It's an inline barrel connector. There are lots out there, with a plethora of different sizes for the various diameters for both the hole and the pin (if any) which is in the hole. I doubt we can help much more than that.
There's a wikipedia entry for them, they are that common.
If you need to get something which mates with this one, and you can't find a datasheet or formal description, you options are either to try and measure it accurately, or trial and error with a bunch of similar looking connectors.
Don't forget, the internal pin length and girth vary along with the diameter and length of the main orifice.
Automotive connectors may very well be proprietary designs done by the company itself or on special sourcing contract with a connector manufacturer. As such it is common that you will not be able to independently source the connectors yourself.
A secondary concern is that these cables also use special crimp on contacts that require very expensive tooling to reliably apply the contacts.
It is an unfortunate byproduct of the mass production world where it is next to impossible to get individual replacement parts and instead have to purchase whole subassemblies instead. Have you considered visiting a auto salvage yard to see if you can get a used cable assembly?
Best Answer
It's called a 4S cell balancer cable plug. But there may be different shells and pitches.
This is your connector Micro JST SH 1.0mm Pitch ( with cable)
Yours may be a different pitch. Measure it. http://www.jst-mfg.com/product/pdf/eng/eSH.pdf
Without measurements, and more effort on your side, this is all that I can offer.