Heartbeat as a last gasp?

[Tacocaster]

Out on a ride yesterday I had my battery die. Everything - gauges, indicators, engine and smile just dropped like a lead fart. I coasted to a stop and failed to get even a neutral indicator to light-up. Interesting. Not even a warning (dragging starter) before that.
While inspecting the 40A fuse, battery and starter (positive) cable connections, I noticed a "heartbeat" from the Speedo & Tach needles. Just a blip where they pulsed-up simultaneously, about 1/8". Then a short interval later, another one. Ignition was off! What the....?? Capacitor discharge?? There is no physical capacitor in the circuit. No UAP's overhead...now what could generate "that" symptom (if even a symptom)?? I ignored it and pulled the battery.

Has anyone ever seen this "Heartbeat" - or failing that, can anyone offer their explanation on how this could even potentially happen?

To close the story, the battery measured 13VDC (yup, 13) but I suspected the Meter's gauge instead of my own sleuthing skills and asked the Shop Tech to load test which the battery promptly failed in spades. Replaced same, engine fired, smile returned and I was on my way again.

[Hossamania]

Try disconnecting the battery for a while then reconnect, see if the gauges move as you described. If so, the symptom you saw was the old battery recovering enough voltage to activate the gauges, but no amps left alive.

[kd]

Do you have security?

[Geezer_Glider]

Battery may have died from an open cell connector. This type of failure may show good voltage with no load (checking with a meter) but open completely under a load such as ignition, lights or cranking. It can also go intermittent under light load. this may cause the gauge flutter you saw. The gauges may blip as you connect a battery to the system even with the ignition off. Open cell connector failures generally happen without warning and can really confuse people. Shorted cell plates will lower cranking capacity and small drop in voltage, giving some warning of impending doom. Also a fun note that open cell connectors  or even plate connections can cause a big burp from the battery! Have both types of failures on my vehicles over the years, still beats riding a hay burner, though!
Just saying,
R Meyer 

[smoserx1]

 
That is the best description yet of two separate battery failures I have had, one with an old battery and one with a fairly new one.  In both cases the no-load voltage would return to about 12.6, but any sort of load would drop it to less than a volt.  One of the LED passing lamps would faintly flicker on and off but that's it.  FWIW my tach has always "bumped" a hair when the ign. was switched on.  Speedometer in mine is mechanical so I can't say if an electric one would behave the same.

[Tacocaster]

Thanks guys - all good responses.

Hoss - I get what you're suggesting (slight voltage recovery - enough to blip the Speedo & Tach gauge needles). The Ignition was off when this "symptom" was occurring. I think you and Geezer have the answer.

KD - Nope, no Security option on my ride.

Geezer - I think you & Hoss nailed it. "The gauges may blip as you connect a battery to the system even with the ignition off." In this case the bad battery was still connected but likely through hysteresis was recovering enough to "blip" the needles after I'd try, then shut-off the ignition during troubleshooting. At least that makes sense to me now.

smorserx1 - Yes, I have also seen the Speedo & Tach Gauge needles "blip" before although I cannot for the life of me remember the application when they did but it was probably after connecting a battery and seeing them do this yesterday didn't shock me at all as I'd seen it before. I was just curious what might cause it in the situation I was experiencing. I think Hoss & Geezer have the answer.

Thanks Guys!

[Deye76]

"Not even a warning"
Nonsense, some recently told of plenty of warning in many many years of riding Harleys. multiple times, even on road trips tearing up the Interstates. To the point of stopping at a dealer in the middle of nowhere and purchasing a new battery, only to save the trip.   

[Tacocaster]

Nonsense? Ahhhh, okay....thanks for your insight.

[Deye76]

Nonsense? Ahhhh, okay....thanks for your insight.

Wasn't directed at you. I had posted on another thread about batteries not giving a warning upon failure, this was just a little sarcasm about that thread. Thought it was explained in my post.  Sorry for the misunderstanding.