Posts Tagged ‘nimh battery charger temperature

nimh-battery-charger-thermal-image

NiMH rechargeable batteries has been available for quite a while and are something very common in our life with a lot of low power gadgets such as remote controls for example relying on them. Recharging NiMH batteries is interesting because they do have an interesting feature, namely that they start to get hot when they are fully charged. The reason for that is actually quite simple, when the NiMH battery cannot store more charge it starts dissipating the extra power as heat. So when you touch a battery that is inside a charger and it feels hot it is most likely charged or will soon be charged, so no wonder that some chargers for NiMH batteries actually use the temperature of the batteries to decide if they are charged already or at least have temperature sensors as a safety measure. If you are charging the batteries with a low rate they will manage to dissipate the extra heat, but if you try to push them with lets say 1 Amp or 2 Amps of power and if the charger does not stop the charge if batteries start getting hot, then you might be facing problems that may even include a fire. On the thermal image above you can see two smart NiMH battery chargers that are charging AA size rechargeable batteries, the two hot sports on the sides of each charger are apparently the power elements that are responsible in providing power to the batteries while they are being recharged. The batteries on the left are about half charged and these in the charger on the right are almost fully charged and their surface temperature is slightly higher


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