"I already have a Metz 60 power pack with a Li-Ion battery. I later bought a spare (no battery) for $2.50. Since it is only a back up, and I'm cheap, I didn't want to spend $80 for a new replacement battery. An SLA battery with the same voltage and capacity, only different in size, is only less than $10." - Bigspecbear.

This is good to know. Thank you for the information. I had to eventually replace the battery and managed to get a dry fit cell from Metz U.K that has now lasted 3 years but it did cost 50 ( about $80). What about charging the SLA (standard lead acid?) battery, I assume with the Metz charger?,