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Total Likes: 2
Original Post (Thread Starter)
by Tigernuts
My 1980 TR7 has a 'Classic Twin' Trispark ignition system (its third and final one!). The other two packed up with little warning (none at all the first time). I'm wondering whether the effects I'm noticing are signs that the third is on the way out, or whether there could be some other explanation.

Just lately, if I'm riding along and then turn the lights on, there's a very brief 'hiccup', as if the ignition momentarily cuts out then comes back. I've done this several times over the past week and it does it every time, but ONLY the first time I do it. If I repeat the experiment (ie: turn the lights off, then turn them back on again), the hiccup doesn't happen. But if I leave it for a while, then turn the lights on again, it does.

Anyone got any ideas about what's going on here?
Liked Replies
by HawaiianTiger
Originally Posted by Tigernuts
What you say makes sense, thanks. I turned the lights on when the bike was in the shed last week and thought the beam was a bit feeble, and slow to fully light up. I put the Optimate charger on (after disconnecting the earth lead), but it went straight t green, ie: fully charged. Are these charger lights reliable? The battery (a Motobatt) is 8 years old, so possibly getting towards the end of its life? Is there some way I can tell for sure?
That often happens when a cell or two is dead. I have several battery chargers that have green lights for fully charged batteries and they all do this. You should do a load test on it to see what the voltage is after a minute or so of full lights on. If it doesn't bounce back to over 12.5 volts, the battery is probably near the end.
I have a ten year old battery in my old Toyota. It never shows more than 11.8 volts after this test. I put the battery charger on it and the light goes green in just minutes. It's going to strand me one of these days, but it keeps starting the car and I'm cheap so I'm tempting fate.
1 member likes this
by koan58
Hi TN, good to see ya again.

As Gavin suggests, it would seem as if the momentary drop of voltage when the headlamp load is added stops the function of the Trispark amplifier for one or two cycles.
It does suggest that the battery is near its limit of supply ability.
If this only happens at lowish rpm (say below 3000) its the battery I'd go for.
If it happens at 4000+ I'd question the charging system as well as the battery.

I like having a voltmeter on a bike. Before I fitted one permanently, if I had doubts, I would tape a multimeter to the tank, crudely connected into feed and ground lines. It is most informative as to what is going on during real use.

Just read the additional posts and your description of the charger quickly showing full on what seemed to be an at least significantly discharged battery is indicative of significant areas of some/all the plates being sulphated. The small remaining active areas of those plates can only accept a small amount of charge. The battery will then still display a seemingly fair voltage, though the amount of charge stored is tiny and will dissipate with a very short time of headlamp (or even smaller) draw.

8 years is pretty damn good for a battery anyway, I'm generally happy with half that!

Bill, yer lucky to live in such a lovely warm place, clapped batteries can get by a bit better than here. When the ambient drops considerably about Nov/Dec, all the car batteries that have just about been starting the cars through the summer months all of a sudden go "oh no ohh noooo!" I'm a tightwad, so been caught out a few times in years gone by.

Best of.
1 member likes this
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