| Author | Message | ||
| dalefleener (64.66.215.120)
Rating: N/A |
Just to throw this out for us to think about. I will be putting a solar electric system on my coach. While researching I came upon a statement in one of the catalogs I got to the effect that if a system was going to support more than six lights it would be better to install 120V lights. The reasoning was that 120V lights are made sturdier, cost less and will last longer. A $avings in the long run as well as more satisfactory. What do you think? Especially those of you with all electric coaches. Thus the can is open, look at all them worms!! Dale | ||
| FAST FRED (63.215.239.138) Rating: N/A |
The usual off grid reasoning is that at 12V there are usually large wire losses, so if you convert to 120V the cheaper wires will do a better job. And 120V appliances are cheaper and better. REMEMBER these folks are using math for amps from the batt VS lumens delivered the light spot. IF your getting to "that age " where you need loads of light , the 12V or 120V florescents will light a large area with less juice. Custom Coach and BB both used multiple 4 ft lamps in the galley and saloon areas to keep folks happy. I would always at least have a back up 12V system , easier to use making Head calls than bright lights. Our 06 is ALL 12 V but most is just a simple rewire of existing wires , with better more functional lamps installed. A bright light JUST where its needed is cheapest on the batts , but that requires some turning on & off. FAST FRED | ||
| Don KS/TX (63.15.244.176)
Rating: N/A |
Well, I vote for NO battery lights. I played with the ideas, but with an electric refrigerator, I realized I MUST always have 120v in the coach anyway, so why have a clunky 12v or 24v system at all? They work ok for the overnighter guys, but we lived in our bus. It has worked out extremely well, and I would definitely do it again that way if I were building another. As Fred pointed out, old eyes need some real light at the right places, and with 120v you have easy choices, to include all sorts of dimmers and low level lighting for getting to the head in the night. I used some of the "rope lights" with success for indirect lighting also. The screw in flourescents have been really good for a bus also. Oh by the way, if you decide to go with 12v stuff, I got a heck of a deal on a bushel or so of 12v stuff I decided not to use. | ||
| Stan (216.95.238.116) Rating: N/A |
If you are using incandescent fixtures, you can buy 12 volt bulbs with the same base as 110 volt bulbs. They are available in different wattages and run cool and last indefinitely. If you have a vibration problem, you can also get them in 'Rough Service'. Current draw on a light bulb is so small that voltage drop is insignificant on any wire that is mechanically large enough to string through a bus. A 50 watt bulb in a good fixture in the right location makes a good reading light without the hot spots common to the small 12 volt bulbs. | ||
| Don KS/TX (63.15.249.100)
Rating: N/A |
You can get the standard base bulbs in 24 volt as well as 12v, (I have a case of them). | ||
| Doug Dickinson (Dougd470) (207.168.131.87)
Rating: N/A |
My thoughts before converting an MC9. I am going to have some 12 V fixtures - mostly automotive type or specific 12V coach type lights but these are mostly for that quick middle of the night trip or getting things stowed inside. All the major reading and kitchen illumination and appliances will be 120V. The drivers cockpit will be 12/24V. Entrance lights (courtesy lights) will be 12V and so will the compartment lights. The idea is - as long as the coach is in motion, I don't want to run the gen set unless I need or Airconditioning. An inverter will take care of 120V lights if needed, and most of the running needs will be attended by the coach itself, except for minimal lighting to "wake up the coach" when I need to put stuff in storage or take it out or get ready for a trip. If the invertor fails, it won't be such a big deal since I will still have minimal lights inside unless I fire up the gen set. Something to beware of with those mogul base 12V bulbs (the same size as a household bulb and fit in the same fixtures) - unless the fixture is rated for 12V use, the fixture wires will be much too small for a 12V bulb use and are a fire hazard. Use special made fixtures for 12V ALWAYS! if you look around, there are some creative solutions like the rope lights and the halogen under-counter lights that run off 12V. Look around and be creative - and always safe. My 2 cents - your thoughts may vary. | ||
| Stan (216.95.238.81) Rating: N/A |
