Charging an EV /w an off-grid solar panel set up?

lolcashcow
lolcashcow Solar Expert Posts: 118 ✭✭
Hi guys,

Just been wondering about something. Would it be possible to charge an all electric vehicle with a set of solar panels/deep cycle batteries/power inverter? I don't mean with a solar panel home set up rather... going camping and bringing your gear with you! Think of it as an RV set up for off grid living, but with out mounting the solar panels on top of the all electric vehicle (Because they are all too small ATM).

Eventually Nissan will release their all electric E-NV200 Small Cargo Van in the usa and I think this would be the best choice.

This should be possible? As I understand it you charge the vehicle at home with the electric power of the grid. You can have a lv2 charger installed to charge it at home. However! I believe that all electric vehicles also come with a 3? prong connector to plug it directly to a regular wall outlet. I believe this is called lv1 charging. Of course, the 3 prong lv1 charges much slower than lv2. At least according to the quote I found online:

http://www.evtown.org/about-ev-town/ev-charging/charging-levels.html

and also

"Electric cars are charged on 3 types of charging stations: Level 1 (110 volt); Level 2 (208/240 volt); or Level 3 (400+ volt = CHAdeMO / DC Combo / Tesla Supercharger). Amperage of charging stations also varies. The higher the volts and amps, the quicker the charge time. The on-board charger in your EV also determines charge time. The Rav4 EV has a 10 kW on-board charger – it accepts up to 10 kWh per hour. "

"Most Level 2 public chargers can add up to 20 miles of range per hour to the Rav4 EV battery. Four hours on the Level 2 chargers at my workplace provides 80 miles of range – more than enough for our daily needs. Overnight Level 2 charging at home, when electricity rates are often cheaper, is more than enough time to fully charge the battery."

"I bought an affordable Level 2 charging station (240 volt, 20 amp = 4.8 kW) that plugs into our dryer outlet and we charge our car in the garage or outside on the driveway. "

"Nissan, BMW, Chevy and others now sell EVs with Level 3 charging ports. Both Tesla and Nissan offer free charging on Level 3 chargers."

https://transportevolved.com/2014/05/30/one-year-life-electric-car-part-2-3/


"Level 1 Charging - Standard house outlet


Level 1 charging is the technical jargon for plugging your car into an ordinary household outlet. For a Leaf, this means about 4.5 miles of range per hour of charging, or about 22 hours for a full charge."

http://www.pluginamerica.org/drivers-seat/understanding-electric-vehicle-charging

So it looks like Lv1 charging ranges from 120V 12A to 120V 16A. That looks to be a requirement of 1440watts to 1920watts per hour.

http://www.l1powerpost.com/blogging/the-case-for-level-1-part-3-calculating-the-cost-and-time-to-charge-electric-vehicles/

Due to the current size of the EVs on the market I would not be able to carry with me 1440 watts worth of solar panels, but batteries tend to be much smaller and compact. RAV4 EV seems to be the largest so far it is a MINI SUV. Going past that though, with a small electric cargo van If I were at camp I would be able to charge batteries across several days. So I think it would be possible to carry a pair, or more if required, of solar panels with me. Though I wonder how many batteries I'd have to bring for it work? My guess is at least twice the amount of watts required per hour to not drain the batteries past 50%?

The RAV4 is pretty small (Mini SUV) so my thoughts is that something like this would work best with the Nissan E-NV200 (Small Cargo Van). To get the best charging with the panels I was thinking on mounting them on a type of dolly like set up for ease of moving/tilting for sun angle. Batteries / power inverter could be set up behind the pannels so they could ride along and be connected at all times. The thought of not ever paying for gasoline or electricity sounds too good to be true!

Any thoughts? :(
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    In theory it would be possible to "bring your charging station with you".
    It'd be somewhat impractical considering how much power you need to produce to charge the EV, though.
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    I would agree, not really practical. The ESEV that comes with the Chevy Volt is a minimum of 8 amps @ 120V, That takes about 13-15 hours to charge the car.

    On that car your could in theory use a generator, but why? The built in gas engine and its generator are much more efficient.
  • lolcashcow
    lolcashcow Solar Expert Posts: 118 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    solar_dave wrote: »
    I would agree, not really practical. The ESEV that comes with the Chevy Volt is a minimum of 8 amps @ 120V, That takes about 13-15 hours to charge the car.

