High voltage off grid

davidwillis · February 2014

I am planning on converting my vehicle to be an electric vehicle, however I would also like to use the car for a battery backup for my house, since it will be able to store a lot of power in it (about 40 kwh). However it will be at about 200VDC. I don't see off grid inverters that go over 48v. So my questions are.

1- are there any inverters that will run off 200VDC input

2- if not, is it best to have some dc disconnects to rearrange the batteries to be 48VDC, or use a DC to DC converter to drop the voltage down to 48 volts, then use an inverter.

This would only be used for backup power when the grid is down. I would be able to charge the batteries using the charger in the car, and my solar panels that currently go to my grid tie inverter. But the grid tie inverter won't work with the power out, so I need a second inverter to use as backup power. I only need about a 2kw inverter.

Thanks
David

peakbagger · February 2014

Re: High voltage off grid

There is an individual this forum that uses a industrial UPS which is rated for a high voltage series input from his prius. If you do some searching I expect you will find his rather informative posts.

Cariboocoot · February 2014

Re: High voltage off grid

I think this is the thread you want to look at: http://forum.solar-electric.com/showthread.php?12962-Using-a-Prius-as-a-generator

techntrek · February 2014

Re: High voltage off grid

That would be me. See the link in my signature. APC SURT3000, SURT5000, and SURT6000 use a nominal DC voltage of 192 volts. These require also buying a transformer to get 120/240 split-phase and the SURT003 works well for this. You can get the UPS and transformer for about $250 each if you search carefully. These can be cold/black started from the battery without AC input.

There is also the Toshiba 1600EP and 1600XP (also found under the Alpha brand name and one other) with nominal voltages of 216 volts. They have built-in transformers which makes them much heavier but you don't have to hunt down a separate transformer. Toshiba groups models with varying specs under the one model number so you must be careful to look at the kVA capacity to get the right ones. The 3.6 and 6 kVA versions have the nominal DC voltage of 216 volts, with an alarm at 192 and shutdown at 170. A downside to the Toshiba line is they can't be cold/black started from the battery - you need AC input first.

One more option is the AIMS Prius 2kw PSW inverter, which can be found on ebay for just under $400.

davidwillis · February 2014

Re: High voltage off grid

Thanks, that is perfect. I will have to read over the details, but the first option looks perfect.

bill von novak · February 2014

Re: High voltage off grid

davidwillis wrote: »

1- are there any inverters that will run off 200VDC input

Here's the one I used for a Prius conversion:

http://www.ebay.com/itm/AIMS-Prius-2kW-Pure-Sine-Wave-Inverter-for-Backup-Power-Generator-/200841111789

180-260 volts in, 2kW nominal, 4kW surge.

mike95490 · February 2014

Re: High voltage off grid

bill von novak wrote: »

Here's the one I used for a Prius conversion:
http://www.ebay.com/itm/AIMS-Prius-2kW-Pure-Sine-Wave-Inverter-for-Backup-Power-Generator-/200841111789
180-260 volts in, 2kW nominal, 4kW surge.

Slick, but without a Prius, what would one charge the batteries with ?

davidwillis · February 2014

Re: High voltage off grid

I plan on using the emw 12000 watt charger. It will take AC or DC voltage, so I can charge with 110/220, or my DC solar panels. Normally I will just charge with 220VAC, but when the power goes out, I can just plug my panels into the charger. However with 40 KWH, it will last days without even charging. But if the power is out for a few days, and it is cloudy, I could always plug in a portable generator to charge them back up.

bill von novak · February 2014

Re: High voltage off grid

mike95490 wrote: »

Slick, but without a Prius, what would one charge the batteries with ?

My first choice would be a Manzanita Micro charger (20 amps at 200 volts.) It's a very versatile charger, but it's pricey. However there are a lot of other EV chargers out there that will work.

techntrek · February 2014

Re: High voltage off grid

Yup, definitely don't want to rely on the built-in chargers in the UPSs, they are designed for much smaller batteries.

davidwillis · February 2014

Re: High voltage off grid

I couldn't find the APC setup, I think it may be easier to just use the AIMS Prius 2kw PSW inverter.

BTW, you can get a kit to build an emw 12000, but if you buy it all built, it is about $2300 for the pfc version. It is pricy, but will do 12kw of charging if you can supply that much....

mike95490 · February 2014

Re: High voltage off grid

Will any of the EV chargers, run off PV. OR would I need to invert it to 240VAC, then feed that to the charger. Any chargers have a internal HV DC buss that PV could feed directly? (and then collapse the voltage as the charger ramps up past the IV curve....)

davidwillis · February 2014

Re: High voltage off grid

I am not sure about all the chargers, but the one I have been looking at will take a DC input.

