camping--inverter power from auxiliary battery--need guidance

Discussion in 'Gen 2 Prius Technical Discussion' started by Ray Moore, Mar 24, 2013.

  1. Ray Moore

    Ray Moore Active Member

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    Hi Y'all
    It's been a long time since I spent countless hours on Priuschat but I need help with something my pea brain can't be certain of. I have read many threads this afternoon but have not found my answer. Most of the threads I've read are related to people using their Prius as a power source for power outages in which they leave the car powered up the whole time. That is not my plan.

    I've owned my 2004 for 9 years and 200k miles. It has been a dream. I'm signed up for a plug-in as soon as they are available but first I'm going to take a true adventure. I'm throwing my camping gear and my bicycle in the back of the car, taking off work for six months and exploring the US and Canada. I'll have lot's of electronics and bike light batteries to charge and some small lighting needs while I'm car camping and would like to use my 400 watt MSW inverter to supply these needs.

    I'd like to use an 18AH secondary battery to run the inverter so I don't run down the 12v car battery when the car is off. That should be enough power to get me through the evening and charge up my stuff for the next day. I've read that I should us a battery isolator but there seem to be choices based on what type of alternator or charging circuit is involved. The Prius doesn't have an alternator per se so I'm a little confused as to what to get. My two questions are these.

    What type of isolator do I need to get so the charging circuit can see the load of the battery with the isolator in place.

    What is the best way to physically connect this to the positive terminal of the battery since it has the relay or terminal of some sort that is bolted to the positive post of the battery.

    I hope the folks at Prius chat can help me out with this. They have never failed to help me in the past 9 years. My trip starts in about a month and I need to get this done soon as it's going to get hairy around here as departure time approaches.

    Thanks,
    Ray
     
  2. jdenenberg

    jdenenberg EE Professor

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    First, 360 watts is 20 amps at 12v so your 18AH battery could be drained in 1 hour. Just leave your Prius in ready mode and you can pull 360 watts for weeks without running out of gas. Use a secondary battery to jump your (or other's) car if required.

    JeffD
     
  3. Ray Moore

    Ray Moore Active Member

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    I will only be using about 60 watts or less when the car is off so it will easily get me through the evening. I need help to make this work. I don't want to leave my car powered on. I will be charging some small capacity batteries and running some led lighting. One of the lights is 14 watts and the other is 19 watts. Rarely will they be used together. If I run my laptop, then the lights will be off. Can anyone help me figure this out. I know it is tempting to tell me that I shouldn't try for one reason or another but I've run all those thoughts through my head and still want to do it. One of the batteries I need to charge is 6 watts while charging and others are less. It is not a large load I'm talking about or I would be planning for a larger battery. Any help?
     
  4. Ray Moore

    Ray Moore Active Member

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    Would it help to get a response if I posted this in a different forum?
     
  5. jdenenberg

    jdenenberg EE Professor

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  6. techntrek

    techntrek Member

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    You will only want to draw down a 18 amp battery to 50% depth-of-discharge, so only plan on using 9 amps (about 100 watts) between charges. One thing you will have to watch out for is the baseline draw of your inverter - even if you have no loads it will probably use an amp while on. An isolator will work as you want, allowing you to charge the extra battery while not drawing down your Prius battery.

    However, with all of the benefits of the Prius I do think you should just leave it on and forget about adding on the extra layer of complexity. Basically you would then be using the massive traction battery to power your stuff for a few hours each night - the 12 volt battery just sits there passing through the amps being supplied by the DC-DC converter. Turn off the AC system, turn off the screen, turn off the radio, and dial down the speedometer brightness. With the light loads you have the engine will only turn on for a few minutes every hour or two. If I were car camping with a Prius this is exactly what I would do. I would even sleep inside to take advantage of the AC in the summer. Oh, and I am one of those using mine to power my house...
     
  7. Ray Moore

    Ray Moore Active Member

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    Thank you so much Jeff. This looks perfect and I wouldn't have found it on my own. I believe this solves the issue of the dissimilar battery capacity, age and charge rates and gives me the ability to have a little power without having the car powered up and able to be easily driven off or left on all night if I fall asleep. This way, in that scenario, I would simply deep discharge the secondary battery until the inverter or smart relay cuts out. The upfront cost of the few components needed to set this up won't make me feel stupid if it doesn't work out and it does not appear to put the Prius at risk in any way other than fire which is not likely if I am careful to allow cooling of the inverter and relay.