I no longer have all the engineering specs for light bulbs and fixtures but I think a mogul base is about 1.5" in diameter and only used on industrial type bulbs. A standard house type bulb is a 'medium screw' and the fixtures that take this bulb have wires that are suitable for the 5 amps or less that a 50 watt 12 volt bulb would draw. If you are really worried about the fire hazard, you change the wires to a larger size, but ensure that you use the high temperature wire that the code calls for. | ||
| Doug Dickinson (Dougd470) (207.168.128.94)
Rating: N/A |
It's a half mogul which is, I believe, AKA, a medium screw. Anyway - I agree you might change the wire and increase the safety margin, but to go one better and safer - rather than replace the wires - spend a little more (OK, a good bit more) and make sure the fixture is rated for DC. Other considerations are any switch that is built into the fixture as a AC rated switch will NOT handle the equal of DC current. You mileage may vary | ||
| Johnny (63.159.185.138)
Rating: N/A |
Boat shops have DC fixtures that use "standard" screw-in 50W, 12V bulbs. I've seen the bulbs at Wal-Mart. | ||
| boogiethecat (24.234.38.109) Rating: N/A |
My solution is somewhat "engineered" I guess, but it works really well... I have mounted both a 120 and a 12 volt bulb in each of my fixtures. Flourescent fixtues each have 2 bulbs- one on a 120 volt ballast and another on a 12v DC ballast. All of my light switches are two pole rocker-units that switch 120 on one of the poles and 12 volts on the other. I then have a "main"relay whose coil is hooked to the 120 volt system mains, and it's function is to disconnect the power to the 12 volt lighting system whenever 120 volts is present in the vehicle. This way everythig just takes care of itself automatically...when the genset is running or I'm plugged into shore power, the 120 volt lamps operate and the 12 volt bulbs don't, and when 120 is off, everything works the same from the user's standpoint (the wife!) but now it's the 12 volt lamps running off of the battery bank. I'm REALLY pleased with the setup and it doesn't confuse the females... cheers Gary Stadler | ||
| Johnny (63.159.194.73)
Rating: N/A |
Any scematics, there, Boogie? That sounds like a good idea. I think I get the wiring, but I'm not certain. | ||
| boogiethecat (24.234.38.109) Rating: N/A |
I'll do up a schematic and post it tomorrow when I get home...right now I'm on trip #3 with the bus, having a ball, shaking out all the final rattles and oil drips... Cheers gary | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
Ten years ago when we wired up our 16' by 34' solar cabin, we decided to go entirely 120 vac instead of ANY 12 volt DC. Saved enough then to almost pay for a used Trace 1500 Watt invertor. Still works today. My guess the same savings would apply today. The coach plan includes leaving the chassis 12 volt stuff alone (except for some interior bulb relocation/updating) and having the entire..... ....."house" be 120 volt AC running some sort of SW invertor with a large battery bank with charger. Diesel electric coach with no propane. This idea would give some duplication but may be the best way for us to do it based upon personal desire and experience. Good luck. | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
Here ya go Johnny... http://www.heartmagic.com/zzlightingCircuits.jpg "Code" probably doesn't like it because 12 volts and 120 volts are in the same switch, the same fixture, etc. But as long as you use 120 volt rated wire on the 12 volt side and do a clean job it will work well for you as it does for me. Cheers Gary | ||
| DaveD (216.18.113.69)
Rating: N/A |
One of the problems with running 12V (ELV)and 120V (LV) circuits in the same boxes and conduits is that the person accessing these circuits may not know that some are at 120V. In addition, circuit clearances, and insulation requirements are based on working voltages and what's appropriate for a 12V circuit will usually not be at all suitable for a 120V ciruit. Unintentional contact with circuits at hazardous voltages may occur with fatal results. Electrical code requirements are the results of years of experience and lots of thoughtful input from regulators, manufacturers, consumer groups and other stakeholders. In my opinion there is no justification or excuse for ignoring them. DaveD | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
