Originally Posted by Doktari
I’ll correct what you mentioned about Lithium charging. Do NOT three stage Lithium batteries. Three stage is best for Lead Acid batteries.
Can you elaborate? I was under the impression that this staged charging was a best practice for Lithium batteries (but I am just beginning to research lithium battery storage, so i'm likely misunderstanding something). It is correct that lithium batteries need some form of 'managed' staged charging correct?
Ive figured out a revolutionary and custom way to charge Lithium or Lead Acid batteries in a bus. It’s custom and requires rethinking the whole system. But it would transform the alternator charging from 30%-50% efficient to 70%-80% efficient and would integrate it with solar in a seamless system. So this is for top notch systems. Would be a investment. And it would be programmable. I hijacked the technology from cutting edge micro hydro/solar technology which is very efficient and integrated. You would even be able to see what it’s doing using Bluetooth on your smart phone. Or on a computer 10,000 miles a way using WiFi.
This a system that expensive and probably only worth doing on a full size bus or Coach. And it requires a large solar array to clamp the alternator voltage.
Step 1: toss out the 12 volt alternator and bolt in a 48 volt alternator but do not connect it to the 12 volt starting battery. Or even better use a Harris alternator with powerful magnets and adjustable magnets.
Step 2: connect the 48 volt alternator to a programmable Mppt charge controller in parallel with a large solar array on the roof to the 48 volt house battery. The solar array acts like a zener diode and clamps the voltage of the alternator. The charge controller tracks the maximum power point. A very efficient and programmable setup.
Step 3: connect a big programmable DC to DC charger from the house battery to the starting battery. Now the starting batteries will also be connected to the solar and alternator through the house battery . Never need to worry about them being discharged.
Step 4: install a DC to DC converter from the house battery to the 12 volt DC loads. Or several step down DC to DC converters if the loads are big.
One could do a trick dual alternator setup if there is a massive 12 volt A/C load. But with a big DC to DC converter this extra alternator should not be necessary. But I would switch to a mini split inverter heat pump A/C that runs from the inverter/charger.
The Mppt charge controller can be programmed to charge Lithium or Lead Acid. The DC to DC Charger can be programmed to charge Lithium or Lead Acid. It offers flexibility.
Basically this is replacing the old low voltage analog DC systems in the coach with all cutting-edge technology high voltage DC digital systems. The entire system can be integrated together fairly easily. Well almost the entire system. It’s not the space shuttle.
This is the type of system I’m considering building on my Overlander Isuzu or my shortie skoolie.
I actually just got through reading your post on this in another thread. Sounds super interesting. I like the idea of being able to charge either battery bank of of either system and I like the idea of a higher voltage more efficient system. I don't love the idea of the alternator not being able to power the vehicle electrical system directly (from a simplicity, resilience standpoint). But understanding the particulars of your system is way over my head at this point.
I do have some questions
What accounts for the efficiency improvement of this system over a traditional alternator? Simply changing from 12v to 48v?
What do you mean by designing the solar to "clamp" the voltage?
What do you gain by connecting the solar and the alternator in parallel to a single MPPT controller as opposed to two separate charging systems (solar --> mppt --> battery bank & alternator --> dc-dc battery charger --> battery bank).
I would be concerned about the complexity of the system (but this is partially because I don't have the depth of knowledge to be comfortable with more complexity). Do you think your system introduces more points of failure or complexity to your vehicles electrical system, or is my concern unwarranted?
I would love to see you build this system. I love seeing people innovating and designing interesting systems like this, and this forum could benefit from more projects like this, and more first hand knowledge! Good luck