Not as fancy as grimjordax's charger, being just for a single purpose.
Our Toyota Prius has a problem. We have no trouble with the big propulsion battery, which holds its charge well, but it also has a small 12-volt gel cell battery (“Auxiliary”) hidden in the back. This battery discharges into circuits which remain live even when the car is turned off. If it dies, the car is completely dead, since it is needed to activate the propulsion battery. This has happened so often that we keep a motorcycle battery in the car to jump-start it.
Once the car is “Ready” the propulsion battery recharges the 12-volt battery, but it needs several hours to do so, since high charging current fries a gel cell battery. The discharge rate is such that the 12-volt battery goes dead within two weeks if the car is not driven. Apparently Toyota assumes that the Prius is to be used for daily commuting for sufficiently long to keep the 12-volt battery charged, but we are retired and only use it for infrequent short shopping trips.
This charger provides a tapered charge with a maximum of 3 amperes, which is about all the little battery will take. We use it for one day about every other week.
For details see:
http://www.projects.worsleyassociates.com/Prius_Charger
Our Toyota Prius has a problem. We have no trouble with the big propulsion battery, which holds its charge well, but it also has a small 12-volt gel cell battery (“Auxiliary”) hidden in the back. This battery discharges into circuits which remain live even when the car is turned off. If it dies, the car is completely dead, since it is needed to activate the propulsion battery. This has happened so often that we keep a motorcycle battery in the car to jump-start it.
Once the car is “Ready” the propulsion battery recharges the 12-volt battery, but it needs several hours to do so, since high charging current fries a gel cell battery. The discharge rate is such that the 12-volt battery goes dead within two weeks if the car is not driven. Apparently Toyota assumes that the Prius is to be used for daily commuting for sufficiently long to keep the 12-volt battery charged, but we are retired and only use it for infrequent short shopping trips.
This charger provides a tapered charge with a maximum of 3 amperes, which is about all the little battery will take. We use it for one day about every other week.
For details see:
http://www.projects.worsleyassociates.com/Prius_Charger