Reply
 
Thread Tools Display Modes
 
Old 05-11-2016, 09:57 PM   #11
Bus Nut
 
Docsgsxr's Avatar
 
Join Date: Feb 2014
Location: Arizona via Baton Rouge
Posts: 640
Year: 1999
Coachwork: Thomas
Chassis: Freight-shaker (Freightliner)
Engine: Cat 3126b 250 HP
Rated Cap: Only 1 seat
Good luck and happy motoring!

-Doc
__________________
My build thread - viewtopic.php?f=9&t=467197
Docsgsxr is offline   Reply With Quote
Old 05-12-2016, 02:28 AM   #12
Almost There
 
tincaneasybakeoven's Avatar
 
Join Date: Apr 2016
Location: on the land of tejas; state of mind
Posts: 84
Year: 95
Coachwork: Amtran ss-33
Chassis: Int 3800
Engine: dt444E
Rated Cap: 29,000
copy what a 18 wheeler has for inverter install. they are as close as you can get to a bus. all the engineering has been done for you.
__________________
claim common law i, a man; claim.... on facebook

if your not a man our doing it all wrong-kp
tincaneasybakeoven is offline   Reply With Quote
Old 05-12-2016, 03:55 AM   #13
Mini-Skoolie
 
Join Date: Jan 2016
Location: Austin, TX
Posts: 30
So, everyone so far has been right. I'm going through this exact thing at the moment. My 3kW invert is getting 4/0 (0000) welding cable on a 4 foot run from my battery box under the floor to the power center under a bench seat directly above it. I'm putting a 400A fuse right off the four 6V GC2 golf cart batteries in parallel pairs of series (2x2 for 12V). Xantrex recommends a DC circuit breaker as well. I'm not sure if I'm going to go that far yet.

Sterling Power (and maybe other companies, but I have a strong preference to their equipment) makes a series of things to help with charging your house batteries from your vehicle's alternator WAY better than just tying them together for a while or switching your inverter back and forth. They have basically three products. A battery to battery charger, an advanced alternator regulator, and an alternator to battery charger.

The battery to battery charger draws a small (relatively) current of about 60A from your starter batteries while they're being charged by the alternator. It's smart enough to never discharge the starter batteries and only do it when they're charging. This is , in my opinion, the worst way to go, but possibly the easiest. It just doesn't give you much power. 720W is the best you can reasonably hope for. You can tie multiples together, but that gets expensive.

The advanced alternator regulator is the middle option, in terms of personal preference for me. It draws the voltage down on your alternator a bit to make it produce higher current, basically simulating a large load. Alternators are real workhorses and can handle this just fine. Plus they include a temp sensor to prevent the alternator overheating. These can pull your alternator's max current rating (which in a bus is generally 120-280 amps) and top off your starters, then put the remaining current (probably 2/3rds of your capacity) into the house batteries. This really works well and is fairly cheap, but it is the hardest of all the methods. You have to disassemble your alternator to solder wires to the brushes, as a start.

The best option is probably the alternator to battery charger. This does the exact same thing as the advanced alternator regulator, but it does it all remotely. You run cables to it from the alternator lugs and both the starter and house batteries. It keeps everything charged and happy with minimal effort or required skill and only moderate cost.

And all three of these chargers do multi-stage charging, just like a charge wizard, MPPT solar controller, or any other high-end charging device. This keeps the batteries from cooking from too much power while charging them as quickly as possible.

Hope this helps.
ashandrik is offline   Reply With Quote
Old 05-12-2016, 11:32 AM   #14
Bus Nut
 
Docsgsxr's Avatar
 
Join Date: Feb 2014
Location: Arizona via Baton Rouge
Posts: 640
Year: 1999
Coachwork: Thomas
Chassis: Freight-shaker (Freightliner)
Engine: Cat 3126b 250 HP
Rated Cap: Only 1 seat
Quote:
Originally Posted by ashandrik View Post
Xantrex recommends a DC circuit breaker as well. I'm not sure if I'm going to go that far yet.


Amazon.com: 200 AMP 12V DC CIRCUIT BREAKER REPLACE FUSE 200A 12VDC Scosche: Home Improvement

It's not hard to install


And all three of these chargers do multi-stage charging, just like a charge wizard, MPPT solar controller, or any other high-end charging device. This keeps the batteries from cooking from too much power while charging them as quickly as possible.

You're alternator already has a charge regulator installed for the load it senses. You'd need an advanced regulator if you were running a mobile crime scene lab with lots of electronics and communications on board. Only way you will cook your batteries is if your alternator goes bad. But that's why you have a charge guage in the dash!!

Hope this helps.
There is no need to spend more money on things you don't need. These alternators are set up for buses, not Civics.......
__________________
My build thread - viewtopic.php?f=9&t=467197
Docsgsxr is offline   Reply With Quote
Old 05-12-2016, 02:38 PM   #15
Bus Crazy
 
Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,328
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
wire recommendations

Adequate wire gauge is important as others already noted. Welding cable might be nice because its higher strand count makes it flexible and easy to work with, and has a durable rubbery jacket which adds to the flexibility. However, if you have screw-type lugs for termination, the finer strands can be a drawback. IMHO it'll be harder to secure and possibly more prone to working loose.

I'll take a moment to debunk one of the claims, though: skin effect. That's the phenomenon of electrical current traveling more on the "skin" of the conductor and less in the core. While it is a real thing, its effect is proportional to frequency. It doesn't exist for dc. Per the wikipedia Skin effect article, skin depth in copper at 60 Hz is about 8.5 mm. For most of us, working with either dc or 60 Hz ac, skin effect isn't a concern until the radius of a wire is greater than 8.5 mm. That's a diameter of 17 mm. The largest "gauged" cable, 4/0, has diameter about 11.6 mm and ampacity around 200 A depending on allowed temperature rise. By the way, even when skin effect is a concern, finer strands alone don't fix it. Each strand has to be electrically insulated as in Litz wire.

