Thought I had my volts/watts/amps sorted, but not sure on this one. 3x12v 20w bulbs in series for battery drain test. Do I combine the watts ie; 60, or is it 36v 20w load?
electrical question
- Thread starter wheeliepete
- Start date
D
Deleted member 4366
Guest
Three 20W bulbs makes 60w however you configure them. If they're 12v bulbs and you give one 36v, it'll blow, which is why you have to put them in series to get 12v each.
The 20W is a very arbitrary figure. The resistance and current change with temperature. Also, your battery voltage changes during discharge, so you can't get an accurate measurement of your battery capacity unless you measure the current and the voltage at regular intervals during the discharge, say every 30 minutes. Then you can calculate the discharge for each interval and then add them all up to get the total.
Having said all that, the bulbs make a good load for doing a discharge and an £8 wattmeter does all the measurement and calculations for you to give a relatively precise and repeatable measurement of your battery's capacity under the conditions that you tested it for comparison purposes.
The 20W is a very arbitrary figure. The resistance and current change with temperature. Also, your battery voltage changes during discharge, so you can't get an accurate measurement of your battery capacity unless you measure the current and the voltage at regular intervals during the discharge, say every 30 minutes. Then you can calculate the discharge for each interval and then add them all up to get the total.
Having said all that, the bulbs make a good load for doing a discharge and an £8 wattmeter does all the measurement and calculations for you to give a relatively precise and repeatable measurement of your battery's capacity under the conditions that you tested it for comparison purposes.
Great thanks d8veh, got a cheapy watt meter to fit between battery and bulbs, so gonna connect it up and see what results I get.
Related Articles
-
Swytch announce new conversion kit with ‘pocket-sized’ battery- Started by: Pedelecs
-
New Swytch launches on Indiegogo, raises £100k in first hour- Started by: Pedelecs
-
Swytch to unveil 70% smaller, 50% lighter conversion kit- Started by: Pedelecs