Solar panel and 12v splitter

[Halcyon]

I currently have a small solar panel connected to my car through the 12v socket. I am looking to acquire a dash cam, and was trying to figure out how to hook both the dashcam and solar panel into the same 12v socket.

If I bought a 12v splitter like this one: https://www.amazon.com/gp/B00G8WLT7CWould I be able to have power going in through the solar panel and power coming out for the dash cam, at the same time?

This is a cleaner solution for me than hooking the dash cam up directly to the car battery.

Any advice would be appreciated. Thanks.

 

[Nigel]

Yes, that should work, looks nicely made.

However it wont be much use if your 12v socket turns off when you park the car as a lot, but not all, do.

Also, small solar panels mounted inside cars don't produce much power, they only work for half the day, they don't work when under cover, they don't work well under trees, and most car windows are designed to block most of the sun's energy so that the inside of the car doesn't get hot. It probably wont fully power the camera even at midday so will just increase how long the car battery lasts by maybe 15%.

 

[Rajagra]

I once hooked a solar panel up in a car I rarely used. It drained the battery and killed it.
I suggest checking your panel doesn't discharge the battery when it's dark/gloomy.
If it does, there are cheap devices available to prevent it. Some have USB outputs too:
https://www.amazon.co.uk/gp/B01CZRTL0U
I haven't tried them though, just something to consider.

 

[Halcyon]

Yes, that should work, looks nicely made.

However it wont be much use if your 12v socket turns off when you park the car as a lot, but not all, do.

Also, small solar panels mounted inside cars don't produce much power, they only work for half the day, they don't work when under cover, they don't work well under trees, and most car windows are designed to block most of the sun's energy so that the inside of the car doesn't get hot. It probably wont fully power the camera even at midday so will just increase how long the car battery lasts by maybe 15%.

After some investigation, it turns out that my 12v socket turns off when the car is parked. Which means the solar panel has done nothing for the 4 months it's been plugged in!

I once hooked a solar panel up in a car I rarely used. It drained the battery and killed it.
I suggest checking your panel doesn't discharge the battery when it's dark/gloomy.
If it does, there are cheap devices available to prevent it. Some have USB outputs too:
https://www.amazon.co.uk/gp/B01CZRTL0UI haven't tried them though, just something to consider.

The solar panel has a built in charge controller to prevent overcharging or draining.

So, it seems that a decent solution would be to buy a small battery pack and connect it to the car 12v socket. This connection would only be charging the battery pack when the car is running. I would also have the solar panel plugged into an input on the battery pack, which should extend the charge a bit. The dashcam would be the sole output on the battery pack.

Anything obvious I'm overlooking with this setup?

 

[Rajagra]

So, it seems that a decent solution would be to buy a small battery pack and connect it to the car 12v socket. This connection would only be charging the battery pack when the car is running. I would also have the solar panel plugged into an input on the battery pack, which should extend the charge a bit. The dashcam would be the sole output on the battery pack.

Anything obvious I'm overlooking with this setup?

Most newer USB power packs will not power devices while they themselves are being charged up.

Of those that can, most are not actually designed to work that way, they have simply failed to block such action. This means the internal charging circuit of the power pack may get confused. It thinks it's charging it's internal battery, but some of that current is going to the external device. So when it thinks the battery should be full, it is not. That may possibly lead to undercharging, which could ultimately lead to damaged cells. Li-ion batteries need to be treated carefully, and that is not being careful.
Having said that, if you find a power pack that lets you do this it might work. Just monitor it very carefully to make sure it doesn't spend too much time in a heavily discharged state. The solar panel should help.

Some of us have discussed using relays to automatically (or manually with a switch) get round these pitfalls. It should be straightforward, but I haven't seen anyone getting round to doing it. I've just received a 5-pack of 12V relays, so maybe I'll make the time to test this soon.

 

[Nigel]

...That may possibly lead to undercharging, which could ultimately lead to damaged cells. ...