    On that car your could in theory use a generator, but why? The built in gas engine and its generator are much more efficient.

    Very true :), but how about if it was done for living off the grid? With out spending money on gasoline or electricity. This would be more practical if it was a more permanent set up? Like for a retired veteran living at a camp or someone who wishes to live in his or her car? It would be best for someone who has a set place to return to, right? What kind of battery bank would we be looking at for something like this? At least 1440 watts capacity? What about DC charging? i'm sure that is more complex, but the original out put of the panels is DC right? That also applies when it comes out of the batteries, yeah? It is the power inverter that chances it to AC, but would you need a special device to do DC charging in an EV?

    Thanks guys!

    Not really practical... but possible! So then you would be able to live with out having to pay electricity or gasoline and still ride a car... great!

    This idea would be more practical if you could use the batteries inside the EV? You would not have to carry an extra set, so you'd only have to worry about the solar panels. What do you guys think??

    120v * 8A = 960watt. Much more manageable than 1440watts. Sure wish that was also an option for the E-NV200, but no one knows when it will be release in the USA.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Except for a couple of things like off-grid power costs a fortune compared to utility power, and that 960 Watts for the 8 Amp 120 VAC charger would need about 1250 Watts of PV to generate it at peak times which comes smack dab up against you can't get 15 hours charging out of daylight running.

    In other words that 960 Watts in the example is near continuous over 15 hours or 14,400 Watt hours AC. That is pretty large for off-grid, and that just for the car. So there you are building this huge and expensive OG system to save ... nothing, in fact.

    If the vehicle had a "direct DC" charging port that would improve efficiency significantly, but I wouldn't recommend anyone trying to hack into one.

    Solar just isn't very efficient. Especially not when compared to the energy density of those darn fossil fuels.
  • lolcashcow
    lolcashcow Solar Expert Posts: 118 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    Except for a couple of things like off-grid power costs a fortune compared to utility power, and that 960 Watts for the 8 Amp 120 VAC charger would need about 1250 Watts of PV to generate it at peak times which comes smack dab up against you can't get 15 hours charging out of daylight running.

    In other words that 960 Watts in the example is near continuous over 15 hours or 14,400 Watt hours AC. That is pretty large for off-grid, and that just for the car. So there you are building this huge and expensive OG system to save ... nothing, in fact.

    If the vehicle had a "direct DC" charging port that would improve efficiency significantly, but I wouldn't recommend anyone trying to hack into one.

    Solar just isn't very efficient. Especially not when compared to the energy density of those darn fossil fuels.

    Oh right Solar Panels won't generate their full potential since weather conditions will always be changing. Good point! Therefore 960 would actually need 1250! Still better than 1440 which would need higher for the same reason.

    So some of these EV cars do have a DC charging port. What kind of issues would we have to go through if we were to use it? Would we have to get a special connector of sorts? It won't be as easy as plug and play would it?

    So all in all to make it more practical we'd need the car to have a small enough input (960watts), plus be able to use/charge the batties in the car so we do not have to buy any, and have a DC port for better convinience.
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    Oh right Solar Panels won't generate their full potential since weather conditions will always be changing. Good point! Therefore 960 would actually need 1250! Still better than 1440 which would need higher for the same reason.

    So some of these EV cars do have a DC charging port. What kind of issues would we have to go through if we were to use it? Would we have to get a special connector of sorts? It won't be as easy as plug and play would it?

    So all in all to make it more practical we'd need the car to have a small enough input (960watts), plus be able to use/charge the batties in the car so we do not have to buy any, and have a DC port for better convinience.

    This is where an ESEV comes into play. It is used to determine if the line is good and how much charging power is requested by the car. The DC plugs on some cars are there to provide a fast charge not a solar trickle by comparison. There is a guy who built a controller to take the opportunity loads (left over solar after his batteries are charged) and use it to charge his Volt off grid.

    http://www.coultersmithing.com/forums/viewtopic.php?f=48&t=571&p=3811&hilit=volt+charger#p3811

    The issues is that you have to be there and attached to the system when the extra power is available. He does have a sizable system as well.

