Converter

Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
I have an old Litton tu 750-6 converter in my camper that buzzes extremely loud. Does this mean it needs to be replaced?

Do they make a converter/inverter combo? I would like to be able to use shorepower on occasion, as well as boost my 12v to 110. Is that possible without purchasing two separate units?
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    For some reason, Xantrex and Magnum do make inverter chargers--but the inverters are not small--Somewhere between 1,800 to 2,800 watts.

    Xantrex does offer some other vehicle inverter/chargers that are not listed by NAWS.

    But, from my point of view, for an RV, you want something that has a fairly hefty battery charger and a small, efficient, and (preferably) true sine wave inverter to power your laptop and small electronics (RV's usually do not have a lot of battery bank capacity compared to a fixed off-grid system).

    I think the larger inverter/chargers are only a good deal if you need lots of AC power (microwave, power tools, etc.). And those are probably difficult to justify being powered from a typical RV.

    So, that ends up being perhaps an Iota, Xantrex, or other battery charger, a MorningStar 300 Watt 12 volt TSW inverter and a 120 VAC transfer switch between shore power and inverter power--if wanted.

    It all depends on your desired loads (AC vs DC) and battery bank capacity.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Converter

    Buzzing or not, if its an old converter it probably doesn't have a good 3-stage charger which would be a good reason to replace it.

    While a combo inverter/converter sounds good on the surface, your average Joe Sixpack would go dry camping and not understand that they can't plug in their space heater and run it all night. 75% of the Joe Sixpacks would kill their battery within hours and the inverter/converter would develop a bad reputation because of that. Even though it would be 100% user error.

    Plus, differently sized inverters have their place. If you just wanted to charge your laptop and cell phone while dry camping a 100 w inverter would be fine (I'm using a 400 w MSW inverter as I type this while dry camping to do exactly that) and would save battery power. If you only had a 2000 w inverter inside your converter that would be poorly paired with a cell phone charger.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    I need an inverter that will power my Carrier a/c, laptop, and some led lights, maybe a few smaller electronics.

    I'm looking at the Xantrex freedom hf inverter/charger. They come in 1000 and 1800 watt versions.

    I will only use a watt space heater when connected to shore power.

    If that is the case, would I be able to use the 1000 watt version for off grid?

    The other question: when connected to shore power, would I be able to run a 1500w space heater from a wall socket since the converter/charger is allowing the ac to pass through?
  • vcallawayvcallaway Solar Expert Posts: 157 ✭✭✭✭✭
    Re: Converter

    Not sure exactly what you are asking, but here goes.

    If your convert is like most older units it is for taking shore power and providing 12v to your low voltage systems. Most of them do seem to buzz.

    A good direct replacement would be an IOTA unit. It will provide 12v, charge the batteries properly when connected to shore power.

    For 120v when NOT on shore power you will need an inverter that takes the 12v and creates 120v. There are units that will do the inverting, provide a transfer switch and charge your batteries. They can get a bit pricey. Depends on how big of one you need. Magnum makes a nice 600w one for under $600. Our board sponsor does not list it on their site though. The MM612AE will provide 30A DC for battery charging and load. Seems like a pretty decent unit by the specs. I've not decided if it is what I'm going to put in my RV or not.

    Both the IOTA and Magnum units are designed to work off of generator power. Not all units designed for battery charging are, shop carefully.
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    I'm wondering if I can use a 1000 watt inverter/charger, and run a 1500 watt space heater through it, while connected to shore power only.

    Basically, I'm asking if there is a maximum amount of watts that can flow through the inverter/charger while connected to a generator or a 120v source. O do I just need the 120v volt switch?
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    You would be better off wiring heavy loads to the shore power / genset directly... And not go AC to DC to AC again... That adds lots of losses and means the charger and inverters have to be that much bigger to handle those heavy loads of an A/C unit or electric heater.

    I don't think you have enough battery bank to power a full sized A/C unit or 1,500 watt electric heater (at least for more than a few hours at a time). Those would be better of being dedicated to AC shore power or your genset.

    What size (amp*hour and voltage) battery bank do you have / plan on running your A/C from? How long do you wish to run them without the genset? How many watts of solar panels are you planning on installing? etc...