Dave, I totally Agree. That said however, That's the way I've done it im my bus and it's safe and happy. I'm an EE by trade and have also got years and years of experience with both the Code , building wiring, and design of such. No one but myself will be working on my bus, and everything I've used in the system is rated at 240 volts or better, wire, swithes and all... it's a safe system and it's been totally reliable from the outset. It's not something I'd recommend to the person who doesn't have a handle on electricity though, because as you said it's always got the possibility of disaster if done poorly. But whether you agree with what I do or not, it is totally possible to make a system like this that is safe, regardless of what the Code says, as long as you know what you're doing and do a good job of design and implementation. Line and low voltage are mixed daily in almost everything we use- stereos, computers, etc. with no problem... safety is simply a matter of using correct parts in the correct way. Like it or not, I'm one of those guys who views the Code as something like a stopsign serving a 100% visibly gated driveway on a lonely road out in the middle of nowhere... It's probably there for some "good" reason but if it's 2AM, the gate's closed and there's no cars or people within miles, it's completely safe to run the stopsign even though a cop (the code) would disagree... Kind regards Gary Stadler | ||
| R.C.Bishop (128.123.62.199)
Rating: N/A |
Gary: What about the unsuspecting fellow that buys your coach from your possible unknowing spouse or other survivor in case of your untimely and definitely unfortunate demise? Food for thought. Course you could leave a note...  Code, or very close to it for me, thanx. RCB | ||
| Stephen Fessenden (Sffess) (65.133.76.88)
Rating: N/A |
All it takes is a warning placard to alert anyone working on the system to the dual volatages. I found my conversion has 115 volt AC circuits on a terminal strip in one corner of the bus 24 volt panel over the engine. I bought tyvek labels and laser printed a warning placard to some mechanic does not get electrocuted. "Warning 115 volt AC circuits inside. Turn off generator, inverter and unplug from AC before working inside this panel." I use the 115 Volt name for AC circuits on placards because it will not be mistaken for 12 volts ever. | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
But of course!! Actually since the 12/120 volt thing only involves a few of my major light fixtures, I could also easily rid them of the 12 volts and keep the DC ballasts for my next bus if I ever sell it! But in case I meet an early demise, I do keep documentation of everything I've done onboard, my own private "da book" as it is, even down to the proper sequence to dump the pooh tanks and why, because I'm sure someday someone will be driving it around without me, and I have a tendency to customize things I live with way beyond the average individual's stopping point. I've found that it's simple to document things so others will understand what I've done, including myself years later when I've long forgotten what I did. For instance, my last bus was a Superior pusher powered by a propane engine...I designed a few temperature controlled valves into the propane vaporizer's water circuit and netted myself a refrigerator that kept perfectly cold while driving, using cold water generated by the propane converter- ie I controlled it so that the volume going thru it gave me a constant 38 degrees output water, and ran that water thru some coils I added to the refrigerator. Worked perfectly but no-one but me could figure it out!! Yeah there are problems with "stepping over the line" but doing that sure makes things nice to live with when they're done properly!! Kind regards Gary | ||
| Don KS/TX (63.15.244.190)
Rating: N/A |
Although this thread has produced some very intelligent and interesting comments and opinions, I still fail to see any reason to have battery powered lighting in a coach of any conversion magnitude, other than trying to copy some stick and staple plastic palace RV (that never has an inverter)for some unknown reasons. I can assure you from lots of living in ours, we NEVER missed battery lighting. It seems to me that if you are going to have a "real" inverter, battery lights serve no real purpose. | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
Well Don, for me 12 volt lighting is very useful because my RV lifestyle has no inverter at all and I don't see why I'd ever want one. I've got four T105's stashed away in the bus, enough to run my 12 volt stuff for a couple of weeks, hooked to the engine alternator via a solenoid that's actuated by a combination of a dashboard switch hooked to the ignition circuit. So when my rig is travelling down the road I turn on the switch and the bank gets charged. When I'm "camping", the DC goes for the water pump, a few vent fans, the heater, and the lights at night... however "my" camping style is that I spend very little time in the RV, and lots of that time outdoors having fun, even at night. No TV, etc...the RV is mostly for sleeping and eating, and weathering out storms. Otherwise I'm not in it. If I need AC power I simply turn on my LPV genset- I carry 100 gallons of propane so it's virtually unlimited. When the genset's off, the only thing I need the 12 volts for is to flush the pottie, heat the place up a bit at night, or see my way to bed, so the 12 volt lights suffice quite nicely. So far I havn't even wanted an inverter or given it a second thought!! So for me the dual lighting works very well- in the boonies I don't have to think about what switch to flip or "did I forget to turn that one off" etc... and on the rare occasion when I'm parked outside of someone's home on shore power, the 115 takes care of everything just fine... Diffn't strokes... Cheers Gary Stadler | ||