Specs

Input voltages:

240VAC or 110VAC for the non-PFC version
90-260VAC for the PFC version (output power automatically limited to ~1.5kW if connected to 110VAC)
Both non-PFC and PFC units can be used to charge your battery from a DC source. This feature can be used to charge one EV from another, to use the charger with a separate rectifier (e.g., for 3-phase operation), charger your EV from your solar array / stationary battery, etc.
Non-PFC units can be used with DC input above the voltage of the battery being charged (up to ~400 VDC)
PFC units can be used with any DC source ~100-400VDC
Output voltage

Field - programmable - use simple button-LCD interface to change parameters at ANY time - see our videos below for examples
~20-250VDC (non-PFC version)
~20-350VDC (PFC version; upgradeable to 450VDC with simple modifications; up to 800V possible with more significant mods)
Output current:

Up to 70A continuous
100A option offered for low-voltage outputs
Output power:

12kW rated
Tested to 15kW in our labs
Efficiency at full power:

95%+ for non-PFC version (offset by higher losses in AC wires, however)
93%+ for PFC version
Switching frequency:

22kHz (PFC stage)
15-20kHz (buck output stage)
Control methods:

Manual - charger can be programmed for any input / output current / voltage at any time in field - no need to do any factory setting!
Automatic:
J1772 support with automatic power regulation (charger reads and interprets the J1772 pilot signal & limits max power draw to the one suggested by the EVSE)
NEW [August 2013]: Serial control now available for fully automatic operation. Multiple chargers can be run in parallel, controlled by one simple head unit. Work ongoing on CAN-to-Serial conversion to enable full CAN-driven operation. Let us know if you can help!
Additional features:

BMS stop-charge TTL input
End-of-Charge TTL output
Hardware current limiting
Thermal output derating above 55C heatsink temperature
Inductor temperature sensing
Flexible battery settings: set your battery type (Li, NiXX are currently available), number of batteries, capacity through a simple-to-use interface

davidwillis · September 2015

So I have been using the Aims Prius inverter and it has been working great. However now I have an application where I would like to use something for a 120VDC input. Does anyone know of anything that will convert 120VCD to 120VAC?

Thanks

MarkC · September 2015

davidwillis said:

So I have been using the Aims Prius inverter and it has been working great. However now I have an application where I would like to use something for a 120VDC input. Does anyone know of anything that will convert 120VCD to 120VAC?

Thanks

The APC SMX3000RMLV2UNC is a line-interactive UPS that uses nominal 120 volt DC input for the inverter section. Pricey!
BTW, do you know of any supplier of a high voltage (DC), mppt charge controller (200+ VDC)?

davidwillis · September 2015

Wow, those are pricey!...

I plan on using two 60VDC charge controllers, and charge half of the bank with each one.

MarkC · September 2015

Midnite made a MPPT style 120VDC CC for a short while - I wonder if 2 stacked could charge up to 240 VDC? which, in theory, could charge a Gen 1 and 2 Prius battery directly from solar - with proper charge profiles AND efficient use of PV panels. Hard to find any of these! For your application, it might be the answer for the CC side of things. Can U tell me more about your "battery" set up as I have a partially functioning, but workable SMX3000 (the display is out, but can be controlled by the network card). I've considered going to it for off-grid as it is very efficient.

davidwillis · September 2015

My battery setup is not very complicated. I just have 10 batteries in series. It is more of an experimental thing right now. But It will just be an emergency backup that I can use to run a 120VAC cooktop stove and a few 120VAC appliances that will run off DC. The reason for this is that is is very simple (less things to fail), and EMP Proof (I can just have a couple cheap charge controllers safely protected). It is also more efficient than using an inverter to run AC. But I was thinking it would be nice to have an inverter to run a few things like a microwave. But it is not worth the price of the smx3000.

I will use two of these for the charge controllers: http://www.ebay.com/itm/141719192969?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

They are really the only thing that can fail, so I will have some backups of them

Photowhit · September 2015

High voltage DC is very dangerous, What type of 40 KWh battery will you have? 40 Kwh lead acid would be in the 2.5 - 4000 lb range. Lithium might bet getting close to 1000 lbs...

davidwillis · September 2015

No, this is small.... My 40kw was for my electric car (lithium). This is just going to be 10 small batteries (8 amp hour). I will also put in a 10 amp fuse, so it will shut down if it is shorted out. I am not really sure if DC is that more dangerous than AC (both are dangerous). It will arc more that is for sure though, but a fuse should stop that before it burns too much...? To bad I can't find a cheap Inverter that will run off 120VDC.

thanks
David

inetdog · September 2015

Your best bet for an inverter that take that high a DC voltage would be the one in a commercial UPS.

The fuse will stop the DC arc as long as the fuse itself has a DC voltage rating that is high enough. The AC rating of a fuse assumes that the arc from the fuse melting will stop when the AC current passes through zero. In some cases the fuse holder cannot withstand a high DC voltage either.

vtmaps · September 2015

davidwillis said:

It will arc more that is for sure though, but a fuse should stop that before it burns too much...?