    For the converter, you could see if the capacitors are hot/swollen (going bad). Otherwise the buzz may be from transformer laminations vibrating (irritating but not a problem) or possibly loose cover/metal shields/inductors inside the unit (possibly fix with high temp RTV or tightening screws, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Converter
    techntrek wrote: »
    Buzzing or not, if its an old converter it probably doesn't have a good 3-stage charger which would be a good reason to replace it.

    And not just that - the voltage is probably low. I was poking around an old early 70's Winnebago that some guy was parting out, and the converter nameplate said the output was 12.6v.

    Maybe that was enough for 70's batteries, but it's sure not enough to fully charge a battery these days.

    3-stage may not be necessary though. Iotas are two stage without the IQ module, and some of the Samlex have a dip switch to put them into what they call "UPS mode", which is two stage instead of three stage.

    According to this:

    http://www.donrowe.com/battery_charger/samlex_document.html

    "If there are permanent or transient loads on the battery during charging, a two-stage charger has the advantage because its circuits cannot be “fooled” into pushing a higher “absorption" voltage than required for charging. "
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    The Carrier a/c is rated at 13.5 amps on high, but I do not plan on running it that often. Maybe a few hours per day.

    A 315 ah battery bank and 540 watts of panels.

    I never plan on running a space heater from the battery bank, when off grid, propane will take care of that.

    So do you think I should keep the factory inverter so I can run a space heater from my wall socket on shore power and to charge my batteries. Then purchase a separate inverter for using the air conditioner and miscellaneous electronics off grid?

    I just was not sure if it was a good idea to run a space heater using shore power, "through" a Xantrex converter/inverter combo.

    Is that what you mean by ac-dc-ac? I thought the 120 would be able to go straight through the converter/inverter without using dc.

    I would like to have one unit, instead of two separate. But, if separate is best, then so be it.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Converter

    My 1000th post!

    Will2020 wrote: »
    The Carrier a/c is rated at 13.5 amps on high, but I do not plan on running it that often. Maybe a few hours per day.

    It also has a hefty startup load. That can be mitigated sometimes with the addition of a hard-start capacitor - but that won't eliminate the surge load, just tame it down some:

    http://www.modmyrv.com/2009/05/27/rv-air-conditioner-hard-start-capacitor


    So do you think I should keep the factory inverter so I can run a space heater from my wall socket on shore power and to charge my batteries. Then purchase a separate inverter for using the air conditioner and miscellaneous electronics off grid?

    I wouldn't depend on an old converter/charger unit to keep the batteries healthy. I'd replace it with an Iota or a good inverter/charger.
    I just was not sure if it was a good idea to run a space heater using shore power, "through" a Xantrex converter/inverter combo.

    The Xantrex will use an internal transfer switch to run the shore power "straight through". Basically, it will disconnect the battery from the inverter and connect it to the charger, and the 120v output will be fed by the shore power. No worries there.

    I would like to have one unit, instead of two separate. But, if separate is best, then so be it.

    Then yea, a good inverter/charger is the way to go. But you'll need a hefty one to handle the startup surge of the a/c.
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter
    dwh wrote: »

    The Xantrex will use an internal transfer switch to run the shore power "straight through". Basically, it will disconnect the battery from the inverter and connect it to the charger, and the 120v output will be fed by the shore power. No worries there.

    This is what I have been trying to understand. So I can run a space heater "straight through" a converter/inverter combo with no problems right?


    BB said

    "You would be better off wiring heavy loads to the shore power / genset directly... And not go AC to DC to AC again... That adds lots of losses and means the charger and inverters have to be that much bigger to handle those heavy loads of an A/C unit or electric heater."

    I take it that running ac straight through is not going to dc, then back to ac again is it? This line got me confused.
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter
    Will2020 wrote: »
    This is what I have been trying to understand. So I can run a space heater "straight through" a converter/inverter combo with no problems right?

    BB said

    "You would be better off wiring heavy loads to the shore power / genset directly... And not go AC to DC to AC again... That adds lots of losses and means the charger and inverters have to be that much bigger to handle those heavy loads of an A/C unit or electric heater."

    I take it that running ac straight through is not going to dc, then back to ac again is it? This line got me confused.

