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electrical:12v:charging [2020/01/13 10:39] frater_secessus [absorption stage] |
electrical:12v:charging [2020/10/18 12:30] frater_secessus [equalization] |
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- | [[lifestyle: | + | [[lifestyle: |
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+ | > “Three stage chargers are easier on your batteries, charge them faster, fuller and help you use less water”((https:// | ||
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+ | > A [ [[electrical: | ||
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+ | > Charging lead acid batteries is not something that you decide to do, or start or stop. The old statement, "I need to idle the engine for a few minutes to "top off" the batteries." | ||
====== charging deep cycle batteries ====== | ====== charging deep cycle batteries ====== | ||
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===== three stage charging ===== | ===== three stage charging ===== | ||
- | Three stage or " | + | Three stage((some mfg claim 4 or more charging stages, including equalization or proprietary stages. |
SternWake sums up smart charging: | SternWake sums up smart charging: | ||
- | > "Bulk rate is maximum amps the charging source can supply until the absorption voltage is reached, at that point the amps required to hold the ABSV will taper. The longer the battery is held at ABSV, the more the amps required to hold ABSV will taper. At some point, either time, or the amps required to hold ABSV fall below a threshold and triggers float mode." | + | > "Bulk rate is maximum amps the charging source can supply until the absorption voltage is reached, at that point the amps required to hold the ABSV((Vabs, absorption voltage)) |
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+ | This graphic((from an unknown Amazon seller)) shows how current and voltage change during the full charge: | ||
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+ | {{https:// | ||
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+ | Charging won't be as neat as the graphic due to [[electrical: | ||
- | The example below will use charging data for Trojan T-105 FLA batteries | + | The example below will use charging data for a 12v bank of Trojan T-105 FLA batteries at 77F.((http:// |
==== bulk stage ==== | ==== bulk stage ==== | ||
- | The bulk stage is a fast and furious rush to get **maximum power returned to the battery bank**. | + | The bulk stage is a fast and furious rush to get **maximum power((or max // |
This stage **begins when charging starts** (as when the sun comes up) and **ends when the battery climbs to the acceptance voltage setpoint**, 14.8v in our T-105 example. | This stage **begins when charging starts** (as when the sun comes up) and **ends when the battery climbs to the acceptance voltage setpoint**, 14.8v in our T-105 example. | ||
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In practice absorption takes longer when the battery has been discharged deeply and shorter when it has not.((http:// | In practice absorption takes longer when the battery has been discharged deeply and shorter when it has not.((http:// | ||
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+ | **Mythbuster: | ||
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+ | > charge current affects the SOC transition point from bulk to absorption charging - MaineSail((https:// | ||
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+ | MaineSail found that | ||
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+ | * charging AGM at C/2.5 (max rate) resulted in the battery being 63.3% " | ||
+ | * charging AGM at C/5 (min rate) resulted in the battery being 77.4% " | ||
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Some controllers will allow the user to configure the time or ratio of capacity/ | Some controllers will allow the user to configure the time or ratio of capacity/ | ||
> If your charge controller only holds [absorption] voltage for an hour or two, that is likely not enough time. As long as [there is a load] and you cycle the battery daily, you could set float voltage to 14.8v((for example - secessus)) [to match absorption] without worry. Only when you stop cycling the battery do you need to return float voltage to more regular 13.2v((for example - secessus)) levels. Premature application of float voltage by automatic charging sources is a battery killer.((http:// | > If your charge controller only holds [absorption] voltage for an hour or two, that is likely not enough time. As long as [there is a load] and you cycle the battery daily, you could set float voltage to 14.8v((for example - secessus)) [to match absorption] without worry. Only when you stop cycling the battery do you need to return float voltage to more regular 13.2v((for example - secessus)) levels. Premature application of float voltage by automatic charging sources is a battery killer.((http:// | ||
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+ | If Absorption cannot be completed in the max amount of time configurable in the controller (due to damaged/old batteries), **charging at the minimum rate and/or at higher voltage may help [[electrical: | ||
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Common Vfloat values range between 13.2v for stored batteries to 13.8v for banks that are deep cycled each day. | Common Vfloat values range between 13.2v for stored batteries to 13.8v for banks that are deep cycled each day. | ||
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+ | also see [[electrical: | ||
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- vigorous Bulk charging((minimum current of [[electrical: | - vigorous Bulk charging((minimum current of [[electrical: | ||
- long Absorption stages | - long Absorption stages | ||
- | - but lower Absorption voltage (to prevent outgassing) | + | - typically |
- | - absolutely | + | - no Equalizing (which |
Many charge controllers have AGM or GEL modes that handle these setpoints and durations. | Many charge controllers have AGM or GEL modes that handle these setpoints and durations. | ||
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===== charging other chemistries ===== | ===== charging other chemistries ===== | ||
- | See [[electrical: | + | Lithium packs don't need Absorption or Float stages in the lead-battery sense but those voltage setpoints can be put to good use. Follow your Li battery mfg's advice on charging. |
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+ | - Absorption voltage - 4S LFP packs are actually 100% [[electrical: | ||
+ | - Float voltage - Li does not like to sit at 100% SoC,((the cells degrade faster at 100%+ SoC)) so a float voltage in the 13s allows them to come down off the peak and rest at a healthier voltage for them while still holding useful capacity. | ||
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+ | Also see [[electrical: | ||
===== equalization ===== | ===== equalization ===== | ||
- | Sometimes called the fourth stage, " | + | Sometimes called the fourth stage, " |
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+ | ----- | ||
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+ | An equalizing charge prevents battery stratification and reduces sulfation which are leading causes of battery failure. Trojan recommends equalizing every 30 days or when batteries have a low specific gravity reading after fully charging... Deep-cycle AGM or gel batteries should NEVER be equalized." | ||
House banks in rigs that are driven regularly are likely already mixed by jostling, so equalization may be less important. | House banks in rigs that are driven regularly are likely already mixed by jostling, so equalization may be less important. | ||
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- ambient temperature as measured by the charger. | - ambient temperature as measured by the charger. | ||
- in the absence of actual measurements the charger will likely use the 77F laboratory standard. | - in the absence of actual measurements the charger will likely use the 77F laboratory standard. | ||
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+ | This automatic voltage tweaking for temperature may result in your actual battery voltages being observably higher in cold temps and lower in hot temps. | ||
===== watering batteries ====== | ===== watering batteries ====== | ||
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**Manual chargers** will not be affected by load as they are controlled by the user. | **Manual chargers** will not be affected by load as they are controlled by the user. | ||
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+ | ===== battery voltage while charging ===== | ||
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+ | Battery Voltage = Battery Voc((resting voltage)) + (Charge Current x Ri((internal resistance))) | ||