Electronics upgrade

[Ralph Cramdon]

Greetings to one and all,

   I'm new to this forum. I come here in search of knowledge, failing that humor will suffice. Since becoming disabled 4 years ago I saved enough to purchase a 20-year-old Winnebago (wcn23rc). I seek to upgrade the electronics to a modern level on the cheap.

   As I can't afford much campground time and I like to fish the thought of a simple floating water wheel generator soon came to mind. After a few weeks of crunching numbers a short internet search for parts lead me to you. Here possibilities abound.

   My old Winne doesn't have an inverter (dc to ac) it only has a converter (ac to dc). It relies on the main engine or the Onan generator for battery recharging. Since I still like to play Doom or watch a movie I'll need an inverter to prevent wasting fuel in the generator. Building an efficient modern inverter from scratch isn't beyond me. I have several hundred pounds of sub systems, power supplies, circuit boards, back planes etc. I even have an old main frame computer (Fortran) that still runs.

   Researching chargers for my (true) deep cycle batteries revealed terms and stages I haven't heard before. My knowledge in this area is seriously lacking. Between the cost and the fact I'll spend most of my time east of the Mississippi solar power isn't feasible right now. This brings me back to the water wheel.

   I would appreciate any and all input. Make it as technical as you wish. Uncle Sam taught me to repair missile systems. Afterwards I spent years servicing/repairing Catscan's and MRI's. Funny thing, after a bump on my head they won't let me repair CT's or MR's anymore. Who'd have thunk? These days I have to read very slooooowly but I'll eventually figure it out.

Thanks again

[picmacmillan]

hello and welcome....i also have an old motor home....we call it the green machine because it is green and every time you pass a bank you have to go in and get money for gas....anyhow, a couple options came to mind during your introduction...you will need some good flow of water to make that happen...what about wind?...thats what a lot of folks including myself have they are relatively cheap to build..i think mine came to 17.50 canadian per panel to build....i did what you're doing and have ruined a couple good batteries in my motor home by deep cycling them too much....anyhow, give us a little more info on what you may be thinking?...take care...pickster

[deerslayer660]

  yea i got one thouse to havent moved from yard in 3 years went down in size to a 3/4 ton streach van with a invalid high top roof  micro wave on a interverter stove top furnace refridge small sink  best way i found to charge battery is to disconect van bat  put batery voltage on feild wire and high charge a hour or littel less

  george

[troy]

One of the key issues is if you have any loads that are sensitive to the sinewave quality.  If you don't have loads that are too fussy, you can get low end "modified square wave" inverters for dirt cheap.  Probably less than you could buy the components.  Even higher quality MSW inverters aren't that expensive.  

However, if it absolutely positively has to be "pure" sine wave, that's a whole different ball game.  They are many times more expensive than the MSW versions.  Home brewing a full sine wave machine is not a trivial task, even for the sophisticated designers.  There is a group on the board that is working on a home-brew open design pure sine wave inverter, but I don't think they're quite finished yet.

I have an Exeltech 1100 w. inverter that has never burped once in 18 mo. of continuous use.  They don't have a lot of features, but what they do, they do perfectly.  

Good luck and have fun!

troy

[Ralph Cramdon]

Hello again,

   I tend to get distracted. I guess my original inquiry should have been more specific. I'm planning a 5-month trip in my motorhome. This is what I've done to my 20-year-old motorhome so far and why.

1. I've replaced all 1-gauge wire between my Onan generator, power distribution/converter box. battery box [containing main engine battery and 1 true deep cycle battery (its weight is127 lbs. with a R/C of 380 minutes)] and main engine compartment.
   
2. I intend to replace all 8-gauge control wiring for the same reason.
   
   

Reason - electron depletion. With age/use a conductor loses free electrons, resistance goes up, heat goes up, insulation starts to fail then old houses have electrical fires and burn to the ground, in my case motorhome.

   I'm also using a grinder with a wire wheel and taking off all rust/paint to the bare metal. I then painted with marine grade primer and came back with a hard enamel topcoat. All fuel lines, brake lines and wire harness covers got the same treatment or were replaced out right. The LP system is next. I do tend to be thorough.

Here is the information I seek in order of importance.

1. Deep cycle battery-charging information.

   I spent sometime researching batteries. This paid off because I didn't purchase batteries that are "called" Deep cycle Marine/RV. These aren't true deep cycle batteries. They are hybrids. The R/C time is the clue, a hybrid has only 100 minutes or so of reserve charge.

   In this research I learned that old fashioned "trickle chargers" cause premature battery failure. They tend to "cook off" the first battery in a chain. This was the case with the batteries that came with my old camper. New modern chargers have 4 stages. I could find no detailed explanation of these stages or how to construct such a device. Does any one have these details along with the math?