    I was assuming worst case charging the batteries and running the inverter to run your heater.

    If you had a inverter charger with an AC transfer switch--then it would run from AC shore power... You would have to be careful. The transfer switch / AC wiring would need to be rated for your heater+whatever loads. Also, if you had a shore power failure, it would fall back to the inverter and drain the batteries in a few hours.

    I would prefer to run the very heavy loads (like heater/AC directly from shore power and not have them go through the inverter/transfer switch setup. Then there is no mistake or errors possible (well--we have humans involved--there is always room for Murphy's Law ;)).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    Ok, then I will buy a separate Iota converter.

    Another problem Dwh just pointed out to me as well.

    My air conditioner is 13.5 amps on high. I was under the impression that it only drew 13.5 amps per hour!

    Am I wrong there? Is it 13.5 amps per minute? Continuous?

    I was thinking that on high for 4 hours it would be 4*13.5=71.8 amps

    I believe my math was waaaaaay off :cool:

    If this is the case, I will have to run the a/c from a generator and I can buy far less panels for my system.
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    The "Units" we use around here are not part of the normal NMS or SI type units...

    For the most part, "Time" in the standard scientific schemes is in "Seconds"... For Homes, off-grid systems, Power Plants, etc., we use Time=Hours... It is a contrived unit--but if we are consistent, it does work for our needs (1 hour = 3,600 seconds--just makes the numbers smaller by 1/3,600).
    Will2020 wrote: »
    My air conditioner is 13.5 amps on high. I was under the impression that it only drew 13.5 amps per hour!

    Am I wrong there? Is it 13.5 amps per minute? Continuous?

    I was thinking that on high for 4 hours it would be 4*13.5=71.8 amps

    As we use Watts and Amps around here--We use "Hours" for time:
    • 13.5 amps * 4 hours = 54 Amp*Hours
    Now, note that we have forgot one thing... Volts. This is 13.5 amps @ 120 VAC:
    • 13.5 amps * 120 Volts = 1,620 Watts (a rate, like milers per hour, gallons per hour)
    • 13.5 amps * 4 hours * 120 Volts = 6,480 Watt*Hours
    Now, if you are going to run that from a 12 volt battery bank, you need to account for the fact is 1/10th that of 120 VAC:
    • 13.5 amps * 120 Volts * 1/12 volts battery = 135 Amps from the battery
    • 135 Amps * 4 hours = 540 Amp*Hours at 12 volts
    Note, the amount of power and energy (Watts and Watt*Hours) is the same at 12 volts or 120 volts:
    • 540 AH * 12 volt battery bank = 6,480 Watt*Hours (12 volts or 120 volts, does not matter).
    Since Power = Volts * Current -- If you reduce the voltage by 1/10th, then the current must be 10x larger for power to be the same.

    Amps and Amp*Hours can be confusing--That is why we are always asking what voltage somebody is talking about... Or, we work in Watts, then voltage does not matter (you just divide by voltage or current to find the other variable).
    If this is the case, I will have to run the a/c from a generator and I can buy far less panels for my system.

    It is possible to run an A/C system from a battery bank--But you need enough batteries, enough charging capacity, and large enough wiring/inverter to carry the loads for a useful period of time.

    Heavily insulating the RV, using as efficient A/C unit as you can find, etc. all help reduce the overall loads, and reduce the size of the off-grid system (or simply reduce the size of genset and amount of fuel you will burn to run your A/C system).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    Ok then, I must radically alter my numbers.

    I have a dometic fridge that pulls 2.7 amps that will be ran continuously.

    2.7*120=324 324/12=27 amps 27*24= 648 amp*hours Is that right?

    Man, if that is correct, then I had better run that fridge with propane.

    So, in a nutshell, if I have a 135 watt solar panel, and a 105 ah battery, the most it could power daily would be a couple of led lights it looks like.
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    http://store.solar-electric.com/dls-30.html


    Will this converter do the trick? Is 30amps enough to charge my batteries?

    I have a Lifeline 105 ah agm right now, but will have two more soon for a total of315 ah.
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter
    Will2020 wrote: »
    I have a dometic fridge that pulls 2.7 amps that will be ran continuously.

