Load solar generator with alternator of a small car

[Tobias_208]

Hello everybody,
I have a question. Can I clamp my small PWM charge controller to the 12V DC power outlet of my car to charge my solar generator.
As background: The car is a small car and has a small alternator. That's why I want to remove max 10A charging current.

Will has shown two solutions to the problem, but they are not quite right for me.
1.

Use an inverter and a normal charger.
By transforming and rectifying, there is too much loss for me.

2.

Using a DC-DC converter
The used converter has 20A, but I want to load the electrical system of my car with 10A maximum.
In addition, a charge controller costs one tenth of the dc-dc charger.

Therefore, I thought that I simply connect a cable from the cigarette lighter to an additional 10A PWM charge controller.
And to charge the battery while driving.

Is that possible?

 

[Aussiecroc]

I like this thing Tobias -you can dial up the voltage and amperage you want. That means you can set it to whatever voltage and amperage you want. Its a dc to dc converter and very cheap.

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There is only ONE problem with it. The output has to be 2 volts more than the input. I need to find one that can take 14.2 alternator voltage down to 13.8 volts and dial the amps to 10amps. Maybe somebody knows one. I will keep looking. Good name Tobias I have a grandchild with that name.

 

[Aussiecroc]

This one is a step down but the difference has to be 1.5 volts lower - that means the highest voltage you could charge with is 12.7 and then dial up 8 -9 amps.

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To solve the problem buy the top step up one and boost the voltage to 16.2 at 9 amps and then use this bottom one to bring it back to 14 or whatever at 9 amps. There must be an easier and better way to do this. I want one to limit the current the alternator gives to the lifepo4 pack. No burnt out alternator trying to do 100 percent. 10 amps is just more than one old headlight. Buying both is still cheap but I'm not sure it would work. Some tech guy here can solve this. A dc to dc board shouldn't be too expensive at 10 amps.

the only thing about this one below is the cost and the charge profiles are not able to be adjusted - what batteries are you planning to charge?

https://www.outbackequipment.com.au/battery-link-10-amp-dc-dc-charger-with-solar?gclid=Cj0KCQjw6eTtBRDdARIsANZWjYaNyU8ELFoSd6wNMVEFXr9nDoIstzwKf9EQJQ9WAFHRhDEUrL90sUcaAsQZEALw_wcB

 

[Tobias_208]

Hello, Aussiecroc,
Thank you so much for your thoughts.

I want to charge an 80Ah AGM Vrla battery with the DC-DC converter.

I already had this Boost Converter in the back of my mind. But then I ordered the MPT-7210A and wait for it to be delivered. Do all boost converters have this minimum boost of about 2V? Then this model would be unsuitable. This is a Boost Converter.

What you suggest is to build a Boost buck converter. I will try if the MPT-7210A works and otherwise I have to consider buying a Boost buck converter with cc cv function.

I think I should have done that right away ?

 

[Tobias_208]

Unfortunately I can only find one buck-boost converter on ebay that can handle a little current (peak 10A), the LTC3780.
So either I'd have to paralel two LTCs or build a boost buck converter in series.

Or do you have other ideas that are still cheap?