Anyway... choose your cable based on how much flexibility you need, what insulation characteristics you need, availability, terminations, and ampacity. Don't worry about skin effect.
family wagon is offline   Reply With Quote
Old 05-12-2016, 03:45 PM   #16
Bus Nut
 
GreyCoyote's Avatar
 
Join Date: Mar 2016
Location: Danglebury, Tejas
Posts: 310
Year: 1999
Coachwork: Blue Bird
Chassis: IH 3800
Engine: Navistar DT466E
Rated Cap: 72 passenger
Ditto what FamWagon said about skin effect. In DC setups however the welding cable gives excellent flex and oil resistance.

On another "hint", twist the inverter input cables together and shrink-wrap them every few inches. At high loads these cables will radiate noise into nearby electronics. By twisting them together and holding them close to each other, you severely limit this problem where its easiest to cure - the initial point of radiation.
__________________
"You can finally say you have enough horsepower when you leave two black streaks from corner to corner"
(Mark Donohue, famed TransAm driver)
GreyCoyote is offline   Reply With Quote
Old 05-12-2016, 04:22 PM   #17
Bus Nut
 
Docsgsxr's Avatar
 
Join Date: Feb 2014
Location: Arizona via Baton Rouge
Posts: 640
Year: 1999
Coachwork: Thomas
Chassis: Freight-shaker (Freightliner)
Engine: Cat 3126b 250 HP
Rated Cap: Only 1 seat
Quote:
Originally Posted by GreyCoyote View Post
Ditto what FamWagon said about skin effect. In DC setups however the welding cable gives excellent flex and oil resistance.

On another "hint", twist the inverter input cables together and shrink-wrap them every few inches. At high loads these cables will radiate noise into nearby electronics. By twisting them together and holding them close to each other, you severely limit this problem where its easiest to cure - the initial point of radiation.

Not sure I get this. Twist your input cables?? I only have 1. Or do you mean your battery connect and your ground?
__________________
My build thread - viewtopic.php?f=9&t=467197
Docsgsxr is offline   Reply With Quote
Old 05-12-2016, 05:06 PM   #18
Bus Crazy
 
Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,328
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
Yes, twist wires returning to the battery + and - terminals. Not too tight; it's heavy-gauge wire and we're not making a rope. Just a gentle twist, maybe one twist per several inches of length with something huge like 4/0.

It's recommended to run a ground return wire rather than simply grounding to the frame. Being able to reduce radiated interference by keeping the currents near each other is one reason. Here's another: somewhere, somehow, the frame/body has to connect back to the battery and the alternator. (Sorry, I'm thinking about start/chassis/coach battery again, but there's a similar frame-to-house battery connection too.) Who knows where their connection is? Who knows how good/clean it is, how many amps it's ready to carry, how much voltage drop across it, etc? Who does maintenance checks on it when they're looking at the other battery wiring? If the answer to the above is "uhhhh..." then that's a reason why high-power and noise-sensitive things should get their own return back to the battery.
family wagon is offline   Reply With Quote
Old 05-12-2016, 05:09 PM   #19
Bus Nut
 
GreyCoyote's Avatar
 
Join Date: Mar 2016
Location: Danglebury, Tejas
Posts: 310
Year: 1999
Coachwork: Blue Bird
Chassis: IH 3800
Engine: Navistar DT466E
Rated Cap: 72 passenger
Yup, I was referring to the battery (input) cables. I should have been a bit more clear.

FWIW, both input cables, both positive and negative, should go all the way back to their respective battery terminals. No using a "local" or "frame" grounding point. Thats cheating.

Edit: FW and I cross-posted about the dedicated ground. Sick minds think alike!
__________________
"You can finally say you have enough horsepower when you leave two black streaks from corner to corner"
(Mark Donohue, famed TransAm driver)
GreyCoyote is offline   Reply With Quote
Old 05-12-2016, 05:17 PM   #20
Bus Nut
 
Docsgsxr's Avatar
 
Join Date: Feb 2014
Location: Arizona via Baton Rouge
Posts: 640
Year: 1999
Coachwork: Thomas
Chassis: Freight-shaker (Freightliner)
Engine: Cat 3126b 250 HP
Rated Cap: Only 1 seat
Quote:
Originally Posted by family wagon View Post
Yes, twist wires returning to the battery + and - terminals. Not too tight; it's heavy-gauge wire and we're not making a rope. Just a gentle twist, maybe one twist per several inches of length with something huge like 4/0.

It's recommended to run a ground return wire rather than simply grounding to the frame. Being able to reduce radiated interference by keeping the currents near each other is one reason. Here's another: somewhere, somehow, the frame/body has to connect back to the battery and the alternator. (Sorry, I'm thinking about start/chassis/coach battery again, but there's a similar frame-to-house battery connection too.) Who knows where their connection is? Who knows how good/clean it is, how many amps it's ready to carry, how much voltage drop across it, etc? Who does maintenance checks on it when they're looking at the other battery wiring? If the answer to the above is "uhhhh..." then that's a reason why high-power and noise-sensitive things should get their own return back to the battery.
Never heard of this, however I am not a DC engineer. I have 2/0 wire. Not going to get too many"twists" unless I braid them. How does that affect heat?? I don't braid my welding leads.......
__________________
My build thread - viewtopic.php?f=9&t=467197
Docsgsxr is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:12 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.