    2.7*120=324 324/12=27 amps 27*24= 648 amp*hours Is that right?

    I am assuming that this is a Dometic RV Fridge... I would be surprised if it drew that much power continuously on DC+Propane--But I am guessing that you are talking about the 120 VAC mode (dual or tri-powered fridge):
    • 2.7 amps * 120 VAC = 324 Watts
    • 324 watts * 24 hours per day = 7,776 WH per day
    • 7,776 WH per day * 1/0.85 efficient AC inverter * 1/12 volt nominal battery bank = 762 AH per day
    If the numbers are correct (2.7 amps at 120 VAC)--then this guy draws about 6+x the power of a a typical full sized Energy Star Refrigerator (which is just a bit more than 1,000 WH per day or so for a simple model).

    If you want to use DC power for the fridge, you should be looking for one with a DC compressor which would probably in the 300-500 WH per day--Or 1/10th the Dometic on AC power.
    Man, if that is correct, then I had better run that fridge with propane.

    Yep.
    So, in a nutshell, if I have a 135 watt solar panel, and a 105 ah battery, the most it could power daily would be a couple of led lights it looks like.

    Assuming you are around Houston Tx... You run and average of >4 hours of full sun per day (2 months of the year, a bit less). Assuming 135 watt solar panel, 0.52 system efficiency or with 0.62 derating for DC power available:
    • 135 watts * 4 hours of sun * 0.52 eff = 280 WH per day of useful 120 VAC power
    • 135 watts * 4 hours of sun * 0.62 eff = 335 WH per day of useful 12 VDC power
    • 135 watts * 4 hours of sun * 0.62 eff * 1/12 volts = 28 AH per day of useful 12 VDC "AH" power
    Of course, more towards the middle of the sunny 1/2 of the year, you are > 5 hours of sun per day.

    From the battery: 105 AH * 12 volts. You can draw 50% of its capacity daily (or less) for long life... For an RV which is used only sporatically during the year, you could draw 80% of battery capacity (shorter life--but not many cycles per year)
    • 105 AH * 0.50 = 52.5 AH per cycle of use full
    • 52.5 AH * 12 volts = 630 WH per day (at 50% cycling)
    Virtually everyone when they first look at solar power underestimates their loads and overestimates ability of solar panels to provide power.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter
    Will2020 wrote: »
    http://store.solar-electric.com/dls-30.html

    Will this converter do the trick? Is 30amps enough to charge my batteries?

    I have a Lifeline 105 ah agm right now, but will have two more soon for a total of315 ah.
    We use around 5% to 13% of the battery's 20 HR rating as a rule of thumb for charging (OK to round off--just showing my work:roll:):
    • 105 AH * 0.05 = 5.25 amps minimum
    • 105 AH * 0.13 = 13.65 amps maximum
    • 315 AH * 0.05 = 15.75 amps minimum
    • 315 AH * 0.13 = 40.95 amps maximum
    For an AGM battery, a larger charge controller is not going to hurt anything (AGM's can take higher charging current).

    If you plan on charging with a genset--You also need to match the AC charger to the Genset's output (not too large of charger--will overload genset; or too large of genset--will be fuel inefficient at charging).

    Watch charging voltages--AGM's do not do well when overcharged (read the specifications for your batteries to confirm).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    Back to the fridge, I want to run it on 12v and propane. The 2.7 amp rating should not be that high in this mode if I am not mistaken. I still would like to use solar to charge the battery for this setup, but I have no idea what the numbers would be like. It's time to call dometic and find out for sure.

    I have a 1000 watt generator, so I should be ok with a 30 amp Iota right?
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    My factory charger says 50 amps maximum 12v dc.

    But if I get a 30 amp for right now, it should not be too much for a 105 ah battery would it? I mean, if the factory one is rated that much higher anyway?


    105 AH * 0.05 = 5.25 amps minimum
    105 AH * 0.13 = 13.65 amps maximum
    315 AH * 0.05 = 15.75 amps minimum
    315 AH * 0.13 = 40.95 amps maximum

    If I have a 105 ah battery, does that mean I need a smaller converter charger? Something under 13.65 amps?
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    Tony/Icarus has an eu1000i (900 watt) Honda and I think he tends towards the 20 amp maximum.

