Transformerless Battery Charger

[srnoth]

Hey there,

I have been doing some thinking recently about charging battery banks from 120VAC grid electricity, since I am only just starting to build a kinda off grid system, and at least for the time being I will need to supplement the system with power from the grid. So here are some of the ideas that have been knocking around my head for the last few days:

First of all, I would like to say the before I do any tests/experiments using grid power, I always use fused in my circuit, and I tend to use light bulbs in series to limit current flow at first, in case something does not work. Also I do not leave live wires exposed (those twist on caps come in very handy for temporary circuits).

So I have been thinking, why bother to use wasteful, heat producing, inefficient transformers to lower the voltage to charge a 12v battery bank, when, by limiting the current flow, they can be charged directly from a 120VDC source?

So here is the basic circuit I though might work;

120VAC --> Rectifier --> 120VDC --> light bulb ---> DC ammeter --> Battery

This is my simplest test circuit to determine whether the idea will work. The light bulb is to limit current flow (amperage) into the battery so that the voltage will not go up two fast. Do you think there is a possibility that this will work, or do you think I am about to blow the house up. This is why I am checking with you guys before I try it.

So if the basic idea works, I was thinking of the following practical methods of making sure it does not try to make my battery bank go to 120 volts!

*    Using a couple of those adjustable voltage regulator things you can get from radio shack to limit the circuit current to 13.7v. http://www.radioshack.com/
product.asp?catalog%5Fname=CTLG&product%5Fid=276-1778

*    Using a voltage sensing circuit to turn on the charger when the voltage drops to 13.5 and turning it of at about 13.8v.

So, do y'all think this idea is practical or not? I got tired of trying to use transformers to do this, `cause of all the heat they produce, and their limited power. With this circuit I though of, I have as much charging power as the rectifier can handle though. I have a couple doubts about efficiency though. Let's say the bulb limits the current to about 1 amp @ 120V, does this mean that my batteries will charge at 1 amp, or 10 amps (which it would if a transformer was used).

So that's what I have been thinking of. I am right now working on making the house renewable energy friendly, before actually producing any energy from renewable sources. I don't have much wind where I live, and the stream has no water for half the year, so there's not much hope there either. If its one thing we have a lot of here in the tropics, its sun, but solar panels seem to be overly expensive right now. So at the moment, I will need to charge my 12v system from the grid. I guess I'll work on reducing the bill for now. Maybe solar hot water. That seems a lot cheaper (and more DIY friendly) than actually producing electricity from the sun.

So, what do you guys think?

Cheers,

Stephen.

[johnlm]

Do you want a straight answer??

If you are so concerned about heat then you should know that the light bulb will be producing more heat than a transformer would.  I could go into detai explaining why but just trust me in the configuration you are suggesting - which will likely work with the selection of the correct wattage bulb you will be wasting more power (aka heat) withthe bulb arrangement. The transformer is much more effecient at transforming 120V to the 14 or so volts you need for charging than dropping 105 volts through a light bulb.  Forget about trying to use an LM317 with this series bulb approach.  The max input V of an LM317 is around 40V and likely you will destroy the LM317.  Also an LM317 will only handle about 1.5 Amps which you are very likely to be trying to draw more than that with this ckt.

[srnoth]

John, I did consider the wasted energy in the light bulb, but I guess I forgot to mention it. But the fact is, with a transformer, all the energy is wasted as heat, which I don't really have any use for. However, I use 100W lightbulbs all the time for light, so therefore that energy will not go to waste. Alteast not more energy than what goes to waste everyday with lighting. Basically I can use the energy for something useful.

Maybe I will end up having to build my own transformer, but, as they say, that is a whole other ball game.

Cheers,

Stephen.

