second battery pack. | Endless Sphere DIY EV Forum

I've got enough mAh li-ion batteries to build either a 36V, 48V or 54V pack. Using the (probably overstated) rated capacity I could make the following:
10 cell 37V 22,800mAh- advantage: already have charger -disadvantage: 36V too low to manage some of the hills
13 cell 46.8V 19,000mAh- advantage: probably better range than 15 cell -disadvantage: new charger needed (~$78 with carriage)
15 cell 54V 15,200mAh- advantage: faster than 13 cell -disadvantage: new charger needed (~$78 with carriage)

Current main battery is 36V 20Ah LiFePO4 but will change the battery next year as more power needed for the hills to (probably) a 48V LiFePO4 early next year. This setup will fill in until then, then be a second battery if needed.

What kind of range / speed differences do you think I'd see between the 13 and the 15 cell setups? eBikes are supposed to be limited to 15.5 mph in the UK so both could easily pass that. Anything else you think that should be considered?

Thanks 54v nominal would require a controller capable of that, while the generic 48v controller would work fine with 36 or 48v in most cases.

Practicality makes me say go 48v nominal. All packs will have the same range more or less, if ridden at the same speed as the lower voltages are capable of.
If you are using cells that charge to 4.2v, go 14s. That way you get the max volts a typical 48v controller can take, when fully charged. About 60v. Also there are 14s chargers on the market, such as the hyperion.

You may be taking the wrong and more expensive approach to curing your hill problem. A slow speed winding dd hubmotor handles hills real nice, at watts- 48v. Yet it's top speed may be as slow as 20 mph. 6x10 9 continent motors are an example of such a motor.

A **lithium thionyl chloride (Li-SOCl₂) battery** is a type of non-rechargeable (primary) lithium battery. It uses lithium metal as the anode and **thionyl chloride (SOCl₂)** as the cathode and electrolyte. These batteries are known for their **high energy density**, **long shelf life**, and **wide operating temperature range**, making them well-suited for applications requiring reliable, long-lasting power sources.

SUNJ ENERGY Product Page

Key Features:

1. **High Energy Density**: These batteries have one of the highest energy densities among primary batteries, providing more power per unit weight and volume.

2. **Wide Temperature Range**: Lithium thionyl chloride batteries can operate effectively in extreme temperatures, from around **-55°C to +150°C**, making them suitable for environments with fluctuating or extreme temperatures.

3. **Long Shelf Life**: These batteries have a very low self-discharge rate (typically around 1% per year), allowing for **10-20 years of storage** without significant capacity loss.

4. **Applications**: Commonly used in applications where battery replacement is difficult, such as **remote monitoring systems, military equipment, medical devices, utility meters, and GPS tracking systems**.

 Advantages:

- High energy density and voltage (usually around 3.6V per cell).

Contact us to discuss your requirements of mAh lithium ion battery pack. Our experienced sales team can help you identify the options that best suit your needs.

- Long storage life due to low self-discharge.

- Resistant to temperature extremes.

 Disadvantages:

- They cannot be recharged, so once depleted, they need to be replaced.

- Thionyl chloride is highly reactive and toxic, so these batteries require careful handling and disposal.

Safety Considerations:

Due to the reactivity of lithium and thionyl chloride, these batteries are generally built with safety mechanisms to prevent issues like **leakage, venting, or thermal runaway** in case of a short circuit or mechanical damage.

For more double lithium ion battery packinformation, please contact us. We will provide professional answers.