Q: How often should I grid charge my IMA battery?
A: There is no exact science on how often to re-balance an IMA battery. Many people have varied perspectives but the majority opinion seems to be as follows: With a healthy battery, charging once every 4-8 weeks and/or anytime the car sits unused for more than three days should keep the battery in top form.
Customers with degraded batteries report that they charge every couple weeks, sometimes weekly or more, depending on how much 'life support' is needed to keep the battery going.
Find more information here:
Grid Charger Installation - Hybrid Automotive