That is wrong. An arc can be sustained at currents that are well within the ratings of the OCPD (OverCurrentProtectionDevice=fuse or circuit breaker) and of the wire. A classic example is arcing that occurs in a loose connection. These types of arcs are called 'series' arcs.

You are probably thinking of 'parallel' arc faults, such as (for example) a hot wire being shorted to ground. The current in these types of faults MAY be exceed and trip the OCPD. But you can't count on that... the arc may be sustained at low current levels.

The reason that building codes now require arc fault protection devices is because OCPD do not protect against arc faults.

--vtMaps

inetdog · September 2015

deleted

inetdog · September 2015

There is some heated discussion about what voltage is required to sustain a series arc, as opposed to an intermittent sparking contact. (The discussion is at its heaviest when arguing whether AC Arc Fault Circuit Interrupters (AFCIs) perform any useful function in a US residential setting.)

The value will as many welders know, be different between DC and AC since the DC arc does not have to re-ignite 120 times per second at the working electrode spacing

PS: A sparking contact such as vtMaps describes will usually go one of two ways:
1. Enough metal is removed to open the circuit permanently, hopefully before a fire starts.
2. The repeated sparking resolves into a steady high resistance metallic connection called a glowing connection This is what most often starts fires and cannot be detected by either overcurrent devices or AFCIs.

MarkC · October 2015

davidwillis said:

My battery setup is not very complicated. I just have 10 batteries in series. It is more of an experimental thing right now. But It will just be an emergency backup that I can use to run a 120VAC cooktop stove and a few 120VAC appliances that will run off DC. The reason for this is that is is very simple (less things to fail), and EMP Proof (I can just have a couple cheap charge controllers safely protected). It is also more efficient than using an inverter to run AC. But I was thinking it would be nice to have an inverter to run a few things like a microwave. But it is not worth the price of the smx3000.

Have you looked into the 48 volt based APC UPSs? FLA or AGM batteries are easily configured and a wide option of AH availability at the lowest of initial costs. One cheap PWM CC might suffice for your "experiments". I actually have several UPSs available in 750 to 5000 VA ranges - all at 48 volt DC. I know that they are not the most efficient, but low cost and extremely reliable. Plus with a network card, you can log all "experimental" data that you want. I've had great experience with this set up to run two ceiling fans, a mid sized refrigerator, big screen TV and sound system, plus a few lights for 10-12 hours off my golf cart deep cycle batteries (2 sets). I've thought about using the 10 series set up with a SMX3000 UPS because it is so efficient, but worried about that many FLA's in series - plus the high DC voltage involved.

davidwillis · October 2015

48V could be done, but since I will have 10 batteries, it would be easier to have a 60V input, and use half the bank. Do you know of any that will work of a 60V input?

MarkC said:

davidwillis said:

My battery setup is not very complicated. I just have 10 batteries in series. It is more of an experimental thing right now. But It will just be an emergency backup that I can use to run a 120VAC cooktop stove and a few 120VAC appliances that will run off DC. The reason for this is that is is very simple (less things to fail), and EMP Proof (I can just have a couple cheap charge controllers safely protected). It is also more efficient than using an inverter to run AC. But I was thinking it would be nice to have an inverter to run a few things like a microwave. But it is not worth the price of the smx3000.

Have you looked into the 48 volt based APC UPSs? FLA or AGM batteries are easily configured and a wide option of AH availability at the lowest of initial costs. One cheap PWM CC might suffice for your "experiments". I actually have several UPSs available in 750 to 5000 VA ranges - all at 48 volt DC. I know that they are not the most efficient, but low cost and extremely reliable. Plus with a network card, you can log all "experimental" data that you want. I've had great experience with this set up to run two ceiling fans, a mid sized refrigerator, big screen TV and sound system, plus a few lights for 10-12 hours off my golf cart deep cycle batteries (2 sets). I've thought about using the 10 series set up with a SMX3000 UPS because it is so efficient, but worried about that many FLA's in series - plus the high DC voltage involved.

MarkC · October 2015

Most of the 1500 VA and above APC UPSs use 48V DC in the SU, SUA and SMX lines. The SMX3000 and the SURT lines use higher voltages (120 and 196 respectively). Can you parallel/series 8 of them for 48 volts - keep 2 available as spares? Just remember the internal battery chargers only work consistently with the original specified batteries for these units. You will have to ignore the battery charge LEDs and turn off the warning beeps!

bill von novak · October 2015

davidwillis said:

48V could be done, but since I will have 10 batteries, it would be easier to have a 60V input, and use half the bank. Do you know of any that will work of a 60V input?

The Outback 48V FX line will work up to 68 volts but you'd have to disconnect the inverter and use a separate charger to charge the batteries fully. The onboard charger will only take a 60 volt pack to about 2.25 volts per cell which isn't enough for absorb,

High voltage off grid

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