Keyu brand AA battery holder in series

When we get batteries in series as power supply for our electronic products, and we will choose right battery holders for them. We provide our customers with various battery holders in series. For example, we have 2 AA battery holder, 3 AA battery holder, 4 AA battery holder,  6 AA battery holder, 8 AA battery holder. 

When we use batteries in series, I have some suggestions as below:

For series use, use the same type of batteries. Do not charge non-rechargeable batteries. When a non-rechargeable battery is charged, hydrogen is produced, even cause an explosion.  

Pay attention to the polarity of the battery.  If one of the batteries is reversed, it will reduce voltage of the entire battery series, not increase it.

Remove the fully drained battery from the suspended device. Old batteries are more prone to leakage and corrosion. Alkaline batteries are better than carbon - zinc batteries at this point.   

Remember not to put all the batteries in one box, as this may cause a short circuit.  A short circuit in the battery can cause heat and may cause a fire.  Please insulate your discarded batteries in small plastic bags. The original battery pack, which is similar to alkaline battery, can be thrown into the ordinary trash can.  But it is better to send used batteries to recycling.