Increasing power to coach/inverters/wiring/solar

[Faderz]

Sent: 3/31/2003

I'm looking for upgrades to do for the summer and was considering beefing up the coach power. My 1973 20' Minnie came with an 85 AH house battery and the existing charge/converter. While I don't plan on going to an inverter that would cost more than the rv, I'd like to be able to run a TV/VCR and still have lights and water in the morning.

My battery compartment under the former dinette can probably house a larger 12V. To go to 2 6V golf carts would require moving the battery area to the unused generator compartment. Here are my questions:

- What gauge wiring should be run to the battery isolator? (The current wiring from the alternator and charger to the isolator looks like 16 guage - small. I wonder if I'm not sufficiently charging the battery.)

-Will a PROwatt 600 (600 watt) inverter be sufficient and what battery setup is recommended? (I don't have sat tv, and only want to watch a movie and some news. Power is also needed for the water pump and lights.)

-What's FULL for a battery? 14V? 12.8V? (Phreds Poop Sheets seem to differ from the nfo available at the inverter website, xantrex.com.)

Thanks!

[MSN Member]

Sent: 4/1/2003

well, the wire first: My solar panel came with 10gauge wire for running to the isolator, but they suggested using 8, which I did. The longer the run to the battery(s), the thicker the wire should be, but I don't think you'd go wrong never using anything for your battery smaller than 10 gauge.
As for when a battery is full.. it's full at 12.1 or 14.7, or at whatever number above 12 it wants to stop at. "12 volt battery" is just an easy way to describe it...it's rarely ever actually 12 volts. Usually, I believe, it's more likely to be somewhere above 14v.
I gather you've been to phreds. He also has a chart, I believe, for figuring what inverter you'd need. If you haven't read his "inverter" stuff, that's a great place to start!
I suspect you'll find a 600 inverter about half of what you'll want. But... what are you going to use for a power source? One 12v battery won't run even a 600w inverter for very long (if at all!) and your power in the morning could leave you in the dark. You'll want those two 6v batteries pretty quickly, I think.

[Boat Nut]

Sent: 4/1/2003

First of all make sure that whatever size battery you decide to install; make it a deep cycle. 12 volt batteries come in #24, #27, #4D, #8D. The 4&8D sizes are commonly used as diesel starting batteries, but that won't be a deep cycle that you need. An engine starting battery is designed to put out a large ammount of current for a few seconds to start an engine and then it is instantly recharged after the engine is started. Drain it flat one time and it will never be the same again. A deep cycle can be drained as you would in boondocking and recharged many more times. Actually it is best to not completely drain either type battery, but deep cycles hurt less.

If you put in a large battery, you will want to have a large charger. I would think 20 anps or more, otherwise it will take too long to recharge.

Chuck (73 Brave)

[Faderz]

Sent: 4/2/2003

Does anyone use an inverter with just a single battery? I did find one very large AGM battery on sale online here: http://www.store4power.com/factory-outlet/factory-outlet-batteries.asp?. Unfortunately, the shipping is really expensive, but the battery offers 205 AH - about the same as 2 golf carts for just $150. They also have good deals on inverters and I'll check phreds calculations, but my power needs are very modest (hey - I was a tent camper a year ago).

My rig is in the shop right now having the exhaust manifolds machined and I'm going to ask my mechanic about the battery charging wiring from the alternator and charger. I will make sure it's 10ga or better. I'll also see whether it is capable of 20 amps. My limiting factor is the size of the battery compartment. They definitely made it to house a single battery. What sort of house battery setups are people here using? Has anyone moved or modified the compartment?

[MSN Member]

Sent: 4/2/2003

Faderz..lol... not too long ago, I was a tent camper also...then a tent TRAILER camper, then a RV camper, and I suspect you'll find your needs increase just a bit after you get inside those walls. Not because they NEED to, but because it would be nice to have a few things.

The difference in price between a 600 w and a 1,200w isn't all that great, especially since you might have to figure in something bigger than 600w in a year or two, so the price of the 600 would have to be considered in the price of the bigger unit to replace it. For example...a microwave is really great when you're boondocking, but a 600 just can't quite manage it. Especially if you want to watch a ballgame & eat at the same time.
Anyway, my sincerest advice would be to get the biggest inverter you can afford, and figure out how to get battery power for it. I've gone to solar and two 6v, and I'm looking at a bigger inverter.

