High voltage charge controller?

WisJimWisJim Solar Expert Posts: 59 ✭✭✭
I am looking for a high voltage charge controller, to use when charging a 120 volt or 144 volt battery in my electric car conversion. It currently has a 120 volt AGM battery and when the time comes to replace the battery in a few years I may go with a higher voltage, probably 144 volts. I would like to charge it directly from my PV panels. I drive mostly early morning and late afternoon, so the car is home and parked most days from 7:30 am to 2:30 pm. Currently I am charging it from 5 PV panels through a diode, and it works well, as the current is low and drops off as the voltage rises during the charge. But it would be nice to use more PVs, and then I would want to go with a more sophisticated system. The MidNite Solar Classic 250KS seems to fit the bill with the current 120 volt battery, although 150 volts is a bit low for equalization of the batteries, and I would like to find something similar suitable for a 144 volt battery, preferably with lots of adjustment in the charging criteria to allow consideration of lithium batteries for the car in a few years.

Any ideas?

Thanks!

Jim, in Western Wisconsin
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Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: High voltage charge controller?

    take a look at this classic model's specs,
    the 250ks
    http://www.solar-electric.com/misocl25mpch.html

    the 144v battery may pose a problem, but it would handle your current 120v battery bank. beyond this i don't know of anything out there that would suffice.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: High voltage charge controller?
    WisJim wrote: »
    I am looking for a high voltage charge controller, to use when charging a 120 volt or 144 volt battery in my electric car conversion. ... I would like to find something similar suitable for a 144 volt battery, preferably with lots of adjustment in the charging criteria to allow consideration of lithium batteries for the car in a few years.

    Any ideas?

    Thanks!

    Jim, in Western Wisconsin
    The commercial plug-in EVs tend to use either custom chargers or CCs built into the vehicle itself that accept a standard input power source and convert it as needed. I do not think that you will find what you are looking for off the shelf. You might consider setting your battery bank up so that it can be charged in the form of two lower voltage halves. (Maybe in parallel, maybe sequentially).
    SMA SB 3000, old BP panels.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?
    inetdog wrote: »
    The commercial plug-in EVs tend to use either custom chargers or CCs built into the vehicle itself that accept a standard input power source and convert it as needed. I do not think that you will find what you are looking for off the shelf. You might consider setting your battery bank up so that it can be charged in the form of two lower voltage halves. (Maybe in parallel, maybe sequentially).

    If you do this, series connecting two (or more) controllers to run simultaneously, you must keep the negative and positive of each controller & array entirely separate. Many controllers have the negative as a pass-through and are sometimes connected to the casing as well. It would be all too easy to short out one controller by accidentally connecting (-) to (-).
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: High voltage charge controller?
    If you do this, series connecting two (or more) controllers to run simultaneously, you must keep the negative and positive of each controller & array entirely separate. Many controllers have the negative as a pass-through and are sometimes connected to the casing as well. It would be all too easy to short out one controller by accidentally connecting (-) to (-).

    Since it will not be used at the same time that the vehicle is moving (that idea has been very thoroughly debunked), I was thinking more of switching the two banks out of series, either into parallel or else connecting them to a single CC one at a time, for charging.
    The idea of trying to use two CCs did not even occur to me. Thanks for the warning.
    SMA SB 3000, old BP panels.
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: High voltage charge controller?

    I ran into the same problem looking for something that would charge @ 192 volts from PV. The only easy solution I found was charging each battery separately @ 12 volts, or four banks @ 48 volts. High voltage AC chargers are about impossible to find, too.

    I can give you one possible AC charging source which may help you. Some larger UPSs use high-voltage battery banks, like the one I have @ 192. They can be adjusted downward in a special programming mode. I've tested mine down to 180 and it could go lower. It does a proper 3-stage charge. Not a PV solution, but its an option.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • boBboB Solar Expert Posts: 1,008 ✭✭✭✭
    Re: High voltage charge controller?

    Using 2 controllers in series does work. Did that a lot with the MX60s for 120V banks. You really DO have to watch out
    and make sure that the two chassis grounds can handle the highest PV + to GND voltage. Remember that there are
    also (typically) MOVs from minus to chassis and PV plus to chassis that may not have a high enough voltage to handle
    both PV arrays in series which is what happens when the chassis grounds are tied together. We just had the customer
    clip the MOVs out to take care of that problem. So, it CAN work well if necessary if you do your homework.