| Don KS/TX (63.15.249.91)
Rating: N/A |
Sure sounds like you have a great setup to me! My wife would not go for that, wants "all the home stuff" all the time. I certainly agree, if you do not have an inverter, you DO need battery power lights. Kinda hard to run the dishwasher, 25 inch TV, washer, dryer, hot water heater, and house fridge all the time without an inverter. (OK Fred, I know you don't have all that "stuff" too):-( | ||
| Stephen Fessenden (Sffess) (65.130.9.0)
Rating: N/A |
Look at some of the small desk lamps and you will see that some are 12 volt halogen with a transformer in the base. Under cabinet lights are often 12 volt with a transformer. Since you will already have 12 volts available straight from the battery I can see no reason to use a transformer but you can use the same lighting used in fine homes. Same goes for running 120 volt lights with an inverter. Just one more thing to fail. If the inverter failed, I would like to have lighting keep working. There is nothing wrong with 12 volt lighting as long as you are charging the batteries adequately while plugged in. As far as bulb life, I have some non halogen 24 volt bayonet base bulbs with a 2000 hour life. 12 and 24 volt bulbs come in some nice sizes that allow you to have smaller fixtures where you want them. I have several custom fixtures that would have needed to be several inches deeper with standard base 115 volt bulbs. 12 volt bayonet base bulbs are easier to find than 120 volt bayonet base (appliance) bulbs. My wife enjoys having the 12 (24 volt in our case) lighting because it is always available. The swithches are all big rocker wall switches like home. If you are going to have a 120 volt refrigerator and turn on your generator when you leave home and leave it on till you return then you can get by with all 120 volt lights and I agree that the many thinline lights looks like they belongs in a camper. But you can have some fabulous lighting with 12 volt if you build you fixtues in. Each of mine is behing a 1/8" thick sheet of white translucent Plexiglass with a bronze colored alulminum frame flush with the cabinet work. Wow that was long. Point is in a nice house a back up lighting system is a luxury. In a coach it is easy to do, so why not have some of your everyday lighting on 12 volts. We have a 12 volt round flourescent in the shower. Would not want 120 volts there. | ||
| Don KS/TX (63.15.249.127)
Rating: N/A |
At one time I had bought a pile of those 12v Halogen also, but them lights do get very hot, and I decided I did not need anything that hot in there (fire hazard). Anybody want them? I think you don't understand the system Stephen, I have a 120v fridge, and rarely run the generator, in fact I did not even have one for the first year! The bus engine gives you more than enough 120v while driving, for the inverter, (charging the batteries as well}, and even running the roof air, and I can watch TV and make ice in the refrigerator for days when I park without starting the genset or bus engine, and then only a short while and it recharges the house batteries for more quiet time. Of course when you are plugged into shore, that is then just like sitting at home. | ||
| FAST FRED (63.214.92.45) Rating: N/A |
Thats QUITE a set up , most house fridges will empty a bat set at 150 to 200A per day , so after "and I can watch TV and make ice in the refrigerator for days when I park without starting the genset or bus engine, and then only a short while and it recharges the house batteries for more quiet time." I would expect a deficit of at least 600A,,, So I'm wondering how you pump back over 700A in a short time? Most deep cycles dont live long if charged over C 20% , what is the seceret? FAST FRED | ||
| Don KS/TX (63.15.244.30)
Rating: N/A |
I must admit I don't know the secret, only that it works. I had four L16 HD Trojan batts at first, now have only two 12v versions of the L16. I have not bothered much with the numbers, and have my Heart link controller set to save the batts. The Heart inverter charger does about 70 amps as I recall when the genset is running, I just watch the blinking lights, when it gets to float I kill the generator. I hate generators. Compared to most, we are not careful with the power usually. I suspect the fridge specs are not as valid as they might be. | ||
| Dummy (216.128.136.55) Rating: N/A |
Fred I can run a 22CF double door refrig.With ice maker For 32 hours on 2 8ds When they are fully charged. Have tested it so I would know | ||
| FAST FRED (63.214.90.158) Rating: N/A |
