One can often use differential ADCs in a unipolar mode, with one input fixed at ground or a different fixed level. Depending on the model one may not be able to use the full range, but usually one polarity is OK. With some models there will be a slightly higher error due to nonlinearity, as the specified linearity of often for differential input with zero common mode voltage.
The mentioned ADC is anyway not a good choice for measuring an accumulator - it's a rather fast one. No need for 2 MSPS on a battery. It's also an ADC in a small case and thus difficult to solder by hand. The input may need a buffer, but I have not checked the datasheet.
I would more like consider something like MCP3421 - a slow 18 Bit ADC.