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--- electrical:converter [2022/10/01 16:20]
frater_secessus [DIY smart converters]
+++ electrical:converter [2024/06/25 16:07] (current)
frater_secessus [charging time available]
@@ Line 22: / Line 22: @@
+===== choosing a converter =====
+If money is no object you can buy a multistage ("smart") converter rated at the bank's maximum curent acceptance at the lowest normal state of charge:
+  * [[electrical:12v:battery_capacity|0.33C]] for AGM at 50% SoC
+  * 0.2C for FLA at 50% SoC
+  * 0.4C is not LiFePO4's //max// at 20% SoC, but is probably a max rate for good cycle life.  0.2C would be optimal if one has the time.
+==== cost ====
+The higher the rating and the more features the more expensive the shore power charger.  There is also a practical limit on what we can pull from a 15A shore power connection for hours/days.
+==== limits of 15A shore power ====
+A off a 15A [[electrical:shore_power|shore power]] plug, or 1,560w is a safe limit for continuous power use. Assuming 10% conversion losses this would give us a **theoretical max of around 100A of converter charging** (14.4Vabs x 100A).((shore power amps are at 120vac, converter ratings are at their nominal DC voltage))
+==== minimum  charge rate ====
+Lead chemistries require a minimum charge rate to stay healthy.  In the absence of documentation from your battery mfg we can assume
+  * 0.2C for AGM
+  * 0.1C for Flooded Lead Acid
+  * [LiFePO4 has no minimum current spec]
+==== charging time available ====
+If you have solar and will be on shore power for more than one day then **a simple converter that charges at the batteries' recommended Float voltage** is fine;  solar will be able to do the relatively light duty of completing Absorption each day.
+If you do not have solar or will be on shore power for only one overnight then we need a three-stage ("smart") converter that can handle Absorption duties.
@@ Line 51: / Line 83: @@
 ==== DIY dumb converters ====
-"Dumb" converters output a single voltage and work fine when solar charging is present (see above).  In this scenario the 12v power supply can is set to ~13.x voltages to provide "float" support while on shore power.
+"Dumb" converters output a single voltage and work fine when solar charging is present (see above) or when the bank is lithium chemistry.  In this scenario the 12v power supply can is set to ~13.x voltages to provide "low float" support while on shore power.
-If loads are run off the converter in the daytime the converter will just be supporting the solar yield and can be rather small.  If used at night the converter will be carrying the whole burdern should be sized to your expected loads ([[https://amzn.to/2WNSIDL|20A]], [[https://amzn.to/3jwQGBO|40A]], whatever).
+If loads are run off the converter in the daytime the converter will just be supporting the solar yield and can be rather small.  If used at night the converter will be carrying the whole burden and should be sized accordingly([[https://amzn.to/2WNSIDL|20A]], [[https://amzn.to/3jwQGBO|40A]], whatever).

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