    OK, so check out this PNW company that makes EV chargers.

    http://www.manzanitamicro.com/

    http://www.manzanitamicro.com/products?page=shop.browse&category_id=14&vmcchk=1

    The battery voltage range is certainly wide enough for almost anything you would need, (12 to 450 VDC) BUT, they don't take
    a solar PV input ! Darn !

    You could still use PV but would maybe need to do an AC coupling arrangement with something
    like an SMA Sunny Boy and battery based inverter to power these PFC chargers. At least they're Power
    Factor corrected. Rich Rudmand has been at this for many years now.

    boB
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: High voltage charge controller?

    I think that there is a key point in your description that is easy to overlook:
    Each CC must have its own panel bank, isolated from the other.
    Connecting two MPPT CCs to the same bank of cells has been discussed and advised against, even if you were not going to put the two CCs in series.
    SMA SB 3000, old BP panels.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?

    In this case it's "doubly so" for the reason boB mentioned.
    MidNite Classic controllers would probably work great for this. :D
  • MPaulHolmesMPaulHolmes Solar Expert Posts: 35 ✭✭
    Re: High voltage charge controller?

    I made a charge controller for just such emergencies. haha. Actually, I make open source motor controllers, and just finished a high side motor controller, which is then trivial to turn into a buck charger. It's just a small change in software. Lead Acid and Lithium are very similar in their charge profiles, and are actually very simple. But you would need a BMS for lithium. Once each battery gets to around 3.6v, the voltage skyrockets in a matter of minutes, and you are officially toasting your battery.

    Basically, you dump in any voltage you want up to a point. The PWM duty is set accordingly so that the current stays constant until the voltage reaches whatever point you want it to reach (programmable through the serial port), and then it holds the voltage constant until current feedback is whatever you want it to be, then the voltage drops down just a bit to officially be in float mode. I don't sell them, but I've built one, and it's pretty straight forward. You just solder the control board, driver board, and then bolt the power section to an aluminum plate.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: High voltage charge controller?

    K & W makes battery chargers for exactly this application. It is adjustable between 48 and 120Vdc for whatever you need.
    Talk to KTA services (909)949-7914 (I built my EV using them)
  • WisJimWisJim Solar Expert Posts: 59 ✭✭✭
    Re: High voltage charge controller?

    I think that a number of the replies have missed my point. As I mentioned in my initial question, Midnite makes a controller for up to a 120 volt battery, but I don't want to spend the money on one that I can't use in a few years when I replace my battery with something with a higher voltage. I have a good charger that I can use with a 120 or 240 volt AC input, put for me that means inverter inefficiencies to get that AC from my PV panels. I want to charge the 120to 144+ battery directly, or as directly as possible, from the PVs. A the moment, the voltage output of the array that I am using matches the battery charging requirements pretty well, but if I add more parallel strings, the current may be a bit much at the float voltage and I need more control over the charging voltage and current. I am not an electronics tech or hobbyist so if I make something, I need a detailed circuit and help with sourcing components.
    Thanks again!

    Jim
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?

    Jim;

    Frankly the problem is that there aren't any PV charge controllers for 144 Volt systems. Using three programmable MPPT controllers in series as mentioned before is the only "off the shelf" solution I can think of. When you're in this Voltage range it is not cheap or easy to deal with. It's also not very safe. I can't say I'd recommend trying a DIY approach to such a charge controller because of that.

    Maybe someone else has another idea.
  • MPaulHolmesMPaulHolmes Solar Expert Posts: 35 ✭✭
    Re: High voltage charge controller?