[johnlm]

Sorry, I didnt realize you were planning on using the light from the bulbs as lighting while you were charging the battery.  Sounds like a sensible idea.  To give you a general guideline to sizing the bulbs look at it this way.  Say you select a 100W incandescent bulb.  in normal operation it will draw 100W/120V = .83 amps.  so it looks like a 144 Ohm resistor (120v/.83A=144 ohms).  So with it in series with your battery you will have actually 168 volts Dc peak (rectified 120 ac) through a 144 Ohm resistor working into about 14 v (battery charging voltage).  To find out the charging current subtract 14V from the 168 v and divide by 144.

 (168-14)/144=1.07 amps peak charging current.  If you use a 200 w bulb you will get 2X this current.  Or if you wired two 100 W bulbs in parallel you would get the same 2X current.  So if you wanted about 4 amps of charging current you would wire four 100 W bulbs in parallel and connect them in the series line between your rectifier output and the battery.

John

     

[XRay]

Who! This is not a good idea. The open voltage of your rectifier output will be 168 volts.

When your batteries are charged the current will drop so the voltage will go up and kill your battery.

Use a current controlled AC/DC charger/converter 120VAC/DC and set the current to maximum and voltage to 14 volts. These converters are 90% efficient. Light bulbs are just 1% efficient, throwing 99% of away in the form of heat.

Greetings,

XRay

[XRay]

Correction: The open voltage of your rectifier circuit (rectifier + light bulbs) will be 168 volts.

Greeting,

XRay

[bob golding]

hi ,

most transformers are around 98% effieicent so you are not saving a lot with your system.without sounding rude i think you need to do more research before  trying to wind your own transformers.

bob golding

[drdongle]

I consider this an incredibly DANGEROUS idea, if there should be a misswire of the AC input or if the regulator should fail ( because of surges or lightning) LETHAL voltages could be present at the 12 volt side. A transformer affords ISOLATION and protection that no light bulb can provide. If you wish to pursue this design add a GFI so as to provide some protection.

Carpe Vigor

Dr.D

[K3CZ]

I can only reinforce the last comment re safety:  Do not mess with equipment connected directly to the AC line; it is life threatening!!! (besides violating all electrical codes)  And, a transformer is the only way to go from the efficiency standpoint - a transformer is about 95% efficient in voltage conversion, where your light bulb setup may be only 10% or so.  Better to use 12 volt light bulbs working from the charger/transformer setup, similar to  UPS!                 K3CZ

[Norm]

If you have a lot of sun start thinking about heat engines...a nice large old satelite dish lined with bits and pieces of mirrors or a trough type reflector, heat water hot enough to run a little steam engine....do a lot of research on solar powered engines there is one around that uses pop cans and ballons....it works and could be upscaled.

              You've got all the renewable energy that you could possibly use...just got to harness it!

                    Have Fun!

                  ( ;>) Norm.

[stop4stuff]

http://www.rotarystirlingengines.com/rotacola.htm

[skravlinge]

If you have a lot of sun-hours, a square meter of parabolic mirror will gives so it can fry a chicken, and probably run a sterling.

[johnlm]

Although I gave you some info on how to do this, I believe the other posts here represent the rational thinking on trying this.  Although it will work, it is not very safe and as someone pointed out when your batteries are charged there is no way to limit the charge current.  I suppose this could be used as a last emergency option to charge batterys under close observation to turn it off before the batteries overcharged.  I should have done what I started to do in my first post and discourage you from attempting this.

Johnlm

[nothing to lose]

As you say your working to cut your usage, all those 100watt lights should be the first to go probably unless for specail uses. Go flouresent instead, saves electric, produces less heat, if you run an airconditioner you have less heat to get rid of by not making it to begin with ect...

I still use some where I need to see in difficult areas and such or limited use places where not used much. Not many of them though.

I also thought about grid charging similar to this, but decided not really a good idea and did not try it. Even if I did not hurt myself or burn down my house, I still don't want to loose all those batteries with a mishap! I was thinking about a highvoltage battery bank, 48-60volts. Using low amp breakers on the AC side also so the least little short would hopefully shut it off ect.. And of course fuses on the battery side, and kill switches on both sides.