    I use grid tie solar to charge both our Volts. My total electric bill so far this year is about $450 and only because I have to buy off peak power to run the AC units in this hot desert, prior to our solar system we would typically pay $4K to $5K annually. My TOU plan doesn't allow on-peak solar generation to commingle with off-peak loads.
  • lolcashcow
    lolcashcow Solar Expert Posts: 118 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    solar_dave wrote: »
    This is where an ESEV comes into play. It is used to determine if the line is good and how much charging power is requested by the car. The DC plugs on some cars are there to provide a fast charge not a solar trickle by comparison. There is a guy who built a controller to take the opportunity loads (left over solar after his batteries are charged) and use it to charge his Volt off grid.

    http://www.coultersmithing.com/forums/viewtopic.php?f=48&t=571&p=3811&hilit=volt+charger#p3811

    The issues is that you have to be there and attached to the system when the extra power is available. He does have a sizable system as well.

    I use grid tie solar to charge both our Volts. My total electric bill so far this year is about $450 and only because I have to buy off peak power to run the AC units in this hot desert, prior to our solar system we would typically pay $4K to $5K annually. My TOU plan doesn't allow on-peak solar generation to commingle with off-peak loads.

    Thank you for the information :). I went through the link and read on that man's project. It seems amazing and he must be really well versed in electronics/electricity. So it seems that trying to do a DC hack is out of my range, but would plugging the car for lv1 charging directly to a solar power inverter work? What kind of power inverter would I have to look into? higher than 1440 watts I suppose?
  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    So some of these EV cars do have a DC charging port. What kind of issues would we have to go through if we were to use it? Would we have to get a special connector of sorts? It won't be as easy as plug and play would it?
    Not really. You'd need:
    1) The connector. Prices I've seen are around $800 for the connector alone.
    2) A CAN bus controller to negotiate the connection. Needed to get the DC contacter to close.
    3) A DC/DC converter that takes some input DC and outputs ~400 volts DC for charging. (not really off the shelf) Would also need a peak power point tracking function to be efficient.

    But the larger problem that I see is that such a panel/controller has one purpose only - to slowly charge EV's at a campsite or something. So you either have to carry it (and thus carry a lot of weight) or you have to set it up semi-permanently and then not use it much. In other words you'd use it 1% of the time or something.

    That being said if you were camping somewhere for a long time and/or returning often you could consider a small 110VAC system with a stationary battery. You wouldn't need to charge continuously - you would charge only when the sun is out, and even then charge for only an hour or so at a time since you'd be drawing down the battery as well. It would be slow (and somewhat hard on the stationary battery) but would recharge the car with enough time, and it would have additional utility (i.e. power when you're not charging the car.)
  • lolcashcow
    lolcashcow Solar Expert Posts: 118 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    That being said if you were camping somewhere for a long time and/or returning often you could consider a small 110VAC system with a stationary battery. You wouldn't need to charge continuously - you would charge only when the sun is out, and even then charge for only an hour or so at a time since you'd be drawing down the battery as well. It would be slow (and somewhat hard on the stationary battery) but would recharge the car with enough time, and it would have additional utility (i.e. power when you're not charging the car.)

    Great that sounds like a more possible idea. Since the car draws out 1440w per hour at Lv1 what kind of battery capacity would I be looking into? How far down will we be drawing down the battery? I hear that less than 50% is a big no-no. Would it be possible to avoid that if an additional battery is used? What type of wattage in the solar panels will be needed for some minimal charging of tthe EV? For the leaf with Lv1 charging it was mentioned that 1 hour of charging gives you back 4.5 miles. This means it would be done best across a nice long camping trip. A couple of days of camping is always nice. Required items would be: Deep Cycle Battery?, Power Inverter, Solar Panel?

    "Level 1 charging is the technical jargon for plugging your car into an ordinary household outlet. For a Leaf, this means about 4.5 miles of range per hour of charging, or about 22 hours for a full charge. Wow, does that sound terrible! But there's a problem with thinking this way: you'll rarely need to do a full charge from flat empty to full. If you drive 40 miles per day and charge overnight, you'll be back to full in 9 hours. When you're sleeping, it doesn't matter if it takes one hour or 9 hours to charge."
  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    Not really practical... but possible! So then you would be able to live with out having to pay electricity or gasoline and still ride a car... great!

    Careful - that is how salesman hoodwink people about solar. Oh you WILL pay, only that payment is deferred 4 or 5 years, when you have to replace the solar batteries, which when all is said and done is about 10X more expensive than charging from the power company directly. The setup you are talking about with lvl1 charging would be huge.