    A single 600volt 70amp ISOTOP mosfet is only around $40, the ISOTOP freewheel diode is $21, and the capacitor bank is around $35. You don't need much of an input filter cap for a DC input. The output cap and inductor are another $40 maybe. The control/driver components are about $60. The control board is $4 each. The aluminum baseplate is $25. That's good for anything from 0v up to 350v, 35amp continuous. It's not mppt, but if you choose your battery pack and solar array voltage correctly, you'll be really close to the peak power of the panels. The way I see it, if you have a 144v battery pack, it's not any more dangerous to charge it than it is to actually have it. I hadn't realized that there wasn't anything for this... We already have like 150 electric cars on the road using the motor controller. Maybe it would be worth making a high voltage DC input charger kit. The motor controller kit is just soldered by people, and then then stick it in their car and drive away:
    http://ecomodder.com/forum/open-revolt-open-source-dc-motor-controller.html

    EDIT: For mppt, could you keep adjusting duty up and down slightly, multiplying current feedback by dc bus voltage, and keep moving in the direction of higher product? Is the max power a single global max, which is decreasing on either side all the way to zero?
  • BB.BB. Super Moderators, Administrators Posts: 32,748 admin
    Re: High voltage charge controller?

    Yes--It would be interesting.

    Once the voltage goes over ~60 VDC max, most regulatory/safety agencies treat it all the same (unless you are talking about very small current and/or floating outputs).

    And once you are talking about battery banks over a couple hundred amp*hours (and in the 24 volt or higher range)--It is already pretty dangerous stuff (needing appropriate protective devices like fuses/breakers).

    When working with higher voltages and large battery banks--Now starting to worry about Arc Flash (i.e., ball of sun one foot in front of you) from shorts/arcs.

    I know nothing about Arc Flash ratings--And you probably have to buy the book or check it out from the library... But here is a short article that discusses the basic requirements a bit:

    http://etap.com/support/articles/electrical-line/arc-flash-hazard-tables.pdf

    It looks like they start requiring protective gear down in the 23.3kAmp area--Which is getting pretty close to what a largish battery bank can feed into a dead short.

    Have you worked with or read about folks with electric vehicles and Arc Flash issues? The modern vehicles usually seem to use a "higher" voltage system (200-300+ VDC?) and potentials of a few hundred amps or so...

    A largish home power system with a 600+ AH battery bank is probably capable of 6,000 to 12,000 amps or more.

    Here is another page about DC arc energy levels and length of time to get a second degree burn on exposed skin (600 VDC system--Not sure what it would be for lower voltages):

    http://www.arcadvisor.com/faq/dc_direct_current_arc.html

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: High voltage charge controller?
    EDIT: For mppt, could you keep adjusting duty up and down slightly, multiplying current feedback by dc bus voltage, and keep moving in the direction of higher product? Is the max power a single global max, which is decreasing on either side all the way to zero?

    For completely uniform panels, uniformly illuminated, there will be a single global maximum, with smoothly decreasing power to either side of it.
    But under some circumstances, such as with mismatched voltage panel strings in parallel, different types of panels, or partially shaded panels, there can be more than one maximum, separated by a valley. To find the true maximum in those conditions, the CC or Inverter has to do a full sweep (or at least sample points) all the way from one end to another of its MPPT voltage range. The tracker will not usually go all the way to zero power (Voc, I=0 and V=0, I=Isc.)
    SMA SB 3000, old BP panels.
  • MPaulHolmesMPaulHolmes Solar Expert Posts: 35 ✭✭
    Re: High voltage charge controller?

    To avoid arc flashes:

    Best practices for battery arrangement is important. You don't want terminals with large potential difference anywhere near each other. This, for example would be very bad:
    +-+-+-+-+-
    -+-+-+-+-+
    (Series string that starts at top left, and ENDS at bottom left)

    Also, you want a good high voltage fuse, and a contactor in the circuit.
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: High voltage charge controller?

    Actually the arrangement you describe is exactly what I have, intentionally. I have 4 battery boxes with a 192 volt potential in the left-most box, but only 48 volts in the right-most box where it loops back in the other direction. I did this so I can open up the right-most box with the "safe" 48 volts and disconnect the farthest + / - cable. Now all 4 boxes only have a maximum 24 volt potential.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • MPaulHolmesMPaulHolmes Solar Expert Posts: 35 ✭✭
    Re: High voltage charge controller?

