Grawlbain

I noticed that my drivers side headlight was out after needing to recharge battery , replaced the bulb but still no joy I have brought a replacment light unit with ballast and ignite , but have not fitted yet , today decided to turn car over to check battery as been sitting for couple of week unused to my surprise the drivers side light came on with very low battery not enough to start car and my passengers side which was fine was just flickering , I jump started car and I again had no drivers light but my passengers on was back to normal at a bit of a loss is this because of the low battery and if I put the other unit in drivers side will it work

hikeit

could be a bad ballast maybe? try just swapping that out?