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DRAFT

====== I bought a pre-built van.  How does the power system work? ======

You already bought the van; it's a done deal.  The time to beat the "understand what you're buying //before// you buy it"  dead horse has past.  Right now we need to figure out, make use of, and possibly modify the system you have. 


===== TL;DR =====

  * **observation** is a major part of both figuring out a system and of troubleshooting.  Look.  Notice.  Pay attention.  Document. 
  * look up the manual or specs for for every component you find 
  * the job of the power system is to accept charge from [[electrical:12v:power_mix|one or more sources]], store that energy, and use it for [[electrical:12v:loads|loads]] you want to run.  On average **charging must be ≥ discharging**((the "average" part is provided by bank capacity)) or you will [[opinion:frater_secessus:running_out_of_power|run out of power]].
  * a system can be working-as-designed and still not do what you want or meeting your needs
  * Some problems are easy to identify ("hey, what happened to the lights?").  Some are so subtle we (or the PO) might not notice them or see them as a problem. 
 


===== figuring out what you have =====

The first step is figuring out what you have, both for your understanding and so others might be able to help you.  Knowing what you have helps you [[opinion:frater_secessus:beginner_mistakes#failure_to_ask_good_questions|ask productive questions]].  Remember, the people you are asking for help cannot see inside your van.  You are their eyes and ears.  


I encourage you to make a text document on your phone or PC to hold info on what we find in this section.  Not only is it handy for you, but if you ever need help you can paste in the data so we can tell what you've got.  win-win

Sources of information:

  * **visible make/model information** on power-related devices
  * the sales listing from when you bought the van
  * communications with the seller or manufacturer
  * receipts and other paperwork (manuals?) that came with the van
  * information from a VIN lookup tool (see below)

Ideally this list also contains links to product pages and online documentation like manuals. Posting pictures of the gear and nothing else [[opinion:frater_secessus:beginner_mistakes#making_helpers_guess|offloads legwork]] onto the people you are asking for free help.  Please don't make us guess or do your homework.  

[Personal note from secessus:  here is [[http://mouse.mousetrap.net/boondocking/parts.txt|my own plaintext list]], and [[https://mouse.mousetrap.net/boondocking/parts.html#power|a fancier version]] with commentary.  I did not know this off the top of my head -- I went through my amazon orders, emails, etc, to gather it all up.] 

==== looking up the vehicle's VIN ====

A VIN lookup tool can tell you what came stock on the vehicle.  Of particular importance is the [[electrical:12v:alternator_details|alternator]] rating.  Engine info ("3.5L V6" or whatever) is indirectly important because stock configurations are often associated with particular engines. 

Caveat: If someone upgraded/changed the vehicle after purchase the VIN will not know about that....

You can find a free lookup tool by searching ''[brand] VIN lookup''.  [[https://duckduckgo.com/?t=lm&q=chevy+vin+lookup&ia=web|Example using Chevy]]


==== general approach to understanding the house power setup ====


It might be overwhelming to try to understand all at once, so start simple.  Look around you.  What can you see that might be electrical?  Are there status lights or displays active at certain times or all the time?  Do installed amenties like light, fan, etc work all the time or just when the engine is running?



==== battery banks ====

House ("living area") battery banks are usually large and often the size and shape of the van starter battery you've seen under the hood.  There are likely thick red/black cables connecting them to the rest of the system.  There may be one or more batteries in the bank, and can be arranged in [[electrical:12v:parallel_serial|parallel or series]]. 

  * Is there one battery or more than one?  If the latter, how are they wired together?
  * Do you see any capacity markings like Ah (Amp-hours) or Wh (Watt-hours)?
  * Do you see any branding like Chins, LiTime, Ampere Time, SOK, Renogy, Eco-Worthy, or a goofy-sounding Chinglish" name?((looks like English but the word choice and word order suggest it's translated from Chinese.  The vast majority of vandwelling power compenents are made in China.))
  * Do you see a model name, like //Smart Lithium Iron Phosphate// or //Ex-500//?  
  * Do  you see any charging guidelines on the label?((charging voltage, float voltage, charging amps, etc))


==== solar panels ====

[[electrical:solar:panels|Solar panels]] are usually pretty obvious if you have them. They may be mounted on a rack, adhered flat to the roof, or be portables/suitcases that store inside the van.  It can be hard to tell how they are wired if everything is tucked away.  Sometimes you have to infer based on panel specs (see below) and what you see on the solar charge controller (see below again). The wires have to enter the vehicle somewhere, hopefully through a weatherproof "gland" (small box).


The label on the backside of the panel will show [[electrical:solar:panels#specifications|the specs]] you'll need to know and share.  

If there is no back label or you cannot access it((you might be able to slip an inspection mirror or phone under the panel to read the backlabel)) you will need to consult the manufacturer's website or manual.  

**Pro tip**:  if you are mounting new panels take a pic of the label //before// mounting them where you can't see it.  

==== charging and chargers ====

We recharge our battery banks almost every day, so there is probably at least one charger present. All chargers have settings of some kind:  battery type, charging voltages, etc.  Look at your manual to see what the defaults are, and cycle through any displays/apps to see if the configuration differs from those defaults. 

