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electrical:12v:mandatory_dcdc
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Table of Contents
Note this is a companion to the Is Solar Mandatory? article
Is DC-DC charging mandatory?
Death and taxes are mandatory. Gravity is mandatory.
In many/most situations direct-charging the house bank with a combiner (relay, isolator, VSR) is both effective and inexpensive. Even with lithium banks.
There are scenarios where one may want to disable the combiner.
situations where DC-DC is effectively required
- small alternators vs. ginormous battery banks of any chemistry
- smart (variable-voltage) alternators, more common in Europe
- exotic alternator or battery bank voltages
- if one needs relatively-stable charge rates1)
- if you want to impose an arbitrary current limit2)
when an influencer says sowhen Chicken Little claims you need one or the sky will fall
situations where DC-DC is preferable
- lead house bank when alternator is the only charging source
In this case DC-DC won't help with Absorption duration3) but it can help with Absorption voltage.
1)
Direct-charging from the alternator with a combiner of some kind tends to start out strongest when battery bank voltage is lowest, and taper as the bank voltage rises; I=V/R. This effect is most noticeable with flooded lead acid batteries and least noticeable with Lithium, at least after reaching the flat middle area of the voltage curve.
2)
0.2C for Gel, 0.4C for lithium, etc
3)
the vehicle is usually not running long enough to fully charge lead-chemistry batteries fully
electrical/12v/mandatory_dcdc.1683558901.txt.gz · Last modified: 2023/05/08 11:15 by frater_secessus
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