Topic: AGM battery failure

[eigenvector]

I really don't consider sealed AGM batteries to be unreliable - but I pulled a name brand battery off my Sabre, gave it a recharge - only to come back later to find it bubbling and leaking from the top.

Obviously the battery has overheated and failed, but I've never seen them actually start leaking.

So I'll be taking this one back to replace it, not sure how I'll transport it - wrapped in plastic I guess.

[MikeSimon]

This sounds really weird. AGMs are supposed to be dry - Absorbed Glass Mat. Even if overcooked, the acid should not come out of the saturated fiberglass packing

[eigenvector]

Well, in any event it's going away this weekend.

Heck - maybe it was just condensation or rain that collected under the vent cap, I sure as heck wasn't going to take the chance.  Besides, even if it isn't leaking - it dang sure won't hold a charge.

I'm almost certain it was acid though.

[TwoTired]

This sounds really weird. AGMs are supposed to be dry - Absorbed Glass Mat. Even if overcooked, the acid should not come out of the saturated fiberglass packing

FYI:  AGMs have a fiberous mat between their plates that absorb just enough liquid electrolyte to saturate the mat material.  They are not dry inside at all.  They function the same as a flooded cell battery, with a measured amount of electolyte to fill the mat.
 Imagine a wet towel.  You can make it wet yet it won't drip until over saturated. It can hold a lot of liquid.

If you over charge an AGM, it will "boil" in that electrolysis will occur, separating the H2SO4 into its component parts. Hydrogen, and oxygen are liberated, as well as heat.  If you gain access to the cells, it can be replenish with distilled water (H2O). The trick is knowing how much volume is lost and restoring only that volume.

Cheers,

[gtmdriver]

I had an AGM battery overheat on me on my Moto Guzzi Cali 3. We were in Munich at the time.
The Guzzi charging system was not sophisticated enough to regulate the charge rate sufficiently for the AGM battery and it overheated, distorted and leaked acid over the bodywork and engine. I replaced the battery with a standard flooded lead/acid battery and the problem never recurred.