Background
Many electrically powered vehicles, such as golf buggies, mobility scooters and go-carts use two or more batteries connected in series and it is important to charge the batteries equally for optimum performance and extended life.
Using the CamdenBoss CEQ12A prevents mismatched voltages at which batteries stabilise when charged in series. Without a balancer (or equaliser), one battery will be undercharged while the other is overcharged. The CEQ12A ensures that each battery in a pair receives the same voltage by measuring the total charging voltage, calculating its middle value and adjusting the voltage to each battery to be equal within 0.1V.
We tested it in an electric go-cart which has five batteries connected in series, supplying 60V to the motor. This system is charged by a 72V supply (14.4V x 5).
Charging without balancer
When charging the batteries as normal with a 72V/20A charger the final voltages on each battery were checked. The five final voltages were: 13.9 + 14.5 + 14.3 + 14.8 + 14.5 = 72V. There are clear differences in the charged voltages meaning that there will also be differences in the state of charge of each battery. The overall capacity of the system is determined by the capacity of the battery with the lowest charge. If one of the batteries becomes fully discharged, there will be a significant drop in voltage and the system will operate poorly.
When charged without balancers, the go-kart ran at full speed for six minutes.
Charging with balancer
Using the same charger with CEQ12 battery balancers resulted in the following final voltages:
14.3 + 14.4 + 14.4 + 14.5 + 14.4 = 72V.
Charged with balancers the go-cart ran for 10.5 minutes at full speed
How and why
Two or more batteries connected in series never charge equally. One always accepts a lower terminal voltage than the other. As a consequence, both (or all) batteries will have shorter lives with undercharged batteries suffering from build up of sulphate while the electrolyte will tend to dry up in overcharged batteries. Both conditions reduce the lifetime of the batteries.
The CEQ12A balancer measures the total charging voltage for a pair of batteries, calculates its middle value and adjusts the voltage to each of the two batteries to be equal within 0.1V. This ensures even charging. The maximum current that will flow is approx. 1A. This results in increased starting current due to the balance of charging and extended battery life.
 | For more details visit: http://www.camdenelec.com/electronics/product-subcategory.asp?Category=BATTERIES&Sub=Battery Balancer |