I was at Alex Sirum,s this past weekend and was asking if
he had any experience with just this subject.
It CAN be done - but as many pointed out - it is somewhat
expensive.
Alex wired a 2500 watt inverted to one used 12volt auto battery
just to see what it would do. He was able to start and run the
std GMC 13500 roof air.
His thoughts to me were:
A LOW power 7500 watt roof AC - which are available.
Put this AC unit in rear (ie bedroom area)
Insulate coach well (especially rear area).
A 1500-2500 watt inverter (Needs min 2,000 watt peak).
6 Golfcart 6volt batteries.
First get the coach COOL using genset before retiring.
Use the AC only to cool the rear bedroom area (ie close door).
Set to med cool temp.
During EVENING hours, if coach is already cool he feels they
could last the night if set up properly.
During DAYTIME driving, a similar setup with the high output
alternator (165 amp), which was an option on my 78, and the 6 GC
batteries could keep it going most of the day if the batteries
are charged.
So spend $1000 (or so) on inverter, $700 on new AC unit, $350 on
batteries,
and for about $2,000 you have it. Now add a big alt and you have
daytime as well. Not cheap.
The advantage is that you can spend a "quiet" evening in a
WalMart, rest area (where allowed), etc. without the need for a
campground or noisy genset.
Check the site at:
http://www.statpower.com/rv.htm
Some other articles seems to follow similar possibilities.
Some time ago Derek Pettingale of Statpower and Dave (73 Sequoia)
both offered some great info on inverters and AC units which I
saved. I have copied that below (Dave, hope you don't mind):
>Derek Pettingale - RV Distribution Account Manager
>Statpower Technologies
>7725 Lougheed Hwy
>Burnaby, BC V5A 4V8
>Canada
>tel. 604 420 4820 x2127 fax. 604 420 1591
>http:\\www.statpower.com
>
>We tested a Coleman 13,500 Btu roof air on our Prosine 3.0/2.5
and
>1800 units. We ran the inverters off of batteries only (8Ds).
>Obviously, with the support of an alternator pumping DC into
the
>batteries the run time for the A/C unit will be extended
beyond the
>capacity of the batteries themselves. The amount of extended
run time,
>as you are aware, will depend a lot on the quality and
capacity of the
>alternator used.
>
>I am somewhat familiar with the alternators available with
Prevost bus
>shells. The shells are popular with conversion shops which
outfit them
>as RVs. The typical situation is that the Conversion shop
orders the
>Prevost shell with 24v/270 amp Alternator option. A typical
13,500 Btu
>roof air needs 17 amps AC while running which is about
2000watts. In
>theory an inverter supplies the 2000 watts off the equivalent
of 85 Amps
>DC (24v system). Conversion experts tell me that the Prevost
buses need
>about 100 amps for general operation. This leaves 170 Amps
available
>for other loads. In theory one can support two roof airs
while running
>the engine without consuming battery power. This isn't exact,
but it
>explains the general system. There are many other
combinations of much
>smaller air conditioners, but the 13,500 roof air is most
popular. We
>run a multitude of smaller capacity A/C units made for boats
and trucks.
>Other RV manufacturers purchase similar alternator options
from their
>enging suppliers, but the Prevost system is the highest
capacity I know.
>Blue Bird for example, makes their own in house. The other RV
OEM
>systems generally support only one roof air. The alternators
are
>options from Catipilar and Detroit Diesel etc.
>
>The only company I am familar with the makes a high quality
output
>alternator and is not associated with an engine manufacturer
is Balmar.
>However, their focus is on marine applications rather than
vehicles.
>
>Contact them at:
>
>http:///www.balmarvst.com or tel. 360 629 3210
>From Dave:
You would double the amperage numbers if you used a 12 volt
system rather
than the 24 volt system he is referring to here. So that means
you would
need to produce 170 amps of current, just to run the A/C!
I looked at the Balmar site and they do have alternators that
would be big
enough. Very pricey though. And the cable to carry that much
current from
the alternator to the batteries & converter would also be costly.
Interesting concept though. It certainly would be nice to have
110vac for
the A/C while on the road and not have to run the Onan.
Does anyone have information on high current 12v alternators for
truck and
bus applications? Maybe a rebuilt Delco from a truck would be
more
reasonably priced.