    Iota chargers are not Power Factor Corrected (PFC) and therefor take more VA than would be expected from the Watt rating:
    • 30 amps * 14.4 volts * 1/0.80 eff * 1/0.6 PF (guess) = 900 Volt*Amps (not Watts)
    It is right on the ragged edge of working.

    It should not hurt anything to try it on the genset--Either it will work or pop the breaker/pull the AC voltage out of regulation--Or it will not.

    You might want to look at two things... First a Kill-a-Watt meter (AC Watt*Hour Meter). About the best bang for the buck out there in 120 VAC 15 amp Watt*Hour meters.

    The second, if you will doing a fair amount of DC work--Take a look at DC Amp*Hour / Watt*Hour meter like one of these.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Converter

    A RV fridge will run for about a month from a 20 pound propane tank. "Dry" campers (off-grid) always always always run the fridge from propane. No reason to use electric for that.

    The next major appliance to ditch is the RV heater. Dry campers all swear by the Olympian Wave heaters - a catalytic heater that does not have a blower. The blower on the standard RV heater is...
    1) way to loud to run at night. I was dry camping this weekend and only ran mine in the evening before bed and in the morning before getting out of bed. No way I would run mine overnight, not only because of the sound but...
    2) they suck down the amps to run that blower

    If you really want to pull off A/C off-grid, check out this thread: http://wind-sun.com/ForumVB/showthread.php?t=9287
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    I did the numbers on the Olympian heaters, and they are not very efficient for long term winter use. The wave 8 uses 1/3 gallons per hour and running around the clock (on high) , this would last a 40 pound bottle a whole 5 days,on medium 7.5 days....no thanks. I'll stick to the wood stove.
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    Hmm... 1/3 gallon per hour of propane: 1 gallon of Propane ~= 4.23 lbs ~= 91500 Btus

    I, obviously, don't know your camping setup or were you camp--but I would guess that you would not run the catalytic furnace 24 hours per day.

    Looking at the specs for three of the models--they only run from 1,600 BTU (small guy on low) to 8,000 BTU (big guy on high).

    10 gallons * 91,500 BTU per gallon * 1/8,000 BTU = 114 hours
    10 gallons / 114 hours = 0.087 gph
    4.25 lbs per gallon * 0.087 gph = 0.37 lbs per hour

    Oh--OK, it was 1/3 lb per hour, not 1/3 gallon per hour on high...

    But that would probably keep my whole home toasty warm in our mild winters (I run a 60,000 BTU furnace only an hour or two per day).

    If you have wood and a stove--sure why not. Just as long as you are not trying to use solar PV system for heating--won't be very practical.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Converter

    Definitely propane for the fridge. My Norcold 323 (the smallest they make) draws 11.7a @ 12v and since it doesn't have a thermostat and runs all the time, that's just way too much to run on batteries 11.7a x 24h = 280ah per day!

    Only draws 1.2a @ 120v though.

    The label says 140w on electric and 640btu/hr on propane.

    It will run for 4 weeks on high, and 6 weeks on low from the frame mounted 5 gallon propane tank and with no thermostat and no control board - draws no electricity at all from the battery. I keep it on low or it freezes things.
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    I'm looking at these Iota converters and they weigh about 5 pounds. My old Triad converter is a tank. Does weight matter when it comes to these?
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    The old converters usually have a good sized transformer.

    The new switching power supplies do everything electronically (they probably have a small high frequency transformer for isolation).

    Which is better? Typically, lighter/less costly materials/production efficiencies, is where all our modern electronics/power systems are going.

    Certainly there are few parts to go wrong with the old tank of power supplies... But, as you now, they are heavy and can develop a hum. Also, for old and new style supplies, the electrolytic capacitors (if used) can age and fail. With the old supply, the output just gets more 120 Hz electrical noise on the 12 volt output. For new inverters, they probably just fail when the capacitors go bad. The new supplies tend to have better voltage regulation and Bulk/Float (and others have remote battery temperature sensors and other functions).

    Many of the newer supplies (like Iota and such) can actually be used without a battery attached (they supply stable 12 VDC). The old converters typically used a battery to smooth the output--If you run without the battery is is just a rectified 120 Hz quasi-sine wave.