This use is fine , if you KNOW that the state of charge LEFT in the battery is over 50% , You need a fancy E meter or let the batt rest for a half day and use a hydrometer, to know what damage has been done Just running a bat down till the inverter kicks out is a sure way to have a 12 year batt set last 6 months (only a few dozen flatenings) , rather than 600 controlled 50% deep cycles {cheap batts }, to 2000,{Surette Marine ). Batts get destroyed by too deep discharges, and unless there Sams club , so you can get NEW ones after every boondock , it can get expensive!!! FAST FRED | ||
| Scott Whitney (66.82.9.25) Rating: N/A |
FF, What exactly does an E meter measure/calculate? Does the Heart Link 1000/2000/2000R have the same features as an E meter? Mine will measure voltage, amperage and then do some funky Puekert formula deal and give a rough idea how discharged they are displayed as 'amp hours' or 'time left' (at present draw). But honestly, I have been just going on voltage and trying to not go below 12.00v or so. How does one determine with some precision just what 50% discharge is? Scott | ||
| Dummy (216.128.136.133) Rating: N/A |
Fred The batteries are 4 years old and they weren't the rear expensive one when I bought them Have about 40K miles on coach in that time. | ||
| Don KS/TX (63.15.244.138)
Rating: N/A |
Scott, I don't think Fred is familiar with the fancy Link 2000R Heart Interface system we use, don't need no E meter for them, and I can set my inverter to cut off at how many amp hours use or voltage I want it to. Can't ruin anything that way, at least I have not been able to. Even the cheapie inverters have a low voltage cutoff, at least all I have had did. | ||
| FAST FRED (63.215.228.193) Rating: N/A |
An E meter or the similar Bogard unit was what the inverter guys copied so as not to reduce the price if their units. The more bells and wistles you add , the less sensative the price is to competition. Any system that measures the charge / discharge for a few times will let you read the batt cap in amps , or % discharged. % discharged ( after a few learning cycles ) is the best to use for long service life. You start with 100% full to cap of a KNOWN amp hours and just watch the gage! Dont discharge below 50% of the sets cap and your set will have a long & happy life ,( with care to recharge soon after going to 50% and of course keeping them watered.) Low voltage cutoffs are more not to fry the inverter , and most go to 10.8 or so. NOT a healthy place for a wet cell. Trojans can be run to 50% discharge about 600 times , and that would be a load of boondockin! FAST FRED | ||
| Tom Caffrey (Pvcces) (64.114.233.142)
Rating: N/A |
Don, I wouldn't be surprised if the L16s were what saved your fanny. Some reading up on how it all works could be helpful, but I think Fast Fred has done a good job of giving you the high points of the problem. We've got some L16s on our boat and you just about can't beat them. Part of the reason that you need a lot of battery capacity is your recharge rate from these big bus alternators could be very damaging to a small bank. While C/20 may be ideal, I don't think you want to exceed C/5 if there is any way to avoid it. With 200 amps available from the bus alternator, that implies that you should have at least 1000 amp hours of capacity. We carry over 1100 for that reason. With the large capacity, the Peukert effect will not be noticed readily, like with a small bank. Heart recommends that you figure on using only 1/3 of the rated capacity for good battery life, bulk charging from 50% to 85% before shutting your generator off. If you stay hooked to shore power for a time, the batteries will be brought all the way up. From 85% to 98% is done fairly rapidly and float takes care of the last 2%. We use the Link 2000 and it takes the guesswork out of state of charge. It can also let you know if a battery is going bad. A good meter may be expensive, but it's worth it. For what it's worth. Tom Caffrey PD4106-2576 | ||
| Tom Caffrey (Pvcces) (64.114.233.142)
Rating: N/A |
Dummy, I just ran the math on what you're saying that you did with two 8Ds. If I figured right, it's possible if two things are true. One, the average draw of your refer was only about 165 wats per hour, including the inverter losses. Without them, more like 150 watts per hour. Two, the 8Ds were pretty dead by the time you were done. This makes me think that it couldn't have been very hot out when you tested the batteries. If you were trying to save your batteries, you would want to recharge them within 16 hours on the first day and within 11 hours each cycle afterwards. Our target for boondocking is a week without the generator, if we can make it. But that does mean being reasonable, and using propane for the fridge for other than overnight stays. Electric powering of the fridge is not part of the plan, because we would rather not use the generator. I would have called you something else, but you didn't leave me much choice if I was to respond to you. Tom Caffrey PD4106-2576 | ||