As for the battery space, I also have a 73 brave, but I have room for 4 batteries in that space. (Right behind the left front wheel) In fact, I have two 6v's in there and two starter batteries. I keep one of the starters disconnected, as an emergency backup. If I go to a 1200w inverter I may put another 6v in there and take the backup starter battery out.
Winnies are "Home Improvement" related. They're always about "More Power!" LOL

[MSN Member]

Sent: 4/2/2003

When I put the 120w solar panel in, and got the two 6v batteries, I knew the day would come, but I wasn't really quite ready for it...but faderz's post got me back into the inverter mood and I bent the plastic enough to order one. I'm SURE it's more than I'll ever need... but... since "I" might want to pop popcorn and watch the game at the same time, out in the middle of the desert, I went for 1750 w. It cost three bills, which really isn't that bad for what it does. No more generator just for the microwave...and in fact, I'll probably never take the gen back out with me again. (I already put the AUX fuel tank in it's space, anyway)

I can still use my 300w inverter if I want, off the regular 12v battery, as long as I don't drain it. (And if worst comes to worst and I drain all three batteries: two carriage and one starter: I still have not only the disconnected emergency starter battery, but I always carry a portable power supply that can start the RV itself.) Can you tell I drained my batteries the first time I went out to the desert in the RV?? Never again!

[Faderz]

Sent: 4/3/2003

Most of my camping is in the desert also. Borrego (So. Cal), Death Valley, the Cal-Neva area (up the 395), and Nipton, California (try to find it!). I thought of solar power, but then realized that I never intentionally park in the sun all day ). I think the 2 golf carts is what I'll do. They'll probably go in the Gen compartment out back if I can run that far from the alternator (mine is a class c Minnie). Where'd you get the inverter and what type is it? 

[MSN Member]

Sent: 4/3/2003

faderz; I got the inverter from the link YOU posted, lol. "Store4Power" I ordered the "XPower Inverter 1750 Plus". I compared the "Portawattz" and a few others, but thought for the price this was best for me. I could've gone with the 1200 for two bills, but thought it might be a little too close to the upper limit of my needs, so I got the extra 550 watts just to be safe.

I've always used a 'stand-alone' gen for power out in the desert, but I hated making all that noise since the peace was a big part of what I enjoy, and I limited my power usages to keep from making all that noise. Now, with the inverter, I can -quietly- enjoy both the peacefulness of the desert and the ease of a microwave. And since I try to have a back-up for most things, with the inverter my refridge won't warm up if I should somehow lose all my LP gas. I can just change to electric and run a cord to the inverter. Even if I only run it often enough to keep it cool, it would be a big help. Not to mention, on long drives I'd rather have the inverter cooling the refer down than LP, which can be especially dangerous when driving.

Just to be safe, after I get the inverter installed, I'll disconnect from Shore power and plug the reefer into the Inverter and see how it affects the battery and how well the solar recharges it. I'll set it up in my driveway as if I was in the desert, using the TV and microwave and lights MORE than I would if I was actually in the desert. If the solar can keep it charged that way, I won't worry at all when I'm in the middle of nowhere. Well...I always worry a little, lol.

[Faderz]

Sent: 4/27/2003

I've completed this upgrade and the final setup is:

- 2 Trojan T-105 golf cart batteries ($80 ea)
- ProWatt 400 Inverter ($80)
- BatteryTender (.com) Maintainer ($40)

I located the batteries in the generator compartment and am running the BatteryTender 24/7. It seems like a cool, little 3-stage charger which should keep them in good shape for a long time.

I'm ready for the summer road trip! Just one or two more final tweaks...

[Faderz]

Sent: 4/28/2003

The charger is a surprise as it's only one amp, yet it can be run continually and it works the batteries while they're, otherwise, just sitting.
 
(Now I want to pull out this crappy old Dometic fridge that I'm hauling around and replace it with one of those 12volt coolers... )

[Faderz]

Sent: 4/29/2003

Last night I took the rig to the local Walmart and stayed overnight, using all of my normal powered items PLUS a 13" TV/VCR. I watched "Tombstone" on video, and in the morning still had 12.47 volts. I believe I could probably watch three or four movies before I was actually deep-cycling the batteries. The 400 watt inverter will definitely power anything that I would want to run off of these batteries. If I need more power, I'll stay home on the grid 

[melyash]

Sent: 4/29/2003 

Good Idea Faderz.

