Looking to replace the battery. This light is decades old. Still works great when plugged in to a 12 V socket. The battery is kaput. Surely since this was made there has been an advance in battery technology. Where can I get a replacement battery for this that fits the case for the original 12 V rechargeable SLA cell. The one that came out is marked HK-6FM2.8X. It has side terminals. Does anyone make an equivalent sized battery that has more than 2.8Ah? Thanks in advance for any assistance you may provide.