When charging the voltage will tend to rise and when discharging it will tend to fall.  The amount of this rise or fall is related to charge/discharge current and other factors in the setup.  Watch for patterns rather than specific numbers.  For example, if bank voltage rises when you start then engine then alternator charging is likely in play.  If bank voltage falls when a dark cloud obscures the sun then solar charging decreased (or stopped) for that reason.  






In order of most common to least common charging setups:  

=== solar charge controllers ===

The [[electrical:solar:charge_controller|solar charge controller]] ("SCC", "controller") will have wires coming into it from the solar panels and out of it to the battery bank. There may also be [[electrical:solar:charge_controller#using_load_output|LOAD terminals]] but these are rarely used in van setups. 

Common controller brands are Victron, Renogy, EpEver.  Morningstar and Blue Sky were premium controllers that are not as common in vans nowadays.  There are also many rebranded inexpensive-but-functional controllers from SRNE, BougeRV, Eco-Worthy, etc.  The two main [[electrical:solar:charge_controller#using_load_output|types of controller]] are PWM and MPPT;  they are different ways of getting power from the panels into your battery bank.  As long as your solar is working the type of controller is not particularly important at this stage.



The lowest end of the market is flooded with [[electrical:solar:charge_controller#single-stage_chargers|very cheap controllers]] (often incorrectly called "MPPT") in the $10-$20 range.  These can work if you understand their limitations. 


=== alternator charging ===

[[electrical:12v:alternator|Alternator charging]] comes in two basic flavors:

  - [[electrical:12v:alternator#combiners|combiners]], simple and inexpensive.  Includes switches, relays, voltage sensing ("smart") relays, usually mounted near the starter battery.((possibly under the hood of the vehicle))  This type of device is basically a pass-through for whatever the battery bank wants / the alternator can give. Often no name on the device at all, although VSR do sometimes carry labels like Stinger, Smart, Battery Doctor, etc. 
  - [[electrical:12v:b2b|DC-DC chargers]], more complex and costly chargers that can regulate current and/or voltage.  Usually mounted quite close to the battery bank.  Common brands include Victron Orion, Sterling, Renogy, etc. Since 2024 less expensive versions have come to market from China, including Li-Time, Etaker, etc.  These tend to have less extensive documenation. 



=== combination DC-DC + solar charging ===

There are are some [[electrical:12v:b2b#examples_-_combo_with_solar_charge_controller|combo DC_DC / MPPT chargers]] on the market.  The most famous is the Renogy 50A, although the Kisae is increasingly popular.


=== shore power charging ===

This is the least common form of charging since few vanfolk have the luxury of access to [[electrical:shore_power|grid ("shore") power]]. Having steady access to shore power is like winning the vandweller lottery because you can do almost anything you want, power-wise. 

When present, shore power chargers might be [[electrical:converter|RV-style converters]] from Iota, PowerMax, Progressive, WFCO.  Rigs that plan on making use of shore power more often might have RV-style [[electrical:inverter#inverter_chargers|inverter-chargers]] like the Victron Multiplus line.

Sometimes people use general purpose battery chargers that might not be made for vans/rvs:  Noco, Schumacher, etc. 


==== inverters ====

[[electrical:inverter|Inverters]] are used if/when you need to run 120vac((in the US)) loads from 12vdc((typically)) battery banks.  

They will typically have a wattage rating labeled on them.  With more reputable manufacturers this will be the continuous duty rating.  With less-scrupulous manufacturers this might be the peak/surge output rating.  

Unless the inverter says ''pure sine wave'' or ''PSW'' on it there is a reasonable chance it is Modified Square((or Sine)) Wave.  See link above.  


==== wiring and fusing ====

While poking about taking stock of the components, also notice the wiring and fusing.  


It can be difficult to tell the construction and gauge of wiring by externals.  If you are lucky that information might be printed on the insulation of the wiring itself.  This kind of info might be printed only on one side maybe only every few inches or feet so it might be hidden at first.  Keep tracing and looking.  

Fuses and breakers are usually labeled with their current limit 

[[https://www.bluesea.com/support/articles/Circuit_Protection/1437/Part_1%3A_Choosing_the_Correct_Wire_Size_for_a_DC_Circuit|This Blue Sea article]] describes appropriate wire gauge for a given current and circuit length. 


===== upgrades =====

You may have to make some upgrades to meet the demands of your particular use case.  A rational approach might be:

  - understand your use case, including [[electrical:12v:dailypowerrequirements|daily requirements]] in Watt-Hours or Amp-Hours and [[opinion:frater_secessus:run_this_load|load requirements]] in Watts or Amps. 
  - understand what the  existing system can do (see above)
  - find the bottlenecks and open them up so it //can// meet your needs 

An irrational-but-common approach would be to [[opinion:frater_secessus:beginner_mistakes#buying_random_stuff|buy stuff at random]] based on impulse,  marketing, or "good deals". 


===== troubleshooting problems =====

There is a famous saying that 

> clearly stating the problem is 90% of the solution

...so we are back to //observation// again.  Once you can clearly state the nature of the problem continue to [[troubleshooting:electrical|this overview of troubleshooting]]. 


==== going forward ====

Once the crisis is over 

  - adjust your cut/paste parts document anytime you add or change a component
  - observe the system in normal operation so you can tell when it's //not// acting normally
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