I was going to go into the fact that you should rarely if ever discharge your batteries below 50% since even for deep cycle batteries this shortens thier life considerably. Most alternators and chargers are pretty fast at charging up to about 80% of the batteries capacity, but after that they taper off rapidly to avoid exceeding the Gassing Voltage of the battery. The last 20% as you posted is the slowest, with it taking upwards of 10 hrs to get the last 20% into the batteries. Some High end chargers like the Xantrex 10 and 20 series charge at a high rate, and turn it down as they approach the "max curve", they will charge faster than a maintainer, but cost significantly more as well. So according to my favorite book on the subject, Most of the time your working with only about 30% of your battery. This being the part between 50% and 80% of the capacity. The nice thing about solar is that it just keeps trucking, charging that last 20% of the battery long after the engine or Genset have been turned off. (yes, providing there is light outside). So you can use the alternator on the engine or the generator to give you the 80% (though the engine alternator is not very fuel efficent) and then turn it off and let the solar do the rest.

A single high output panel during the peak charge periods, can output up to 6 amps, and the peak period as I understand lasts about 4 hours depending on orientation and weather etc. You can also add a charge booster which as I understand it, converts excess voltage from the solar cels to additional amperage which gives up to a 30% increase in output amperage. I have a genset, but the charger I have is not up to snuff, so I will be looking at a newer faster charger for my unit soon.

The bucks I spent on my rims and tires would pay for two or even three panels for the roof of my rig,  but safety first efficency second, I will have to wait for a while to see how we do after the new budget at the state is signed. I to make sure I still have a job.

Three things for improvement on my rig, Towbar install on Grand Cherokee, Brake system for same, and a Solar system or a high output charger for the Electrical system. Amy one of these will cost almost more than the rig itself.

On my rig currently (no pun intended) I have 2 12V 115Amp Interstate Batteries currently installed and a Die Hard 850CCA start battery. I look forward to working on the battery tray because I think with a little work I can slip a larger set of batteries with more capacity in without too much trouble. I have the room, It is just that the wood blocks that are there are constricting the size batteries I use presently. But at the same time with the amount of weight I have on that tray already I wonder If I will be able to get it slid out with the bigger batteries. We shall see.

Matt

[Faderz]

Sent: 4/29/2003

I had written off solar panels since I always try to park in the shade. I'll have to think back to see how often solar would work for me. Maybe... The BatteryTender is also an intelligent, 3stage charger. I can see the advantage of that type of charging without a hookup.

[Collyn down-under]

Sent: 4/30/2003

Re discharging deep cycle batteries.

Matt's comments are quite right, 50% is the optimum, but it's essentially a matter between you and your bank manager. Discharge to 50% and you'll get about 500 charge/discharge cycles. Discharge to 20% and you'll be lucky to get 100 cycles.

The important thing to bear in mind is that standard vehicle charging systems effectively cut out at 70% charge. So if you discharge to 50% - then you only have 20% usable capacity!

There's heaps of ways around this - but needs a book to explain them - that's why I write them!
There's a fair bit of advice re this on my website
www.caravanandmotorhomebooks.com
Collyn down-under

[Faderz]

Sent: 4/30/2003

Collyn,

Maybe you can explain the amp-hours vs. running minutes thing? I appearantly have doubled the running minutes by having the two 6 volt batteries (to 900), yet the amp-hours remain at 225.

[mightybooboo]

Sent: 4/30/2003

Solar boost 2000....real world numbers
Just got back from a 4 day solar test,these are the results
with boost off I had 6.15 amps,with boost on got 7.1 amps at 10 AM
with boost off I had 7.1 amps,with boost on I got 8.1 amps between 11AM-1PM
My panels pull 8.9amps(2-BP275 panels,75 watt/4.45amp each) at maximum rating,real world flat mounting got me 8.1 amps.With refer on 12volt and fan for furnace on to pull the max panel output of 8.1 amps.Batt stayed fully charged with 1 amp charge at no load.
Solar boost real world,70 degree outside temp gave me about 15% boost in amps.3/4/99 solar boost was purchased at 219.00 US dollars.
BooBoo

[melyash]

Sent: 4/30/2003

Thanks for the data Mightybooboo, those are great numbers and are alot better than I can get off the MFR sites! Sounds like you have a winnner there!