2. Water wheel concept.

   As I stated earlier I plan a 5-month trip. My funds are limited. Over the course of the trip if I could shave off 10% of the fuel cost of battery charging it be great. Plus I have 2 bedrooms full of old catscan and computer parts. I have to use them for something. I even have tetrodes that weight 14 pounds. They were used to amplify and regulate 150KV. They make great paperweights.

   Back to business, the design I have for my floating water wheel was simple. When traveling it can be flipped upside down and mounted behind my rooftop air conditioning unit (a decent airfoil). Again I'm only looking for a small amount of free electricity. Charging from the main engine bleeds off 1 or 2 horsepower hence fuel.

   Any input is appreciated.

3.  Inverters are my next subject of inquiry.

   My motorhome only has a converter (ac to dc) for charging my batteries from my Onan generator or shore power. I thank "troy" for his input but ask if he could be more detailed about perfect sine wave inverters. I will be running a very good computer I built. It'll be integrated with a satellite/entertainment system. Neither the microwave and toaster oven need clean ac.

   This brings up another thought I had. Why convert dc from my batteries to perfect ac only to have the ac converted back to dc? Most modern electronic equipment takes 120 volts ac and then converts it to 12 or 24 volts dc to be useable in the unit in question. Why not just build a dc power distribution panel then add a few resistors and chokes? It seems like a wasted step to me. Does anyone have any ideas? Am I over looking something?

   I know it gets a little tricky with equipment that need several different dc voltages. Still, why not just add a special power cord for your equipment to be used in a RV? If on battery power for a few hours the actual voltage would change over time. A simple feedback loop for control comes to mind. There would also have to be a bottom level cut off. If you want to get fancy and want to see the end of the movie you were watching without interruption it wouldn't be to difficult to have the ac generator power up and switch over automatically.

   You need to be able to switch from the dc panel to an ac panel when running your generator or when you're connected to shore power anyway. Again, any input will be appreciated.

4. I'd like to ask pickster to expound a little on air power and the ?panels? he mentioned. I'm confused a bit on this matter.

Many Thanks to All!

[DanG]

BTW your situation and mine are alot alike, but I have a pick-up truck already so am on the hunt for a good travel trailer. Where is your destination for this walk-about, er, drive-about? I've been threatening to run away to Alaska for a couple of years now

http://www.rv.net/forum/index.cfm will overload you with minutia on full-time RV living if you haven't seen it yet.

>>Most modern electronic equipment takes 120 volts ac and then converts it to 12 or 24 volts dc to be useable in the unit in question. Why not just build a dc power distribution panel then add a few resistors and chokes? It seems like a wasted step to me.

I know you know 120VAC switching power supplies isolate the electronics & have demand surge capacity. Without isolation electronic noise of a refrigerator door opening w/ light blinking on would be seen as a nearby lightning strike to your PC mainboard power regulation system. Your 5V rail on mainboard can demand 25+amps within a few clock cycles or else throw data errors. If you are worried about 10-15% losses of DC--> AC--> DC I'd sell the homebuilt desktop and get a good notebook

[ghurd]

1 Bulk-Taper-Float-Equalize.  How much or how long depends on the battery chemistry and amp-hour rating of the battery. The battery manufacturer can provide specific information.  I personally believe most bulk amperage ratings are too high.  100 amp-hour true deep cycles are made, but they don't weigh 127 pounds. Most trickle chargers are not voltage regulated, even the ones that claim 'automatic'.

An alternative to B-T-F is Pulse Width Modulation.

2 There is not as much power in water as most people think.  The water must be moving quite fast or under considerable pressure before there is much potential.  Fishing water is not going to have much if any potential. To get even a trivial amount of power is going to take a large device that will be difficult to set up, if there is even a location for it at a camp site.

It would be an expensive proposition. Steel, bearings, machine work, cables, pipes, wire to the battery...  And it would be big and heavy.

What the toaster oven uses in half an hour, a portable water wheel couldn't replace in a week.

The drag of the thing on the roof would use more gas than it saved in the Onan.

3 Inverters power about everything. They are not too expensive.  If the inverter qiuts, get a new one at Radio Shack, or the auto parts store anywhere.  

If the cell phone needs 3.7 volts from a homebrew device that quit, the parts are not cheap or easy to find for that on a camping trip, even if all the meters and tools to build it are in the camper.

4 Pickster means build a small windmill generator or buy solar panels. I agree.

The windmill only works whan it is windy. The solar panels only work in the daytime.