Then I decided just to not bother, even comming from batteries it's still grid power anyway!!

[srnoth]

Yeah guys, I suspected that the efficiency would be pretty bad, and then there are all those safety hazards, I guess it's just not worth it.

For the time being I will have two put up with the only transformer I have, which puts out 16VDC open circuit (after rectification). It can charge an almost full deisel truck battery @ about 15amps. When charging the battery and running an inverter with about 200W load at the same time, which is bascially what I am doing all the time, it trickles down to a couple amps charging, and the voltage rarely gets beyond 13 volts. I guess what I will do is try to increase efficiency by shortening the wire length and increasing wire size between the low voltage side of the transformers, the recitifier and the battery bank.

My major concern with this setup is:

1. Charge controlling, which I can solve by making a circuit to turn off the charger at 14v and turn it on at 13v or something like that.
   
2. Getting rid of the heat produced. I currently have the transformer in a bucket of car oil to keep the temperature down, but after about half an hour of charging @ 15 amps even the oil starts to get pretty warm. For this I plan to use some computer fans to cool the oil, so that should keep the temperature resonable.
   
   

So I guess that is what I will go with. Maybe I'll try to get a larger transformer. That should help. In the mean time, as has been recommened, I am working on changing most of the lights to those screw in type florescents that can be used in a normal bulb socket, and use only 20% the power of a incandescent of equivalent brightness.

Those ideas for harnessing the solar power without panels look pretty interesting. I must admit, I have plenty power available in the sun, so it work be great if I could find a way of using it. You can fry an egg on a piece of metal left out in the sun, so I will definately look into that. I think I will also look around on Ebay and stuff for used solar panels at reasonable prices. I must say that they are a lot more expensive than wind or water power, and at this point probably out of my reach.

Cheers,

Stephen.

[nothing to lose]

" Getting rid of the heat produced. I currently have the transformer in a bucket of car oil to keep the temperature down, but after about half an hour of charging @ 15 amps even the oil starts to get pretty warm. For this I plan to use some computer fans to cool the oil, so that should keep the temperature resonable. "

Maybe you should change the oil? Don't forget the filter

Really I think engine oil is not that good a coolent. Ever drained a HOT engine changing the oil, see how long it stays hot after drained! For storing heat oil is good, for cooling I don't think so though. Sure it does kinda cool the lower part of the engine some, but it's mostly  for lubricating, and that's alot more heat than you should probably be getting anyway. Lots of other things to it's use. But for just cooling I don't think it's very good, and your in a standing bucket, not circulating it or driving producing wind to remove the heat either.

I don't do all that much with transformers so I don't know whats safe to use on those myself. Maybe WD40 if your going to use oil, maybe 50/50 mix antifreeze and water?? Either would probably get rid of more heat and do it faster too. Don't know if either is really good to use in this case though.

Fans will eat power, maybe not much but they will use some anyway. Maybe make some air fins to strap onto your bucket to pull out the heat. Increasing surface area should help. If you have or get cheap some aluminum, a homemade heat sink will help suck the heat out of the bucket.

I think finding something beter than engine oil would be the first step though.

[srnoth]

Hey nothing to lose,

It certainly does seem that car oil does not work very well. It is great for short charging time (less than 1/2 hour), because it takes a long time for the heat from the transformer to increase the temperature of the oil. But it also takes a long time to cool off after I have turned it off. I did consider water, but a few crude experiments showed that it most certainly does conduct electricity, even if only very small amounts, but I decided to play it safe and stay away from the water. I will certainly look into what other forms of colants are available. Someone on this board recommended something called 'transformer oil', but I have not found anyone selling it yet.

I have been considering adding fins and using a metal bucket instead of a plastic one so that the heat can be transfered more easily to the air around it. And I have a computer fan actually in the oil (spinning very slowely - I hope it does not burn the motor out) to help circulate the oil.

Cheers,

Stephen.

[jimjjnn]

Cooling woth oil brings up a thought.

Over a period of time, will the oil cause deterioration of the insulation on the windings ?

