Clarity as a back-up power source? (DC-DC converter size, idle behavior)

Discussion in 'Clarity' started by M.M., Mar 31, 2018.

  1. KentuckyKen

    KentuckyKen Well-Known Member

    Thanks for giving us the amp numbers. That’s another good data point about the Clarity.
    I am lead to believe from other posters on this forum and from common sense that everything but the motor and starter generator (and of course the HV batts/converters/inverters) are on the 12v bus.
    The question I would ask is if you load the 12v bus up a lot more than normal for the DC to DC converter, will that in and of itself trigger the ICE sooner than it normally would otherwise? Or will it act like normal and not trigger the ICE until it depletes it’s usable SOC?
    Last edited: Jul 12, 2018
  2. Garry2

    Garry2 New Member

    I came across a technical puplication that lists the output of the DC-DC 12v converter at 2.3kw. it is cooled by the same loop as the battery and charger. That would mean pulling 2kw off the 12v battery would be no issue. Also interesting is that at AC charger is listed as outputing 750w of waste heat.
    V8Power likes this.
  3. briano

    briano New Member

  4. Hi.Ho.Silver

    Hi.Ho.Silver Active Member

    I have a 1000w continuos output inverter that I bought on amazon for $65 specifically for use with my Clarity. I used it successfully after our hurricane this fall to power our large fridge, chest freezer and a few lights. I think a 5000 watt inverter is too much to power from the Clarity battery.
  5. Robert_Alabama

    Robert_Alabama Active Member

    Yes the 50A at 120V output sounds great, but I'm worried that 500A at 12V on the input side isn't going to work out well.
    Sandroad likes this.
  6. Sandroad

    Sandroad Active Member

    If the info from @Garry2 is accurate, the inverter you linked to is way too large. I’m leery of the inverter info on that site too. 50A from a standard outlet is crazy and could lead to a fire, but it claims it can do that. And, it mentions wiring to your fuse panel but supplies no transfer switch. That’s deadly. Skip that one, IMHO.
  7. M.M.

    M.M. Active Member

    As noted by others, that inverter is not the right device. As Garry2 mentions above, Clarity's 12V DC-DC converter apparently maxes out at 2.3kW (about 190A at 12VDC), so when you factor in parasitics on the 12V bus and the fact that you probably don't want to be pushing the DC-DC converter to its limit if you don't have to, you really don't want anything over 2kW max. Personally, I would be wary of putting a steady load above the 500-1000W range on it (very ballpark guesstimating that as the sort of 12V load the climate stuff in the car might draw for an extended period and therefore be confidently what the system is designed to handle long-term; one could measure this for a better number).

    Not to mention that at 500A you would need huge cables to feed the thing off a 12V bus without it hitting the 10.5V undervoltage shutdown (that's if the Clarity's battery could even manage 10.5V at the terminals under 500A load, which I doubt), and it's going to run very inefficiently down at the power levels you can realistically use it.

    Even if it were suitable, though, it's a modified sine wave inverter, which generally are cheap (and I personally wouldn't trust expensive appliances or electronics to), it's not a major brand, and it doesn't even seem to be UL listed. If you don't mind modified sine for your stuff, get something cheap; if you're going to spend that much money, you might as well get a true sine inverter. For example, something like this:

    That inverter is by a long-time off-grid inverter manufacturer Xantrex (which is now owned by major conglomerate Schneider, along with major UPS manufacturer APC), is true sine, is sized correctly for the Clarity, and the 2000W version retails for around $600 so is about the same price.

    Or this model by the same manufacturer, which is also true sine but has a few less features and isn't marine rated, but is half the price:

    Indeed, it says specifically the outlets have no individual protection and each can supply the full load, which is nuts. No wonder it's not UL listed. It's probably targeted at "The bigger the number the better!" idiots who really just want to run a drill or something, will never actually plug 6000W into it, and if they did would be seriously disappointed when it either set their cable on fire or shut down on DC bus undervoltage because they didn't have three parallel 2/0 cables feeding the DC side.

    Hypothetically they might be talking about a transfer panel for that "wire it direct to your fuse box" bit (who the heck even has fuses in a panel in this day and age?), but somehow I suspect if they're willing to let it output 50A from a 15A outlet they just expect someone to use a double-male extension cord to plug into an outlet, backfeed the house, and kill whatever lineman is up on a pole fixing your neighborhood's power because you forgot to open the main breaker.
    Last edited: Dec 16, 2018 at 3:40 AM
    Sandroad likes this.
  8. MNSteve

    MNSteve Active Member Subscriber

    This is the part of the whole thread that bothers me the most. Please do not unknowingly put the linemens' lives at risk.
  9. M.M.

    M.M. Active Member

    Given what the topic of this thread is it does indeed bear noting:

    If you are planning to use your Clarity as a back-up power source, either hook the inverter up to the generator side of a properly-installed, inspected transfer panel, or just plug your loads directly into the inverter using an extension cord and power strip. Do not ever scab it into an electric panel not designed specifically for this, by any means or method, even if you think you know what your'e doing.

    A) It's illegal in most places for a very good reason, B) It runs a non-zero risk of causing an electrical problem and damaging stuff, C) If you screw up at best when the power comes back on your inverter will explode, possibly damage your Clarity, and maybe start a fire when the hookup wires melt, and at worst it will backfeed the pole through the transformer and kill somebody.

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