Testing.. 1...2.. Testing
E-Bike batteries, or whatever else you might be using batteries for ( I won't judge, promise ;-o . ) are expensive, a quality lithium battery pack and charger can cost as much as the rest of your kit and bicycle combined !
You want to make sure it performs as expected and that you got what you were sold ! The vast majority of battery users don't know anything about their batteries, and vendors take advantage of this !
Learn a bit and don't get ripped off !
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The only way to know if your pack is any good, is to test it !
One option would be to strap a pack to a bike and go for a ride!
However, as much fun as it is.. this is not always practicle.
You can buy dedicated battery testing equipment, some are complicated, and expensive. But, with a few spare parts and some creativity, you can build a pack tester without breaking the bank that will give you accurate enough info to know when your pack has a problem, or when everything is good !
First, a method to record " CAPACITY "
Personally, i love the Cycle Analyst .. It displays valuable info like Watts, Amps, Volts, Amp Hour, Distance, Speed.. And it records the data when it shuts down !!.. A VERY IMPORTANT DETAIL.
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Another options, much less expensive is a Watt's Up meter
The Watts'up only goes up to 60v, is not backlit, and will NOT RETAIN DATA when it powers off, so you need to keep a close eye on the display near the end of your test... it works.. but the CA is a far better option.
The above will display and record your pack's performance. But to drain that battery, in a controlled way, you need some sort of device that consumes energy. You can use any number of things, like a toaster oven or a blender.. or anything that will work at your battery pack's VOLTAGE !
Below is one of many ways, but it's how i did it and it works really well from 12 to 100 volts !
No.1 : Double lightbulb ceiling fixtures = 2$ each, Singles work as well.
No.2 : Scrap piece of wood = Free
No.3 : Lightbulbs, regular old style house bulbs = 2$ each
No.4 : Anderson Powerpoles = 1 $ each
Total 19 $
There you have it, for 20$ or so, depending on your scavenging skills, a device that will drain your battery, safely ( relatively safely.. at least.. ) for cheap !
I c onnected all white together and all black leads together, you can add as many fixtures as you like, more of them means you can add more bulbs and burn more energy. Just one will do, but more is better ! You can simply unscrew as many bulbs as required depending on the pack and you are testing.
Connectors, a huge debate could be had over this topic but I use anderson Powerpoles
Video on how to crimp powerpoles :
Once you start to gather different battery packs and more charagers, having every connector the same makes life much easier. Some people prefer " Deans " or " Bullets ' or xyz connectors, but personally I prefer Andersons.
Example of the cheap tool:
Above, On The Left are 15/30 Amp tips - On The Right you see 45 Amp tips for larger gauge wire.
Better Tool :
Below, an example of the professional version of the above tool.. insert tip, wire, crank once and voila.. a perfect crimp everytime !
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So, why do household lightbulbs work ?..
Use Incandescent bulbs ( the regular filament type, NOT LED or Compact Fluorescnt ie : twisties.)
All lightbulbs come with a " Watt " rating.. typically 40w to 100w
They are made to run on 120v AC house voltage, they will consume the rated watts at 120v, however, with lower voltage they will consume less power, so at 60v you can expect roughly half the rated watts.
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The higher watt bulbs have less resistance and allow more energy to flow thru them and in the process, shine brighter..
As long as the battery being used has less voltage than 120v, the bulbs will not blow.
Do not make the mistake of using automotive bulbs rated at 12v, however if you want to drain a single cell or a few cells below or at 12v, they can also work fine !
For the complicated answer, see: Ohm's Law !
Lower voltage will result in less light, more voltage = brighter = more amps
There you have it, a cheap way to exercise your battery packs !
Alright, so if you made it this far, next step is to learn about the testing process itself.
Depending on the type of battery you are testing, generally one of 3 types
1- Lead Acid ( aka : SLA )
2- Nickel ( NiCad and NIMH )
3- Lithium ( Li-Ion - Lipo - LiFePo4 - etc )
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With Lead Acid and specially with Nickel, a few charge and partial discharge cycles in a row are needed to condition the batteries prior to a capacity test, if they have been sitting on a shelf for months, they will not perform well for at least 3 cycles.. do not drain the packs completely, just drain 25% or so of their capacity and repeat a few times.
Lithium on the other hand, pretty much ready to go even after a long period of rest.. but i like to cycle them anyways, it makes me feel better.. but i have no scientific reasons to give.
Ok, so you got your pack, Capacity testing gizmo, and your discharge device, what's next ?
Fully charge the pack, to make sure you are starting the test with 100% of potential capacity .
Plug in the Cycle Analyst or other gizmo and note the voltage, and make sure to reset the gizmo if need be and start at 0
Plug in the bulbs and watch the display, i highly recommend taking pictures with a digital camera or jotting down notes for reference
- Starting Voltage
- Amps / Watts being drained
- Voltage drop at the start of the test
And most importantly the capacity in " Amp Hours " with symbol " Ah "
The gizmo is measuring how much energy has been used,