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I am designing a circuit for a high powered LED that needs to have a redundant battery power supply. The LED is around 380W and nominal 24v so draws around 16A when lit. The LED will flash for up to a second, every 5sec so no fast switching but it is pulsing.

The below image shows what I am testing with but I am not 100% how it should be behaving. V1 and V2 are 24v 100Ah AGM batteries. V3 and V4 are 250W battery chargers that output 27.6v. D1 and D2 are Schottky diodes used to isolate the redundant power supplies and so there is no equalization between the batteries.

Redundant battery and charger circuit

I was expecting the load to sink current from the batteries primarily as the batteries should have a lower series resistance than the chargers however my measurements are not reflecting that. I can measure with a clamp meter, 16A going to the LED and proportionally more current coming from the chargers than the batteries.

Can someone explain why more current would be sourced from the battery chargers? Will it also cause issues for the chargers if they are sourcing the bulk of the current every time the LED flashes? If one half of the redundant circuit fails then the LED sinks more current than the remaining charger can source which could cause damage and the battery will not charge properly at all?

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The chargers can increase their output to maintain voltage as current demand increases; the batteries can't. So the battery voltage sags and the charger ends up pushing charge into the battery. In that sense, the battery chargers actually have lower dynamic impedance than the battery, even though the battery might measure a lower static impedance.

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