Most AED's use NiCd or NiMh cells. I've disassembled several packs we've received in our County's CESQG (conditionally exempt small quantity HAZMAT generator) program. Typically these contain multiple series /parallel strings of shrink-wrapped "D" size NiCds with solder-type terminals. Battery packs on most medical and diagnostic equipment are tested and replaced on a maintenance schedule to ensure that critical systems are changed well prior to a likely failure.
If you are able to load test, recondition and match up sets of matches cells to rebuild matched cells into suitable packs, it CAN be done, but doing so is quite labor intensive. Some test equipment is required and there are some safety precautions which need to be observed, such as temperature monitoring and taking precautions against fire and thermal runaway. We generally do nothing more with NiCd and NiMh cells than to assist the hospitals in collection and transport of them to a County collection site for recycling and proper disposal. We view this as necessary customer service in exchange for other support we receive from hospitals.
Given the huge volume of batteries available, we must direct limited resources where they will do the most good. Our primary emphasis is not on small (2-7ah) batteries to power HTs for parades, but on larger ones of 17ah up to BCI Group 30 to power mobile radios in base applications, packet nodes, portable repeaters and HF equipment when the power grid goes down.
I often need several people with strong backs driving pickup trucks to make a "run" after work to remove an entire UPS "string" from a government building or hospital to a staging area for testing. Later those volunteers may transport a ton of tested and recharged batteries several hundred miles downstate to issue somewhere at a training session. Batteries collected and tested by Virginia RACES have ended up in our neighboring states, Maryland, D.C., North Carolina, West Virginia and Tennessee. Virginia RACES collects and distributes TONS of batteries every year, free. We only ask that ARES and RACES volunteers maintain them for the good of their communities, and dispose of them properly when no longer useful.
Most of the battery tonnage which we actually use comes in the form of sealed lead-acid and AGM from fire alarm panels, emergency lighting, building UPS systems and telecomm central offices. Most suburban hospitals change out these batteries on 4-year replacement schedules, and from a large regional trauma and cardiac center we get about 2 tons a year of batteries in the 15ah to 34ah size on a continuing basis. We also get a ton or so of smaller SLAs from 2ah to 7ah which we provide members for powering HTs.
The quantities of available SLA batteries are vast and are well worth pursuing, but you must to train a group of people carefully screen and test 100%. This is too much work for one person to do, if done correctly.
73 de KE4SKY
Virginia RACES State Training Officer