Lezyne Deca Drive 1500xxl Battery Upgrade

November 2015 I bought a new bike light, I was getting into cycling at the time and wanted to be able to commute home from work in the dark. My choice of light in the end was the Lezyne Deca Drive 1500xxl. For those of you that know its an all in one light capable of delivering 1500 lumen’s for over an hour.

Now, almost 2 years later I am still using this quality bike light. However just like laptop batteries, the factory batteries in this light lost some capacity meaning less run time which has become a problem having let me down a couple of times.

Having some electronics experience. I decided to see if I could replace the batteries myself.

Getting Started

The cells inside the Lezyne Deca Drive 1500xxl are 2 x 2800mah 18650. You can get these from eBay or Aliexpress. The ones I am using are Panasonic NCR18650B with tabs. Tabbed cells make assembling the new pack much easier. Not only are 18650 cells hard to solder due to sinking heat rapidly from the soldering iron. The cell can also become damaged from excess heat.

Before building the new battery pack. I charged the cells to ensure they were balanced. This is not absolutely necessary, but if you have a 18650 charger give it a go.

Dismantling

  1. Remove the small T6 screw on the bottom of the light.
  2. Remove the Allen Key bolt holding the mount to the light body.
  3. Using a finger nail, lift up the rubber on off switch button.
  4. Push on the light lens, so the inside of the light slides out the rear of the body.

The battery pack is in the bottom of the light. In this case it was wrapped in a blue heatshrink layer protecting the cells.

Building a new battery pack

Before building the new pack salvage the protection circuit PCB from the old pack. Do this by using a hobby knife to cut the heat shrink wrap from the existing battery pack. Once inside you will see the PCB attached between the two parallel 18650 cells. Using wire cutters, carefully cut the metal tabs which are attached to the PCB. Cut them as close to the top of the cell as possible. Otherwise you will need to solder new metal tabs to the PCB when building the new pack.

Using a flat surface, glue the two cells together with super glue and solder their tabs together. You MUST ensure the cells are soldered together with the correct polarity. Solder positive to positive and negative to negative. It’s really important you get this right otherwise it is likely the batteries may catch fire or explode. Put some electrical insulation tape length wise between the positive and negative terminals. This helps prevent any short circuit between the PCB and cells.

Now solder the PCB tabs to the positive and negative terminals of the pack while ensuring the correct polarity. You should cover the tabs with heatshrink prior to soldering. Finally wrap the battery in electrical insulation tape. Start with one layer across the top and bottom terminals. Be careful to not make the wrap too thick otherwise you will struggle to fit the new pack in the light upon reassembly.

Testing the new battery pack.

Before putting the light back together, test the battery pack to make sure it works. If you accidentally shorted the batteries when building the pack, the protection circuit should have kicked in. You will need to charge the pack before you can draw power from it. This is a safety feature.

lezyne decca drive 1500xxl testing

Reassemble

Slide the new battery pack into the light. Tuck the connector into the recess at the back. Make sure not to trap any of the wires. You may note the plastic casing looks ever so slightly bowed. I think these cells might be slightly wider than the originals, it does not cause an issue though.

lezyne deca drive 1500xxl upgraded battery

Reassembly is the reverse of disassembly, make sure none of the o’rings or seals are snagged, otherwise water may get into the housing.

lezyne deca drive 1500xxl

Test the light again and feel awesome in the knowledge the battery will last longer.

lezyne deca drive 1500xxl

11 thoughts on “Lezyne Deca Drive 1500xxl Battery Upgrade”

  1. Hi Greg,
    Thanks for your post, I have also had the same problem with the Lezyne Deca Drive 1500xxl battery giving up. I have ordered my batteries and will be making my pack up soon. It is such a shame that these expensive lights aren’t user replaceable for most people, although I have noticed that at least one Lezyne currently available is.
    Thanks once again for you post.

    1. No problem, you are more than welcome. I hope the new pack works well for you. Mine is still going strong. I think one of the key things with lithium batteries is not to leave them fully charged for too long or fully discharged. Somewhere in the middle is optimal. Let me know how your battery pack build goes, I would be interested to see it.

  2. I went to use my Lezyne Superdrive 1200xxl recently and it was dead. So I stuck it on the charge and it never stopped charging and still would not switch on so I presumed the cells had died. Dismantled the light unit and saw that it was 2x 18650 cells with a circuit board so then turned to Google to try and source one and found your blog post, thanks for thank. Might have a go if I can find someone with a soldering iron I can borrow.

    1. Thanks for your comment Derek, how did you get on with the soldering? It takes quite a powerful soldering iron to solder directly on to the 18650 as they tend to wick up the heat quite easily. I think I ran mine at 60W to get the solder to flow well enough.

  3. Thanks for the instructions. My deca 1500 light just died, wouldn’t take any charge. FYI, Lezyne sells a replacement battery with wires, ready to go for $40. I’m going to order as I’m not comfortable sodering myself 😉

  4. Thank you for this guide! Just rebuilt the battery of my Super Drive 1200 with 2x Samsung cells (lower capacity, but it’s fine as long the light is functional). The replacement is fairly straightforward, save for the soldering part, which I left to a local battery service shop. All in all, a 12,5€ job – well worth it if I can get another couple of years life out of my light.

    1. Thanks for your comment Nikolay. I am glad you got your light fixed, they are good quality products and it would be a shame to have to buy a new one just for a dead battery. Safe riding.

  5. Thanks for the detailed review Greg. I noticed that within the rubber button it had a plastic knob with 1 flat end while the other is rounded. It dropped out too quickly and I didn’t remember which direction am I supposed to place it in.

    Flat side against circuit board: On/off switch becomes stiffer and harder to press.
    Round side against circuit board: On/off switch is ‘softer’ and easier to press, but mode switching becomes an issue e.g. it occasionally gets stuck on max setting instead of econ setting when I pressed the button on overdrive mode.

  6. Hi Greg, thanks for sharing your expertise.

    There is a white plastic knob within the rubber switch with 2 ends (1 flat, 1 rounded). Which end should face the circuit board?

    I noticed the following:

    Flat end against circuit board: button is stiff and harder to press

    Rounded end against circuit board: button is easier to press, but the lighting modes are occasionally stuck e.g. while on overdrive mode, the button press does not switch between max and min mode.

    1. I can’t recall which way round it was when I took the light apart. I would have to strip it down again and check which way I have it. Also make sure the PCB is fully seated inside the light housing.

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