I am running an AC HID lamp on a battery through an inverter, with the following constraints:

1. The voltage of the battery range from 16.5V when full to 12.5V when depleted.

2. The inverter has a 15V high voltage shut-off and a 10.5V low voltage shutoff.

3. The LAMP + control gear consumes about 25W. Assuming the inverter also consumes something, I think the current draw from the battery is 2A-2.5A.

without modifications, the lamp won't run if the battery is charged over 75-80% capacity.

As a temporary kludge, I placed six MUR810 8A diodes in series. That works, but it means I have a 5W hip warmer that I really don't need.

looking for a magic bullet, but I'll settle for a silver one ;-) Any ideas?

Thanks for reading.

 

Hello,

You could use a buck-boost converter.
This will regulate down in the input is to high and up if the input is to low.
With the LM5118 you could make a converter to give 12 Volts constant at the output.
http://www.national.com/pf/LM/LM5118.html

The datasheet has some example schematics.
On page 23 there is an example for 4 - 70 volts input and 12 volts output.

Greetings,
Bertus

 

Thanks! .

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