I have a Battery Tender 12v 1.25a battery

probably damaged/ burnt up battery test battery

Sorry but what you are describing is a defective battery or batteries. The manufacturer's use the cheapest batteries they can get, and some have a very short life span. I suggest you buy a "Battery Tender" that maintains a full charge and monitors battery voltage, the battery is left on this whenever the cart is idle, it will greatly extend the life of the battery even a cheap one. I have provided a link to the product. Battery Tender Plus 021 0128 12V Battery Charger

Most likely, Yes.
If you plan to leave your car or not to use it for a month, always remove the negative terminal of the battery. It also depends on the age of the battery, If you have an old battery then it should be 2 or 3 weeks instead of 1 month.

Buy one of these:

http://www.ebay.com/itm/New-Deltran-Battery-Tender-Junior-Jr-12V-12-Volt-Maintainer-Motorcycle-Harley-/171194965880?pt=Motorcycles_Parts_Accessories&hash=item27dc03df78&vxp=mtr

See the pig-tail on the lower right?

The two lugs bolt to the battery, and are left on permanently.
Route pig-tail to where you can access connector at other end from the outside of bike.

When you want to charge, plug charger connector into pig-tail, and plug charger into wall outlet.

It's under the seat.

Buy a "BATTERY TENDER JUNIOR":

http://www.ebay.com/itm/New-Deltran-Battery-Tender-Junior-Jr-12V-12-Volt-Maintainer-Motorcycle-Harley-/171194965880?pt=Motorcycles_Parts_Accessories&hash=item27dc03df78&vxp=mtr

The "pig tail" on the lower right attaches to the battery terminals, and stay on the battery,
The charger plugs into this pig tail when charging.

No, you can charge it in place.

In fact, a "battery tender" is a good idea:

http://www.ebay.com/itm/BATTERY-TENDER-12-Volt-Trickle-Charger-CAR-BOAT-ATV-12V-Junior-Jr-Motorcycle-/231110566640?pt=Motors_Car_Truck_Parts_Accessories&hash=item35cf4362f0&vxp=mtr

The "pig-tail" on the right of the pic is installed to the battery posts, the the charger plugs into the other end that you have mounted remotely in an accessible area.

Product Detail Model No.: HB-1206S
The item is used for charging 6V-12V lead-acid batteries
Max Charging Current: 6A
AC Power Input: 64W
Output: 6/12V DC 3. 52A
Batteries Capacities: 15AHR-80AHR
Unit Packing: Colorful box
Dimension: 18cm x 10cm x 20cm
G. W. / N. W.: 1. 85KG/1. 75KG
Certifications: GS, CE, BS, ROHS, SAA

Main functions:
(1) The HB-1206S battery charger has the features of convenient operations, reliable safety and high performance.
(2) During charging, if turn up overload, the battery charger will keep itself at normal current and normal voltage with its self-automatic protecting function.
(3) If being short circuit, the battery charger will switch off itself, and turn normal after one or two minutes.
(4) The output current of the battery charger is very stationary, so it can protect the battery charger very well. It only costs 3 or 4 hours to fully charge the batteries.
(5) Indication of charging: the battery charger has 6 pilot lamps. The more pilot lamps shining, the less electric quantity is. The charging process finishes when all the pilot lamps go out.
(6) The battery charger can be switched between 6V and 12V, so it can charge for 6V and 12V accumulators. You can select 6V or 12V according to your own needs.
(7)The operations are very convenient: Put the red clip to the positive pole of the accumulator which indicated "+", and put the black clip to the negative pole of the accumulator which indicated "-", then plug in power source, the accumulator will be charged.

I've got an old corvette that I store also. I basically disconnect the battery and when I'm ready I charge it for 3 hrs, then start the car. Usually get close to 6 and a half years out of a battery. Five ain't so bad.

hello, if you also have 230V in sweden then look at your electronic supplier for a: Input AC 230V/50Hz/90mA/21VA Output: AC 22V/520mA/11,4VA
that's written on the charger.

Any 12v battery tender will do the trick. I use them often with no problems on many different bike batteries.

Regards,

Joe