# Inverters



## Haystack (May 22, 2016)

Would a inverter be something worth investing in for electrical needs in a van? I know truckers use them for their little microwaves, fridges, tvs, etc, but I've never heard of anyone using one for their van.


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## Dmac (May 22, 2016)

they are very handy to have, but they can run your battery down fast. or completely if you forget and leave them on when you are parked.


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## kecleon (May 22, 2016)

It depends what you want to use it for.

A TON of stuff already runs off of DC and the power adapter is actually an AC to DC converter so if you were to plug in a laptop you'd be going DC to AC to DC which is losing you a ton of efficiency.

And inverters aren't much efficient at the best of times.

with some wiring or eBay purchases you can run most everything off DC.

For something like a fridge I think its a good idea since DC fridges are expensive as hell and fridges dont use a ton of power, but you can't run it off of the car battery and for that matter shouldn't run anything much off the car battery when its not running. You want a deep cycle camper/boat (leisure) battery and a way to charge it. You can charge off your alternator most likely.


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## goatfloat6000 (May 22, 2016)

i have 2 deep cycle marine batteries that i swap out when the other dies, not connected to my alternator, just sitting in the back. i use a cheap 1000W inverter to charge my laptop/phone. works ok, but sometimes my laptop pulls too much power while running and charges best when not in use.

i pull the batteries out and just use a wall charger on them at a friend's house. i don't drive enough to warrant setting up a house battery that charges via the alternator, but if i take off and travel, i'll probably end up setting that up in a different van.


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## TMG51 (May 22, 2016)

There is some information already posted in this thread which is not ideal. E.g., you should never run your battery down unless you are willing to significantly shorten its life. This sort of topic could have its own forum, let alone its own thread, so I'll try to stick to a brief overview of the question posed.

Most will tell you to use an inverter. I disagree. Inverters carry an inherent efficiency loss, and most everything you need can be run from DC directly. I am of the opinion that anything that doesn't, you don't need.

I've been full time on the road a while and I don't use an inverter for any daily items at all. I run my laptop with a DC adapter, make coffee with a percolator, etc etc. It's always more efficient to up DC voltage than to covert to AC.

Never buy a 120v AC refrigerator for your vehicle life. Trust me on this. Yes, DC compressor refrigerators are expensive upfront but they are the only electric fridge that is feasible to run off grid. You'll spend more money on an inverter and then killing your batteries prematurely with a household fridge.

Two things you're never gonna run off your batteries: air conditioning, electric heat. Forget both of them. Microwaves are doable but I consider that a waste of resources. Just put a Pyrex dish in boiling water to heat whatever you might have heated in the microwave.

What else do you need to power that can't be done off DC? I'll wager nothing.

Y'know that block in a power cord with numbers on it? It'll often say things like "input: 120v AC. Output: 18v DC 4.5a". Use a DC adapter to replicate whatever the output is, send it to the device, and forget about an inverter. Once in a while you'll get lucky and see something with an output of 12v DC on its power brick. In such an occasion, cut the block right off and write it up directly. Note positive wire first.

I do keep a small inverter, only 170 watt, which I use for recharging small electronics (cameras, clippers) simply because it isn't convenient to modify some small items to a 12v adapter. This amount of power inverted is minuscule. I might use it once a month, tops.

That oughta be a good start. Plenty more info to get into here.


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## kecleon (May 22, 2016)

1000w (2000 peak) Inverter under $50, fridge $100. DC fridge (not cooler) $500~ plus battery for both. 

Domestic fridge power consumption is generally equal to dc the real problem is peak is huge so for a small fridge you may need 2000w peak so then you end up with low running efficiency (around 75%) but at ~30w per hour 75% efficiency isn't making a huge difference - pushing it to 35w. So it's certainly not going to kill a battery more so than a DC and the low draw isn't going to send an inverter to an early grave either. 

Real things to consider with domestic fridges in vans is they make noise and don't like being moved very much which I imagine would affect the fridges lifespan but not the inverter or battery.


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## Haystack (May 22, 2016)

This is all very good information, thank you all!

Basically right now I'm trying to figure out a solid plan for my van build (I don't have a van yet, but actively looking).

After thinking about it I'm kind of second guessing what exactly I NEED for what I intend to do with the van. I'm not looking to permanently live in it (at least not right now), but I do plan to go on some short trips at first to make sure my van can handle it and to get a feel for what I might need to improve or change for a long trip. Then I want to do a 3 month long trip around the west/mid-west. Who knows maybe I'll end up in it permanently depending on how things go.