Undercharging lithium batteries is not a problem, in fact not charging the last 10% will maybe triple the battery's lifespan.

The only real problem with most lithium power banks is that they don't charge fast enough, most USB powerbanks will only charge at 10 watts, although there is no good reason why you can't put enough charge for 24 hours dashcam use into a lithium battery in 20 minutes, that's charging at around 80 watts for 24 hours from a B1W dashcam which is the same rate my DJI Phantom battery charges.

 

[Nigel]

The solar panel has a built in charge controller to prevent overcharging or draining.

Do you have a link for it? The small ones sold for cars normally have a diode built in to prevent discharge, not seen one with a proper charge controller, although the electronics to do it are reasonably cheap these days...

 

[Halcyon]

Do you have a link for it? The small ones sold for cars normally have a diode built in to prevent discharge, not seen one with a proper charge controller, although the electronics to do it are reasonably cheap these days...

https://www.amazon.com/gp/B004Q83TGO
I'd like to think it has a charge controller, but I don't know too much about that stuff

 

[country_hick]

Most solar panels will overcharge. There needs to be a voltage regulator added to ensure you stay in the proper charging limits.

 

[Nigel]

Most solar panels will overcharge. There needs to be a voltage regulator added to ensure you stay in the proper charging limits.

Most of these small panels don't produce enough power to ever overcharge a car battery!

However this panel does say:
"battery charger solar panels are the only panels available with a built-in charge controller to prevent overcharging."
so nothing to worry about

 

[Rajagra]

If you have a lead acid car battery, then not only will it regulate the voltage output from any small solar panel, it will also benefit from float charging as it reduces sulfation.

The problem with lithium ion packs I was referring to is severe discharging, which is very bad, even dangerous.

Having a USB power pack "charge and discharge at the same time" is only a problem as I see it if it confuses the charging circuit, ultimately leading to a severe discharge state.

(Quote marks used because the cells inside cannot charge and discharge at the same time. Current either flows in or out, both can't happen at the same time.)

Sent from my SM-G903F using Tapatalk

 

[Nigel]

If you have a lead acid car battery, then not only will it regulate the voltage output from any small solar panel, it will also benefit from float charging as it reduces sulfation.

You can overcharge lead acid batteries, too much power and they split their electrolyte into oxygen and hydrogen which can end up very badly, possibly a big explosion, so you do need to be careful, but a 5W solar panel isn't going to do it on a battery the size of a car battery that is busy supplying power to the alarm system and dashcams.

The problem with lithium ion packs I was referring to is severe discharging, which is very bad, even dangerous.

Having a USB power pack "charge and discharge at the same time" is only a problem as I see it if it confuses the charging circuit, ultimately leading to a severe discharge state.

(Quote marks used because the cells inside cannot charge and discharge at the same time. Current either flows in or out, both can't happen at the same time.)

Over discharging is indeed very bad, they always need a low voltage cut off.

I don't think "charge and discharge at the same time" ever results in over discharge since there should always be a low voltage cut off that will prevent it. What can happen with some chargers is that they over charge since charging is supposed to be ended when the charge current drops below a certain level and if you are using some current for things other than charging then you will prevent that happening so it can over charge by a small amount. I think it is only a significant problem if you are using a quick charger though and is solved if you use a charger that stops charging when the battery is only 95% full which also improves battery life significantly.

As you say, "the cells inside cannot charge and discharge at the same time", so any problem is not an issue with the lithium cells, it is a problem with the charger and with a charger that is designed to charge and discharge at the same time there should not be a problem.

 

[Rajagra]

What can happen with some chargers is that they over charge since charging is supposed to be ended when the charge current drops below a certain level and if you are using some current for things other than charging then you will prevent that happening so it can over charge by a small amount.

I see what you mean. Chargers vary a great deal in how sophisticated/safe they are, some might well have that problem.