Is there an auto-electrician in the house?

[numbnuts]

Interesting. Especially the idea of charging via the OBDII port, which I've never heard of, but which sounds like the smart option. Googling suggests this is doable, and if it works is surely the easiest (and potentially very neat) solution.

It is only 4.8w which is quite low, I would go for a higher wattage if you can, also I read about a warning, don't start car with it still connected or you could blow fuses if using EOBD port .

 

[swee'pea99]

It is only 4.8w which is quite low, I would go for a higher wattage if you can, also I read about a warning, don't start car with it still connected or you could blow fuses if using EOBD port .

Thanks. I did read during my googles that the port can't handle high wattages. 5w was said to be a sensible limit. Needless to say I haven't a clue whether this is true.

 

[keithmac]

Can’t really tell what you’re testing but from the photo I’m guessing you’re measuring the voltage across a one ohm resistor in which case a 70mV reading will indicate a current of 70mA.

I just worked it out from his 75mv and same as you came to 75ma which is perfectly normal.

Scotty Kilmer is an absolute nob, if you want to watch someone who knows what they are doing watch some "South Main Auto" on YouTube, Eric O is the master of vehicle wiring and diagnostics.

I do the same on motorcycles and watching the SMA videos appreciate the skill he has, methodical and precise. Genuinely worth watching even if you don't like cars!.

I use an Otimate 4 battery tender on my GTO, best in the business.

 

[raleighnut]

Scotty Kilmer is an absolute nob

Yep

 

[swee'pea99]

FWIW & in case anyone's interested, I've ended up getting one of these, which is even feebler, at a frankly laughable 2.4w. Mainly because it's one of very few that come with an OBDII port connector, which seems to me clearly the way to go. Gets lots of good reviews online, and as I said earlier, I don't think I have a major problem, so this may be enough to do the job.

Thanks again for all responses. I've got from wondering how to go about pulling fuses to investing in a solar charger, which will hopefully sideline the fuse issue indefinitely. Fingers x'd...

 

[numbnuts]

FWIW & in case anyone's interested, I've ended up getting one of these, which is even feebler, at a frankly laughable 2.4w. Mainly because it's one of very few that come with an OBDII port connector, which seems to me clearly the way to go. Gets lots of good reviews online, and as I said earlier, I don't think I have a major problem, so this may be enough to do the job.

Thanks again for all responses. I've got from wondering how to go about pulling fuses to investing in a solar charger, which will hopefully sideline the fuse issue indefinitely. Fingers x'd...

OK when you get it take the car for a good 30 mile drive and then connect it up, it will not charge a battery, but it will maintain the battery level, so in turn should not go flat.
Good luck

 

[CXRAndy]

Most modern vehicles have a small drain on the battery. It usually around 10-40 milli Amps after the car goes to sleep, this is anything from 10mins to 1hour.

Cars will flatten a battery in 30 days if left without a charger.

70mA sounds a little high, but did you test the drain after an hour, with every door and switch disabled? 70mA could be the pre sleep figure.

I use a Ctek battery maintenance charger on my vehicles which i dont use much

 

[swee'pea99]

Ok, it's arrived, and looks like a reassuringly solid piece of kit. The only thing is, it stresses the importance of having it disconnected when starting the engine, but there's no really obvious way to do it. Is it going to be a case of unplugging the OBD connector every time I start the car? Sounds like a faff. Might it be possible to cut the lead and fit a little torpedo switch or similar? Presumably there's just two leads inside that OBD lead - a red & a black. It does seem weird to me that these things don't incorporate a switch as part of the basic setup, but I guess the upside is that if it is possible to cut & fit a switch, that way you get to choose where exactly the switch goes.

So, anyone have any idea? Is a switch technically a sound idea?

 

[CXRAndy]

Ok, it's arrived, and looks like a reassuringly solid piece of kit. The only thing is, it stresses the importance of having it disconnected when starting the engine, but there's no really obvious way to do it. Is it going to be a case of unplugging the OBD connector every time I start the car? Sounds like a faff. Might it be possible to cut the lead and fit a little torpedo switch or similar? Presumably there's just two leads inside that OBD lead - a red & a black. It does seem weird to me that these things don't incorporate a switch as part of the basic setup, but I guess the upside is that if it is possible to cut & fit a switch, that way you get to choose where exactly the switch goes.

So, anyone have any idea? Is a switch technically a sound idea?

What have you ordered?

 

[swee'pea99]

What have you ordered?

Thanks. One of these.

 

[newfhouse]

I wouldn’t worry if I forgot to unplug it. I guess there’s a theoretical chance of some back-EMF from the starter motor, but you are not advised to disconnect your radio every time you start your car, are you? Also, the blurb says

• Built-in discharge protection and reverse polarity protection

so I wouldn’t bother.

 

[swee'pea99]

I wouldn’t worry if I forgot to unplug it. I guess there’s a theoretical chance of some back-EMF from the starter motor, but you are not advised to disconnect your radio every time you start your car, are you? Also, the blurb says

so I wouldn’t bother.

Thanks. Hmmm. The only thing that gives me pause is the

Also a handful of horror stories from posters whose charger has been fried, or worse. Screwed up car electronics and the like. I'm not sure what 'discharge protection' means. Does it mean it's built to survive any surge from the battery/starter? I'm just wondering why they've made it #1 'important point' if the thing's immune from any such issue.

Sorry, I don't mean to quibble. I'm just caught between a helpful poster & some pretty heavy sounding small print...

 

[numbnuts]

Just had a look at said unit, it plugs into the solar panel so unplug it from there, which is good as you don't want the thing on top of your dashboard while driving

 

[newfhouse]

Sorry, I don't mean to quibble. I'm just caught between a helpful poster & some pretty heavy sounding small print...

Fair enough. I’m only saying that I’d be pretty relaxed about it because I can’t see how something so simple could be so electrically fragile. I expect the protection they claim is just a diode, designed to stop current flowing into the unit if your battery voltage exceeds that of the panel. That would be enough to allow me to feel quite relaxed, but my advice is only worth what you paid for it.

Just had a look at said unit, it plugs into the solar panel so unplug it from there, which is good as you don't want the thing on top of your dashboard while driving

It looks like this is a simple workaround that ticks all the boxes.

 

[swee'pea99]

Thanks. That's what I'll do for the moment. I can't help feeling a switch makes more sense than constantly plugging/unplugging plugs that don't look massively robust, but it'll do to be getting on with. Thanks again.