Choice of electric wheelchair dual battery vs single battery

It is feasible for electric wheelchairs to use two independent batteries (dual batteries), but in actual application, there are things that must be paid attention to, otherwise the consequences will be serious. This article will explain it to you.


Benefits of dual battery design:

  1. When one battery runs out of power, there is a backup battery for backup
  2. If it is detachable or has an independent switch, the battery can be replaced at any time.

It sounds good and is feasible in theory, but what are the drawbacks in practice and is there anything we should pay attention to?

Practical application notes:


First, in practical applications, it is best for the two batteries to have the same voltage. Otherwise, there is a potential difference (that is, a voltage difference). If two batteries are on the same circuit, the current of the high-voltage battery will flow to the low-voltage battery to charge the low-voltage battery. Because in the same circuit, the current will charge directly to the other battery as quickly as possible. Each battery will generate heat during the process, accelerating battery wear and shortening the life of both batteries.

Solution: It is best to use two batteries together when they are fully charged. It is best to use two batteries at the same time and from the same manufacturer.

Second, the wire connecting the two batteries must be thick enough. The smaller the wire, the greater the resistance. Even if there are two batteries shipped from the factory at the same time, one battery will always age first, which will cause the potential difference mentioned above, especially when one battery is dead and the other battery is still running. A strong current will be generated, the wire will heat up, and a wire that is too small will not be able to bear the load, resulting in a short circuit and even a fire.

Recently, a customer came to us for help, saying that the wires of his wheelchair (not a product of our company) were short-circuited, caught fire and burned down, and he wanted us to perform repair services. After inspection, it was found that the wheelchair had a dual-battery design. In order to save price and cost, the manufacturer uses small wires to connect the batteries, which results in the wires being burned.

Single battery vs dual battery electric wheelchair

Question: Will dual batteries outlast single batteries?

Answer: You have to look at the capacities of the dual batteries. For example, if there are two 9Ah batteries and one 20Ah battery, the 20Ah single battery will last longer than the 9A dual battery.

wheelchair battery

Of the above batteries, which one do you estimate is the largest and has the highest capacity?
To calculate the capacity, we don’t look at one/two cells. The most practical thing is to look at the voltage (V ) , the larger the Wh number, it means that the battery contains more energy and can travel farther.
Note: For electric wheelchair batteries used on airplanes, the maximum single battery can only contain 300Wh output.

Note when choosing:
Question: Will dual batteries outlast single batteries?

Answer: You need to look at the capacities of the dual batteries. For example, if there are two 9Ah batteries and one 20Ah battery, the 20Ah single battery will last longer than the 9 A dual battery.

Q: How thick do the wires need to be?

Answer: Because the rated current of electric wheelchair motors is usually 5A, and considering the safety factor, it is recommended to use wires of 2x2.5mm or more.


Question: What if I use a single large battery but want to increase the battery size?
Answer: It is best to connect two batteries in parallel. When connecting in parallel, use the charging cable to fully charge the two batteries to avoid voltage differences.

We would like to remind everyone to be careful when choosing a wheelchair. You should pay more attention to the hardware of the wheelchair, such as the thickness of the wires, connections, etc. You may also directly choose a single-electric wheelchair to be careful of wires that are too small or poorly modified. If users have any questions about electric wheelchairs, please call us at +852 35680755.