    I can still use the Prius in the on mode to run AC power indefinitely and I can use the auxiliary as a backup battery to power up the car in case the primary battery fails as is likely to happen along the way given it's age. I replaced the 12v battery 4-4.5 years ago when it was 4.5-5 years old. I don't want to replace it preventatively as I will be replacing the car at the end of this trip with a new Prius.

    techntrek- Thanks for your helpful input. I know the inverter uses power by being on and assumed it was substantial but had no way of knowing how much. One amp is a bit higher than I would have guessed but given the cooling fan and the cheap nature of these beasts I don't doubt it. This solution keeps things pretty simple and still gives me a bit more flexibility than just using an inverter and leaving the Prius powered up. I will likely leave the Prius powered up as I set up camp and prepare dinner and turn it off and go to auxiliary power as I start to dial back loads and activity later in the evenings or any other time it makes sense.

    Sleeping in the car is something I have done and it does simplify things in a way but it really limits me in other ways. I have taken out the rear seat and built in cabinetry for storage and I am taking lots of stuff including a bike workshop with lots of spare parts, three different structures for different needs, a 6 foot sturdy table and an extra large folding recliner. I'm going to be out for over six months. I intend to be comfortable but with very little use of motels. I want to keep my total cost for 200 days to around 12,000$. That means I carry my comfort with me. I will be riding over 10,000 miles on my bike so I can't get away with poor rest or poor nutrition. I'll have most of a full kitchen to cook the gazzilion calories I burn on the bike. (actually only 1/2 million plus the normal daily calories) The real deal killer to sleeping in the car though is that I won't leave my bike outside. It sleeps in the car and I sleep outside. The bike is a 12k investment that I don't let out of my sight so being able to lock it in the car is a must. It is all insured but God forbid if it were to wander off on it's own.

    Thanks for the help Y'all. Let me know if I'm being dumb. There are a few ways to solve the problems involved in this kind of endeavor and I really do appreciate anyone that takes the time to offer their insight. I think I'm one step closer.

    Ray Moore
     
  8. fuzzy1

    fuzzy1 Senior Member

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    My Prius 12V battery usually runs at significantly lower voltage than the household's non-hybrids, so I suspect it is usually well be full charge. Thus, even drawing 9Ah repeatedly is risky. Just leave it in 'Ready'.
     
  9. Ray Moore

    Ray Moore Active Member

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    I've decided to replace the 12v battery preemptively. I ran the diagnostic and it was borderline. I checked records and the first battery failed at 4 years and nine months. By the time I return from my trip I will be beyond that on the current battery. I ordered an optima battery and will replace it while wiring in my inverter and isolator. Thanks Priuschat for coming through once again. Considered using the existing 12v battery for the backup but I'm thinking not at the moment. I may reconsider that option based on space and testing.
     
  10. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    This is the flaw in your plan.
    Leave your car in Ready and all is good. If you insist on turning it off, bring a jumpstart box every time.

    Schumacher IP-55 Instant Power Portable Jump Starter : Amazon.com : Automotive

    I predict that you will still replace your 12 volt battery twice as often as someone who treats it well.
     
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  11. mtbiker53

    mtbiker53 Junior Member

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    Ahhh.....12k.....a bike snob
     
  12. Ray Moore

    Ray Moore Active Member

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    Been called worse, but never so eloquently. Your use of the period is awe inspiring.
     
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  13. techntrek

    techntrek Member

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    We are talking about his secondary 12 volt battery, not the Prius' own 12 volt battery. I agree he should just leave the car on in the evening, but when using his secondary battery a 50% draw-down is considered normal for a deep cycle battery.
     
  14. techntrek

    techntrek Member

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    Again, he's talking about using a secondary 12 volt battery so he won't harm his Prius' 12 volt battery.
     
  15. livingandlearning

    livingandlearning Junior Member

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    If anyone stumbles over this thread like I did, I want them to know that YouTube has excellent videos that cover these topics. One is by PriusStealthCamper...

    I have a 2012 Prius V and am modifying it to be a stealth camper. Yes I own a nice home and other nice minivan car.