    Oh ya, some anderson connectors to break up the pack in pieces before working on it is a really good idea. In EVs they generally frown on having high voltage points close together, since someone could drop a wrench in a bad spot. Actually, Plasma Boy(who drives the White Zombie, and got his name from dropping a wrench in a bad spot) melted his whole car in a giant plasma ball because he didn't do what you suggest, and had 350v or so of Odyssey Lead Acid batteries with the 350v separated by inches. It welded the wrench instantly to the posts. He almost died.
    In my EV I also had some connectors that I would pull before working on the pack. It would turn it into 36v chunks. My only point is that if someone wants to avoid shorting a high voltage pack, you can take a few precautions that makes dead shorts extremely improbable, since BB was worried about arc flashing.
  • t00lst00ls Solar Expert Posts: 239 ✭✭✭
    Re: High voltage charge controller?

    I dont know why someone hasnt mentioned the new xw cc mppt 80-600......surely 600 volt is enough
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?
    t00ls wrote: »
    I dont know why someone hasnt mentioned the new xw cc mppt 80-600......surely 600 volt is enough

    That's up to 600 Volts on the input. It won't charge a 144 Volt battery; only 48.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: High voltage charge controller?

    Ingeteam has an inverter/charger between 2-6kW that can handle up to 250V batteries. Lead acid, Ni-cd and Li-on. It uses an AC coupling topology, so it looks like you'll need their brand of grid tie inverters to feed it.... which could be expensive.
    Frustratingly little technical information available on their site beyond the spec sheets.

    http://www.ingeteam.com/EN/ProductsandServices/Energy/Photovoltaic/Products.aspx?TIPO=PTD&ITEMID=11693&IDIOMA=EN&PRT=SBP&PRTID=2
  • aarifaarif Banned Posts: 7
    Re: High voltage charge controller?

    Hi All,

    I'm actually in the similar situation. I'm trying to designing my first larger scale setup. This will be a 10kVa installation and I was hoping to design the battery bank around a 192v system....sadly, I've come to realize that indeed there aren't any controllers out there that could fit into such an application.

    So this makes me question, what are the larger high-kVa to MW installations using for control?

    The reason I want to design this at a higher 192v system is that its for a friend's building where only one floor is going to be 10kVa, and if it works out then he wants to expand it and it could potentially become 20-30kVa (yes there's enough roof space). So the other option is to go down to 120, but in the long run of expansion, it becomes inefficient....

    Any thoughts?
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: High voltage charge controller?
    aarif wrote: »
    So this makes me question, what are the larger high-kVa to MW installations using for control?

    These all use 48V batteries and high voltage grid tie inverters in an AC coupled setup:

    - 1MW system powering an entire (small) country: http://www.sma.de/en/press/current-news/news-details/news/3943-tokelau-becomes-the-worlds-first-100-solar-powered-country.html
    - 60kW: http://www.windandsun.co.uk/case-studies/islands/isle-of-eigg.aspx
    - 45kW: http://www.windandsun.co.uk/case-studies/islands/isle-of-rum.aspx
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?
    aarif wrote: »
    Hi All,

    I'm actually in the similar situation. I'm trying to designing my first larger scale setup. This will be a 10kVa installation and I was hoping to design the battery bank around a 192v system....sadly, I've come to realize that indeed there aren't any controllers out there that could fit into such an application.

    So this makes me question, what are the larger high-kVa to MW installations using for control?

    The reason I want to design this at a higher 192v system is that its for a friend's building where only one floor is going to be 10kVa, and if it works out then he wants to expand it and it could potentially become 20-30kVa (yes there's enough roof space). So the other option is to go down to 120, but in the long run of expansion, it becomes inefficient....

    Any thoughts?

    192 Volt battery bank to run what?
  • aarifaarif Banned Posts: 7
    Re: High voltage charge controller?
    192 Volt battery bank to run what?

    It's mainly just a floor of lights - tube lights mainly - but eventually going to put on all the computers/monitors and other miscellaneous machines found on the floor.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?
    aarif wrote: »
    It's mainly just a floor of lights - tube lights mainly - but eventually going to put on all the computers/monitors and other miscellaneous machines found on the floor.

    This was what I was wondering about: you're planning on power standard AC loads from a battery bank via an inverter?
    I'm not familiar with any inverters that run on 192 VDC.
  • aarifaarif Banned Posts: 7
    Re: High voltage charge controller?
    This was what I was wondering about: you're planning on power standard AC loads from a battery bank via an inverter?
    I'm not familiar with any inverters that run on 192 VDC.

