Tiga headlamp battery swap

1st post so please be gentle!
I have a tiga SL85 headlamp with a battery that only holds charge for a short time. Im a novice when it comes to anything electrical so I was wondering if someone with some knowledge of this could avise me on a cheap replacement battery. This is a 6v 8.5ah battery, I've seen some batterys on ebay that are 6v 1600 mAh (think there for a remote control car) would 1 of these be any good for my lamp? If not what should I be looking for?
This is my standard charger + battery.

Thanks for any help

Hi, welcome, I am pretty sure that just one or a couples of batts died, I am not sure if you can replace the bad ones, with a DMM you can find the bad one...


Sent from my phone with camera with flash and internet on it...

What country are you in?

Do you know how large a capacity you need (how long do you need to run the light between recharges?)

A 1600mAh pack would only have a runtime of about 1/5 of the standard pack when new.

If in the UK, it might be worth looking at http://www.component-shop.co.uk/html/large_packs.html as well as ebay. I'm sure they would do custom packs if you asked them (like a 5xD cell pack).