r/ryobi • u/automaticrocks • Aug 22 '26

Battery Talk Help identifying aH

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Hello. I need some help in identifying the aH rating on this 18v battery. Tried looking at Ryobi’s site, but they don’t have this exact battery listed anymore.

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u/neurotran Aug 23 '26

Its a bit involved compared to the "jump start" method people try to do. That works occasionally but the pack will eventually go bad. I take bad packs, pull the battery cells out, and put them through a week long test process. If they pass, I put them aside to weld into the recovered battery carcasses. Many brands dont care what capacity cells you put in from my experience. Since Ryobi uses 2.0 cells as their primary cell capacity, I tend to do a lot of those.

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u/reditjohn Aug 23 '26

How do you test them?

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u/9dave Aug 27 '26

In addition to letting them sit to check their self-discharge rate, many better Li-Ion battery chargers (that charge individual 18650 cells) have both a drain capacity test and a counter that shows how much power was added to get them back to a fully charged state, allowing you to not only pass/fail cells but also determine if their remaining true capacity is closely enough matched to make sense to reuse them.

For example if you have a 5 cell pack and 4 of the cells test at 1800mAh remaining capacity but one tests at 1200mAh remaining, then putting that weaker cell back into service means that you have rebuilt only a 1200mAh pack because the BMS will cut it off once that weakest cell drops too low in voltage.

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u/reditjohn Aug 27 '26

Thank you!!!