Modifying lead acid charger for lithium batteries

[iovaykind]

As you all know, lithium batteries use a CC --> C/V method for charging lipos. Lead acid chargers however use CC --> C/V --> Float charging, making them not suitable for lithium charging (BOOOOM!)

Anyone know how to modify the chargers from lead acid to lithium, aka turn off float charging? These are the chargers I am working with. I want to turn the first one into the second one:
http://www.aliexpress.com/store/product/110VAC-60Volt-73-5V-2-5A-E-Bike-Electric-scooter-charger-for-60Volt-17-20Ah-lead/313864_936133621.html
http://www.aliexpress.com/store/product/36V-42V-2-0-2-5A-Lithium-Battery-Charger-High-quality-E-bike-charger/313864_455606765.html

Disregard voltage differences.

I've done things like modify current, and end voltage. But this lead acid charger has 2 voltage pots right by the output, whereas the lithium chargers have one there. I wonder if I remove one of them, if that will get rid of the float charger, but wondering if anyone else has tinkered with them.

 

[iovaykind]

if anyone wants a look in these chargers. I have a picture of the lead acid next to the lithium one for comparison. Only a few minor differences, most notable is the VR4 is filled for the lead acid but not for the lithium. The lithium one also has that board that basically cuts off voltage after it detects the charge is complete. I've taken that board off in the past with no issues so I'm not worried about that being necessary to convert it.