[wooferhound]

 I can't remember who posted this circuit, But I saved it and am using it again. This is a transformerless charger that just uses a bridge rectifier and some capaciters.

[finnsawyer]

You can protect the battery with a Zener diode and a maybe a couple transistors and some resistors.  When the battery voltage (or battery voltage in series with a small resistor) rises to the Zener voltage it allows current to flow to the transistor(s) effectively by passing the battery.  The real issue is why give up the current gain you get with the transformer.  Also, charging at 1 amp takes about ten times as long as at 10 amps, so you actually waste more power using the light bulbs.

[srnoth]

Looks like a simple, easy circuit. I have a couple questions though, do you loose the current gain associated with transformers? In other words, when you use a transformer, 1 amp @ 120V goes to 10 amps @ 12v. Is this the same with this circuit, or is it the same amperage at any voltage, in which case it's only 10% effiecient?

Cheers,

Stephen.

[nothing to lose]

I have NO understanding of even the simplest drawings! (BUT I will, I just found my books again )

This sounds too easy. If I got it right and it is supposed to work I'll use it alot!

1 amp for every 24UF? I have  330UF 200wv caps in a dead computer power supplies, so I wire one to 1 AC line and I get 13.75 amps, connect that to one AC connection on my 35 amp 200V bridge rectifier and the other AC line directly to the other AC connection. run + and - out to the battery. ??

That's it and I have a 13.75 amp pulse charger?? I suppose 60 pulses a second too right??

Maybe I just make things harder than they should be, but that seems far to easy to me to be so simple and work?? Have I missed something really important?? Of course I will use fuses on the DC side also.

Now if that is correct, would I wire 2 330UF 200wv caps end to end, or side by side to go to 27.5 amps?

Since I only have a 35amp bridge, I geuss that's as high as I get, or use smaller caps to get the other 7.5 amps along with these 330uf's??

Should I be happy with 27amps from the 35 amp bridge, use 2 bridges and join them for about 55amps? Twist the + together and - togther from each?

How do I know if the caps are non-polar? These are HEC ZR+85 C 330uf 200wv caps.

I have about 8 other physical sizes in there I can't read the numbers on right now.

About safety and such. What if a cap blows, circuit goes dead or a problem? If my bridge blows and I have fuses on the DC side, I just blow them at worst?? This holds down to battery volts and doesn't burn them out? What about the "Constant Currant" it mentions, am I still pushing the same 35 amps at the bank when it only needs 10amps?

 If I have the inverter running and charging at the same time, the batteries suppling the load to the inverter or will the charger pulses be hittng it? Any chance of blowing it?

 Would this work well wired some way with like a dump load, except instead of dumping power the relay simply turns it off till power is needed again.

I "THINK" I know most those answers, but want to be sure, plus others reading here might benifit also.

What should I expect for losses? What I am really thinking here is get my battery bank and inverter online. Basically everything set up and running as if totally off grid, except the well. Charge the bank from the grid with this as needed, and use any other power I can make also as I start getting the projects completed. Also I could kill the grid and see how long my battery bank lasts at times without input. For those dead spells.

Also it would be worth a little loss just to have a nice reliable house UPS instead of this crappy grid with all it's problems. Let the grid do what ever and just use smooth clean battery power

The 6 month average for everything was 708 watts an hour 120Vac, so thats about 59 amps 12Vdc per hour average and I think it should be way down now from that.

It might be a way to wean the family off the power usage

Make a charger putting out about our needs and slowly reduce it over time. Start with 50amps an hour, drop to 45, 40, 30 ect....

When the TV goes off in the middle of a movie because they left an unused light on half the day, they'll start turning them out more often

Also lots of other goodies in the power supplies too, those 3 legged black thingies( mofsets??), 3 various small transformers, looped wire coils(chokes?), resisters.

Seriously don't know what those grean and brown Chicklets are though right off hand.

Anything in there for small bridges or diode type uses??

