Flat Battery On New S - Recommendations For A Tender

I have trawled through many threads but am still a little unsure - Do I need to buy a new 'high-tech' Optimate 4 type charger or will the 7 year old basic optimate I already have in my garage drawer be OK on my new Speedy?
My last 2 bikes, which I had from new, lived quietly in my garage through the winter without any form of battery 'care'. Neither of these had an alarm of course, but neither does my S.
They always started up without fail after a couple of months without use. I had a Street for 2 years and a Yam XSR900 for 3 years with no issue. But my 7 month old Speedy was not interested yesterday. Lights and fuel pump came on but pressing the starter just shut everything down.
The last ride was on last the weekend of September and was just under 200 miles round trip - no short journeys ever.
I did have the same problem when the bike was under 500 miles old - when I came back out to the bike after filling up a mile from home. I left it 15 minutes and it just about started so i was able to carry on. Reported this to my local Triumph dealer and they checked it out at the first service and, of course, could find nothing wrong. So it was fine all summer but I always had that nagging doubt when I opened up the garage door on a Sunday...
So with that issue in mind I thought I'd take her for a ride yesterday with the roads nearly dry and salt washed away, and top it up. Ah well.
I want to report it to Triumph (through my dealer I guess ) and see if they'll replace it, but of course I need to get it running.
Not a happy chap right now

 

Thanks Dozers Dad, I will probably invest in one for the long term, I just wonder if I can use the one I have to get the bike going for now. Hopefully someone will know.
Last thing it was used on was an SV650 - a little less sophisticated electrically!

 

Brilliant, Thanks. I'm off to the garage right now

 

It's the original battery so hopefully that's ok. It was 11.9 volts when I checked it, and it was up to 12.8 late last night so it seems to be charging. I'll go out and check it now.
I will look up ctek too...
Going to call Fowler's about it but suspect I won't get any joy. I suppose I have to accept this bike draws current at idle unlike my last ones, and 8 weeks is too long without charging.

 

It's the original battery so hopefully that's ok. It was 11.9 volts when I checked it, and it was up to 12.8 late last night so it seems to be charging. I'll go out and check it now.
I will look up ctek too...
Going to call Fowler's about it but suspect I won't get any joy. I suppose I have to accept this bike draws current at idle unlike my last ones, and 8 weeks is too long without charging.

 

I'm using an Oxford 600 oximiser so it sounds like it should be intelligent but the battery is at 13.8v this morning so I've unplugged it. I will get something smarter.

When I switch it on It's also telling me I need a service, which I don't! Hope that will clear when I run it. Not tried starting as I would want to ride it for a while - not in this weather!