About two years ago, I ditched the remains of the stock charging system on my NC35 for one of Rick's MOSFET reg/recs and an Electrex stator. These are directly connected to each other, and the pos/neg from the unit is taken directly to the battery using 30A wire. The old battery had been abused by many charging system issues, but was still soldiering on. The only signs of age were the customary sluggishness of starting if the bike didn't pick up first time.

A few months ago, I installed a new Yuasa YTX7AB-S battery, exactly the same make and type as the old one. I filled and prepped as per the instructions. It was sat overnight on an Optimate 4 after it had stopped gassing. Upon testing, I recorded no difference in figures on the charging system to those with the old battery.

I work away from home, so I generally only use the bike at weekends, and often only every other weekend at that. It lives in an unheated garage and my previous woes with the charging system have meant that my ritual on arriving home on Friday evening is to check the battery voltage and make sure everything is happy for the morning. The old battery was starting to settle around 12.5, 12.4V with the age and lack of use, which is why I replaced it. Out of habit, for a little while I still measured the new one. I would regularly find that it was holding 12.7V, 12.8V after a week of sitting, which is what I had measured in off bike tests during my charging system woes. So, I stopped faffing and just trusted it.

About three weeks ago, we had a really cold spell during the week. So, just in case, I measured the battery one Friday, and discovered to my disappointment it was down to 12.25V (the cold does the same to the missus' car that also has a new battery!). However, it started fine, the output measured fine, and so I figured a good run the next day would have it fully charged again. It started fine, but upon going to leave, it barely started, and the cheapo voltmeter I have on the top yoke was reading a little low (it normally says 13.3V when the true figure is 14.2) upon returning home, the multimeter concluded the battery was not completely charged. About 12.4V on switching off, certainly no 'float' charge. The following week, it was back to 12.25. Started fine, and a quick trip out got it up to 12.4V. The next day it started fine at both ends of the journey, and I arrived home with a slightly better 12.5V. Still not great. And the meter on the yoke was reading 12.9V which equates to a little under 14 in real terms (I must get a better one).

This weekend just gone sealed the deal. The battery was once more down to 12.25 after resting. However, this time it refused to crank the bike over. It was put on charge and retained a modest float charge of about 13V overnight, and all was good when installed on the bike. No issues getting to my destination or leaving, however after a small amount of moderately spirited riding, the meter on the yoke dropped back to the 12.9V or so it was previously indicating, and upon switching off at home, I measured 12.62V at the terminals, where I was hoping to find 13 or more.

I do not believe there is an issue with the charging system. I have not changed anything electrical on the bike since I installed the bits from Rick, and until I put this battery in, everything has been bombproof. I do run a low beam relay and 60/55 H4s up front, however these were installed a good while after the issues that prompted the new parts, and I had also run them in the past many years ago without killing the system (instead killing the low beam switch before going to H4Rs for a few years).

Now, I did buy the battery in November 2012. So it has sat about waiting to be activated for three years in my hands plus however long it was on the shelf. Do they have a shelf life even before they are activated? Could I be unlucky and just have got a crap one? I've used this brand and very model in the past without problems (at least, not ones caused by the battery first...!).

Hi, whats your voltage when the bike is running? I would just buy a new battery for a start. But you should get an output of at least 13v (should be about 14 really) when running.
Can you try the battery in another bike?

I get over 14V when the bike is running at anything above about 2000rpm. I could be wrong, but I don't believe the charging system is at fault. It's usually 14.2V, however being an RVF that is with the lights on. I get a few tenths more if I push the start button just enough to switch the headlight off.

Charging problems are one of 4 things...generator, reg/rec, wiring, battery. You've ruled out 2 (and possibly 3) of the 4...

My info says an un-activated AGM battery has an indefinite shelf life, provided it remains sealed until activated, but there are always exception. From your narrative it appears that the new battery does not attain a full charge during your ride.

Your comments regarding charging voltage suggest past tense, what values do you get at the moment. How good is the new battery under a load test.

I get 14.2V with lights on at anything above 2K rpm.

To recap, the stator reg/rec came from Rick O about two years ago and are directly connected to each other and the battery. The battery was new but I had had it (unactivated) for several years. As Magg says, the manufacturers claim storage should be indefinite in a dry state.

