Hello fella's, I took the advice of several forumers above, and bought a new voltmeter and got a reading from the battery. I tested in 2 ranges with the meter, and got -1.2V and -1769V. I am intrigued how I can go into the minus, but the battery is 48v,and that's not coming up, so I'm guessing it must be the battery that's at fault. Hope to hear back from your good selves with more advice, Thanks.
... Primer on using a multi meter.
The multimeter as the name implies can measure three separate electric properties with its two leads ... But has to be connected up differently for each purpose. The three properties are electric resistance, electric voltage difference and electric current. More elaborate meters sometimes add other functions like transistor test....
To measure resistance... when the component or circuit to be tested is isolated from any electrical power. The meter then injects a small test voltage between the leads , and measures the current which then flows in the circuit. It then computes the effective resistance and displays it. If there were to be a voltage present in the circuit under test, then it will at best cause an erroneous reading or more probably destroy the meter.
The meter must be set at the resistance knob otherwise it will not be able to inject the test voltages
To measure voltage difference between between points, the meter must be set on the voltmeter knob, and a large voltage range selected .. e.g the 200v range or higher. Then the two leads are connected accross the two points to be measured. If the voltage reads less than 20v, then you can go to the more sensitive voltage scale and get a more accurate reading. In the voltage measuring mode, virtually no current flows into the meter .
There are often two voltage measuring modes DC and AC . In the DC mode, which is the suitable one for ebike s , if the red lead is connected to the positive connection on the circuit then reading will have either a positive symbol or none , if it were connected to the more negative part then it display a minus sign. .. this just signifies that the black lead is more positive.
In the AC mode, and not all meters have this, the electronics inside the meter, assume that youu are trying to measure a 50 Hz. Sine wave... Such as UK mains voltage and it adjusts the readings .the readings will be erronous if a DC voltage is being measured. .. however there will be no ill effects or damage to the meter by being in the wrong mode.
Measuring current is the most difficult and potentially damaging measurement. You can only measure current by breaking into a circuit, and inserting the two leads into the break, so that the current which would normally flow will also flow in series through your meter. You will instantly damage a meter if you connect a meter while in current measuring mode , accross the circuit, ... Eg the position for measuring voltage. This is because the resistance of the meter while measuring current is designed to be very small, so a large current can flow in it if connected accross a source of voltage...
again some meters can measure DC and AC currents.
1. Most multimeters use only two leads and may have either two or three connections. .. one used for common or the black terminal, and maybe one for current and a third one for voltage. .. the red lead gets connected to one of these . These are slightly safer to use than the two connection types as you have to make an explicit decision to use the current terminal
Turn on the meter while disconnected from the ebike . Switch to resistance mode and then bring the two leads together, the meter should read 0 and maybe beep, indicating zero resistance. If that happens then you know the battery in the meter is ok.
Then ensure that the leads are in the voltage connection and the function selected is DC and voltage, and the range set at 200v. Or 2000v , and then feel free to measure.. reduce the range , increasing sensitivity and note your readings. ..
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