The size to match the battery is M8 x 1.25 x 16mm.

Yes, you can. The maximum number that can be connected in parallel is 4. In series, there are no limitations.

• Install the battery in an open, well-ventilated, dry, clean place with a temperature between -4℉~140℉/-20℃~60℃ (recommended temperature range is 59℉~86℉/15℃~30℃)
• Make sure it is away from heat sources and places prone to electrical sparks, and at the same time fix the battery in fixed position so that it cannot be easily shaken.
• The installation of the battery requires vertical upward (the positive and negative battery ports face upward), the battery cannot be installed sideways and upside down, while the battery cannot be installed stacked.

Batteries can be connected in series and parallel, the number of series connections is not required, the number of parallel connections required for 4; While requiring the initial state of the battery before the battery series or parallel connection is the same (the same model, the same brand, the same voltage, the same capacity), series and parallel connection between the battery wiring cable specifications and length should be the same. At the same time, when the battery is connected in series, it is recommended to install an equalizer to ensure that the battery charge and discharge balance to ensure battery cycle life.

No, you can't. All the batteries you connect together should be the same brand, the same model, the same voltage, and the same capacity.

The battery cycle life varies greatly under different discharge depths, and the corresponding relationship is shown below; therefore, in order to ensure the battery cycle life, it is recommended that the battery discharge depth does not exceed 50%.

You should choose the GEL battery settings, and ensure that the charging parameters of the controller charger and the battery charging parameters are match. Lead-acid batteries are not recommended to be used to less than 50% of the battery power.

We recommend installing Renogy's Battery Monitor (RBM500) to monitor battery data (voltage, charge/discharge current and capacity). You can also set a low capacity alarm value in the RBM500. If the battery capacity falls below the set low capacity alarm value, the RBM500 will sound an alarm to prompt you to use the battery not to over discharge.

• It is recommended to charge the battery to 70% capacity and remove all wiring from the top of the battery and place the battery in an open, well-ventilated, dry, clean place with a temperature between -4℉~140℉/-20℃~60℃(recommended temperature range 59℉~86℉/15℃~30℃).
• The positive and negative battery terminals need to be covered with a protective cover.
• Store the battery gently and do not hit the battery violently.
• Every three months, the battery needs to be charged once.