    If you plan on running the converter/charger from a small AC genset--The newest ones with Power Factor Corrected AC input are really sweet.

    Basically, old style power supplies / battery chargers only take current during the crest of the AC sine wave (the current is short, large pulses, 120 times a second). The PFC power supplies take current in a full sine wave over the entire AC voltage size wave (just like a filament light bulb or resistance heater would).

    A typical PF for a non-PFC supply is around 0.6 or so. For a PFC supply it will be near 1.0 (better than 0.95?).

    The math behind this is how you calculate power for AC circuits. We always use the equation for power as:
    • Power = Volts * Amps
    But, in reality, if you have a non-linear current (AC pulses for one example), the true power is:
    • Power = Volts * Amps * Power Factor
    What happens is the wiring has resistance (and transformers have peak current limits) where they respond to the "effective" current flow. Remember another equation for power is:
    • Power = Current^2 * R
    So, heating losses in the wire increase with the square of the current... If you use twice the current (because PF=0.5), you actually get 4x the heating/losses in the wiring.

    The term for Volts*Amps is VA (or VAR or kVAR) or Volt Amp Reactive. For a generator and your house wiring, they "care" about VA.
    • Power = V*A*PF = Watts
    • VA = V*A
    For a small genset, many times you can make a (worst case) assumption that its limits are VA=Watts. So, if you have a PF of 0.6 for a 1,000 Watt rated generator (which may have a VA rating of 1,000), you can only load it to 600 watts maximum with a non-PFC power supply:
    • 1,000 Watts * 0.6 PF = 600 watt load
    With a PFC type power supply (Xantrex has PFC on several of their battery chargers and inverter/chargers), you can pull the full 1,000 watts from the generator.

    Roughly, the generator's fuel use will be for 600 watts (plus a bit more for I^2*R heating losses) for a 1,000 VA input power supply.

    So, for various reasons, I personally, would look at power factor corrected battery chargers / inverter-chargers. PFC has some other nice features (typically, they have a very wide 100-260 volt input range) and work very nicely on less than clean power (like a generator).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Converter

    I spoke with a tech from Iota engineering, and he said a 30 amp might work with the 1000 watt genset, but he would not go any higher than that.

    Next to that, my father used the 1000 watt gen to power a battery charger on 40 amps, and he said it charged the batteries fine, next to little strain.

    I would like to go with the Xantrex, but it is a little bit out of my price range. Would it really be worth forking out the extra cash for it?

    What would be the advantage of purchasing the IQ smart controller for the Iota?
  • zeuspaulzeuspaul Solar Expert Posts: 59 ✭✭✭✭
    Re: Converter
    I have a 1000 watt generator, so I should be ok with a 30 amp Iota right?

    I have the same question. The spec indicates a 7 amp draw which seems like it should work. However the spec also indicates a 30 amp inrush current which seems to me would exceed the capacity of a 1000 watt generator unless it had a huge surge capacity.

    One source for a 55 amp Iota charger modifies it to reduce the inrush current.

    http://www.evsource.com/tls_dcdc.php
    These problems are due to the in-rush current (IOTA indicates as much as 27A is possible) drawn by the three capacitors at startup. To remediate this problem, we add an inline in-rush current limiter which throttles the initial current draw down to a safe level.

    I have an 800 watt generator and I have been considering Soneil battery chargers http://soneil.com/products.html because they specifically state in their specs that they have a soft start.

    Just questions, no answers;)

    Zeuspaul
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    If you are charging deed cycle batteries that are well under 80% state of charge--A good battery charger is going to pull more power than a car charger clipped onto a single 80AH battery.

    The IQ module is only useful if you have the charger permanently attached to grid power. It does a simple equalization every couple weeks for batteries that are on constant charge.

    Is the more expensive charger worth the money? My guess--if you plan on running the generator a lot (poor sun in winter, not a lot of solar panels, large barry bank and smaller fuel efficient generator, battery bank in esteem climate with charger that supports a remote temperature sensor, etc.)--They probably are worth the extra money.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Re: Converter

    I have not measured the surge current, but a PFC supply should have low surge current.

    Interesting question.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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