Troubleshooting a battery/charger issue.

This guide covers 3 related topics: Charger issues, battery issues and miscellaneous testing procedures. Highly advisable to read each section fully to help understand how your ebike works and basics of troubleshooting. Post #1 focuses on chargers, Post 2 and 3 are about battery, Post#4 is about misc questions and answers as well as troubleshooting videos


In this article we do not cover the wiring, we assume that you inspected all the connections and the power wiring.


First off inspect everything, both battery and the rest of the system, check if it is in good shape, check if anything has been modified in any way, check that your battery connections are done the right way and check the wiring for shorts, cuts, cable crush or loose connections.

You also need to read the FAQ'S for your respective pack, specially if you have a Jumbo Shark and a Killer whale pack, they have a charging procedure. The special procedure is found at the bottom of the Hard Case FAQ.

Resources on charging procedure and installation for all types of Luna battery packs.


#1: The Charger

NOTE: If your battery charges normally then move to step #2 (click here)

Make sure you understand how to use your charger properly


Basic charger operation for Luna Chargers: 

a mini and Luna advanced chargers FAQ'S


These 2 chargers have a knob to change the charge level (%). Before changing it you need to unplug the charger completely and let it sit for 10 seconds before selecting a different %, then plug it back.




The Charger is completely dead and the AC outlet is fine?

Then it's possible that the input fuse is blow, it can happen with a simple surge from the grid.

Some chargers have a external fuse mount , some have internal fuse so you will have to remove the top cover (4 screws)... Just remember to unplug it first!

The fuse used is a F6AL250V


1.1 First troubleshooting step: Measuring

Make sure your charger is working properly. Having an extra charger around can make this step a snap...if you don't have an extra charger around consider buying one. If your charger requires a charging adapter, make sure you have a spare too. The charger (or adapter) is usually the culprit and not the battery and it’s almost necessary to have a back up. It doesn't have to be an expensive unit is could a 30$ basic one.

Troubleshooting electronics starts with a proper multimeter or even just a small voltmeter. Luna Cycle sells a very good multimeter for 20$ Or borrow one… but it’s good investment, especially since you love your ebike!
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Let’s measure stuff, I won’t go into details showing you how to use your multimeter, but just select a range in Vdc up to the max voltage of your battery.


Or watch this tutorial on using a multimeter

TEST your multimeter first to see if it works, could be a AC outlet (110-120Vac) or a AA battery (1.5Vdc)


1.2 If you have a charging adapter (Male barrel to XT60) and you can't charge the battery, you need to test it first:
  1. Unplug the adaptor completely
  2. Take your multimeter and set it to continuity (2nd setting on the Luna UNI-T meter and press the yellow button twice)
  3. Take the probes (polarity does not matter in continuity)
  4. The XT60 has a "+" and "-" sign stamped on the sides on the connector. On the other side the inner barrel is the "+" while the outer barrel is the "-"
  5. Test like the 2 picture,
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Next: if it passes the continuity test there is still a chance that there is a false contact when the adaptor is inserted in the female barrel port of the battery

Here is how it looks inside the port of the Shark pack, there is a large spring tab (negative terminal) that keeps pressure on the male barrel to make a contact between the male inner barrel terminal to the center pin (positive) of the female barrel.
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Please follow this simple test:


  1. Connect the charger in the wall AC outlet
  2. Connect the male barrel adaptor in the female barrel
  3. Connect the XT60 male to XT60 female
  4. And rotate the adapter and move it a bit to see if the charger starts charging normally. (see next video)









If the barrel end if broken, here is a nice cheap and effective fix for it, click this link.




1.3 Testing the charger:
  1. Plug the charger in the AC outlet. If you have a Luna mini or advanced , select the 100% position before the AC plug.
  2. Is there any lights on? (Luna blue charges should show 2 leds (one green and one red) if not change the outlet and check the fuse (if any, all luna blue chargers have one), If no leds continue with test #3 and if no voltage you will need to replace the charger.
  3. Led’s are on, now test the voltage with a multimeter, on the connector you normally plug into your battery to charge it (XT-60, barrel plug, anderson poles or else) you should have the full voltage (Ex: 58.xV for a 52V charger) If you use a Charging adapter, make sure it’s plugged in and test the voltage on the male barrel (outer rim is the negative, the inner barrel is the positive).If you dont have a voltage output or it’s the wrong voltage your charger may be defective (Just make sure you read the notes below

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Notes on this testing procedure:
* Some of the Luna mini advanced has a auto-shut off feature so 3 min after plugging the AC it will shut down if no load is detected so make sure you test fast enough.(see video at top)

* Very rarely you might come across a charger that will not output any voltage if no load is detected, so jumpstarting and testing is not possible with them like the other chargers, this charger MUST be plugged into the battery before the wall. (opposite of how all other chargers should be used) Otherwise it will not charge even if nothing is wrong with the battery.


1.4 ALTERNATIVE to test the charger,

That way you will be sure that it will sure that the charger can actually detect a load and start the charge:

You will need a light bulb (standard incandescent type the higher the wattage the better, like 300W, not Led or CFL)
A XT-60 with pigtails or wires to make an adaptor

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Next this is to connect the 2 wires up to the bulb, it will be very dim but you should see the fan kick in and RED led on the charger glow!

That means your charger can charge and do a jumpstart!
This is what you should see:

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Typical charger Behavior:

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  • 1. A luna charger
  • 2. A 52v standard plastic charger that only outputs when it sees a battery is connected. (this is rare and Luna does not stock a charger of this type)
  • 3. Another type of 52v plastic charger
  • 4. Same concept but testing using wiring directly from barrel

1.5 Alternative to charger testing.

You can try to power your ebike with the charger , you just have to remove the battery and hook up the charger directly to the power wires, if you can power the display and make the motor spin with the wheel up that would indicate that the charger can power a load, rule out the controller and would point out to the battery.

This video will explain how to connect the charger to a BBSHD motor.


Luna Advanced charger: Assuming that you see the voltage on the charger either with a multimeter or the above lightbulb test, the display on the charger may need to be replaced. Replacement displays are sold here and we have a guide here

Intermittent charger functionality:
In rare cases an old charger might have worn out wiring from mechanical strain, repeatedly bending the wires on the charging cable back and forth might break the strands to the extent that it can no longer send power through that cable unless the cable is oriented a certain way. The best way to check for this would be to first see if you have power coming out of the charger while flexing the cable in various positions.

Jumbo Shark and Killer Whale charging issues, see the miscellaneous section below (post #4)