull it off!

It was very unusual circumstances - England had won the ashes and the sun was shining!

The battery had gone flat that day because some imbecile had left his wife to do some shopping, while he sat on the rear bumper of the CRV with the boot open, making sure his dog stayed cool and had water to drink.
He put the keys in the ignition so he could listen to the radio, but forgot to turn the aircon off. So for quite a while the AC was working at full blast trying to cool a hot car that had its boot open. Silly WTFH

AdrianC

WTFH wrote: »

He put the keys in the ignition so he could listen to the radio, but forgot to turn the aircon off. So for quite a while the AC was working at full blast trying to cool a hot car that had its boot open. Silly WTFH

You do know that the aircon isn't electrically powered, right? Just the fan - which uses relatively little power.

Strider590

WTFH wrote: »

Strangely enough, it plugs into the EOBD port.

Also, I have used it to get a battery from "unable to turn over the engine" to started car in 15 minutes.

Well, I'm no expert on the OBD port power supply on other cars, but I do know mine has a diode in series, because the voltage at pin 16 is always 0.6 volts lower than the battery voltage.

If I were intent on connecting a solar panel, I'd pick out one that exceeded 8w (0.7A is close a decent float charge), I'd then secure it to the parcel shelf and wire it into the rear fuse box.