Hopefully not too daft a question on a forum for old school lighting and heating enthusiasts. In a past life, I spent a few years living a long way from civilisation in the depths of the African bush and living out of the back of an old Land Rover. A Coleman petrol lantern and hurricane lamps provided light when required and cooking was either on a woodburner or Coleman petrol stove. Those days are over (for now!) and I find myself living in a cottage on the side of a hill in rural Wales with mains electricity but water from a spring, heat from a woodburner and bottled gas for the cooker. The internet connection is sluggish but adequate. The “Beast from the East” which hit the UK a few years ago had us snowed in for 9 days and Storm Arwen has blocked our lane in one direction with trees which have not yet been cleared. Our remoteness and occasional interruptions to services are a feature of life here rather than a fault and if we ever do have a prolonged power outage, it will not be a major problem and would be an opportunity to justify the variety of petrol and paraffin powered lighting and cooking appliances I have accumulated over the years. Others in the UK have not been so lucky and some parts of the north of England are into a fourth day without power and the price of portable generators has rocketed as some people are keen to cash in on others misery. I don’t have a generator (there us a small inverter hardwired into the Land Rover) and do occasionally think that getting one would be a good idea but never get around to working out what I really need and justifying the cost. The one issue that a prolonged power outage would cause us is that our spring fed water supply depends on electricity to pump it to the house and power the UV lamp which sterilises it. Not a real problem, it would be perfectly possible to collect water and boil it but it did occur to me that an inverter to power the pump and UV light would be more useful than a generator (at any time we usually have 3 or 4 12 v car/leisure batteries around), particularly as the pump only kicks in a few times a day for a total of 15-30 mins. All a long and rambling way of saying, could anyone please help me work out what size inverter would I need to power a pump like this; and a lamp like this To my simple mind, if the max power input for the pump and UV light is <1000W, an inverter like this rated at 1500W with a peak capacity of 3000W should be more than adequate and that a pure sine inverter (which I don’t pretend to understand), would not be required. https://www.amazon.co.uk/EDECOA-150...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ== As I said at the outset, I hope this isn’t a daft question on a forum like this and any help would be appreciated. Cheers, LKO’R
Do you have a storage tank for water? If so, is the steriliser on the downstream or upstream side of the tank? If you don’t get the answer you need about your inverter here, I’ll ask my next door neighbour who is an electrician experienced in “off-grid” solar generation. Tony
Thanks, Tony. Yes there is a tank maybe 2500 litres and the particle filter and uv lamp are downstream (on the house side) of the tank. Water is from a spring and the house water is tested annually. Any help on inverter much appreciated. Thanks, LKO’R
Emotors eg. In pumps, compressors etc have startup current/power requirement, which 3-5 tims of normal operation. Means 3kw peak inverter might be sufficient to start 1kw pump. But could as well 5kw required. You only will know after trial an error. Pls note as well 3kw startup power means approx 280Amps at 12V battery (at 90% converter efficiency) Must be pretty large battery, to keep 12V at 280A. Pls note , inverters switch off conversion below 10,5V typically. = pump won't start.
I put electricity to the (quite remote) shed this year so I no longer need to run wires to the neighbour's stables if I need electricity. I connected 6 x 12V batteries and a charge controller to three 100W solar panels. It works fine. For general lighting I use some 12V LED lights and have a 1000W (/ 2000W peak) inverter for 230V~ running. As I use it for some battery chargers and for the laptop a "pure-sinus" inverter is the only thing to use. It depends on the motor of your pump if it will work with the square wave voltage of a simple inverter. If the UV light has some more built-in electronic elements then a filament it also needs sinus wave. So better get a "pure-sinus" inverter,. Triple the max load you think you need and you are fine. I sometimes use a fine old-fashioned 1000W light bulb to heat the shed a little. If you pull 1000W by a tension of 12V you force over 80 Ampere (ie. 83,333) through the wires at the 12V side of your power supply. So make sure your wiring is appropriate. 50 sq mm are OK. When I run my inverter for over 10 Min at maximum power (1000W) the wires (included from the factory) get bloody hot. I replaced them. Please do not forget the whole thing also needs power to run. My inverter uses 14W for doing nothing simply when switched on. Erik
Thanks for replies - funnily enough just had a 15 min outage! As far as I know, the UV system is simply a tube (which I replace annually) not sure whether i us on 24/7 or comes on with the pump. I’m guessing therefore that a pure sine inverter will be unnecessary? I guess that I need to get a better idea of what the pump actually draws. The inverter and battery would be a few feet from the pump and UV set-up and I have a pile of 4x4 winch power cables somewhere which should be more than thick enough. This is very much an emergency set-up which may never be used and the pump is probably only working 15-30 mins a day normally and would be far less if we were only using water for cooking and drinking so hopefully a 70-90Ah battery would be OK for short periods of use to top up the header tank in the attic. I have a few batteries for electric fences and barn lighting so could rotate these and recharge with solar in summer or a generator or just running the Land Rover which has twin battery set up anyway. A bit more thinking to do and perhaps one of these 2500/5000W inverters may be a better starting point? https://smile.amazon.co.uk/SUDOKEJI...Z3H1YPQ,B08XP1JKY8,B07DHKDTKB,B087FDNBWN&th=1 Thanks again.