Either (or both) is going to make a lot more power for a lot less money and aggravation than a portable water generator.  

I would go with solar. Camping is usually a summer activity, with lots of sun. Campgrounds I have been to are protected from wind somehow (trees or geographically).

Click 'hydro' at the top of this page and read through the posts.

Limited funds and saving fuel almost lead to conservation. 12vdc compact fluorscents would be an effective start, with much more light AND much less power.  Our host sells them at wondermagnet.com at the top.

G-

[troy]

The vast majority of computers don't mind MSW (modified sine wave, which is really just glorified square wave AC.).  Some audio and video (TV) equipment will produce some hum or whine, or picture artifacts if operated on MSW.  No big deal to most folks.  Some chargers for battery powered tools don't like MSW (they fry right away).  AC electric motors tend to run a bit hotter on MSW, and less efficiently.  Your mileage may vary.

You're way ahead of the game on batteries.  So called RV/Marine deep cycle batteries are absolutely NOT deep cycle and will die a painful early death in deep cycle applications.  The key issue with more sophisticated chargers is that they charge quickly up front, and then taper down as the battery nears full charge.  Once charged, the charger just adds enough to replace self discharge in the battery.  Cheaper (dumb) charger just reduce to some "safe" low charge rate.  It doesn't take into account how big the battery is, or what the temperature is, or how old the battery is.  

Good chargers are also generally temperature compensated with a probe on the battery itself.  The voltage at which a battery is fully charged is temp. dependant.

Anything you can run directly off your DC source, you will be ahead of the game as far as efficiency goes.  Most inverters are only 80% efficient overall.  However, it may become too much of a hassle to provide for all those different DC voltages, and there are efficiency losses in DC/DC converters too. You might be ahead to just go with the inverter if the majority of your loads don't match your system voltage (probably 12V nominal.)

Solar panels are pretty much plug and play. Put them in direct sunlight, electrons magically flow. No moving parts.  You will need a charge controller to prevent overcharging.  Photovoltaic panels are not cheap though.  Typically $4.00 per rated watt of output from a good dealer, and "rated" really means under best possible lab circumsances.  So if you decide you really need 200 watts of output from your panels, I would buy 400 watts worth, as far as the rating goes.

If you want more (lots more) of an education, there's a free periodical you can download at:

www.homepower.com

They also list lots of vendors that carry all this kind of renewable energy stuff.

This board is also a tremendous resource for home brew stuff in general, and home built wind turbines in particular.  

Normally, a build it yourself wind turbine to make electricity will be cheaper per watt of output than the solar photovoltaic panels.  Depends on your shop skills, sunlight resources and wind resources.  Some do both.  If the sun isn't shining, it's often windy.  They complement each other.

Sounds like your motor home will be better than new when you're done.

Good luck and have fun!

troy

[picmacmillan]

looks like a couple of my lines went missing....firstly we all build wind generators for around 350 bucks...they generate tons of electricty...you could build a 4 footer and use it whenever you stop..like hugh piggots book...also there is a guy on ebay selling solar cells...you have to do some work but you can make your own solar panels...go on ebay if you're interested and type in broken chipped solar cells...this will take you to his site...we made solar panels and each one has app. 46 watts per panel,,per hour..(with sun of course)and i made 7 panels with my 5 pounds of cells...i did the math on mine and it cost around 17.50 per panel to build...we live in canada, if you live in the states it will be much cheaper as you don't pay the brokerage and duty and all the fees we do! :)pickster

[Chiron]

>   This brings up another thought I had. Why convert dc from my batteries to perfect >ac only to have the ac converted back to dc? Most modern electronic equipment takes >120 volts ac and then converts it to 12 or 24 volts dc to be useable in the unit in >question. Why not just build a dc power distribution panel then add a few resistors >and chokes? It seems like a wasted step to me. Does anyone have any ideas? Am I over

>looking something?

Most desktop computers, monitors and TVs along with some VCRs and other devices rectify the incoming AC and charge a cap or caps to 180V or so, then use switched mode power supplies to get the voltages needed. If you used a DC/DC converter to generate 180V to charge the main caps in the PS the frequency and waveform wouldn't be much of an issue but most of the above use a standby circuit that's active even when the unit is off.

XT supplies have a "hard switch" built into them that turn off the incoming AC while TVs and such usualy don't, when you hit the on button it enables the main SMPS rather than do any high voltage/power switching. The caps are charged whenever it's plugged into AC if it doesn't have this switch,

The method I used to discharge these caps when I was in the Audio/Video repair business was to plug the unit in, turn it on, pull the cord out of the wall/isolation transformer. That usualy drops the voltage on the caps to <80V, still bite you but probably won't knock you across the room, A high wattagge resistor of 10 Ohms or so should be used to discharge it the rest of the way. That or wait 30 mins or so since most will self discharge but I'd still check with a voltmeter before getting my fingers in there. The screwdriver across the terminals is a bad idea

I've been doing this kind of work for 20+ years and have had my share of shocks and burns. I've learned to treat electricity like I would a firearm, loaded until proven otherwise and disabled.

