8/31/2023 0 Comments 7.2 v nimh battery![]() For instance, if your battery is 20% charged, you'd enter the number 20. Optional: Enter your battery state of charge as a percentage. Select your battery type from the list.ĥ. Depending on the combination of units you selected for your battery capacity and charge current, the calculator may ask you to input a voltage.Ĥ. If the calculator asks for it, enter your battery voltage or charge voltage. The unit options are milliamps (mA), amps (A), and watts (W).ģ. Enter your battery charger's charge current and select its units from the list. The unit options are milliamp hours (mAh), amp hours (Ah), watt hours (Wh), and kilowatt hours (kWh).Ģ. Enter your battery capacity and select its units from the list. If a servo has jerky movement when operated and/or jumps around randomly then a bad power supply is the most likely culprit.Tip: If you’re solar charging your battery, you can estimate its charge time much more accurately with our solar battery charge time calculator. If your battery and/or wiring are not able to handle high current draw with low voltage drop then the servos may glitch due to voltage spikes. The HK15298 is very powerful servo that draws a lot of current (>2A). Try disconnecting the servo signal leads (orange wire) from the Arduino - do the servos still move around? If not then the Arduino may be sending spurious pulses. Unexpected movements suggest noise in the circuit, perhaps due to bad wiring, weak power, or glitches coming from the Arduino. It is normal to hear this when the servo is making fine corrections, even when holding a fixed position. The frequency is usually in the mid to upper audio range, and is heard as a high pitched squealing noise. Most digital servos use high frequency PWM to control their motors. A servo which is rated at 7.4V should be able to handle a fully charged 2S Lipo which is 8.4V - the same as a fully charged 6 cell NiMH battery. Note that voltage will drop when current is drawn from the battery, and will slowly rise again when the load is removed - thus the open-circuit voltage is only a rough guide to state of charge.ħ.4V is the nominal voltage of a 2 cell Lithium Polymer battery. At 7.58V your first battery is about half charged. ![]() When fully charged it may be as high as 8.4V (1.4V per cell). If it is while charging it is too low (probably).ħ.2V is the nominal voltage of a 6 cell NiMH battery. ![]() So IF the reported voltage if 7.58V is OFF the charger it is close to OK. Once charged and disconnected from the charger a fully carged NimH will read about 1.3V/cell. The "nominal" OPERATING voltage is 1.2V/cell so 7.2V battery contains 7.2V/1.2V = 6 cells.Ħ cells fully charged on charger should be ABOUTĦ x 1.45V = 8.7V, so your measured voltage is about right at 8.35V.Ĩ.35/6 = 1.4V / cell which is OK at very low charge rates.ħ.58V/6 = 1.26V/cell so too low if on the charger. NimH cells have a fully charged voltage ON the charger of about 1.45V per cell at lowish charge rates - say C/5 and below. This varies with charge rate and somewhat with battery model and manufacturer so you need to take due care. If the battery gets too hot to hold it's charged :-).įinally, cell voltage while charging can be used. When the heating rate suddenly increases the cel is ~= charged.Ī 3rd method is absolute temperature - not recommended unless essential. The normal means is to charge at about C/1 rate (eg 2500 mA for a 2500 mAh battery etc) and monitor the battery voltage for a DIP in voltage at full charge.Īnother OK method is to charge at about C/1 and monitor the RATE of heating (not te temperature). NimH cell voltage is not the best way to determine state of charge - but it can be used if other means are not available.
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