re-inverters

[freewill2008]

When I did the numbers to determine whether I wanted an inverter
solution for over-the-road air conditioning, the result was a 320 amp
12 volt alternator and a two kilowatt inverter.

The inverter would draw about 170-180 amps at full load.

Going down the road our bus also needs about 50 amps at 12 volts for
lights, re-charging house batteries, my too-big stereo, and whatever.

There is also a Telma retarder which can draw up to 120 amps while
going down hill.

These are worst-case numbers, however they are the right numbers to
use unless one wants to be discharging the battery banks while going
down the road.

Since you basically never want to discharge while going down the
road, I did not even consider the size of the battery banks. In
theory, you should be able to disconnect the batteries while under
way and never run short on electrical power. Adding up the numbers
above, you can see that even 320 amps could come up a little short.

One more factor to add: A good electrical system is always designed
to have about 20% more power available than is required.

One of my responsibilities at work is power engineer for 75 big
servers that *must* operate 24/7. The whole system runs continously
on a 30KW inverter which operates either on batteries or from utility
power. The system is very much like our buses except for the big
numbers; the alternator serves the utility power function and the
batteries act as, well, batteries. All the calculations for load
capacity and depletion are the same.

Bob Griesel '84 FC31 WLII WA


>
> Rob:
> On the bus which I owned before, it had a DD engine, with a gear
driven alternator which produced 320 amps at 24 volts (ok 28.4 volts
or so)
> When you do the calculation that gives one almost 7.7kw's of
power. That is almost as big as the genny on the SP models and some
of the FC models.
> That would give you lots of power to operate the AC's plus other
stuff if you wish, and still enough to keep the batteries charged.
> As Gardner mentioned, the alternator will feed the inverters first
instead of pulling it from the batteries.
> I would love to have a 300 amp 12 volt alternator, then I could run
an airconditioner as well going down the road - ok, I should recharge
my engine driven a/c hehe.
>
> Bill 84 FC 35 SB "$quanderlodge"
> Terrace, B.C. Canada
>
>
> ----- Original Message ----
> From: aokkoa2003
> To: WanderlodgeForum@yahoogroups.com
> Sent: Sunday, January 7, 2007 8:36:17 PM
> Subject: [WanderlodgeForum] re-inverters
>
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> Thought I would throw in my 2cents worth.... We have a
totally
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> electric coach. The former owner of our 85pt36 removed all of the
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> propane stuff and added a battery bank in it's place.. 4 large
truck
>
> batterys wired for 24 volts dc. He then installed 3 2500 heart
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> inverters in the passeger side compartment, with the matching link
2000
>
> controls in the coach. 1 for each leg of the 220 system, and the
3rd
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> for a charger. We can switch them around by changing the plugs
anyway
>
> we need to,such as in the case one should quit working. On the back
>
> side of the engine, he installed a 24vdc alternator. As I probably
>
> can't explain all of the tech stuff, I can tell you that this
>
> arangement really does work.. We can run both roof airs going down
the
>
> road WITHOUT the generator INDEFINATELY. We have a small 4.0 diesel
>
> generator that has 14 hours recorded on it. I start it up now and
then
>
> to make sure it will run when we are dry camping and the battery
banks
>
> need a charge. I realize that this would be a costly undertaking to
do
>
> this kind of conversion, but well worth it. I hate to run that damn
>
> genny. Rob Sargent. 85pt36
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