On XT computers it's +5V and on the PS I've got pulled apart here it uses a resistor to draw power from the AC line to feed a seperate SMPS for the standby voltage. I haven't pulled many XT supplies apart so someone else who has may be able to give you pointers on this or you could pull your's apart and see how it derives it's standby voltage. Older and "budget" TVs and monitors usualy use the capacitive coupling to the AC line to get the stanby voltage. Some newer units just use the +180V and a small SMPS.

Voltage used varies by make but since most drive a small microprocessor/controller it's usualy +5V. A small fixed voltage regulator like an LM7805 could be used for this from your 12V with a minimum of fuss.

My prefered method for building DC/DC converters uses hand wound torroidial cores since my main hobby is Shortwave listening and I want to keep RF interferance to a minimum but ferrite pot and E cores are easier to wind if RFI isn't a big concern.

HTH

.

[Ralph Cramdon]

   Now that my screwball ideas are out of the way I clearly see the path that I must take. Thank you "ghurd" for your input. Your advice is sound. Do you have any preferences as to battery charger brands? Thanks again to "troy". I pose the same question to you also about charger brands and inverter brands.

   I'm going to have to add items in stages. The old Winne needs lots of work. Anyway, this is why I'm turning over every rock I can find in hopes of saving a few cents.

   The motorhome has 47k original miles. The tires are new, both A/C systems have been rebuild in the last year. I changed plugs, plug wires, distributor cap, a complete tune up along with all belts and hoses on the main engine and Onan. I had a cousin (who owns a transmission shop) pull the tranny and verify everything. I rebuild the carburetor on the Onan generator. I used a tiny camera to check a few of the valves in the main engine and dropped the oil pan and checked the bottom end. Everything is sound and I have no leaks in seals or gaskets.

   By April I'll have finished all the replacement wiring, rebuilt the suspension and replaced the refrigerator. I hope to have a quality charging system installed also. I'll be ready for my first road trial. I'm trying to hookup with tornado chasers in Oklahoma for 2 weeks of run and gun. I want to be sure the Winne is up for a 7000-mile road trip starting in May. I might add this one will be at a sane pace.

   Again many thanks to one an all. I needed my screwball ideas labeled as such and a course correction for what I really need to focus on. I'll be posting the solar area as of today. I purchased 5 pounds of cells from ebay.

   If you see a 20-year-old Winnebago come through your town that sounds like it has a 454ci with headers and a 4 barrel flag me down and I'll buy you a cup of coffee. (Bama plates)

P.S. Does anyone have ideas on how to get an extra, extra large Birkline recliner into a 23ft Winnebago?

[ghurd]

Some people like those 'smart chargers'.

Like Vector from Wal-Mart or Schmucker (sp?) from lots of places. I'm sure there are others.  I would go with a brand name.

I don't have one.

I believe they have a 2-10-20amp setting, a 50a boost (for motor starting) and a switch for regular or deep cycle batteries. Some models may not have that many settings, others may have more. I did a quick search of the board, there is more info.

With shore-power, I believe slow charging is better. Not more than C/20, if you have the time (2 days?).  C/20 is capacity in amp-hours divided by 20.  100ahBat/20=5amps.  Meaning if you are in a place with shore-power, use it for charging the batteries and running the loads.

If the solar or wind puts out more than that, fine! Take it while you can! The controller will watch whats going on and protect the battery.

G-

[troy]

Howdy,

Grid powered battery chargers really depend on how big your battery bank is.  Mine is eight golf cart batteries.  Since my battery bank is rated at 450 amp hours at 24V, my C/20 rate is 23 amps.  There's no way I can get that out of a regular $50 charger.  So I got a very nice sophisticated charger from Arizona Wind and Sun.  It was well over $200 though...

If you have a smaller capacity 12V battery, you can get along with a much smaller charger.

I have had terrific luck with my Exeltech XP1100 pure sine wave inverter.  Not a bad price for a full sine wave inverter, but still not cheap.  If square wave will work for you, any cheapie will do, some have better guarantees than others.  I think you'd be doing well to get a year of full time use from the low end MSW inverters.  But hey, they're less than a hundred bucks and you can waltz into any Wal-Mart and pick one up.

Good luck and most especially, have fun!

troy