inline > On Sep 18, 2019, at 9:30 PM, Robert <i...@avantwireless.com> wrote: > > This confuses me.. Don't all devices basically get equal shot at the > current? i.e. the output voltage of the charger reflects the voltage of the > batteries at that time and the service devices run off that voltage too.
Correct > Unless the charger dies because it tries to output more than it's actually > capable of in continuous operation (Is that what you mean by current > limiting?). Power supplies come in 4 varieties with respect to protection against overload: None: They put out current until they overload a component and fail (few of these exist as there is a real potential for the failing component lighting on fire) Constant Power: When the load reaches the rated power of the supply they will reduce voltage to stay inside the power rating. For example if it’s a 100W supply and you are drawing 10A the voltage will be 100W / 10A = 10V. Foldback: When the load exceeds the rating of the supply the current will be reduced to a value well below the supply rating until the voltage recovers. Shutdown: When the load exceeds the rating for the supply the output will be shut off until the input power is cycled. The Meanwell SD series does this. For a battery charging application the only version you want is a constant power unit. > But don't most of these systems basically float all boats on the same rising > tide? Yes > Most battery banks are capable of sinking way more current than most > chargers can output, so they charge at 1/10C instead of 1/4C? It’s not the battery that limits the charge current - that is a function of the charger. You have to be careful that your supply isn’t so large as to charge the batteries too quickly. > or 1/x and take a very long time to charge and don't do a good job of > clearing the plates ( wet batteries ) ? A true rectifier system is a much better solution than just a power supply. It will separate the battery charging function from the supply to the load so that the batteries are properly charged, compensate for temperature, disconnect the batteries when the voltage is too low, bring the batteries to a safe voltage before restoring load, provide monitoring and alarming, and periodic tests of the batteries to ensure you have capacity when you need it. Yes - it’s more expensive. Outages are expensive too. Mark > > On 9/18/19 5:33 PM, Chuck McCown wrote: >> If the batts are fully charged, then your charger/rectifier should be >> putting out exactly what the load is needing (plus a tiny bit of battery >> leakage current). >> >> If your load picks up, your charger will carry it up to whatever current >> limit the charger has. >> If you have an extended outage, the batts might suck more than the charger >> can put out once the power comes back on. So the best systems have some >> form of current limiting to ensure the load gets its current first and any >> extra can go to charging the batts. >> >> From: Sterling Jacobson <> >> Sent: Wednesday, September 18, 2019 1:19 PM >> To: AnimalFarm Microwave Users Group <> >> Subject: [AFMUG] DC Battery Charge/Load Question >> >> I’m still learning this stuff. >> >> If I have a 48v battery string and it’s being charged with 10A, and my load >> is connected directly to it taking normally 2-7A, the load will not receive >> that full 10A current meant to charge the batteries, correct? >> >> Or does it? >> >> >> >> -- >> AF mailing list >> AF@af.afmug.com <mailto:AF@af.afmug.com> >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> >> >> > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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