    As a goof, I suppose one could build a simple solar system (panels, battery, inverter for lvl1 charging) to enable them to go 5 miles a day or so. For most, it is not practical, but a technical exercise that proves too expensive to start when taken to the real world. It is even more ridiculous in areas with low solar-insolation, especially in winter.
  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    Great that sounds like a more possible idea. Since the car draws out 1440w per hour at Lv1 what kind of battery capacity would I be looking into?

    OK. First off I would strongly recommend you going to the lowest charging rate you can. For a J1772 EVSE (the most common kind out there) you can cause it to back off to 6 amps at 120 volts, or about 720 watts. You'll need an "open source" EVSE that lets you change this, but they are not hard to come by. That reduces the size of inverter you need and reduces the load on the battery.

    From there I would do a standard load calculation for all your other loads, then make sure your battery was sized to handle them first. Let's assume you wind up with the "standard" GC2 batteries (golf cart batteries.) Two of them will give you 220 amp-hours at 12 volts, which is about 1kwhr usable (you don't want to regularly discharge MORE than 50%.) So on battery alone your car would charge for just over an hour.

    Now add C/10 worth of solar panels, which is a good rule of thumb based on battery size. That's about 300 watts worth of panels. Let's double it in this case to 600 watts because we assume we are going to be charging the car often. That's in the range where a MPPT charge controller starts to makes sense.

    You will also need some way of discontinuing charging when the battery is low. (Do NOT rely on the inverter LVD; they are not that accurate and really kill the battery.) A good charge controller provides an aux output that can be used for things like this, but the ones that do this are expensive. A Trace C40 might be a good alternative, used as a simple voltage controller. To disconnect the car you can either use a relay to shut off power or use the pilot signal in the EVSE to tell the car to stop charging.

    You'd need:
    1000 watt 12 volt inverter
    MPPT 12 volt charge controller
    2x GC2 batteries
    Open source EVSE
    Cabling/circuit protection
    On/off control
    When you're sleeping, it doesn't matter if it takes one hour or 9 hours to charge.
    Although in this case you won't be charging when you are sleeping (assuming you sleep at night of course.)
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Maybe the LVD on a cheap controller is unreliable, but the ones on good inverters work fine. There you're looking at $2,000 for the inverter.

    Is this project making any sense? Not in terms of economics it isn't.

    Especially not given the typical end-to-end efficiency of an OG system, which would likely come into play as most people would be charging their car at home overnight meaning all the power would have to be stored in and taken from batteries.

    Sounds like a government project.
  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    Is this project making any sense? Not in terms of economics it isn't.

    Definitely. But as a trick that would enable an EV to reach more distant campsites it might have some utility.
  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Depending on how many kwh/mile it uses you could be looking at spending some where around $300 to $400 worth of solar equipment per mile per day you want to support driving.
    And that's using grid tied. It gets a lot more expensive and less efficient when you start adding more batteries that don't belong to the vehicle its self to this equation.

    I think it would just be cheaper to get a gas guzzling pickup truck.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    Definitely. But as a trick that would enable an EV to reach more distant campsites it might have some utility.
    As in reach a more distant campsite that does not have grid or generator available and get back again :)
    SMA SB 3000, old BP panels.
  • lolcashcow
    lolcashcow Solar Expert Posts: 118 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    oil pan 4 wrote: »
    Depending on how many kwh/mile it uses you could be looking at spending some where around $300 to $400 worth of solar equipment per mile per day you want to support driving.
    And that's using grid tied. It gets a lot more expensive and less efficient when you start adding more batteries that don't belong to the vehicle its self to this equation.

    I think it would just be cheaper to get a gas guzzling pickup truck.

    If we could just use the batteries that are already in the car that could save some expenses. I believe the NV200 gas unit has 2 1000w outlets for use with tools and what not. You'd practically camp in the van!

    http://www.camper-van-fun.com/images/roof-tent227C.jpg

    Solar Panels out put DC originally, right? and the car can take in DC, but I believe the charge needs to be ridicously large. I believe it charges the vehicle in 38 minutes or so from empty to full.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    If we could just use the batteries that are already in the car that could save some expenses. I believe the NV200 gas unit has 2 1000w outlets for use with tools and what not. You'd practically camp in the van!

    http://www.camper-van-fun.com/images/roof-tent227C.jpg

    Solar Panels out put DC originally, right? and the car can take in DC, but I believe the charge needs to be ridicously large. I believe it charges the vehicle in 38 minutes or so from empty to full.