    We have owned a total of 4 Prius cars and given 2 to our now adult kids - and a 3rd was totaled in a wreck which I survived because of the fantastic passenger side metal bar that protects the passengers from side impacts.

    The 2012 Prius V was pursed to replace the regular Prius. The Prius V is a car we love when car camping. It is a second home to me because I glampnwhen I camp.

    I have added a 1 1/4 inch hitch. I am adding a riser bar with a 2 inch receiver for a metal rack so we can sleep in the Prius in bad weather or extreme temps and tent camp in good weather and chain and lock our stuff outside.

    I have not bought a bike, but with the tray I will have more storage locked and chained outside the car.

    Also, I bought racks for the top of the car for storage, and am planning to install solar.

    We have almost 150,000 miles on the car and have had zero battery problems.

    I hope the OP had a great trip.

    My favorite trip so far was beach camping at the Texas National Seashore near Corpus Christi, Texas and watching the stars at night while climbing inside to escape the weather and heat on one night and cold on another night. Recently, we visited Florada’s Emerald Coast and loved it.

    We have figured out how to add air conditioning to our huge lightweight tent.

    The Prius is a great car for camping. Please don’t let people scare you from following your plans.

    The Prius is a workhorse - and sometimes I think “he” wants to travel too :)

    The key is pack as if you are lightweight backpacking. Everything I have in the Prius is designed for lightweight camping - even my tent.

    The company REI is my go-to for all things good quality and lightweight. My tent is huge yet weighs less than 25 pounds. Some tents are as small as 2 pounds - maybe lighter.

    In addition, I study bushcraft techniques on YouTube to let the environment work for me.

    We stay in nice hotels like Hilton Home2Suites - but had a break-in when using our minivan as a camper so now we are using the Prius again because in the same hotel parking lot, no one touched our Prius. (We we’re moving one child from a college apartment and stayed overnight at a hotel.)

    Always cover your stuff with a blanket or sheet - always. I use black. After the other car was broken into, I had all the windows on both cars tinted with ceramic UV protection as dark as legally allowable. I am still working on Stealth. Not to live in my car but to protect my stuff. The thief sole my large capacity recharger. I highly recommend a car battery recharger like Suaoki, powerful inverter (at least 300 watt,) and long extensions so you can work comfortable while recharging gear.

    As others recommended, I have been running my engine all night to stay comfortable but for recharging, I recharge while I drive. I think the OP was planning very long bike rides maybe camping away from the car, so did not want the car running all the time. We ran the AC all night and lost about 2 bars. I totally understand why the OP did not want to leave the car running unattended. If Stealth is used, no one can see inside the car. I have become an expert at stealth. Try at home first and cover ALL sources of light. In the front seat area. Those extra lights caught me off guard.

    If you stumble over this webpage - please be encouraged that there are many ways to camp in a Prius. Adventure is awaiting you! Happy campus in your Prius mini RV.
     
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  16. Haschwalt

    Haschwalt Member

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    The way he wires the batteries in his video in parallel isn't that great. Can ruin the original battery. How did you wire your 2nd battery?
     
  17. edthefox5

    edthefox5 Senior Member

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    You keep asking questions on years old threads.

    Start a new thread and ask questions instead of tagging years old threads.
     
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  18. Haschwalt

    Haschwalt Member

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    Is there a rule against it? I find the threads on Google & I prefer to message people in the thread who started it since the contents & discussion are relevant. That's the whole point of a forum – sorry I don't spend all day long on forums raging over any every new post. Perhaps spend less time all day on the computer, & not get your panties in a bundle & if it still bothers you, you can kindly ignore the post ;)
     
    #18 Haschwalt, Jul 19, 2019
    Last edited: Jul 19, 2019
  19. ChapmanF

    ChapmanF Senior Member

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    If you tag on to an old thread and you mention the screen name of an older poster with an @ in front, then they will get a message that you have mentioned them (if they still have an active PriusChat account and they check it). Otherwise, you haven't really messaged anybody, just put new content on the end of an old thread that the original poster may have long forgotten about and might never see.
     
  20. Haschwalt

    Haschwalt Member

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    The post I responded to was in August 2018 - not even a year ago. By pinging the user in question, he will receive an email notification, as well as see which thread he posted in. I find the complaints redundant.
     
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