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DRAFT

> “It is cheaper and easier to use less power than it is to make more power.” – highdesertranger

> ...the //why// is important. If you are trying to **meet a specific performance goal** you can save money by identifying performance bottlenecks and upgrading the relevant components. If you want to do the upgrades because they sound like **a fun project** then throw all the parts at it you want with my sincere blessing. I certainly am not immune to fun projects. -- secessus((https://www.reddit.com/r/RVSolarPower/comments/1keb0or/dc_to_dc_questions/mqq64ma/))




====== upgrading an existing power setup ======








So your existing [[electrical:12v:intro|power setup]] isn't meeting needs and you want to change it.  Maybe your [[electrical:12v:dailypowerrequirements|daily power requirements]] have increased, you bought [[opinion:frater_secessus:prebuilt_van|a pre-built]] van, or your use case has changed.  



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


  * the first step to fixing a problem is to **understand** and **clearly state** the problem.
  * human nature leads us to want simple solutions to complex problems
  * marketers and influencers have vested interests in convincing us that simple solutions exist:  "What you need is a [insert product here]"
  * successful upgrades are more about **understanding needs** and what interventions are practical for your use case


[[opinion:frater_secessus:pareto|about these summaries]]


===== big picture:  how close are we to the goal line? =====

  * if your existing system usually meets needs but **occasionally falls short** in anomalous circumstances it might be simpler/easier/cheaper to reduce consumption at those times. 
  * if your existing system is **close to meeting needs** ((like within 10% of hitting [your daily power requirements](https://rvwiki.mousetrap.net/doku.php?id=electrical:12v:dailypowerrequirements)) then upgrading the bottlenecked component can close the gap with no other changes needed.
  * if your existing system is **far from meeting needs** then the [[electrical:12v:power_mix|overall charging mix]] could stand to be reconsidered.  



===== define the problem =====

There is a saying that 

>> defining the real problem is is 90% of the solution

... and that applies here.  I understand why we humans don't want to spend time/effort figuring out the problem.  It's not fun and we don't get to buy stuff yet.  

There are two main areas where the problem can reside, or it can be in both.

==== demand problems ====

This is listed first because **reducing demand is free**((usually)) and trivial to test.  It's like the old joke:

Patient - "it hurts when I do //this// (sticks finger in eye)" \\
Doctor - "Stop doing that."

Some loads are mandatory and we can't "stop doing that".  Your insulin might require a powered fridge at all time or a CPAP might be mandatory. But many high-current loads newbies try to run (and crash their power setup) are easy and cheap using traditional methods.  Electric water heating vs propane water heater (or kettle over a stove), for example.  

=== demand scheduling ===

Sometimes just changing when the load runs can eliminate/reduce required upgrades.  Consider a system with limited Ah capacity that sags under load and trips the inverter's low voltage protection.  Running that same load when the solar or alternator are making power can reduce the sag, reducing or eliminating the problem. 


==== supply problems ====


Supply problems can the broken down into charging, bank capacity, and throughput bottlenecks.

=== charging bottlenecks ===

Charging bottlenecks occur when the battery bank could happily [[opinion:frater_secessus:charging_faster|charge faster]] and more often but we aren't doing so.  

A major cause of underperformance is **reliance on a single form of charging**.   The sun is not always out (solar), you are not always driving (charging from alternator), and access to the power grid is not always available (shore power). 


  * solar
    * maybe we have no solar at all
    * maybe we have unused roofspace to devote to more panel
    * maybe the panel we have is [[opinion:frater_secessus:beginner_mistakes#mounting_or_deploying_panels_where_they_will_be_shaded|shaded by other things on the roof]]
    * maybe we went with portable panels but [[https://rvwiki.mousetrap.net/doku.php?id=opinion:frater_secessus:beginner_mistakes#believing_they_will_set_out_portable_panels|don't deploy them consistently]] for whatever reason.  Some mounted panel could make a big difference.
    * maybe we went with mounted panels but park the rig in the shade.  Portables on extensions set out in the sun could make a big difference. 
  * alternator
    * maybe we are not charging from the alternator at all 
    * maybe we are forgetting to enable charging from the alt after [[electrical:12v:alternator#disabling_alternator_charging|disabling]] it
    * maybe the alternator has [[electrical:12v:alternator_details#current|excess capacity]] to devote to house bank charging
  * shore power
    * maybe we are not [[electrical:converter|charging from shore power]] at all when we have access to it


=== bank capacity bottlenecks ===

If you can charge the bank consistently but run out of power overnight or in periods of decreased harvest you may just need more bank capacity.  Also see [[electrical:autonomy|Days of Autonomy]].


=== throughput bottlenecks ===

These are related to the systems above, but are less obvious.

  * panels and PWM solar charge controllers poorly matched, resulting in [[electrical:solar:pwm_tweaking#pwm_s_achilles_heel|underperformance]]
  * insufficient panel wattage
  * panel wattage grossly oversized for the MPPT controller (>30% [[electrical:solar:overpaneling#vs_charge_controller|overpaneled]];  this is relatively rare)
  * DC-DC [[electrical:12v:b2b#sizing|undersized]] relative to the alternator and bank
  * wiring undersized for alternator charging with a combiner (relay/solenoid/"isolator", etc.  Since they don't alter voltage this kind of setup is sensitive to resistance between the chassis electrical and battery bank.
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