They never do. One of the many disappointment with ISDT.
Again, new firmware 2.0.0.5 dated 27.1.2026. I returned my ISDT C4 EVO charger, so I cannot verify that the new firmware solved this problem.
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I have just puchased the ISDT C4 Evo - just arrived and updated to firmware 2.0.0.5.
On a 1.5v Li-ion AA on charge I am seeing 5.2v across the battery with the periodic drop to 1.5v (assume stop charging to check voltage). So, if that is a change from what others had on earlier firmware, it looks good.
I was though expecting to do an Discharge/Analyse on these batteries to get the capacity (just based on current x time until voltage cuts out) but menu only shows charge or destroy. I haven’t read what destroy would do to this type of battery as the internal battery circuit would cut the discharge so cannot be destroyed?
Any advice?
Discussion with Copilot on the destroy mode for 1.5v liion batteries, i finally got it to give me this.
Final, precise summary
For the type of 1.5 V Li‑ion AA/AAA cells you described:
- The C4 EVO cannot damage them in Destroy Mode
- Destroy Mode acts as a normal discharge test
- The capacity reading is accurate and useful for real‑world runtime
- The internal Li‑ion cell is never exposed to the charger
- The converter protects the cell from over‑discharge
Everything you reasoned through is correct.
They probably gave it that name specifically because the charger’s purpose is to discharge the cell to zero. The fact that the cell has a circuit that only simulates this is a different matter. Additionally, the ISDT is protected in case the circuit fails or you insert a discharged Li-ion battery without the circuit.
Tried two times Auto with latest 2.0.0.5/ First time with old AAA Eneloops. Detected first as NiMH, then switched to LiIon, had to override. Second time with 1yo Panasonic 18650 - detected as LiIon, then switched to LiFePo, had to override too.
Why don’t they make FW opensource? It would have been fixed in a matter of weeks.
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I bought it again to test the updates, and it seems to be even worse. I was charging three LADDA 2450 AA batteries. One ended at about 2700 mAh, but the other two were still charging. At 3400 mAh, I pulled them out, they were incredibly hot, and I couldn’t hold them. I chose NiMh mode 1A.