With that said I've been thinking about what exactly would I bring with me and what do I need to power. Now of course I'll have my cell phone which is nothing. I might bring my laptop, but there's a good chance I probably won't even need it if I have my phone, but I might change my mind. I'll have a stove so no need for a microwave, I don't drink coffee (tea guy) so I don't have a need for a coffee maker. Now I'm thinking about a fridge and if I really need that at all? Maybe I can get by with a cooler.. I'll have to do some more research on them.

So with that said I'll have my phone, maybe a laptop, and some led lights for in the back of the van. I'm sure I might think of something else but I'm trying not to get too crazy with the build yet, I want to keep it real simple.

Would a dual battery set up with a isolator (and maybe a bigger alternator depending on what size is in the van already) be a good idea for my needs then?


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## Kim Chee (May 22, 2016)

I hear a lot about inverters, but nothing about modified sine wave vs pure sine wave inverters.

If you're going to buy an inverter, make sure you get the type you need.

The differences have been covered extensively elsewhere so I'll spare everybody the mumbo jumbo.

I just purchased a pair of 100w inverters (kind of small) off of ebay for under $10 each delivered. 

I think they are useful.

*the nicer inverters will shut off in a low voltage situation to keep the absent minded from running their batteries down. (Relying on this feature often will have a detrimental effect on the life of your batteries).


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## Deleted member 8978 (May 22, 2016)

This makes me wonder how effective that solar power can be and how that would impact overall mobility.


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## kecleon (May 22, 2016)

Haystack said:


> Would a dual battery set up with a isolator (and maybe a bigger alternator depending on what size is in the van already) be a good idea for my needs then?



Yes that'd be more than enough and I doubt you'll need a bigger alternator for LEDs, phone and a laptop. If you're driving it's easy to charge your phone and laptop as you drive and need very little power once you stop. And you should definitely be using 12v for that stuff. Check eBay for 12v car charger for your laptop and USB charger for other stuff.

I've never wanted for a fridge in a van or anything, I just have experience from setting up solar panels off grid that were running a fridge, washing machine and oven. Unless you're staying in wilderness for a while its not a huge benefit.

@quad8 Solar power is great if you're in one place for some time, with 100w and a deep cycle battery you can charge phone laptop and run lights no problem.

The only thing is to get nice panels that fit to your roof securely enough for driving and that are still somewhat aerodynamic is expensive and they're less efficient if you can't angle them at the sun, so you either have to pony up for nice fitting aerodynamic but less efficient or keep putting them up and taking them down, storing them and risk theft.

Sinewave is like a can of worms. Not all modified sinewave are made equal. Best thing is to go off reviews for specific models. I hope soon it will get to the point modified gets phased out as pure prices fall


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## Haystack (May 22, 2016)

charmander said:


> The only thing is to get nice panels that fit to your roof securely enough for driving and that are still somewhat aerodynamic is expensive and they're less efficient if you can't angle them at the sun, so you either have to pony up for nice fitting aerodynamic but less efficient or keep putting them up and taking them down, storing them and risk theft



There's a guy on youtube by the name of Cyclecruza that built up a bug out van for his motorcycle and he used I think 4 of these 100w panels that are flat/bendable and stick to the top of the roof. He seems pretty happy with them.

Edit: for some reason the amazon link won't show up when I post. They're called 
*HQST 100 Watt 12 Volt Monocrystalline Flexible Solar Panel*


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## Kim Chee (May 22, 2016)

Next thing you know you'll be asking about a charge controller


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## Rob Nothing (May 22, 2016)

_are_ there forums anyone here might recommend on the subject? I had a brief intro course on this stuff last year but most of that knowledge has faded out as there was not serious interest or further study at the time. Solar can be incredibly efficient and simple if you have the key ingredients down and know to look after your 12volts.


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## kecleon (May 23, 2016)

Haystack said:


> There's a guy on youtube by the name of Cyclecruza that built up a bug out van for his motorcycle and he used I think 4 of these 100w panels that are flat/bendable and stick to the top of the roof. He seems pretty happy with them.
> 
> Edit: for some reason the amazon link won't show up when I post. They're called
> *HQST 100 Watt 12 Volt Monocrystalline Flexible Solar Panel*



Yeah that's pretty much what I'd go with on a van, but they're expensive - usually 100w is around $100 for poly and $130 for mono and you can't angle so less efficiency.

