Hello friends,

I try to figure out the best option to have adjustable load current for this charger
Click image for larger version. 

Name:	Untitled2.png 
Views:	4 
Size:	58.4 KB 
ID:	134680

I have a external device that may experience low temperatures for several days (-10 deg C or more). The battery is a special Li that can be charger from -10 normally and up to -30 deg with reduce rate of about 0.02C.

Now despite is expensive, I like LT3652 because of simplicity and option to charge other chemistries too, such as last resort - VRLA. But first I'd like to have some real life tests with lithium, due to more appropriate Vdd to my system and of course, weight.

I'm trying to figure out the best option to automatically adjust load current from normal 1C (or 0.5C) to much less 0.02C when temperature decreases under -10, just to not destroy the battery.

One option will be to alter MPPT pin which is normally track the MPP point by lowering load current. This should work, but will operate solar panel well under MPP with low efficiency.

Other option comes into my mind will be to put a OA across the Rsense and fed the SENSE pin with gain of 10. This way I hope will fool the sense amplifier to see a 1/10 of current. I could alter the OA gain with a thermistor.

Any thoughts about this?
Tnx,