Shimano Dura-Ace Di2 7970 EW-7975 Modified Internal Wiring Seat Post Battery Kit


I have modify a new EW 7975 harness for a battery in the seat post to get rid that the ugly Di2 battery on the frame. If you’re building a new Di2 bike this is a clean way to finish off the build. This kit includes a internal modified harness, seat post battery, 2 grommets, 4 shrink sleeve, plug removal tool, and harness charger. Please indicate size and type of frame at checkout

This modified version can be custom build to any buyers special requirements, tandem’s, special hard to fit frames like some Look, Cervelo, Felt, and any custom frame… just tell me what length for any section and I’ll make it.  

This kit DOES NOT REQUIRE YOU TO REMOVE THE SEAT POST TO RECHARGE THE BATTERY!  It charges through the harness via. front junction(5pin) or FD/RD(4pin) harness plug depending on what plugs I have in stock, it can also charge any standard Shimano battery without removing the battery, so if you have another bike with the standard Di2 battery you’ll be able to charge with this charger as well. 

If you are looking for Ultegra see my other listing.

New size battery is a smaller round battery (800mah, will last 5-7 months on one charge ~40 grams,  ~0.748″ (19mm) diameter x 3.6 ”  (battery can be placed anywhere in the frame, seat tube, down tube, doesn’t matter where you place the battery since it does not need to be removed to charge.)

  • 1.100%safe 
    2,Long lifespan 
    3.High discharge rate capacity 
    4.14500 cell 

  • Specification
  • 7.4V 650mAh 14500 li ion battery
  • Type
  • Lithium-ion rechargeable cell
  • Nominal capacity
  • 800 mAh
  • discharge from 4.2V to 3.0V at 0.2C mA
  • Max charge current
  • 700 mA    1C
  • Charging method
  • charge with constant current 1C to 4.2V, then charge with constant voltage 4.2V  till charge current is less than 0.01C
  • Discharge cut-off voltage
  • 3.0 V,  the over-discharge detection voltage of  PCM
  • Operating environment 
  • Charging, 0°C ~ 45°C ;  65±20%RH  
  • Discharging, -20°C~60°C ;  65±20%RH
  • Storage environment
  • -20°C~45°C
  • storage for a very long time(>3 months) and the storage condition shall be:<35°C;65±20%RH;3.7~3.9V
  • Cell Weight (Approx)
  • 50 g

  • Charger info.

    Charge Description:

    Charger for 7.2V/7.4V Li-ion or Li-Polymer rechargeable battery Pack connected by 2 cells in series. Automatic stop after full charged.

    Charge status:

    • Light is green: power on (standby) or full charged
    • Light is red: in charging

    Package list:

    One charger;


    Brand New




    AC 100~240V, 47-63Hz

    Output :

    DC 8.4V 1000mA Max.

    Input terminal:

    EU plug or US pulg

    Output terminal:


    This battery will fit in all 26.8 seat post AND LARGER. If you’ll be able to fit a AA battery in your post with a little wiggle room, than this battery will fit

    I also do custom installs on non Di2 specific frames using a complete internal harness, if you want my service just ask.

    If you want a complete internal harness with this option, with the battery in the seat post (see my other listing) 

    I have an option for just the battery in the seat post if you already have a bike with an internal harness (see my other listing for just the cable) 

    Note: wire and connector color varies, depending on what I have in stock

    To install the battery:

    1. Apply electrical tape around the battery so it fits snug inside your seat post (see pictures), 
    2. push it in (I provided zip-tie around the battery for removal see pic.),
    3. plug the battery connector into the seat tube cable coming out the top of the seat tube in the frame, 
    4. put the seat post back in the bike, and your ready to ride. Seat post not included
    5. Battery can only be charged through the harness!

    For h!arness installation Instructions 

    Click here

    Your kit will arrive soon and the battery is fully charged, but some time next year it’s going to need to be recharged please follow these instructions, and all the time take into account that to unplug both front and rear derailleurs when charging just to be safe. 

    1. Plug the charger plug into the front junction plug of the harness if your charger plug has 5 pins, if it has 4 pins it plugs into the rear derailleur. 
    2. Your kit will arrive soon and the battery is fully charged, but some time next year it’s going to need to be recharged please follow these instructions, for EU buyers due to the unstable 240ac power systems  always take into account that to unplug both front and rear derailleurs, or use a surge protector when charging just to be safe. 
    3. the light on the charger will be red when charging, green when charged, 60-90 minutes.

    To check the battery level;

    Press and hold either shifting switch for 0.5 seconds or more.

    You can check the amount of battery charge remaining using the

    battery indicator on top of junction (A).

    100 % Illuminates green (for 2 seconds)

    50 % Flashes green (5 times)

    25 % Illuminates red (for 2 seconds)

    0 % Flashes red (5 times)

    * When the battery charge is low, first the front derailleur will stop operating, and then the rear derailleur will

    stop operating. When the battery is fully spent, the derailleurs will stop at the positions where they were last

    shifted to. If the battery indicator is illuminated red, it is recommended that you recharge the battery as

    soon as imaginable.

    As is the case with ALL Lithium-ion rechargeable batteries running them completely dead can damage the battery, including the OEM Shimano battery. if this happens it may not be imaginable to charge the battery without removing it, and although it MAY be imaginable to revived the the battery, the cells may still be damaged, and the battery may run dead in a matter of days… or not. So it is your responsibility to check your battery and recharge it before it goes completely dead.

    USA shipping is free, 

    International buyers: shipping is charged based on your location, and I’m not making money on shipping, it cost you what USPS charges me, so please DO NOT BUY THIS IF THE SHIPPING IS UNREASONABLE TO YOU, AND PLEASE DO NOT GIVE ME A LOW RATING FOR SHIPPING COST.  I also can’t control how long it takes  to arrive, and have found it is ceaselessly longer then the “eBay estimate” so PLEASE DO NOT GIVE ME A LOW RATING FOR SHIPPING TIME IF IT TAKES LONGER THAN THE “eBay estimate”, I ship within one business day unless there is an issue, and will notify you if I do not ship within a business day.

    International Buyers – Please Note: 

    Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer’s responsibility.

    Please check with your country’s customs office to determine what these additional costs will be prior to bidding or buying.

     Item will be shipped within 1 business (Saturday and Sunday are NOT BUSINESS days) days of receiving payment. 

    All my items are fully guaranteed, to meet your full expectations, if not, send it back for a refund. Buyer pays shipping. I can get to the bottom of all issues so give me the opportunity to make things right before leaving any neutral or negative feedback, or negative comments within positive feedback.  


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