Calcium Lead Acid Battery and Vibrations

[Sruk]

Dear all,

Recently I've encountered a strange phenomena with the gel Calcium Lead Acid battery.

I did some shock/vibration testing with our device powered by YUASA NP7-12 battery. The highest amplitude applied to the device was around 40G. Battery was full and it wasn't discharged while testing.

When the battery returned to the company I found out that her performance on the peak load (impulse load) has decreased. In a way that when it's connected on a 6ohm wire resistor the load current requires about 2 seconds to reach about 2 amps. The current starts with 0.5A, after one sec. is about 1.2A and after 2 sec. is about 2A. If I repeat the test right after last one the current is 1.8A on start and rises to about 2A. If the battery rests for a while it again has a load current lag. When I used a non-shocked battery of the same type load current was instantaneous at about 2A. Voltage on the battery terminals of both batteries is 12.8V unloaded.

I did look for some information on Google but had no luck. I found here that a special type of batteries (such as AGM) was invented for the vibration rich environment.

Can You help me on demystifying this situation? Is it really the vibrations that damaged the battery impulse performance? Are there any scientific explanations?

Thx!

[PChi]

As no one else has any ideas I'll put my two pennies worth.
I believe that the Yuasa NP series have a glass fibre sponge that holds the electrolyte rather than a gel. Possibly the vibration shook the electrolyte out of the glass fibre or posssibly the electrode plating has fallen off.
Yuasa may have an answer. Their technical back up was pretty good a couple of decades ago when I last used it.

[bills]

Calcium/lead plate grids are much more brittle than antimony/lead grids and it is possible one or more of the plates broke off. 

[Sruk]

Thx 

[djQUAN]

Calcium/lead plate grids are much more brittle than antimony/lead grids and it is possible one or more of the plates broke off.

I'm with this guy^

And most SLA batteries are generally not recommended in high vibration environments unless specially designed. I remember back when I was young, I accidentally dropped a perfectly good 6V 4Ah SLA on the floor and it went open circuit.