Car Battery or just more Lipos?

[maineyak]

Getting kitted up for racing again and I need a bit of advice regarding Lipos.

I've already purchased a Lipo charger that is mains or 12V and am now looking to purchase a leisure battery, which seem to be around £70 to £80, plus I'll require a charger/conditioner for around another £30, equalling around £100.

So rather than spend £100 on this why don't I just purchase another 2 packs of Lipos (I'll have 4 then) and charge them from home the night before the meet? No hassle carrying a car battery around or charging on the day sounds good and meeting are usually 3 heats and a final from what I remember.

So I'm guessing if I charge the night before there will be a voltage drop overnight meaning I won't get full performance the next day. Is that correct? Is there much difference in performance compared to charging just before the race?