Charging 12v LiFePO4 w/ car alternator (mppt/pwm/boost converter)

[bigjoncoop]

Hey my fellow DiYers,

I'm building a portable "solor gernerator" that consists of 5kwh LifePo4 batteries, a good 2000w inverter etc...

This will be in my work truck and I would like to charge the batteries using my vehicles alternator so it is always charged and ready to go....

The batteries are wired so there 4s 12v. I was thinking of going to 24 volt but unfortunately the inverter I have is 12 volts...

So I'm curious of your guys's ideas on the best way to charges battery pack while in the car. Should I use a MPPT or PWM charge controller or maybe just a CC/CV Voltage Converter?

The biggest issue I think is the fact that the battery pack and the car alternator are basically the same voltage... So using boost or buck converter will be difficult since normally the voltage needs to be at least a couple volts higher or lower...

Now I'm not sure which would be better for this situation a MPPT or a PWM charge controller... I you know that normally you would want to stick with an mppt since it is much more efficient but this application deficiency is not that important. And I'm not sure if either one is better or worse in my situation since the source voltage is so close to the battery voltage...

I've used mppt solar charge controller many many times without solar panels and just using a DC voltage source as the input and they've always worked perfectly fine.

*** another solution would be to why are the batteries so they're 24 volts and then use a buck converter to power the inverter. The buck converter would have to be fairly large and capable of 100+ amps though...

So if anyone has some suggestions that would be great!

Thanks

 

[Bobert]

Hey my fellow DiYers,

I'm building a portable "solor gernerator" that consists of 5kwh LifePo4 batteries, a good 2000w inverter etc...

This will be in my work truck and I would like to charge the batteries using my vehicles alternator so it is always charged and ready to go....

The batteries are wired so there 4s 12v. I was thinking of going to 24 volt but unfortunately the inverter I have is 12 volts...

So I'm curious of your guys's ideas on the best way to charges battery pack while in the car. Should I use a MPPT or PWM charge controller or maybe just a CC/CV Voltage Converter?

The biggest issue I think is the fact that the battery pack and the car alternator are basically the same voltage... So using boost or buck converter will be difficult since normally the voltage needs to be at least a couple volts higher or lower...

Now I'm not sure which would be better for this situation a MPPT or a PWM charge controller... I you know that normally you would want to stick with an mppt since it is much more efficient but this application deficiency is not that important. And I'm not sure if either one is better or worse in my situation since the source voltage is so close to the battery voltage...

I've used mppt solar charge controller many many times without solar panels and just using a DC voltage source as the input and they've always worked perfectly fine.

*** another solution would be to why are the batteries so they're 24 volts and then use a buck converter to power the inverter. The buck converter would have to be fairly large and capable of 100+ amps though...

So if anyone has some suggestions that would be great!

Thanks

Usually you would use a dc to dc charger in this situation. The voltage is not high enough to feed an scc. You also need to be certain that you have enough extra alternator capacity for whatever setup you go with as you can burn out your alternator pretty quickly.

 

[TheWanderingJackalopes]

I'm using a Sterling Power Products battery to battery charger for a similar application. In my case, the alternator and service batteries are 12v and the house batteries are 24v. They're a little pricy new, but I found one on eBay for quite a bit less.

 

[Pappion]

CAREFUL... SCC are typically Positive Ground, a short between PV+ and Battery+.