Difference between pages "Parallel Batteries" and "Connectors"

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(Created page with "There are two methods you can use to safely parallel batteries. ==Direct connection== To safely parallel batteries directly for more capacity, you must first ensure they are the same chemistry (lipo, li-ion, lifepo4, lead acid, etc) and the same voltage. Never attempt to directly connect batteries in parallel of different chemistries. It is also best if they have a 2 wire BMS (Charge and discharge through the same wires), since otherwise directly cross connecting th...")
 
(Created page with "Connectors are everywhere on an e-bike and are super important to being able to maintain and expand your e-bike. A brief list of common recommended connectors is as follows: *XT90-S: 2 pin, 90A rated. Soldered. Very good connector with anti-spark functionality that reduces/eliminates sparking and erosion of the contacts upon repeated connections. *XT60: 2 pin, 60A rated, Soldered. Very good connector but no anti-spark functionality and hence best only for occasional...")
 
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There are two methods you can use to safely parallel batteries.
Connectors are everywhere on an e-bike and are super important to being able to maintain and expand your e-bike.  


==Direct connection==
A brief list of common recommended connectors is as follows:


To safely parallel batteries directly for more capacity, you must first ensure they are the same chemistry (lipo, li-ion, lifepo4, lead acid, etc) and the same voltage.  
*XT90-S: 2 pin, 90A rated. Soldered. Very good connector with anti-spark functionality that reduces/eliminates sparking and erosion of the contacts upon repeated connections.  


Never attempt to directly connect batteries in parallel of different chemistries.
*XT60: 2 pin, 60A rated, Soldered. Very good connector but no anti-spark functionality and hence best only for occasional disconnections.  


It is also best if they have a 2 wire BMS (Charge and discharge through the same wires), since otherwise directly cross connecting them may defeat the overcharge protection.
*MT60: 3 pin, 60A rated, Soldered. Good connector for phase wires.  


By directly connecting the positive wires to each other and the negative wires of a 2 wire BMS, you can charge both batteries and discharge them through the same wires at the same time.  
*Anderson Powerpole: 40A rated, Crimped. Very good connector that has a sacrificial tip designed to take the wear of sparking without eroding the main contact area.  


You must first however charge both batteries to the exact same voltage (fully charged is recommended as its easiest to reach) as directly connecting batteries of different charge states can cause huge currents to flow. Its best to verify with a DMM that they are the same voltage before connecting.
*JST-SM: Low current rated, Crimped. Good for signal lines like throttle and very low power like LED turn signals and such. Good connector for hall sensor wires.


It is recommended to have an individual fuse or breaker for each battery, but not strictly required as the BMS should be able to disconnect the battery in event of over-current.  
*Higo: An over-molded type of connector that can't be easily used in DIY as you have to splice to a pigtail to use one. Water proof and very good, comes in many formats and current ratings including combined hall/phase wires for motors. Highly recommended to get if you can find a controller and accessories already using them.  


This means you can not directly connect a second battery in parallel as a backup unless its going to stay attached or only be attached when both batteries are fully charged. Use an A or B battery switch instead if you need to switch to a backup battery.


==Diode connection==
Connectors we don't recommend:


By using high power diodes, you can ensure your one battery won't discharge into the other and can even connect different chemistries of battery or even different voltages, although they won't share the load if you do mix voltage/chemistries and you will need separate chargers.
*Bullet connectors: These are generally only good for around 15A, often have poor tolerances and can come loose with vibration and melt even when used at rated current levels.


The diodes need to be rated for higher then your max battery voltage and the full current you expect to draw, ideally much higher. This will make them rather large and likely require heat sinks. The diodes only need to be on the positive wires, directly connect the negatives. 
*Spade connectors and terminal blocks: Often found on the phase wires of cheaper motor kits, these connectors often are of poor quality and melt under the currents.
 
You also need to use additional diode or separate connectors for charging. If you use diodes they will need to be rated for the full current of your charger and batteries.
 
Note that if you use diodes, your controller will no longer be able to recharge your battery and regen braking must be disabled.

Latest revision as of 08:26, 15 January 2022

Connectors are everywhere on an e-bike and are super important to being able to maintain and expand your e-bike.

A brief list of common recommended connectors is as follows:

  • XT90-S: 2 pin, 90A rated. Soldered. Very good connector with anti-spark functionality that reduces/eliminates sparking and erosion of the contacts upon repeated connections.
  • XT60: 2 pin, 60A rated, Soldered. Very good connector but no anti-spark functionality and hence best only for occasional disconnections.
  • MT60: 3 pin, 60A rated, Soldered. Good connector for phase wires.
  • Anderson Powerpole: 40A rated, Crimped. Very good connector that has a sacrificial tip designed to take the wear of sparking without eroding the main contact area.
  • JST-SM: Low current rated, Crimped. Good for signal lines like throttle and very low power like LED turn signals and such. Good connector for hall sensor wires.
  • Higo: An over-molded type of connector that can't be easily used in DIY as you have to splice to a pigtail to use one. Water proof and very good, comes in many formats and current ratings including combined hall/phase wires for motors. Highly recommended to get if you can find a controller and accessories already using them.


Connectors we don't recommend:

  • Bullet connectors: These are generally only good for around 15A, often have poor tolerances and can come loose with vibration and melt even when used at rated current levels.
  • Spade connectors and terminal blocks: Often found on the phase wires of cheaper motor kits, these connectors often are of poor quality and melt under the currents.
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