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Is solar mandatory?

Solar isn't mandatory. Here are some cases where it might not be worth the trouble:

  • the camper has Lithium, carbon-foam, or similar battery chemistries that are not bothered by sitting at partial state of charge and there is enough charging capacity to meet needs.
  • the camper has lead batts but will be sitting on shore power
  • the camper has lead batts but is equipped with a DC-DC charger will be driven for several consecutive hours at least a couple times a week.1)

The rest of this document assumes the camper is equipped with normal lead-chemistry batteries (flooded, AGM, gel etc).

Solar is incredibly useful for nomads with lead-chemistry batteries. There should be a good reason why they would plan a build without some solar. Even just a small amount. Some reminders:

  • solar brings higher voltages to battery charging, which is healthy for them. Lead-acid batteries that don't get a full, higher voltage Absorption stage will not be fully charged. Which will kill them.
  • Absorption stage is high voltage and decreasing current, which is exactly what solar does well
  • This higher-voltage solar charging can be combined with the higher-current nature of alternator/isolator charging for maximum power and minimum expense.
  • solar is silent and can be discreet
  • solar works when the sun shines
  • solar doesn't wear out or get used up in the normal sense. No maintenance required!

getting by without solar

For whatever reason you are not going to have any solar in your build. So how will you charge your batteries?


[note: this section is based on a reddit post]

An isolator will do the heavy lifting, but is unlikely to get/keep the house battery fully charged snce the voltage isn't high enough.

There are a couple of ways around the low voltage issue:

  • use a battery chemistry that doesn't care about partial state of charge (PSoC), like lithium or carbon foam. Bring lots of money.
  • use a b2b charger that boosts alternator voltage to a voltage that has a chance of fully charging the bank, given enough time.
  • Augment with shore charging when possible unless you are driving for several hours 1-2x/week.


Like alternators, generators have a lot of current on tap. But as with alternators you have to run them a long time to get a full charge. Deep cycled lead-acid batteries require hours of charging at Absorption voltage to get fully charged. The most efficient time to run the generator is when the batteries are deeply discharged (early morning).

shore power

If you are staying at campsites with power you can just plug in and let your converter handle loads and charging. You could skip a day or two and get back on the charger without causing too much damage.

an isolator might suffice for lithium banks
electrical/12v/mandatory_solar.txt · Last modified: 2024/02/09 13:21 by frater_secessus