I actually got these (many of them) bad power supplies for just the heat sinks to begin with. Most actually have tested to be fine for me so I don't even know why they were tossed, but I don't need em as is, working or not.

I apreciate all the help here and hate to be a pest about these little things.

Good news though, I found my old electronics books (some of them) and the Ratshack 600 in one project kit. Though I think the connecting wires are all gone from it. (about 10 years old maybe more) So now that I am getting into more of this stuff maybe it will do me more good than it did before. This time I actually have something to use it for

In the mean time while I study up a bit, I have those parts and do need a charger that works when power is on, and also when it comes back on after an outage without having to be manaully turned back on. The "SMART" chargers like the vector isn't cutting it in that area.

[kell]

Electrolytic caps (like in power supplies) are polar.  You can't use them for a circuit like the one in the drawing posted... unless you put two electrolytics in series and reverse the polarity, in which case you effectively get a non-polar capacitor.

You won't get any current gain.  Since caps conducting AC dissipate little real power (depending on their ESR), it brings up an interesting question.  You're still drawing current from the grid at 120 volts but only using it at 12 volts (nominal), so it would seem you would still be paying for ten times the power you actually get... but since the cap doesn't dissipate power (wattage) but reflects it back into the grid (I think), will the power company bill you for it?  It is a power factor question I don't know the answer to.  I do seem to remember that the same circuit is used for some sort of power factor correction in certain applications.  By using a cap you might be escaping the inefficiency problem associated with resistors and light bulbs.  You have other difficulties, however.  You have to turn off the circuit when the batteries are charged, or you have big problems.  Do you fab up a regulating circuit and trust it to prevent the damage?  If you can't build a rock solid infallible circuit your only choice is to monitor the system and turn it off manually.

By the way, I have used that circuit with a very small cap (like 1 uF) to trickle charge.  For anything more it's pretty risky.

[nothing to lose]

Ya that was something I wondered about, what am I paying for?

I kinda figure 700 watts is 700 watts in a way. About 5.8amps at 120Vac or 58amps at 12Vdc, unless I am only using half the cycle and get billed for both halfs which would be a 1400watt bill for 700watts power. NOT GOOD!!

As far as actual usage, I am looking at lower amps than that since I don't really plan to go above 55amps and maybe just the 27 amps DC. Fairly large 12V battery bank, and manual switching for the charger. 5k inverter. Total amp hours of bank unknown since these are salvage batteries, rated well over 1000amp hours for sure total, but what they will actaully do is another question. If they all acted as new ones I might have a 2500amphr total going if using them all. But I know that's not gonna happen.

If all else is ok with it, I figure a low amp breaker on the AC side like maybe 10amp, don't know if I could even get less like a 5amp or not. Fuses on the DC side. Kill switch on both ends as well as plugged into a wall outlet maybe so the wire could just be ripped out in a hurry also if ever needed! Probably a 30 or 35 amp fuse for 27amp DC charging, low as I can go for AC breaker.

Of course everything would be outside away from the house, use the existing lines from the breaker box by the well to feed the house from the inverter. Just change it there to charge batteries from the grid and pull the house lines out and wire them to the inverter instead.

[nothing to lose]

"Then I decided just to not bother, even comming from batteries it's still grid power anyway!!"

OK, hmmm, do I sound like a hypocrite now???

Actaully the reason this sparked my interest again is the pulse charging part. I paid about $100 for a pulse charger awhile back, would like another and not gonna pay the money. Also want a charger that turns on when I turn it on, not one giving me an error on a led because the battery is dead. And last but not least is I want one that when the grid comes back online so does the charger, not one I have to manually reset everytime the power blinks off for 2 minutes.

I can use the "SMART" charger for 40 amp charging and topping off a bank if needed. So this other circuit is to kick on manually when I am down 100amps or more and can let it run charging and pulsing and not worry about the grid problems shutting it off on me when it pops on and off a few times a day like the grid does around here alot.

I don't expect to need it long either now!!

