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electrical:12v:charging [2019/01/03 16:47] frater_secessus [equalization stage] |
electrical:12v:charging [2020/05/13 12:17] frater_secessus [charging while using the 12v system] |
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- | In general, manufacturers of lead chemistries | + | In general, manufacturers of flooded |
===== three stage charging ===== | ===== three stage charging ===== | ||
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==== absorption stage ==== | ==== absorption stage ==== | ||
- | The absorption stage, sometimes called // | + | The absorption stage, sometimes called // |
+ | |||
+ | Absorption **begins when the battery reaches the absorption voltage** ([[electrical: | ||
+ | |||
+ | Example: | ||
+ | |||
+ | |||
+ | In practice absorption takes longer when the battery has been discharged deeply and shorter when it has not.((http:// | ||
+ | |||
+ | **Mythbuster: | ||
+ | |||
+ | > charge current affects the SOC transition point from bulk to absorption charging - MaineSail((https:// | ||
+ | |||
+ | MaineSail found that | ||
+ | |||
+ | * 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% " | ||
- | Absorption **begins when the battery reaches the absorption voltage** ([[electrical: | ||
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 [to match absorption] without worry. Only when you stop cycling the battery do you need to return float voltage to more regular 13.2v 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)) |
+ | |||
==== float stage ==== | ==== float stage ==== | ||
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- | ==== equalization ==== | + | |
+ | ===== charge-and-hold ===== | ||
+ | Charging can be achieved with a simpler methods like charge-and-hold where the charger has a single setpoint which it holds; | ||
+ | |||
+ | |||
+ | Examples include: | ||
+ | |||
+ | * [[electrical: | ||
+ | * power supplies, which will usually have a potentiometer (//pot//) to adjust voltage by +/- 10%. Shore power assumed. | ||
+ | * [[electrical: | ||
+ | |||
+ | |||
+ | ===== charge-and-stop ===== | ||
+ | |||
+ | [[electrical: | ||
+ | - charge to [[electrical: | ||
+ | - fall in voltage to a High Voltage Reconnect (Vhvr) | ||
+ | - repeat | ||
+ | |||
+ | **This differs from PWM** because PWM can hold an average voltage by cutting power hundreds or thousands of times a second. | ||
+ | |||
+ | |||
+ | These setpoints may or may not be user-configurable. | ||
+ | |||
+ | Charge-and-stop may be useful when charging battery chemistries like lithium, or when [[electrical: | ||
+ | |||
+ | ===== charging AGM batteries ===== | ||
+ | |||
+ | AGM batteries are kept healthy by: | ||
+ | |||
+ | - vigorous Bulk charging((minimum current of [[electrical: | ||
+ | - long Absorption stages | ||
+ | - but lower Absorption voltage (to prevent outgassing) | ||
+ | - absolutely no Equalizing (which would create heavy outgassing) | ||
+ | |||
+ | Many charge controllers have AGM or GEL modes that handle these setpoints and durations. | ||
+ | |||
+ | ===== charging other chemistries ===== | ||
+ | |||
+ | See [[electrical: | ||
+ | |||
+ | ===== equalization | ||
Sometimes called the fourth stage, " | Sometimes called the fourth stage, " | ||
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- | Water levels | + | If water levels |
- | ==== temperature compensation ==== | + | ===== temperature compensation |
Accurate charging requires the charger know the temperature of the batteries being charged. In hot temps a full charge will require somewhat lower voltage. Cold temps will require higher voltage((https:// | Accurate charging requires the charger know the temperature of the batteries being charged. In hot temps a full charge will require somewhat lower voltage. Cold temps will require higher voltage((https:// | ||
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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. | ||
- | ==== watering batteries ==== | + | |
+ | 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 | ||
{{ http:// | {{ http:// | ||
Flooded lead-acid batteries outgas during Absorption, causing a slow loss of water. | Flooded lead-acid batteries outgas during Absorption, causing a slow loss of water. | ||
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- | A [[http:// | + | A [[http:// |
Batteries that are older, in poorer health, or are charged at higher voltages will be " | Batteries that are older, in poorer health, or are charged at higher voltages will be " | ||
- | ==== charging while using the 12v system ==== | + | ===== charging while using the 12v system |
Smart chargers handle charging under load gracefully. As long as there is enough solar power coming in to hold the absorption or float voltage steady those charging stages will not be disturbed. If there is not enough power to hold the prescribed voltage the charger may restart Bulk charging. This behavior may be configurable by the user. | Smart chargers handle charging under load gracefully. As long as there is enough solar power coming in to hold the absorption or float voltage steady those charging stages will not be disturbed. If there is not enough power to hold the prescribed voltage the charger may restart Bulk charging. This behavior may be configurable by the user. | ||
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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. | ||
- | ===== charge-and-hold ===== | ||
- | Charging can be achieved with a simpler methods like charge-and-hold where the charger has a single setpoint which it holds; | ||
- | |||
- | |||
- | Examples include: | ||
- | |||
- | * [[electrical: | ||
- | * power supplies, which will usually have a potentiometer (//pot//) to adjust voltage by +/- 10%. Shore power assumed. | ||
- | * [[electrical: | ||
- | |||
- | |||
- | ===== charge-and-stop ===== | ||
- | |||
- | [[electrical: | ||
- | - charge to [[electrical: | ||
- | - fall in voltage to a High Voltage Reconnect (Vhvr) | ||
- | - repeat | ||
- | |||
- | These setpoints may or may not be user-configurable. | ||
- | |||
- | Charge-and-stop may be useful when charging battery chemistries like lithium, or when [[electrical: | ||
- | ====== charging AGM batteries ====== | ||
- | |||
- | AGM batteries are kept healthy by: | ||
- | |||
- | - vigorous Bulk charging, sometimes greater than solar-only charging can provide.((http:// | ||
- | - long Absorption stages | ||
- | - but lower Absorption voltage (to prevent outgassing) | ||
- | - absolutely no Equalizing (which would create heavy outgassing) | ||
- | |||
- | Many charge controllers have AGM or GEL modes that handle these setpoints and durations. | ||
- | ====== charging other chemistries ====== | ||
- | See [[electrical: | + | ===== battery voltage while charging |
+ | Battery Voltage = Battery Voc((resting voltage)) + (Charge Current x Ri((internal resistance))) | ||