| Dummy (216.128.137.242) Rating: N/A |
I diden't mention that my frig. has 3 exter inches of foam insolation on all sides except front and it wasen't opened in the test. So this reduces the time it runs.And the frig was about 3/4 full The inside tempin the coach was around 78 | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
I second that. I have an OLD big dometic fridge that I glued 2" of extra insulation on (to both sides and the top) I can turn it off for almost 12 hours and the freezer is still frozen, the cooler is still plenty cool. With good enough insulation and keeping the door closed, there's no reason a fridge should have to use a ton of power to keep food healthy... Cheers! Gary Stadler | ||
| Gary Carter (206.144.20.83) Rating: N/A |
Basic question is how you use a refreg without opening the doors? BTW our new (to us) coach has a 20 cubic foot amana side by side. With 8 (watts unkown at this time) solor cells (max seen so far of 15amps) on the roof the invertor shut down at 11.8 volts in about 36 hours. The house is powered by 6 8Ds. But we also were watching TV, and just generally living. | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
Philosophy Change: I recently aquired an "intelligent" 12 volt 55 amp charger/converter from Progressive Dynamics (including their "charge Wizard") ( http://www.progressivedyn.com ) installed it, and fell in love. It's small, smart, quiet, takes excellent care of my house batts, and it easily powers everything on my bus while I'm plugged into shore power. So I decided to can my mixed 12/120 volt lighting system and convert it to 12 volts only. I went to New England Solar and got four 12 volt DC 40w fluorescent ballasts (40W 12V DC ballast #850-040 $27, 1-800-914-4131) and replaced the 120 volt ballasts in my larger fluorescent fixtures, then I got some really nice (new) 9 watt fluorescent screw-ins from "The Engine Room"store on ebay for ten bucks a pop to replace all the lightbulbs. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2057607331 Hooked it all up, and along with the 12 volt lamps I already had in the bus, I'm immensly pleased. No more having some lights that don't go on when I'm not on AC power, and for those of you who don't like mixed voltage systems in the same box...well...you're safe now if you ever decide to visit my bus!! I originally did the mixed voltage thing because I wanted 40 watt fluorescents here and there..I have to say, the DC ballasts are perfect. besides coming on more reliably and faster, they weigh many pounds less than those old tar and steel monsters.... Cheers Gary Stadler | ||
| Scott Whitney (66.82.9.14) Rating: N/A |
Hi Gary, Any idea how efficient the 12v ballasts are? (compared to AC ballasts) Scott | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
Scott,I just stuck my ammeter in series with two of the ballasts, and as usual, electronics rules!! Two 40 watt lamps on 120 volts AC draw 80 watts, equivalent to 6.66 amps on 12 volts. But these two DC ballasts illuminate the lamps just as brightly and draw a mere 4 amps... two amps each. So effectively they are very close to twice as efficient as 120 volt ballasts. Makes sense, because as fluorescent lamp excitation frequency goes up, so does illumination efficiency. These ballasts run at 20khz+.... Lamp life goes accordingly down at higher excitation frequencies, but the amount of use these will see in my bus means I will probably never see them die. So figure it this way- running them at almost twice the efficiency on 12 volt DC ballasts vs running your batteries thru an inverter (-10 to 15% gone right away) and then 120 volt ballasts at almost half the efficiency, yer house batteries will go more than twice the time with the 12 volt ballasts. It's a no brainer!!! Cheers Gary | ||
| Driving Miss Lazy (66.190.119.82) Rating: N/A |
Gary, unfortunately you cannot really go by the AC amps measured by your ammeter to calculate watts. Since the ballast is an inductive load, the power factor may be quite high which would throw off your calculations. Watts calculation for AC loads is volts times amps times power factor. The power factor may be 0.7, which would reduce your calculated watts by 30%. Richard | ||
| Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A |
Um, on AC, 40 watt lamps simpy draw 40 watts each right? And on DC, power factor doesn't exist... I used a DC ammeter for the DC ballast but for the AC lamps I simply read the ballast label... It says .77 amps/ high power factor, which actually calcs out to 92 watts for two lamps...since "high" power factor isn't actually spec'd with a number, I'd guess it's still very close to 80 watts... Cheers Gary |