Electrical questions

[jimbo69ny]

I need help understanding/designing my future electrical system in my teardrop.

I have a one of a kind build happening. I am building a range extending teardrop for my EV. (Check out and subscribe to my youtube channel for more info. http://www.youtube.com/jimbo69ny No one in the world has ever attempted this before.

I need a some help with my electrical system ironically enough. lol Because I have an EV, I need to save as much weight as possible. I need to get this right. I will be pulling around a 1330lb lithium ion Tesla 85kwh battery pack with a foamie on top. I am looking for an electrical solution to use my 300-400 v DC battery to power lights, usb plugs, and AC plugs. I have a lot of experience with 12v car audio/video and quite a bit with 120v/240v home but none with inverters.

I know this isn't a normal topic here but there has to be an electrical engineer in here somewhere.

As far as I can tell I need a powerful DC to DC converter as opposed to a large 12v battery bank correct? I already have a large battery, I dont need an additional 12v battery bank right?
I have heard of people hacking the Prius DC to DC converter but I haven't researched it yet.


I cant imagine I would have a very high draw. I will have lights, my wife and I need a coffee maker, and I will have a ceramic heater for the winter.
Is there a 300-400v DC to 120/240 AC converter that you would recommend?
The inverter could be liquid or air cooled, either way I would make it work.

[friz]

I would try to find an industirial transformer to take the the 400vdc to 12vdc and use an automotive inverter to get your 110vac from 12v. Your battery pack will be bunch of smaller packs connected in series so depending on where you tap your pack, you could have many different voltages available.

Sent from my SM-G930V using Tapatalk

[M C Toyer]

No electrical expertise here but a question. Will the teardrop be primarily for covering / disguising your auxiliary battery or will you incorporate sleeping, galley and cargo functions?

[jimbo69ny]

No electrical expertise here but a question. Will the teardrop be primarily for covering / disguising your auxiliary battery or will you incorporate sleeping, galley and cargo functions?

Sleeping, galley and cargo too

[GTS225]

Friz's transformer idea won't work, as you're working with DC. Transformers are dependent on internal fluctuating magnetic fields to converter one energy level to a different energy level.

You want to go from high voltage DC, to 120 or 240 AC. I know of no convertor for that, but I haven't researched it, either. Seems to me that if you can find a convertor to do that, it's a simple task to then pull off your new AC circuit with a 120VAC-to-12VDC power supply for your tear's low voltage circuits.

What you're going to need is some kind of electronics package to do the job, or a resistor network.

A resistor network is going to take up real estate, though, and would require a cooling medium of some type. Even then, it'll only get you to a lower DC voltage. You would then need a converter to get back to a 120VAC level for those circuits.

I suppose that opens up the opportunity to use the heat from the resistor network to heat the camper, though.

But, you also said; "I have heard of people hacking the Prius DC to DC converter but I haven't researched it yet."
I don't know how Toyota does it, but you should already have a 12VDC supply coming out of the Prius's system. I have no idea how much current it's capable of, but if you could find that out, you may have enough power reserve to run cables back to the tear, and then use a moderate-sized converter for your 120VAC needs.

Personal observation; Seems to me that the electrical hookup from TV-to-tear is going to be expensive, what with having to supply the TV from the "extra" battery bank in the tear.
Now, how long does it take to recharge a Prius, and how much additional time will be required if your really tax both battery banks on an extended drive?

Roger

[tony.latham]

I cant imagine I would have a very high draw. I will have lights, my wife and I need a coffee maker, and I will have a ceramic heater ...

Keep in mind, in most of our world.... the 12V crowd... the coffee maker and especially the heater (with an inverter) is a huge draw.

Tony

[friz]

Friz's transformer idea won't work, as you're working with DC. Transformers are dependent on internal fluctuating magnetic fields to converter one energy level to a different energy level.

You want to go from high voltage DC, to 120 or 240 AC. I know of no convertor for that, but I haven't researched it, either. Seems to me that if you can find a convertor to do that, it's a simple task to then pull off your new AC circuit with a 120VAC-to-12VDC power supply for your tear's low voltage circuits.

What you're going to need is some kind of electronics package to do the job, or a resistor network.

A resistor network is going to take up real estate, though, and would require a cooling medium of some type. Even then, it'll only get you to a lower DC voltage. You would then need a converter to get back to a 120VAC level for those circuits.

I suppose that opens up the opportunity to use the heat from the resistor network to heat the camper, though.

But, you also said; "I have heard of people hacking the Prius DC to DC converter but I haven't researched it yet."
I don't know how Toyota does it, but you should already have a 12VDC supply coming out of the Prius's system. I have no idea how much current it's capable of, but if you could find that out, you may have enough power reserve to run cables back to the tear, and then use a moderate-sized converter for your 120VAC needs.

Personal observation; Seems to me that the electrical hookup from TV-to-tear is going to be expensive, what with having to supply the TV from the "extra" battery bank in the tear.
Now, how long does it take to recharge a Prius, and how much additional time will be required if your really tax both battery banks on an extended drive?

Roger

True. My terminology may have been off. To do this you would need to modulate the dc going in and smooth it out coming out. Not outside the realm of possibility. I think these "converters" do exist. Tapping 12v straight out of the pack would be optimal.

Sent from my SM-G930V using Tapatalk

[MtnDon]

Tesla cars incorporate a converter to keep the on board 12 volt battery charged from the high voltage pack. Maybe look into that

[jimbo69ny]

Ok I found these. http://store.evtv.me/products.php?cat=19
As long as I pick one of the units with my input voltage I’ll be fine.

Another question, how much power do I need?
Do you guys have some 12v fridges that you recommend?
Know of an electric hot plate for cooking?
12v coffee maker?
Any other appliances you guys use?

I can’t think of what else I would really need to power. I’d like ac outlets so I’d need a 12v to 110v inverter. I’ll have to keep looking to see if I can get a 400v dc to 240v ac converter. It seems like that would be better than going down to 12v then back up to 110v. Anyone know which way is most efficient?

[tony.latham]

Know of an electric hot plate for cooking?
12v coffee maker?
Any other appliances you guys use?

Gas.

Tony

[MtnDon]

Truck fridge
https://www.truckfridge.com/all-models/
We have the large one

[jimbo69ny]

Truck fridge
https://www.truckfridge.com/all-models/
We have the large one

12v? How well does yours work? Can you freeze water?

[MtnDon]

Yes, 12 VDC. Yes, it can make ice; came with a small cube tray. The freezer section is kinda small, but the fridge works very well.

[jimbo69ny]

Yes, 12 VDC. Yes, it can make ice; came with a small cube tray. The freezer section is kinda small, but the fridge works very well.

Cool thanks! Sounds like a winner.

[MtnDon]

I have not been able to watch the video yet (low bandwidth 3G is all I have till I get back home). But I am very curious about whether or not, and how, you are going to use the heating/cooling system for the Tesla pack?