Electrical System Setup

jnizzle · 01-23-2008, 11:44 AM

First I must say this is an amazing site. So many different ideas and great ingenuity on here. With that said, me and my friend recently purchased a 1991 Blue Bird school bus to convert to a party/tailgate/road trip machine. I have been doing a lot of research and it seems that the electrical will be by far the biggest task to tackle. How do most of ya'll set up your electrical systems? I noticed a lot of you guys have generators which is a little out of our budget. Any time we road trip we will most likely stay at a RV campsite that provides electrical hookups. Tailgating will only last a day which could easily be charged by running the bus a little while. With that said, I was planning on using a battery bank in connection with an inverter to provide 120v on the road and a converter to charge the coach batteries at the campsite. Hopefully I will get the diagram I drew up posted so you guys can tell me what you think. One more question, what type of power requirement do most of your skoolies require? If you don't mind would you also list what all is being powered? How much power for 12v, 120v? Thanks in advance!

lapeer20m · 01-23-2008, 10:32 PM

i'm a big fan of a 2,000 watt inverter, you can find them new for around $200. that's about 20 amps @ 110 volts and there isn't hardly any 1 single device that you cannot run. even a large microwave or toaster oven. Also, having a large inverter makes it easier to run smaller loads like your tv, lights when your batteries get low. i find that if you have a 200 watt inverter running a 180 watt tv and your batteries begin to get a little low the inverter will kick off much earlier than a 2,000 watt inverter would running the same 180 watt load.

i also prefer 8 D batteries to golf cart batteries. I started out using brand new 6 volt golf cart batteries and find that for the money 8D's are a better value and have equal or better performance. Especially with large loads.

i've never spent the $$ on a converter to charge battteries, but i really like my $100 40 amp charge/100amp engine start computer controlled charger i got from wal-mart. I've had it for 3 buses now and used it for hundreds of hours and been really happy.

jnizzle · 01-24-2008, 11:50 AM

I might have to correct myself here. The only 120v things I am looking at running down the road would be the TV/DVD, Refrigerator, and A/C. That is about a peak of 30 amps. That would need about a total of 3500W inverter or better. That translates into a 290 amp draw on the batteries. I don't know what size alternator buses usually have but I don't think it would keep up the charge on the batteries. Am I wrong here? Is having a generator to power the A/C going down the road inevitable?

Lapeer, are you just running one 8D battery? How much 120v power draw do you have on your bus? Thanks for the help!

the_experience03 · 01-24-2008, 04:45 PM

Running an AC on battery power is pretty much a no go for most of us. You could do it, mind you, but you're going to have to spend some time and some money. If I were going to go that route I would be looking at a 24 volt alternator (lower amperage per watt) and inverter setup along with a LARGE battery bank that can absorb some of that load and still function. If you draw 290 amp hours from an 8D over the course of an hour it's going to be hurting. All this would be in addition to your regular 12 volt system, mind you.

300 amp 24vdc alternator=7200 watts
(30amps*120 volts)/7200=50% duty cycle

A duty cycle of 50% should keep that alternator alive and happy for a long time provided you have an adequate battery bank to absorb surge loads like when the compressor kicks on.

It's possible, but it isn't necessarily affordable. Personally, I would just look into a generator for the same cost with far less tinkering. The plus side of the generator is that it is portable should you need it for other purposes. It will also work when you're parked. A 6 horsepower gas engine is a lot cheaper to feed than a 5.9 liter diesel.

jnizzle · 01-24-2008, 07:30 PM

This is what I pretty much figured, that is why I started looking at generators. Why do most of ya'll suggest the Honda eu2000i? Just because it is quiet? I have found a used 6000W Honda generator for about $600. What is most people running as far as a generator. Thanks again for the suggestions!

the_experience03 · 01-24-2008, 08:54 PM

Anything with a Honda engine is going to be good. The EU2000i is just the cat's ass because it is super quiet and super efficient, all while weighing less than the average lady's overnight bag. I've been impressed with a buddy's EN2500 which is just an entry level Honda generator. Sure, fuel consumption and noise were a little higher than an EU2000i, but the cost was lower, it was available at the time, and it is still lightyears ahead of most generators.

timbuk · 01-28-2008, 10:26 PM

lapeer what are 8b batteries? thanks

tim

lapeer20m · 01-29-2008, 12:24 AM

if i didn't say 8D, i meant too.

and 8d battery is about 3 times the size of a standard 1000cca pickup truck battery. they are reasonably popular in buses and large trucks (semi's) any heavy duty battery shop will carry them. I would immagine that just about any napa either has them or can get them. Places like autozone and the like probably do not have them available. They are designed to give up tons of electrons in a hurry to start HUGE diesel engines, but they are also engineered to give up a few electrons over a long period of time...good for running stuff when the engine is not turning. They are heavy. I can take one out of a bus by myself, but it takes 2 of us to put one back in. There is just a ton of lead on one of these things.

141 pounds

only 1250 cca

reserve capacity 425 minutes @ 25 amps

volts: 12

I like to use a pair of them. If i only have 1 alternator, i hook both the starting and house battery together. I have a geni for backup in case my batteries were drained to the point that the bus wouldn't start, but i try to not ever let the voltage get that low. The new bus a separate 24 volt alternator and a pair of smaller 4D batteries in series to make 24 volts. This system only supplies current to the 24 volt inverter. I haven't done a lot of testing, but with the bus not running i can run the rooftop air and the jacuzzi with stock 1hp pump at the same time for at least 10 minutes. 3000 watts @ 24 volts is only 150 amps...that's the reason i went with a 24v system...that and i found a good deal on a 24 volt alternator.

it's not practical to run a/c off a bank of batteries in most cases unless your engine is running.

i also agree that any honda generator is better than just about anything else out there. Honda recently (in the past couple years) came out with a line of el cheapo engines to compete with briggs and stratton and they are black rather than the traditional red color. i digress. it seems that you can leave a honda sit for years with old gas in it and it'll still start on the first pull.

SD26 · 01-30-2008, 05:17 AM

Quote:

Originally Posted by jnizzle

This is what I pretty much figured, that is why I started looking at generators. Why do most of ya'll suggest the Honda eu2000i? Just because it is quiet? I have found a used 6000W Honda generator for about $600. What is most people running as far as a generator. Thanks again for the suggestions!

Seems like the eu2000i is going to be small if you need 30amps of power. The cost of what you get might dictate low loud the generator is. 3500+ watts is certainly something you might grow into.

I have a couple of Yamaha generators.

Vern1 · 01-30-2008, 12:00 PM

Greetings,
They make a harness to plug two of the little Hondas together to up the capacity.
They are quiet and don't use much gas.
I found that I got tired of carrying them around and putting them outside to run.
That was one of the reasons to go with an onboard genset - just touch the start button and go.....
It is hooked up to the gas tank on the bus so I only have to fill one tank and don't have to carry extra gas tanks for the generators.
I run mine while going down the road mainly due to not having an indash AC....it get's hot here in Texas!

If you have other (non-RV related) uses for generators, seperate systems may be the way to go.

Whatever you do, use a gas stabalizer to protect and preserve the carbs on them.
The new EPA regs are so tight that the jets and passages on the motors are very small and it only takes a couple of months of non-use to cost you a healthy repair bill!

Hope this helps!

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