    Yes exactly. The inverter isn't a big problem as finding an inverter that runs on voltages above 150 are fairly common to source in international markets (forgot to add that this installation is international), its just that darn controller that is being elusive. Also the safety factor for such a big bank does come into play, so I may just resort to 96V bank, and then use multiple controllers like the midnites....was just hoping for something else, haha.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: High voltage charge controller?

    aarif;

    Could you provide some links/sources for these high Voltage inverters? It's one of those things that has often sparked interest on the forum.
  • BB.BB. Super Moderators, Administrators Posts: 32,748 admin
    Re: High voltage charge controller?

    I have seen "high voltage" Inverters too--But they typically are larger units used as backup power in Computer Rooms. Not something that works well in our day to day off grid settings (from what I have seen).

    The Prius folks use them too.
    techntrek wrote: »
    I bought my inverter (a large UPS) 3 years ago specifically because it could run from the Prius' traction battery, but I ended up buying FLA's instead and never hooked it up to my wife's Prius. Fast-forward to this recent thread about doing the same thing with a Volt, which gave me the kick in the pants to finally try it. I need to buy a few parts first - O-ring lugs, washers, nuts - before I can dig in and make the connection to the battery, but my Saturday is looking wide-open so I hope to do it then.

    According to info from http://www.priups.com the Prius can supply 3 kw continuous, with a surge of several times that. The limitation isn't electrical, but thermal. It expects to be moving down the road when its doing more than just topping off the battery to keep the air conditioning system and 12 volt systems going. My inverter can do 6 kw, 12 kw surge, so its compatible, and my loads are always well below 3k unless I plug in my vacuum cleaner. The Prius keeps the traction battery between approximately 210 and 235 volts, which is also compatible with the inverter specs. Since the inverter is already hooked up to most of the 120 volts circuits in my house all I have to do is unplug my battery bank and plug the Prius in its place. It could even work in tandem to keep the battery bank charged but I want to run tests to see what the current curve looks like before I'm comfortable leaving it unattended... the Prius is designed to recharge NiMH and not FLA, plus it isnt expecting to be attached to a 22 kw battery bank, only slightly over 1 kw... lots of potential to let the smoke out in a big way.

    Anyway, the connection should be easy so hopefully I'll be up and running by mid-day. Then I'll probably go fill up the tank and let it run for 24 hours to see how much gas is used. I'll report back.

    SIG: 12 kw Generac, 22 kw battery bank @ 192 v, 6 kw Liebert UPS, 4.2 kw APC UPS, slightly modified Prius powering either UPS when the house battery isn't. Really.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • boBboB Solar Expert Posts: 1,008 ✭✭✭✭
    Re: High voltage charge controller?
    aarif wrote: »
    Yes exactly. The inverter isn't a big problem as finding an inverter that runs on voltages above 150 are fairly common to source in international markets (forgot to add that this installation is international), its just that darn controller that is being elusive. Also the safety factor for such a big bank does come into play, so I may just resort to 96V bank, and then use multiple controllers like the midnites....was just hoping for something else, haha.


    What can and has been done to charge higher voltage batteries with lower voltage charge controllers is to take 2 charger
    controllers and charge each battery half separately.

    For instance, we used to use 2 MX60s set for 60V battery to charge one 120V battery. You could also use more than
    2 controllers set for lower battery voltage. Each controller must have its own PV array though.

    Similarly, you could take 2 Classic 250KS controllers to charge one 240V battery. I haven't tried that but I would
    think it would work the same way.

    Things you have to watch out for is connections that are common to each controller, like, communications lines.

    Isolated Ethernet connections are typically OK as long as the shield is not connected at the controller end.

    The other thing to watch out for is the input of course so each PV array must be separate and the high half
    PV array must be floating.

    Also, since the PV side MOVs are connected from PV+ to GND and PV- to GND, the PV side MOVs must usually be disconnected.

    This is because the 2 PV arrays connected in series can make the MOVs conduct because the 2 arrays are in series if the MOV
    conducts from the top PV + and GND and the bottom negative connection. That's usually easy to fix... Just clip out the MOV
    but don't forget to use external lightning protection such as a MidNite SPD300 or maybe an SPD600 which breaks over
    at a higher voltage than the internal charge controller MOVs.

    boB
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