Solar Chargers

[Sybaris]

Hey all,

I'm looking for an OBD II or a 12 cigarette plug solar charger to plug in when I go away for a couple of weeks, so I can keep the Battery topped up.  I read that this is a good precaution.

Is there any difference between one that pugs in to the OBD port and one that plugs in to the 12 lighter socket?

Also is there a max wattage I should use as I see quite a wide range of sizes.  I am guessing that the tiny ones won't do much but what about some of the bigger ones?  Can they cause damage by dumping too much solar power in at a time?  Looking at maybe a 20W or a 50W

Thanks

[RXtoNX]

Left ours for 4weeks, no problems at all 👍

[Duggie B]

1 hour ago, Sybaris said:

Is there any difference between one that pugs in to the OBD port and one that plugs in to the 12 lighter socket?

I believe the 12v socket may only be in circuit whilst ignition is on/ready mode, once vehicle is switched off it may not be permanently live to feed back to 12v Battery....better option to use OBD port where there is a constant 12v from/to the Battery.

[Herbie]

2 hours ago, Sybaris said:

Is there any difference between one that pugs in to the OBD port and one that plugs in to the 12 lighter socket?

Also is there a max wattage I should use as I see quite a wide range of sizes.  I am guessing that the tiny ones won't do much but what about some of the bigger ones?  Can they cause damage by dumping too much solar power in at a time?  Looking at maybe a 20W or a 50W

The main difference between the OBD and the cig/12V power sockets are that the OBD will work and the cig/power socket won't, because it's only energised when the ignition is on.

As for the solar panel, Ohm's Law gives us I (current in Amps) = P (power in Watts) divided by Voltage, so 50W / 12V = 4.16A (although in reality I expect the panel to be less efficient than that).

So, 4.16A should be fine and the Battery itself will regulate that downwards as it charges. Just because the panel is rated to output 4.16A, it doesn't mean that the Battery will draw that amount.

[Sybaris]

Thanks again.

So I should look at a 50W OBD charger.  Do you think anything bigger is overkill?  

[Barry14UK]

If the Battery on your car holds its charge wel,l it should perform its job for two weeks without being top up. When my car was unused for much of the lock down, I received an email from Lexus recommending it be checked and topped up every two weeks. They mentioned switching the ignition on so 12v Battery draws off the traction Battery as they recommend in the manual.  However, this is not helpful if you are away so if you have access to a power point you could use a smart charger connected to your 12v Battery which will keep it charged as required.  It should not be one that provides more than 5A. Depending on light conditions, a 50w solar charger should help keep the 12v Battery sufficiently charged for two or more weeks unless your Battery is so weak it really needs replacing.

[Bluemarlin]

2 hours ago, Sybaris said:

Thanks again.

So I should look at a 50W OBD charger.  Do you think anything bigger is overkill?  

I would imagine so.  If it needed more than that then I'd suspect something was wrong with either the Battery, or the amount of current being drawn when sitting idle.

Just be sure to remember to unplug it before starting the car.

[Sybaris]

11 hours ago, Bluemarlin said:

Just be sure to remember to unplug it before starting the car.

Images of Bond's Lotus Esprit come to mind

[Sybaris]

I had a look at that famous online vendor named after a rain forest but all they have are 12v versions.  Anyone know any UK site that has a 50w charger that comes with an OBD lead?

[Bluemarlin]

That's what you want, a 12v one.  They come with a range of wattages though.  I'm not sure if there's a 50w one with an OBD lead though.

[PeterI]

I had a good result with the 4.8W AA solar charger via the OBD port when I was away recently, car was undriven for a month, but it was very sunny.

https://www.lexusownersclub.co.uk/forum/topic/134346-aa-battery-charger-12v-battery-charger-one-month-test-result

I'm not sure if there is a limit on how much power can be delivered via the OBD port. If you're looking for something a bit beefier then I did look into the Optimate Solar Duo 20W but I really didn't fancy having to hard wire to the Battery.

[Herbie]

1 hour ago, Sybaris said:

I had a look at that famous online vendor named after a rain forest

You are allowed to say Amazon; you're even allowed to link to the item if you wanted to.

1 hour ago, Sybaris said:

but all they have are 12v versions

Erm, given that the car Battery is 12V, what else would you want?

[Sybaris]

ah no, sorry really tired when I wrote that.  I meant they aren't OBD,  only 12v lighter plugs on them 

[Bluemarlin]

Happy to be corrected, but if your Battery is fully charged and in good condition, left in daylight with a reasonable amount of sunshine,  there's no unusual drain, and it's only for two weeks, then the AA 12v 4.8w EOBD solar charger will be fine.

[plastic orange]

I wasted money on the solar charger recommended by the AA - it actually flattened my Battery rather than charged it. This was during winter though, so may just possibly work in our summer, but it won't have a chance as it was binned.

 

Pete

[Moleman]

15 minutes ago, plastic orange said:

I wasted money on the solar charger recommended by the AA - it actually flattened my battery rather than charged it. This was during winter though, so may just possibly work in our summer, but it won't have a chance as it was binned.

 

Pete

For this to happen, you would need a faulty controller or broken diodes. If the panel is not broken and these two parts are working, it should not be possible for the panel to drain the Battery. May be some other fault within the car. 

[Illogan]

On 8/2/2022 at 3:05 PM, Sybaris said:

Hey all,

I'm looking for an OBD II or a 12 cigarette plug solar charger to plug in when I go away for a couple of weeks, so I can keep the battery topped up.  I read that this is a good precaution.

Is there any difference between one that pugs in to the OBD port and one that plugs in to the 12 lighter socket?

Also is there a max wattage I should use as I see quite a wide range of sizes.  I am guessing that the tiny ones won't do much but what about some of the bigger ones?  Can they cause damage by dumping too much solar power in at a time?  Looking at maybe a 20W or a 50W

Thanks

This is the one I bought, and plugs into the OBD port

https://www.amazon.co.uk/Urban-Company-Battery-Maintainer-Caravans/dp/B09X6CVQX8/ref=sr_1_6?crid=1LTX2EXNQGEJ8&keywords=12v+solar+panel+battery+charger+obd&qid=1659786925&quartzVehicle=29-10519&replacementKeywords=12v+solar+panel+battery+obd&sprefix=12v+solar+panel+battery+charger+obd%2Caps%2C107&sr=8-6

[Duggie B]

Toyota/Lexus dealers were selling solar chargers a while ago