[wooferhound]

I am fairly sure that the pusles from this circuit would be coming out at 120hz, once for each half wave . . .

[ghurd]

Yes.  120hz pulse DC.

12v, 1a, = 12w.  But it takes 120v, 1a, = 120w.

Oversimplified, yes.  1a @ 12v = 1a @ 120v.  12w=120w?

If the timing (cap) is just right (lead/lag) for the battery AH and SOC, it could be OK, efficiency wise.

What if a 12v 105ah battery is at 16 v and still getting 1a?  It is junk.

The cap only limits the current, not the voltage, in this circuit.

Someone step in if I am wrong.

G-

[jacquesm]

not to rain on your parade here (that's been done enough already, looked like a veritable downpour !), there really is not much point in charging batteries from the grid for later use unless you're trying to charge a vehicle battery for use in that vehicle. The reason why is that the charge/discharge cycle of a battery is nowhere near perfect (as in less than 100% efficient) and that batteries wear out when you charge/discharge them. It is a fairly commonly used estimate that for a large 'pack' it costs about US$.04 to store and retrieve a kilowatt hour !

[nothing to lose]

"since I am only just starting to build a kinda off grid system, and at least for the time being I will need to supplement the system with power from the grid."

Might be a difference here in what you were wanting to do and what you got me thinking about again

"supplement the system with power from the grid" is NOT what I would be wanting to do here. I thought I should mention this in case I end up doing something like this latter myself and post anything on it.

My grid is LOUSY. We may go for weeks with what "SEEMS" to be decent power. Then we have a spell where the power goes off and on many times in a few minutes. Like flipping a light switch on and off rapidly. Sometimes the power is not even off long enough for a 100watt bulb to go fully out before it flips back on, and about the time it gets full brightness goes off. Or it may go off for 1-2 full minutes come on for 5 and go off again. Most people around me don't even know about the other problems it has also.

 I have about 6 UPS's sometimes I have a rolling beeper/clacker through out the house.

What I mean is something with the power grid causes all the Ups's to kick to battery and back to grid power so fast they all go BEEP and I can here most click and clack as they switch. Each is a fraction of a second apart in the time it takes them I geuss because it's a rolling beep/click/clack as it does there thing in differnt parts of the house. It does this often at times, sometimes not for weeks. I have noticed it 5 times in 1 hour, about 30times in one day as I sat counting them. Funny thing is 100watt light does not even flicker and nothing else seems effected.

It's that kinda stuff that I want over to batteries, provided it only costs a little more for the grid (not double). Cleaner more reliable power, even with mod wave cheap inverter!!

And I need to start testing alot of stuff using the batteries for power. DC stuff and things on the inverter, so they need charged anyway somehow. Also they are salvaged and I need to put them to use and see how well they hold up under heavy fulltime loads and use. They may be fine, or I may need to buy new ones and I need to know that soon

Under testing and running loads for a time the recycled bats seems to be fine now, but only real use will tell for sure. They are much better now than when I got them for sure. And the PULSE charging is what actually got my attention again on this.

And that reminds me, I am wondering what the difference is with the cap and rectifier pulse charger shown above and plain rectifying from a genny?? I know the CAP set the max load/amps that can pass from 120AC. But isn't running off a windmill genie making AC, and that being rectified with out the cap basically the same thing as far as the pulsing part?? Or does the Cap have something to do with the pulsing also??

[nothing to lose]

"What if a 12v 105ah battery is at 16 v and still getting 1a?  It is junk.

The cap only limits the current, not the voltage, in this circuit."

Yes I was thinking on that too. Now could we easily add a relay as in dumploads that instead of dumping the power, simply turns off the charger after a set Volt like 12.5 is reached. Thinking more as a safety feature for manual use, not automating it really.

 Just in case it is forgoten about for an hour longer than planed!

 Or could the voltage be limited on the DC side to never go over 12.5-13Vdc?

Actually I would want a point at less than full charge with something like this. Leave room for errors, top off with other devices.

