Device Controller Trigger Low Battery And Shut down Itself

[rednote]

Hello, I have portable obstruction lighting system, controller with integrated IC Max1648. It use 2unit 12v 7ah lead acid battery. After 2month replacing to new battery, the device trigger lowbattery after using it 2hour, the indicator will blink and shutdown itself after few minutes. Normally it can operate 6 to 8hours. I checked the battery voltage shows 10.8v after using it 2hours from 12.4V.

Then i replaced with new battery it happened the same. What cause or which component trigger the lowbattery. I have 4 unit, all same problem..

 

[mikefitz]

The battery is not being charged correctly. 'Low battery' is being triggered because the battery is empty, the battery at 10.8 is completly discharged.
When under charge the battery should reach over 14 volts. If the battery is at only 12.4 its only partially charged.
The MAX 1648 looks after charging and need a DC input. There are numerous support components that the 1648 needs to function, there is a probability of failure either in the IC or the additional components.
Data and application notes on the Internet.

 

[rednote]

Sir,
Thank you for your feedback. After charged it for 5hours the indicator shows green (full charged) but after 4minutes indicator turns red.
I checked the integrated board. The output voltage at battery terminal very low 2v to 2.8v instead of normally around 11v to 13v at battery terminal which coming from Dc input. Maybe the faulty/short component.

One more question if i may.. I took out both battery and charged it using different charger, after few hours charging, at 12.5v put battery back to the case & obstruction light works normal, lighted up to 6-7hours. This indicate Max1648 have problem in charging section.

Can i use separate charging module board ie.. (XH-M8604 and connect battery Vout from the module to battery terminal +/- on the existing board.

Is it possible to do that? Will it defect or bring damage to Max1648.. Do i need to deactivate protection on any Max1648 pin?

Tried but hard to find troubleshoot or repair references for this device/ circuit as it is private use for aviation/military use.

Highly appreciate your fast respond.
Thank you