Electrical System Help,Thoughts,Ideas???

[H3-45]

Hello Everyone,

I am asking this question for a friend that is not a member here. He is building a Semi-Truck based Motorhome and has come to the design of the auxillary electrical system.He is using a 20 Kw Diesel Generator, 2-3000 Watt Dual Sine Inverters with built-in Battery Chargers. The truck engine will have a large aux. Alternator installed. His main question is about Battery's,what type and how many? Any thing else he needs to know or do while desigining his system. I have shared my ideas and expierence. He would like some other opinions. The cost is not a big problem for him,he is looking for ease of use,durability,and enough power to operate what he is wanting to operate.probably will add more battery's than a normal system. I know this is not a Bus it is going in,But the system for a bus could be used in a Semi-Based Motorhome. Any do's or Dont's, Ideas,what to stay away from,what to definately do?? Looking for everyones opinion,wether on a home-built unit or a high dollar factory built unit. Thanks in advance for your time.

Robert

[Jon]

Robert,

Do your friend a favor and have him look at professional motor home conversions. Copy them. He has the elements but what he needs to decide is how to hook them up to have a user friendly house electrical system.

He can use the inverters for specific dedicated 120V circuits, or he can pair them up (depending on the inverter) and use them in series to provide 6000 watts for multiple circuits. He can also create a system like Vantare and a few others do and run 100% of the house electrical loads through the inverters. All of the methods I mentioned above are in widespread use on conversions, all are very reliable and time tested, and all have their benefits and disadvantages.

There are some very qualified folks on PC who would undoubtedly love to engage in a discussion of his options based on their experiences with the various systems in their coaches and how well they work for their applications.


How is your coach coming. Haven't heard from you for a while

[Tikvah]

Everything you need to know about the best battery systems is here: http://www.technomadia.com/lithium/

Lithium Ion is expensive, but if money is not a serious roadblock, then it might be the only way to go.

[TomC]

I am doing a Kenworth based truck conversion also. The truck has 4-31 batteries for starting. I have a 12kw Wrico genset, 2800 watt Magnum true sine wave inverter/charger, and will use 4-L16 Lifeline AGM batteries for a total of 800am/hours at 12vdc. Lifeline also makes 2v batteries. He could use 12 L16's for a total of 1200amp/hours @ 24vdc.

I just made a visit to Lifeline and they said that all of the batteries are identical-just difference in size of case. So capability of the battery is directly proportionate to the dimensions.

Do yourself a favor. Use AGM batteries for deep cycle. My last set of Lifeline AGM's were 2-8D. They lasted 7yrs and did nothing to them in that time. Once you experience an AGM battery, you'll never go back to a wet battery. The AGM requires just about zero maintenance, can be mounted in any position except upside down, don't gas so you can install them inside, and can charge as fast as you want so long as you don't over volt them (14.1 volts on a 12vdc system).  They are expensive though-about twice of a normal battery. Good Luck, TomC

[Seangie]

Have your friend make a list of everything that will need to run on battery power when boondocked.

Have a column for -
Device
Power (inverted or straight battery 12/24v)
Hours of use in a 24hr period
Amps used
Wattage used

And from that calculate how much battery power is needed in watt or amp hours...typically batteries are rated in amp hours.

Then double that for your battery bank.

Simply put - lets say he has a fridge (12amps/hr) a fan (4 amps per hour) and a light (2 amps per hour)
He figures that all 3 devices will run half the time in a 24 hour period-

Fridge is 12amps x 12hrs - 144AH
Fan is 4amps x 12hrs - 48AH
Light is 2amps x 12hrs - 24AH

So he would use 216 amp hours.  Double that so the batteries don't get below 50% and he would need a bank that has at least 432 amp hours.

There are benefits and downfalls to each battery type (lead acid, agm and lithium ion) but Ill leave that up to him to research and figure out.  Plenty of info out there on the web without having to go into detail here.

-Sean

Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org

[mikelutestanski]

Hello     AGMs are fine batteries, however lead acid (taken care of properly) can have a long life.  My Trojan T 105s are on their 11th year.    I do have a 625 amp set    24V   3 groups of 4  for a total of 12 batteries with a trace 2500 watt inverter.
    Regards  and happy bussing   mike

[eagle19952]

I would advise him to buy these, and have them fully refurbished,( these are no longer made), but IMO they are as good as it gets. They are virtually bullet proof.
http://medford.craigslist.org/for/4481696486.html

You can read about them here:http://www.wholesalesolar.com/products.folder/inverter-folder/sw4024.html
and here:http://pdf.wholesalesolar.com/inverter%20pdf%20folder/Xantrx_SW%204024-4048-5548InverterDatasheet.pdf

the SW 4024 offers sine wave, utility grade output power, high capacity battery charger, high surge current ability,