My thought on using this myself (maybe) is run the house all night off batteries, charge for an hour or so as needed in the morning and shut it off, then charge again in the afternoon or evening as needed and shut it off again. Still it would be nice to have an auto off switch maybe voltage limit also just in case they came up a bit faster than expected sometime.

Might set this up that way and run it manually, then run a "Smart" charger the rest of the time at 40AMP or less, it does what it wants itself, not what I try to set it at.

 So if the bank needs 100amps, smart charger does 40amps, if bank needs 20amps, smart charger does less. Shuts off when full. Maybe comes back on also if the start dropping, not sure. We always lose power before they are full charge and I start using them so I have to manually turn it back on anyway.

And of course I would be charging 24/7 with what ever power I get from windgenies, and the goal is to meet the need or exceed!

 Eventually.

[srnoth]

Hey there,

That sounds almost exactly like what I am trying to do. The grid by me is, as you put it, lousy. At one point, anytime it rained, power went! It goes for a couple hours atleast twice a month, and goes out for short periods (less than 5 mins) several times. Not to mention low voltage and that sort of thing. I once measured only 100 volts coming from the grid! It is usually 115 volts, and you could definately see the lights dim.

Anyway, so because I was tired of grid failures, because I like the idea of making my own electricity, I decided to start work on a sort of 'fake' off grid system. Basically, I have a couple cheap inverters, a small battery bank and I put in a separate 120vac circuit in part of the house. So what I would like to do is run the computers off the inverters, so they get constant electricity, while charging the batteries from the grid. So the batteries would more realistically be at 'float', and the power would go straight into the inverters, with the batteries acting as regulators. So one circuit is conected to the inverter permenantly. And on one circuit I am planning an emergency light circuit using CFLs that come on when electricity goes. And the last circuit will be used for non-essential items, and will be connected to the grid through a voltage regulator, and I will make a transfer switch so when the grid actually fails, I can switch them over to inverter power.

So that is why I am interested in the easiest way to charge the batteries. I think I will have to see if I can find a surplus transformer, since the one I am using now can only put out about 20amps at battery voltage.

Cheers,

Stephen.

[(unknown)]

I have a place that is remote,no electricity, but if i wanted to run 400w 24/7 how is this possible, what would i need,how could i do it with batteries and so on. any ideas? this answer is much needed for a project i have in mind

thank you..

[nothing to lose]

"That sounds almost exactly like what I am trying to do. The grid by me is, as you put it, lousy. At one point, anytime it rained, power went! It goes for a couple hours atleast twice a month, and goes out for short periods (less than 5 mins) several times. Not to mention low voltage and that sort of thing. I once measured only 100 volts coming from the grid! It is usually 115 volts, and you could definately see the lights dim."

Does the name Howell-Oregon ring a bell?? If so howdy neighbour

 I know the power goes out AFTER the rain stops very well! I think they have a leak in the roof here and it starts dripping on something when the rain stops. Can have a really nasty storm and I have power through it all, till it's over!

When the post first started, I thought you were doing something else actually. Not really just trying to get reliable power same as me.

"since the one I am using now can only put out about 20amps at battery voltage."

 Look for a LARGE UPS, I have an older model that has a VERY large transformer and a smaller large transformer. Might be a good place to find something cheap. I haven't tested them to see what they actually are, I still use the UPS off 2 deep cycles. I got it cheap because the batteries were shot. This one charges at 24Vdc but I never checked the amps it puts out or how it monitors the batteries.

May want to use a couple to get up to the amps you want instead of one big one anyway.

Could look at battery chargers, maybe find a junk one cheap or free. Don't know what it has for a transformer but I have a charger that does 40 amps and 100amp boost. I don't figure much use for the boost part, probably not very strong for heavy use, but the 40 amp part I think is.

I been thinking along these lines myself, but working on too many things at once..

One day I will get something done and by the end of the week everything will be done, then I will have nothing to work on. But for now, nothing gets done but too many things are being worked on.