Charge controllers are easy at least! Just get the right amps, amps x volts = watts so generally for 100w you'll get a 10amp controller for 200w 20amp, 500w 40 amp. Even cheap controllers work fine in my experience.

@Kim Chee Real question is 12 vs 24 volts 

@severin check out forum.solar-electric.com and solar paneltalk.com


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## TMG51 (May 23, 2016)

Haystack said:


> Would a dual battery set up with a isolator (and maybe a bigger alternator depending on what size is in the van already) be a good idea for my needs then?



Let's take a step back here, again. A dual battery set up is ideal, yes. How you charge them is a whole other story. An alternator alone cannot optimally maintain your house battery. Many people mistakenly believe that it will. The limitation is not the output of the alternator, but rather how much charge the battery can accept. A deep cycle battery might be quickly brought up to 80% charge or so, but that last 20% charge (which is important to achieve) will take hours, regardless of the source. So unless you're driving for hours on end daily, you're never getting that top charge out of your alternator. No need to get a bigger alternator because it still won't be a magic battery maintainer.

Many people will tell you that their house battery works "just fine" off their alternator alone. That's surely true. It will work just fine until it doesn't work anymore, and you've killed your batteries. I'm not here telling everyone they have to do it the *right* way, I'm just saying what the right way is. If you're going to set up a two battery system off your alternator alone, then don't spend a lot of money on your house battery because you're going to be killing it anyway. If you're happy with that then I'm not here to tell you you're wrong.

Solar is totally passive. You spend the money once, it sits on your roof, you get free energy. It works for hours on end to get you that top charge on your battery. It works whether you're parked or you're driving. No reason not to invest in solar.

Quick note - three main types of batteries. Starter battery, marine battery, deep cycle battery. Deep cycle batteries and marine batteries are different, even though many think they are the same. A starter battery is designed to have a large output (start your engine) and then recharge, nothing else. A deep cycle battery is meant to have a long, slow discharge (e.g., running your lights, charging electronics, etc). A marine battery is halfway between the two and attempts to do both jobs, but it does neither as well.

The best way to get a true deep cycle battery is to buy two 6v golf cart batteries and wire them together to make one 12v battery bank. Golf cart batteries can be bought on the cheap at Costco or Sam's Club. If you're going to set up a two battery system, this is my suggestion.

If this all is becoming overwhelming and you don't care that much, or you aren't going to install solar, then my honest suggestion is this: 1) Replace your starter battery with a marine battery (it will start your car and allow for modest discharge) and 2) install an automatic battery cut off device such as this one. Between those two, you'll have a functional electrical system for small needs and you won't be leaving yourself stranded with a dead battery.

For the 'fridge, best choices are a real DC compressor refrigerator (expensive) or just use a cooler and ice. I don't recommend anything else.


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## TMG51 (May 23, 2016)

Oh yeah. And about the isolator. Those are typically used by RV manufacturers and such, but they carry an inherent efficiency loss due to uninteresting reasons. Short version of the story: If installing a two battery system, use a continuous duty solenoid, not an isolator. It creates a direct mechanical connection when you start the engine and there is no efficiency loss. Make sure the solenoid is a continuous duty, not a starter solenoid.


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## MilkaNoobie (Jun 26, 2016)

charmander said:


> Yes that'd be more than enough and I doubt you'll need a bigger alternator for LEDs, phone and a laptop. If you're driving it's easy to charge your phone and laptop as you drive and need very little power once you stop. And you should definitely be using 12v for that stuff. Check eBay for 12v car charger for your laptop and USB charger for other stuff.
> 
> I've never wanted for a fridge in a van or anything, I just have experience from setting up solar panels off grid that were running a fridge, washing machine and oven. Unless you're staying in wilderness for a while its not a huge benefit.
> 
> ...


Solar city recently was bought out by Elon Musk but before they were they invented a Solar Panel that's a huge improvement on older models ...if I remember correctly it was a 30% increase in performance for same size of older model's


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## kecleon (Jul 17, 2016)

I don't know about that but mono panels are mor efficient size wise than poly panels. Also seen a lot more flexible panels at reasonable prices lately. Dont know who invented them.


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