Connect van’s cigarette lighter socket to controller’s PV terminals?

[Gficht001]

I’m interested in building a small system similar to Will’s Minimalist design...

• 100 amp hour usable deep cycle battery
• 100-200 watt solar panel
• 20 amp MPPT charge controller (PWM controller if on a tight budget)
• 750 watt inverter

I’d like to use it for travel/camping in my minivan. While camping/stationary, I plan to use a suitcase style solar panel as a charge source. While driving however, I’ll have the solar panel packed away. Can I connect my van’s cigarette lighter socket to the PV terminals on my controller to utilize my van’s alternator as a charge source while driving?

 

[Pierre]

The cigarette socket current is about 10 amps max and the voltage 13,8 - 14,2 v may be too low for the SCC. The PV panel output will normally be about 17v. You may have to run thicker wires from the vehicle battery to a dc/dc converter direct to the battery terminals.

 

[Gficht001]

Thanks Pierre.

 

[itsnotlevel]

In theory you would think this would work. The SCC takes ANY voltage or amperage and pushes it into the battery. I cant think of any reason why this wouldn't work.....I think you may have found a hack for a dc to dc charging type of situation? It sounds like a good hack to me. I would be curious to know if it works, but it might cause damage of your SCC even though I dont see how as of yet. The SCC uses ANYTHING it gets and uses it....maybe voltage drop would make it worth not doing and the low amperage might be too little to even help your batteries. Best imho....just get the renogy 20a dc to dc charger for when youre driving.....stretch that gas dollar bro! Hope this opinion helps.

 

[Brewman]

If your battery is low it would draw max current through the lighter port and could melt it. It's not made for long term draw like that.

 

[itsnotlevel]

If your battery is low it would draw max current through the lighter port and could melt it. It's not made for long term draw like that.

Great point! I love the idea as a hack... Might be a way around that.

 

[Brewman]

Could always upgrade the wiring and get a better type of connection point.

 

[gnubie]

In theory you would think this would work. The SCC takes ANY voltage or amperage and pushes it into the battery. I cant think of any reason why this wouldn't work.....I think you may have found a hack for a dc to dc charging type of situation?

Trying to use a MPPT controller fed from the vehicle's DC system probably won't work if it's 12V and the battery is 12V too. MPPT controllers will have minimum voltage difference requirements. Victron SCCs require the voltage from the PV input be 5v or higher than battery before they will start charging and that it must remain 1V or higher to continue charging. Epever requires 2V or higher to maintain charging, not sure of the start voltage.

The cheapie $20 PWM controllers will usually self-destruct if you tried this with them. They have no current limiting at all, relying on the fact that what ever is connected to their PV input will limit the current, ie a suitably rated solar array. Connecting two battery systems across them with the load battery discharged will immediately exceed the switching transistor's abilities and the smoke will be released.

 

[Gficht001]

If your battery is low it would draw max current through the lighter port and could melt it. It's not made for long term draw like that.

Thx. Good to know. I wonder if a controller could limit this. Or maybe an in-line device.

 

[John Frum]

If your battery is low it would draw max current through the lighter port and could melt it. It's not made for long term draw like that.

One would hope that the fuse blows.

 

[John Frum]

One would hope that the fuse blows.

Best to keep one nostril on smoke alert though.

 

[Gficht001]

Trying to use a MPPT controller fed from the vehicle's DC system probably won't work if it's 12V and the battery is 12V too. MPPT controllers will have minimum voltage difference requirements. Victron SCCs require the voltage from the PV input be 5v or higher than battery before they will start charging and that it must remain 1V or higher to continue charging. Epever requires 2V or higher to maintain charging, not sure of the start voltage.

The cheapie $20 PWM controllers will usually self-destruct if you tried this with them. They have no current limiting at all, relying on the fact that what ever is connected to their PV input will limit the current, ie a suitably rated solar array. Connecting two battery systems across them with the load battery discharged will immediately exceed the switching transistor's abilities and the smoke will be released.

Mmm... I didn’t know that. I wonder if that voltage threshold is programmable on any controllers

 

[Pierre]

Best to keep one nostril on smoke alert though.

Again You crack me up - go to bed !

 

[mandrews44]

You can charge it If you use a buck/boost converter with CC, Amazon carries them. With this, you can directly charge the battery from your cigarette lighter plug. Set it to 14.2 and limit the current to less than your fuse. Your vehicle voltage will vary so you will need buck/boost. Current limiting is required with LiFePo4, without out it, it want it all and will burn up anything that isn't CC.

 

[mandrews44]

Mmm... I didn’t know that. I wonder if that voltage threshold is programmable on any controllers

MPPT is all about the charge, not source. It is only BUCK, not Boost.

 

[gnubie]

Genasun GVB-8 (Boost)

 

[Gficht001]

You can charge it If you use a buck/boost converter with CC, Amazon carries them. With this, you can directly charge the battery from your cigarette lighter plug. Set it to 14.2 and limit the current to less than your fuse. Your vehicle voltage will vary so you will need buck/boost. Current limiting is required with LiFePo4, without out it, it want it all and will burn up anything that isn't CC.

Woohoo... I think this is what I’m looking for. Reading up on the GVB-8 that gnubie posted. Thank you both!

 

[mandrews44]

Woohoo... I think this is what I’m looking for. Reading up on the GVB-8 that gnubie posted. Thank you both!

I'm not sure the GVB-8 will work as it is designed for 24v / 48v charging. I'd be careful with that and make sure it will work for your battery or it will be bad. Never hook up a 24v charger to a 12v battery.

 

[Tabuk]

Hey have you got any updates?
Can you now charge your battery with the cigarette plug?

 

[mandrews44]

If you use an adjustable converter that regulates current, you can charge the battery from any source. Some are boost only or buck only. Some are buck/boost and will adjust the voltage up or down based on your source. Up = 5v source to charge a 14.2v battery. The most important, besides not charging with too high of voltage is limiting how much current is drawn from the source. If you are into building your own devices, I have give you inexpensive ways of doing this. Yes, it's possible. If you use the correct device to limit how much power goes into the battery at once. Otherwise, fuses will be blown or alternators damaged.