    Yes, hence my earlier comment about a direct DC charging port.

    Do not assume an accessory port will allow charging: there may be limitations to it. For example the EV battery pack being 290 Volts DC while the port is regulated 12 VDC. In other words, a one-way connection. Likewise with a 1 kW 120 VAC socket: it's an inverter powered from the battery and not meant to be a bi-directional connection.

    That 38 minute high-power charging connection is an example. Remember the 8 Amps over 15 hours? Re-arrange that to operate in 1/30th the time and you have 30X the current demand: 240 Amps! I realize I'm mixing numbers from different vehicles. The principal is the same however: if you want to replace X Amp hours over Y time then the rate Z changes somewhat proportionally. Shorter charge time demands higher current in other words.
  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    If we could just use the batteries that are already in the car that could save some expenses.
    Yes, that's ideal in some ways; a "port" that accepts a range of voltages from a solar array and directly charges the traction battery. However that would be a very large scale project, involving DC/DC design, CAN bus controllers, and an MPPT design. The parts are not available off the shelf.
  • lolcashcow
    lolcashcow Solar Expert Posts: 118 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    Yes, hence my earlier comment about a direct DC charging port.

    Do not assume an accessory port will allow charging: there may be limitations to it. For example the EV battery pack being 290 Volts DC while the port is regulated 12 VDC. In other words, a one-way connection. Likewise with a 1 kW 120 VAC socket: it's an inverter powered from the battery and not meant to be a bi-directional connection.

    That 38 minute high-power charging connection is an example. Remember the 8 Amps over 15 hours? Re-arrange that to operate in 1/30th the time and you have 30X the current demand: 240 Amps! I realize I'm mixing numbers from different vehicles. The principal is the same however: if you want to replace X Amp hours over Y time then the rate Z changes somewhat proportionally. Shorter charge time demands higher current in other words.

    Okay I see what you guys mean. DC is completely out of the picture because of the amount of power needed and complexity, but there is at least some hope with Lv1 Charging. Especially if the requirement per hour is dropped down to 720 watts per hour. Per bill von novak's post I will be looking at:

    - An "open source" EVSE that lets you change the out put on a J1772 EVSE to back off to 6 amps at 120 volts, or about 720 watts.
    - Do a standard load calculation for all other loads then make sure the battery bank is sized to handle them first.
    - For the EV alone 1 Kwh (1000watt) capacity would be the minimum; "standard" GC2 batteries (golf cart batteries.) 2 = 220 amp-hours at 12 volts.

    But... on the solar panel requirement I am a little confused. What is C/10? 600 watts seems like a good number, but would it not be best to boost that number at least over the required draw of the EV (720w)? That way the EV would not have to be phased in and out of charging every hour. It would just charge continously under the sun, right? Though, that also means carrying more solar panels.

    1000 watt 12 volt inverter
    MPPT 12 volt charge controller
    2x GC2 batteries
    Open source EVSE
    Cabling/circuit protection
    On/off control
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    But... on the solar panel requirement I am a little confused. What is C/10? 600 watts seems like a good number, but would it not be best to boost that number at least over the required draw of the EV (720w)? That way the EV would not have to be phased in and out of charging every hour. It would just charge continously under the sun, right? Though, that also means carrying more solar panels.
    If you have a battery pack with a capacity at the 20 hour rate of C (or C20) of 240AH, then C/10 would be 240AH/10H = 24A.
    For a 12V battery bank, 24A will be close to 288 watts on the DC side of the inverter.
    For a 24V battery bank, 24A would be 576W, etc.

    The use of C/10, C/12, C/8, etc. for charge and discharge rates lets us use one description which can be applied to any size or voltage battery bank.

    Floating Lead Acid (FLA) batteries like your GCs need a minimum charge rate of C/12 to stir the electrolyte, and a maximum of C/8 to avoid plate damage. (All during the Bulk stage and the start of Absorb).
    AGM batteries can take higher charging current, usually C/4, sometimes greater depending on the manufacturer's recommendations and how well you monitor battery temperature, etc. during the process.

