Battery in the (toy) RX7
 

The RX7 is a third car, a toy, and does not get used a lot. I’m sure some of you have same issues with battery going flat due to disuse.

The FC got a new Optima Redtop in 2008. By 2010 it was going flat within a week. I bought a generic trickle charger, which helps keep it topped off enough to start and run, and have limped along. If it sits for more than a couple days off the charger the batt is dead. There is little or no parasitic loss; this happens with battery connected or disconnected.

It gets annoying to replace a fancy $200 batt every couple years. I spoke to Optima, did a little reading and just ordered this:

XC100-P Xtreme Charge 12V Battery Maintenance Charger Desulfator


I hope it’ll help push the sulfating process backwards. If so, that would be awesome. Optima makes their own for $200 but this is a lot cheaper.

No offense but if you would have bought two,you wouldn't need them,and exchanged then for a battery!.
IF you haven't bought it yet,I would borrow a battery and stick it in the car for a week and test out the theory that your Battery is Sheot!
If so,get a new battery.You already had a charger!

Already verified not the car
- disconnected batt, it still goes down
- tried another batt, it was OK after a week
this is typical behavior for car batts which don't get used much. Hoping to save the $200 batt with a $60 gizmo :)

Form an auto mechanic stand point a battery can die from 3 things. Extreme temps, disuse, and time. After time the lead plates will corrode and sulfate. The sulfate flakes build up in the bottom of the plastic case when the pile is high enough and touches the plates inside it will cause an internal short draining the electricity from the battery. Over a long time this happens with normal use. However the process is speed up when the car isnt aloud to fully recharge itself. Thats why every knowledgeable auto mechanic will say start it and take it on at least half hour drive every week. Contrary to popular beliefs a car dosent charge at idle. It needs to have a load on to charge. And rpm greater then idle. You will find the same issue you are having with the "little old lady" situation. She drives 2 miles away to the grocery store and 1 mile to church every Sunday. The car in this case is never aloud to fully cycle and charge. The plates sulfate and the little old lady is buying a battery every year or 2.

Now a easy solution to your problem would be buy a new battery. Dont buy a $200 battery every 2 years buy a $40 battery every 2 years. Or evtend the cheap battery's life by taking the car out more often. And unless a stabilizer is used your fuels octain level decreases by 2 to 4 points a month depending on tempratureand once it gets below 50 or 60 octain it wont work well if at all.

Battery Tender?

Oh, just saw you got the XC100-P, is that better than the Deltran Battery Tender?