I am a little late to this show, but thought I would share some info I put together in the past that may be of use to others.
I had been pondering the details of migrating to two 6 volt batteries to increase my battery
capacity for about two years.
capacity is an enabler for extending boondocking
adventures for longer periods without running my generator
. My solar
panels recharge my current battery so fast I wanted a larger battery bank to support my ever growing energy demands.
The previous post about first calculating your needs is right on. You will have no idea what battery capacity you need unless you so so. You will find that users out there vary from minimalists (great fit for small fiberglass trailers), to those with more extreme energy needs (guility as charged). I would not even do this analysis without first changing out my lights
with LED lights
and spending some time in your trailer boondocking
, understanding your energy usage in the field.
A simplistic example follows:
In this example I would want to ensure I used a battery that had something like 130 amp hour capacity so that it would still have approximately 50% capacity when the 66 amps discharge.
A standard Group 27 battery in a Casita
is not a true deep cycle battery. It is a hybrid designed for cranking and deep cycle use. It utilizes thinner lead plates and contains less battery fluid than a true deep cycle battery. This battery is not intended to be discharged more than 50% on repeated basis or its life will be shortened.
What do I hope to gain in capacity with this modification?
I used the specification for capacity minutes at 25 amps for comparisons. I also wanted to include in the analysis the element of the recommended discharge capacity for a more realistic real world comparison.
Migration to twin 6 volt batteries should give me more than twice the capacity minutes at 25 amps than a standard group 27 Casita
Lithium ion batteries were considered and look promising for the future but I chose not to be an early adopter of an emerging technology and the cost and risk that sometime go with it. The cause of a recent fire in a Boeing 787 APU with lithium batteries is currently being studied.
The Trojan T-105 is a 6 volt battery and is a true deep cycle battery with heavier lead plates and it contains more battery fluid per volume than the Casita
group 27 battery. The Trojan T-105 is considered the best on the market for golf carts because it has a cycle life--how many times you can charge and discharge the battery--of 750, and it weighs 62 pounds.The T-105 is readily available in an decent sized town.
Gallery of conversion to twin 6 volt batteries:
120606 - Casita Modification to Twin 6 Volt Batteries - Casita Adventures Photography by Rob Rupp