Install a new battery on Honda CBR125R


Yesterday, I finally installed a new 12V battery on my Honda CBR125R. The reason why I did it is that the engine did not turn on anymore when I pressed the starter button. I also noticed in the past weeks that the engine did not start very quickly. Sometimes, after pressing the starter button, it took much time for the engine to rotate properly (I could feel some strange drops of engine speed when starting the engine).

Then, last week, when I tried to start the engine, the battery voltage was dropping so much that even the ECU was resetting. I noticed it because when I pushed the start button, the display and lights shut down, and the display restarted the power-ON check, and also I could hear the sound of the gasoline pump turning ON again (this is usually done when the ECU turns ON - when turning ON the ignition key).

For these reasons, I understood that the battery was close to death. I am not sure about that, but I suppose that the guys who had the motorcycle for 2-3 years before me, never changed the battery.

Using Amazon Japan, I bought a TAIWAN YUASA TTZ7SL ([ 台湾ユアサ ] シールド型 バイク用バッテリー [液入充電済] ) for 5,730 Yen (40 Euro). This battery is compatible with the one recommended in the Honda CBR125R Service Manual, but not the same; the battery recommended in the service manual is YTZ6W (12V, 5Ah @10h charge, 5.3Ah @20h charge).

The characteristics of the TAIWAN YUASA TTZ7SL are the following.

  • [ 10時間率容量, 10 hours]:6.0(Ah)
  • [ サイズ , size]:高さ105㎜ 幅70㎜ 長さ113㎜ 液入り重量約2.5kg
  • [ 互換バッテリー, compatible batteries ]:YTZ7S/FTZ7S/RBTZ7S/DTZ7S

The installation is very quick, and it required just 10-20 minutes, assuming that you have some simple tools such as a hexagonal keys and screwdrivers.

  • First of all, you need to remove the passenger seat (using the motorcycle key), and the driver's seat (using the hexagonal key).
  • After removing the seats, you have to remove the black battery cover.
  • Then, remove the minus (-) pole cable connection, and then the plus (+) cable connection, and remove the battery. Be careful not to do any short circuit, or to cut the cables.
  • Install the new battery and connect the (+) and (-) poles.
  • Put the black cover on the new battery, the driver's seat, and the passenger's seat. Insert the key and turn ON the engine using the starter switch. In case the battery is correctly installed and connected to the motorcycle harness, the lights should turn ON when you turn the key, and the engine should rotate when you press the starter switch.

In the following picture, you can see the battery which was installed on the motorcycle before I changed it to the new one. It is written "Maxima Power Battery" (マキシマパワーバッテリー).


Author: Davide Cavaliere

I am an Italian Electrical Engineer graduated at Politecnico di Milano. My interests are motorcycles and cars, electronics, programming, Internet of Things, and Japanese culture.

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