Might be my problem as I don't use it a lot it losses charge
I tend to ride to work and errands more than long weekend excursions. The low voltage situation from lots of cranks with too few miles ridden to regenerate that charge left me just below that magical battery voltage threshold of the ECU on more than one occasion.
Two things I did that really helped were adding a Powerlet outlet and upgrading the rec/reg.
The Powerlet outlet (and DIY adapter with wires terminated into clips) was great for easier access to the battery. That allowed verification of battery voltage and ability to connect to an external power source so the ECU sensed enough voltage to allow the starter motor to engage. And of course it also provided an easier path to charge the battery without having to remove multiple parts using three different tools. *I did also change all those fasteners leading to the battery with SS Phillips screws so only one common tool was needed!
An aftermarket MOSFET rec/reg (Rick's Hot Shot) helped to provide a much more stable
and a bit higher
charge voltage to the battery.
I think changing to an LED headlamp also helped the battery situation when the key is first turned on. The LED drawing a fair bit less voltage than the OEM incandescent lamp from the battery when the ECU is sensing that voltage and determining if it will allow the starter to engage.
...so why not keep it on a battery tender?
Like the OP I do not have a garage. I do park under a car cover and can run an extension cord for a needed charge but not practical for regular or daily "Battery Tender" use.