The rule-of-thumb sometimes used is that a generator or inverter should be capable of producing twice the maximum notional rating of an inductive load (such as the pump) and one-and-a-half times a resistive load (such as the UV). On this basis, around 2000W or, as some like to say, 2000Va. According to the label, the UV lamp draws a max 0.23a (at 250v) or 0.39-0.43a (presumably at 250v) or 10w - 40w. You decide. But at, say, 0.4a at 250v, you would be drawing around 10a to serve a 12v inverter. Assuming it is continuous, you would need about 6 reasonably new, well-charged lead-acid leisure batteries (around 100ah each - such as are typically used in caravans and boats) to last one day, taking one hour of the pump at its maximum of around 950w. Any less - or knackered batteries - and the risk of the pump not starting and burning itself out increases - and/or you will be killing the batteries by sulphating. The latter is not such a problem if you do so only occasionally. I think your challenge here is that if the outage is short - just manage without running water for a while. And if it is lasting, you will have issues supplying it via lead-acid batteries (or mucho expense in using lithium-ion). Were it not for the lamp, a generator would be fine for the pump; but you need one that is liable to start when called-upon.
To be on a safer side, get an inverter that is rated for continuous output of at least 2kW at single-phase 230V~/50Hz. The input voltage can be 12Vdc, 24Vdc or any multiples of the basic 12V battery nominal voltage. The higher the input voltage, the less the current ratings required for the components, cabling, etc at that side. Your preference would likely be based on the battery charger output available to you. A decent quality 2-3kW inverter would be sufficient to cater for the momentary high current draws of the pump motor during starting(assuming you are not using a softstarter). The germicidal UV lamp won't be an issue since the loading is small and they work with high frequency switching inverter outputs even better than from a smooth sinusoidal wave power supply. In actual, an induction motor wouldn't mandate a pure sine-wave inverter for operations. I frequently work with variable speed drives in my job. These produce highly distorted PWM-switching type waveforms with non-linear current draws, characteristic of the usual inverters. Although a pure sine wave would be more conducive for the motor windings' lifespan, it is not absolutely necessary for an intermittent duty pump motor. However, take note that there is a starting capacitor at the motor side. They are not compatible with inverters that have high frequency switching square waves. For that, you might really require an output choke(as a low-pass filter) or a pure sine wave inverter. I'd usually prefer motors without starting capacitors(these frequently fail) or three-phase ones.
Last month i added a Honda 10i to my emergency materials stock. For emergency power supply of Gas heating, fridge and freezer, lights , radio. With 2nd external fuel tank for continuous operation of up to 48h. Reverse power supply from socket in garage to the house.
Thanks all for feedback will need to do a bit more thinking about what to do. I’m not planning for the zombie apocalypse and in any realistic scenario, the combination of a prolonged powercut and the roads being cut by fallen trees or deep snow so that it is not possible to get the nearest town is only likely to happen in winter so refrigeration should not be an issue. Looks like the most sensible solution would be an inverter to use to pump uv treated water to the tank in the attic (which realistically should be more than enough for a day or two without baths and showers) and maybe a generator to keep the fridges and freezers topped up. @bp4willi - looks a nice generator but GBP1000 here in UK so a bit out of budget for me. Thanks again. LKO’R
@Lee K O’Ring All other generator brands have thes or those negative comments. Honda i the top standard for reliable generators, long term . And they are really quiet. Important... Look for an inverter generator. Those run at variable speed depending on power surge, which saves fuel and extends runtime up to 100%. Simple generators use synchron generator at fixed speed for 50Hz. Those are loud too.
Honda generators are great - had one for mobile power while working in the African bush but can’t justify the cost these days!
So - in the face of accelerating heating costs I have become more interested in Solar solutions. I do not have lots of cash to throw at this and I see a lengthy return on investment on the classic panel/inverter/battery solutions. However I am lucky enough to have an "unvented" boiler/pressurised hot water solution in place. The hot water tank has a "backup" 240v 3KW heater element. I have found that I can buy "drop in" 12v/600W or 24v/900W DC heater elements. I have a clear run for a cable : 900w/24v= 37.5A so a 4mm Dia copper cable (12.5 mm2) should in my circumstances (externally clipped to masonry) carry 57A. This should allow for a safe margin as well as help counter voltage drop (about 3% over 5 Meters). What I do not know is if I need any sort of controller/regulator device. A fuse is a given but I am not familiar with solar panels and all I can find online are people who want to charge me lots of money for full 240v solutions.