    On the discharge side, AGM can again work with higher rates, up to C/4 or more on a long term basis with surge currents of C or higher.
    FLA, on the other hand, will droop badly in voltage and capacity with rates above C/8.
    SMA SB 3000, old BP panels.
  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Inetdog
    So for an 48 volt 800 anp hour battery c10 would be 80 amps and c8 would be 100 amps? So a lower c# means higher charge rate? If I have it right thanks for the explination cause I have always been confused.
    gww
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    lolcashcow wrote: »
    Okay I see what you guys mean. DC is completely out of the picture because of the amount of power needed and complexity, but there is at least some hope with Lv1 Charging. Especially if the requirement per hour is dropped down to 720 watts per hour. Per bill von novak's post I will be looking at:

    - An "open source" EVSE that lets you change the out put on a J1772 EVSE to back off to 6 amps at 120 volts, or about 720 watts.
    - Do a standard load calculation for all other loads then make sure the battery bank is sized to handle them first.
    - For the EV alone 1 Kwh (1000watt) capacity would be the minimum; "standard" GC2 batteries (golf cart batteries.) 2 = 220 amp-hours at 12 volts.

    But... on the solar panel requirement I am a little confused. What is C/10? 600 watts seems like a good number, but would it not be best to boost that number at least over the required draw of the EV (720w)? That way the EV would not have to be phased in and out of charging every hour. It would just charge continuously under the sun, right? Though, that also means carrying more solar panels.

    1000 watt 12 volt inverter
    MPPT 12 volt charge controller
    2x GC2 batteries
    Open source EVSE
    Cabling/circuit protection
    On/off control

    OK again the problem with 6 amp charge rate is the 15 hours of time, your solar will only produce power about 4 hours of sun equivalent time per day. The reference I made previously to DCFusor is an opportunity load. He uses an L2 ESEV and it will charge his Volt in a few hours assuming he has the excess power from his Solar system after the house batteries are charged. The key to charging off solar would be to have enough input over a short enough time.
  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    gww1 wrote: »
    Inetdog
    So for an 48 volt 800 anp hour battery c10 would be 80 amps and c8 would be 100 amps? So a lower c# means higher charge rate? If I have it right thanks for the explination cause I have always been confused.
    gww

    Your C number, when you are not talking about the speed of light is your number of amp hours.
    So if you have a 100ah battery and you charge it at 100 amps that is a 1C rate. If you take the same bank and charge it with 200 amps that is a 2C rate. If you only have a 50 amp charger then you are charging your bank at 0.5C. Same thing goes for discharge, if you are using say 90 amps from your battery you are discharging it at a 0.9C rate.
    Not this is actual amps going to the battery, not the lies printed on or in the battery charger its self or in the owners manual.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Oil pan
    Your 1c looks the same as ineidogs c/20 for an 800 amp hour 20 hour rate battery. Now I am really confused. The c/5 type term is what I see here mostly.
    gww
  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Ok c/20 would be 40 amps on an 800 ah battery? 1c would be 800 amps on an 800 amp hour battery?
    gww
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    It depends on which way you express the math.

    Capacity divided by number: C/10
    Capacity multiplied by number: 0.1C

    The result is the same current rate and can also be expressed as a percentage to reduce (or perhaps increase) confusion: 10%.
  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    I understand percentages, Therefore I understand some of the post here. was the examples I gave in my very last post correct? if so I understand better then I did.
    Thanks
    gww
  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    If I am charging an 800 ah battery at 12.5% that would be 100 amp charge rate so .125c and c/8?

    gww
  • gww1
    gww1 Solar Expert Posts: 963 ✭✭
    Re: Charging an EV /w an off-grid solar panel set up?

    Thanks every one. The caculator says I am on to something.
    gww
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charging an EV /w an off-grid solar panel set up?
    gww1 wrote: »
    Ok c/20 would be 40 amps on an 800 ah battery? 1c would be 800 amps on an 800 amp hour battery?
    gww

    This is correct.
    800 Amp hours divided by 20 equals 40 Amps.
    800 Amp hours times 1 equals 800 Amps.

    Normally you'd see C/20 or 0.2C or 20% for the first example.
    Not likely you'd ever see the second as there are very few batteries that could take that much current rate.