This is far from the best APC product

I have 4 Back-UPS 500 for over 10 years and one broke down.
I bought this UPS to replace one that was defective and I quickly realized that he had the bad habit of beeping without reasons. I came back from the best of the range, ie the price for the first Back-UPS 500 and 650 ...
It took long enough to understand why he would alert ...
The culprit is the battery whose terminals are not connected using "pods" on this model, but simply by contact with the pressure of the closure case. As the battery is attached under the device, Contacts is sometimes unsteady because of the weight of it and the inverter then goes into alarm. I made contact with APC to submit the problem and an answer was given to me "put a small piece of wood to ensure contact more frank." That's what I did, but it still happens very often that the inverter goes on alert. It is perhaps this time the heat making the plastic less resistant to pressure from the hold ...
All this is not very serious and surprised many APC. I bought a Back-UPS 500 and I do not have any trouble since.