Matt

[mightybooboo]

Sent: 4/30/2003

Matt,
I am truly jazzed with the results I got on the solar test.I have room for 3 more panels and the solar boost 2000 handles just over 20 amps,which is exactly what the 5 panels will produce.When I get the batts properly upgraded this thing will be toooooo nice.Ive been smiling since I got home,solar works great in these rigs.
Boo


Edit: 
Make that 0.1amp charge to batt with no load, batt full charge.
Boo

[Rick Shaw]

Sent: 4/30/2003

I thought that you were supposed to drain your deep cycle batteries to make them work better.   That was the scuttlebut.   
How about the    "dual" and "mom" switches....I think we need to put to rest the position of the switch when you are driving.   Anyone have the correct answer for this?
Rick

[mightybooboo]

Sent: 5/1/2003

Dual charges both the house and motor batteries when engine is running.MOM is for momentary,hold it in that position to send house current to the engine battery for starting if engine battery is low or dead.If alternator is dead you can hold switch in the mom position and send the house battery current to the engine battery and keep running the motorhome,and I would ?guess? you could also run the genny to charge house batteries and use that as an alternator replacement to get you home or to the auto parts store if the house batteries are dying,again while holding the switch in the mom position.And no remarks about the Mom position you perverts!Do NOT leave in Dual position with engine and genny running,I hear it back feeds to alternator,yet then again is that why the switch has a fuse?
Yeah,we deep cycled the engine battery real well with our leave the key on stunt.
BooBoo

[Collyn down-under]

Sent: 5/1/2003

Two quick responses.

Faderz re amp/hours. Electrical energy is best measured and visualised in watts.

One watt equals one amp times on volt.

Thus, a 100 amp/hour 6 volt battery can also be described as a 600 watt battery. If you connect two of the batteries end to-end (i,e series) then each is still a 100 amp/hour battery but as you now have 12 volts across them, the output is now 1200 watts.

Likewise, if you were to connect the same two 100 amp/hour 6 volt batteries in parallel (negaitive to negative, positive to postive) each remains 100 amp/hours/ voltage remains at 6, but yoiu now have 1200 watts of energy.

If you think in terms of watts it bceomes much clearer.

You can also think of it like this:

Voltage is like water pressure in a pipe, amps is the amount of water flowing that pipe. If that water pipe is used to fill a bucket, watts is the measure of the water in the bucket.

If you try to measure that amount of water in terms of water in the pipe (amps) then you must also know the water pressure (volts). But watts is watts!

Re rsdhaw500 and flattening deep-cycle batteries to keep them healthy. NO NO NO! You'll b--y kill them doing that!!
Collyn down-under

[Collyn down-under]

Sent: 5/1/2003

Re Solar Boost. I don't know the actual product but the principle it works on is technically sound.

Solar modules produce their maximum power when feeding a load at about 16.5 volts. These boost devices act as a 16.5 volt or so load and then 'swap volts for amps' . Along the way you pick up watts - more or less in the ratio of 16.5:12.8 (will vary from module to module).
Collyn down-under 

[Rick Shaw]

Sent: 5/2/2003

Chuck,
Thanks for clearing up the "dual and mom" positions.   You are correct about the batteries also.   I was confusing the batteries that they say have a brain.....where you must drain it completely or else it will only go as low as you took it the first time..thus allowing you to only use the battery partially.
Rick

[Collyn down-under]

Sent: 5/2/2003

rshaw

Nickel cadmium NiCad) batteries are best totally flattened and then recharged - otherwise they sulk like teenagers. But not lead acid batteries - that wrecks them.

Someone asked if we have kangeroos in Broome. They are not hopping around in town - but we have at least 150 of them on our 10 acres at home. Curiously they co-exist with our huge (>170 lbs) female Great Dane..
Collyn down-under.

[Faderz]

Sent: 5/3/2003

Collyn,

Thanks for that explanation. I guess it's the terminology that is confusing, particularly "amp-hours". It suggests that you have a certain number of these units, which would make you think you could increase the number by adding another battery. In fact, your amp-hours remains the same, but your "running minutes" goes up. As you imply, there could probably be better terms for all of this.