--- In alinerchaleta-frames@y..., Mark Maisonneuve <markrm@y...>
wrote:
Is the battery in an Aliner a regular car battery? A
friend recommended substituting a deep-cycle marine
battery for the longer periods of draw that a camper
would experience. Comments?
Long anwer and maybe stuff you know, but...
It is not a normal car battery in the Aliner.
The battery box for the Aliners accepts a Group 27 deep cycle (or
marine) battery. These provide between 105 - 120 Amp Hours. Since
you don't want to drain deep cycle batteries below 50%, to prevent
shortening their life, you really have 55-60 Amp Hours of useable
power.
Costco sells a "wet" (lead acid) 120 AH Group 27 battery under
their "Kirkland" brand for $65. It has a three year pro-rated
warranty.
You may be able to go with a larger battery such as a Group 4D (165
amp hour) or Group 8D (210 amp hour). You will need to find the
space for new boxes and be handy with re-routing wiring. Best to see
if the factory might be willing to do some customizing of your
order. More important, you have to be able to recharge that battery
in a reasonable time to make it worth while.
A 210 AH Group 8D AGM battery (Lifeline is one brand) battery will
run you about $400-$500 and last about 6 years. It also weighs about
140 lbs and is 21 inches long.
Figure what your power needs are for a 24 hour period.
Someone correct me if I am wrong here:
The standard charger built into the Aliner was not designed to handle
high Amp bulk recharges (like a TrueCharge +40 charger). I think it
recharges at 20 amps max. This means that it will take longer for a
larger battery to recharge. Any power used in the trailer when
plugged in into shore power is power not available for recharging.
Charging via the tow vehicle:
Car and trailer batteries are essentially tied together if you have
battery charge wire going to the trailer (your typical 7 plug Bargman
RV connector). When stopped with the engine turned off, they will
act as water tanks connected by a pipe and try to balance each other
out. The battery with the lower charge taking power from the one
with the higher charge. If you have a large enough AH rated trailer
battery, you could theoretically kill your starting battery. Yes,
you could disconnect the RV plug when you stop, but I know I will
forget to reconnect it some time and drive away without brakes or
lights available. This is why battery isolators are installed - so
batteries are disconnected when a tow vehicle is turned off.
To recharge a battery in the 200 AH range by driving and using the
tow vehicle alternator will require thought, planning, and/or time.
Oversizing the alternator will not cause the trailer battery to
recharge faster. Alternators sense the voltage level of the starter
battery and are designed not to exceed 14v so as to protect the
starting battery from bubbling and gassing. Once that 14 volts is
sensed the alternator's regulator drops the voltage and amps output.
A car battery isn't discharged beyond 5% of it's capacity, so the
recharge is quick and the alternator output drops within minutes
after starting the car. A 200 Amp hour trailer battery needing 100
AH replaced each day will require lots of hours of driving to
recharge.
One solution is to have a manual "cut out" switch in the car which
removes the car battery from the circuit. You would flip this switch
when the starting battery is fully recharged. The alternator would
then only sense the trailer battery and spin up the voltage and amps
to recharge it. You need a large enough alternator so it can handle
the car's electrical loads and recharging and not burn out.
Another option may be to install a dual output alternator. These
have two sets of leads. One set of leads for the car battery and a
second set of leads for the trailer battery. The voltage regulator
in the alternator senses which battery has a lower load and sends
power to it. It does not balance power between them (20% to this and
80% to that). It just sends power to the lowest load. These types
of alternators have built in battery isolators. Again the alternator
needs to be large enough to handle the vehicle electrical loads and
recharging.
Hope this is of some help.
Chris M.
