Reddit mentions: The best automotive replacement heating equipment

You are going to want 2 identical batteries (volts, amps, age, size) and run them in parallel. This will combine the amp hours of the two, making them last longer (vs series which would double the voltage). When you jump a battery, you are just putting the 2 in parallel.

You are also going to want valve regulated deep cycle AGM batteries. A normal starter battery does not do well with discharging below about 50% more than a few times. Deep cycles are designed to handle discharges without drastically reducing the life of the battery. Basic lead acid batteries and non-valve regulated AGMs require venting due to the gasses they give off when charging. Even if a battery is sealed and maintenance free, it could still have a case designed to vent gasses. You do not want these things putting out fumes in your cabin.

I don't have much experience with inverters yet, so I don't want to give any advice that might be wrong. I do know that if you want to just charge devices, a modified sine wave inverter will be fine. If you want to run things directly off of the batteries/inverter, it is best to go with a pure sine wave inverter. They come in all different wattage ratings and efficiency ratings. You will have to decide what your required specs are and pick one out based on that.

You only really have 3 options as far as charging the batteries. You can:

1. Hook them up to a solar kit along with a controller and inverter. Recharging the batteries will depend on the amount of sun you can get during the day. Being in the north during winter around the great lakes will probably all work against a solar setup being practical for you.
   
   
2. You can connect the deep cycle array up to your alternator with an isolator to keep you from draining the starter battery. This will charge the batteries when the engine is running. You can then just run whatever inverter you want off of those auxiliary batteries. If you get to a camp and sit there for a few days, you won't really be running the engine enough to charge your system.
   
   
3. Charge them at home and use the heater sparingly on the road. Obviously not ideal for long trips, but for a 1 - 2 night trip and using the heater in moderation, it might be an option.
   
   I tried finding a decent 12v dc heater that doesn't require plumbing, and was only able to find this: DC Thermal SA12-2000 12 Volt Brushless Cab Heater 220 Watts/20 Amp. I believe you can connect this directly to your battery and not have to worry about an inverter.
   

I'm having multiple issues with my AC and heater. My 2008 honda civic si has about 120,000 miles on it.
For the past 2 summers I've had my Air Conditioning recharged, each time at a different shop. When I took it back in a couple days later to check for a leak, I was told to bring it back in a week because they couldn't find anything. Over time, when the recharge isn't working and the AC stops blowing cold, it will still blow cool when I'm moving, but blows warm/hot air when stopped or in crawling traffic.
This winter, for the first time I had my heater start doing pretty much the same thing. It would blow warm air when moving and cold air when stopped.
A new issue arised a few days ago that my AC or Heater won't blow air out until my speed is above 40 mph for 20 seconds or more. I replace my blower assembly with this about 2 years ago. I'm thinking that I may need to replace the blower assembly again?

Most commonly I read the blower assembly is the culprit if the Prius AC dies. Mine was no exception. https://www.amazon.com/TYC-700153-Toyota-Replacement-Assembly/dp/B002E5FOR8/ref=redir_mobile_desktop?_encoding=UTF8&psc=1&ref=yo_pop_d_pd_title