As yet, I have not had the opportunity to do a load test or retention test on the battery, however it is my belief that it has a poor capacity as it has almost no guts when partially discharged. I have a new battery to replace it with. I bought a cheap (just in case it is not the battery) Numax job, and went for the slightly larger capacity YTX9. I will find out on Friday how much of the charge the battery has retained from last weekend. Given that as soon as I switched off it dropped to 12.62, I am assuming it was not very well charged despite having had an overnight charge the night before.

Pretty sure the battery was to blame. After being left for two weeks, the battery had dropped to 12.47V, which to be honest was a higher figure than I was expecting to see. The bike fired up absolutely fine. I ran it for a few mins and switched off. Remembering a minor issue with the rear lights, I switched back on and for less than a minute I attended to them. Figuring I'd rather not deplete the battery, I decide it would be best to have the bike running. Except the battery had other ideas. The battery simply would not turn the bike over, yet after I took it out, it still registered 12.22V, a figure which has in the past happily started it. I figured that this proved my theory that the cranking capacity of the battery is for some reason terminally degraded. I stuck it on charge just in case the new battery didn't activate to a high enough voltage without itself needing a charge, as I needed the bike the next day.

I activated the new, pretty cheap (hopefully not nasty) Numax offering, of the YTX9 variety. I figured the extra capacity might possibly be handy one day. I was expecting the instructions to insist on a charge overnight, but they stated that if after 30 mins the battery was at or above 12.7V that it was fine to use immediately. Happily, it exceeded 12.8V, so I installed it to see what would happen. I started the bike several times to find to my horror that it wasn't charging. Then I found that I'd managed to pull the positive connection apart on the reg/rec plug.... The battery now had a whisker under 12.5V on it, and I said a few choice words at my error.

Upon being correctly plugged in, the bike started with extreme gusto, and the reading at the battery was in the 14.2V range, a few hundedths higher than with the old one. Out of curiosity, being an RVF, I unplugged the headlamps to see what unloaded voltage would be (give or take the rear lamps) and it was 14.62V. I ran it for a few mins and switched off. After nattering to my friend whose garage it lives in for a good 15 mins, I went back and measured the battery and it was reading 13.00V, so I went off to get my riding gear. A quick ride to the nearest petrol station (4.5 miles) then on to the next town to collect my Optimate from a friend who had borrowed it (another 8 miles). After another natter, I went home. The switch-off voltage was 13.08, a figure which pleased me because the old battery had never managed to get any sort of float charge on it, even when it went in the bike with the same 12.8V on it as the new one and was ridden for 25 miles out and 25 miles back the previous time I had used the bike. The following morning, it had depleted to 13.00V, which I was happy with. Following my 25 mile trip to play trains, I arrived with it showing 13.20V, and almost seven hours later it was showing 13.18V when I left to go home. I arrived once more with 13.20V.

One minor item of trivia is that the voltmeter on the top yoke (which due to crappy wiring reads low) was reading lower by 3-4 tenths than it used to before I started getting issues with the old battery. As I have mentioned before, it used to hold 13.3V (equating to 14.2 at the battery), but on the way home was dipping down as low as 12.8V for a time. I arrived home with 13.1, expecting to find the battery not fully charged, but as stated above, it was actually above the nominal resting voltage and had a decent float charge on it as well.

So, I think this puts the issue to bed, but does beg the question of why a properly stored and activated dry shipped battery would turn into a pile of crap well inside six months without having had any issues previously? The old old one was exactly the same maker, fitment and model (Yuasa YTX7A-BS) which had been killed any number of times by the charging system before I fitted over £200 of Rick's goodies. The second one was activated by the book, given time to rest, given a charge on my Optimate, then fitted to the bike. It had never been flattened, never even been significantly drained, then all of a sudden it became very weak and wouldn't charge properly. Yuasa claim the shelf life of a properly sealed and stored dry battery for home filling is basically infinite. There were no signs the foil seal was damaged when I unpacked it. Just a case of s..t happens, perhaps?

Hard to tell why the old battery didn't work properly. Doesn't Yuasa come with a year warranty?

I think it might be two. But that's not really relevant considering I had if for longer than that before I activated it. Plus, I would imagine that it's going to be impossible to convince someone that their battery failed when they can just claim your charging system killed it.

Doesn't hurt to try.