Dave
73 Sequoia
he had any experience with just this subject.
It CAN be done - but as many pointed out - it is somewhat
expensive.
Alex wired a 2500 watt inverted to one used 12volt auto battery
just to see what it would do. He was able to start and run the
std GMC 13500 roof air.
His thoughts to me were:
A LOW power 7500 watt roof AC - which are available.
Put this AC unit in rear (ie bedroom area)
Insulate coach well (especially rear area).
A 1500-2500 watt inverter (Needs min 2,000 watt peak).
6 Golfcart 6volt batteries.
First get the coach COOL using genset before retiring.
Use the AC only to cool the rear bedroom area (ie close door).
Set to med cool temp.
During EVENING hours, if coach is already cool he feels they
could last the night if set up properly.
During DAYTIME driving, a similar setup with the high output
alternator (165 amp), which was an option on my 78, and the 6 GC
batteries could keep it going most of the day if the batteries
are charged.
So spend $1000 (or so) on inverter, $700 on new AC unit, $350 on
batteries,
and for about $2,000 you have it. Now add a big alt and you have
daytime as well. Not cheap.
The advantage is that you can spend a "quiet" evening in a
WalMart, rest area (where allowed), etc. without the need for a
campground or noisy genset.
Check the site at:
http://www.statpower.com/rv.htm
Some other articles seems to follow similar possibilities.
Some time ago Derek Pettingale of Statpower and Dave (73 Sequoia)
both offered some great info on inverters and AC units which I
saved. I have copied that below (Dave, hope you don't mind):
>Derek Pettingale - RV Distribution Account Manager
>Statpower Technologies
>7725 Lougheed Hwy
>Burnaby, BC V5A 4V8
>Canada
>tel. 604 420 4820 x2127 fax. 604 420 1591
>http:\\www.statpower.com
>
>We tested a Coleman 13,500 Btu roof air on our Prosine 3.0/2.5
and
>1800 units. We ran the inverters off of batteries only (8Ds).
>Obviously, with the support of an alternator pumping DC into
the
>batteries the run time for the A/C unit will be extended
beyond the
>capacity of the batteries themselves. The amount of extended
run time,
>as you are aware, will depend a lot on the quality and
capacity of the
>alternator used.
>
>I am somewhat familiar with the alternators available with
Prevost bus
>shells. The shells are popular with conversion shops which
outfit them
>as RVs. The typical situation is that the Conversion shop
orders the
>Prevost shell with 24v/270 amp Alternator option. A typical
13,500 Btu
>roof air needs 17 amps AC while running which is about
2000watts. In
>theory an inverter supplies the 2000 watts off the equivalent
of 85 Amps
>DC (24v system). Conversion experts tell me that the Prevost
buses need
>about 100 amps for general operation. This leaves 170 Amps
available
>for other loads. In theory one can support two roof airs
while running
>the engine without consuming battery power. This isn't exact,
but it
>explains the general system. There are many other
combinations of much
>smaller air conditioners, but the 13,500 roof air is most
popular. We
>run a multitude of smaller capacity A/C units made for boats
and trucks.
>Other RV manufacturers purchase similar alternator options
from their
>enging suppliers, but the Prevost system is the highest
capacity I know.
>Blue Bird for example, makes their own in house. The other RV
OEM
>systems generally support only one roof air. The alternators
are
>options from Catipilar and Detroit Diesel etc.
>
>The only company I am familar with the makes a high quality
output
>alternator and is not associated with an engine manufacturer
is Balmar.
>However, their focus is on marine applications rather than
vehicles.
>
>Contact them at:
>
>http:///www.balmarvst.com or tel. 360 629 3210
>From Dave:
You would double the amperage numbers if you used a 12 volt
system rather
than the 24 volt system he is referring to here. So that means
you would
need to produce 170 amps of current, just to run the A/C!
I looked at the Balmar site and they do have alternators that
would be big
enough. Very pricey though. And the cable to carry that much
current from
the alternator to the batteries & converter would also be costly.
Interesting concept though. It certainly would be nice to have
110vac for
the A/C while on the road and not have to run the Onan.
Does anyone have information on high current 12v alternators for
truck and
bus applications? Maybe a rebuilt Delco from a truck would be
more
reasonably priced.
Dave
73 Sequoia
