Trickle Charging

If you have a 2005 Prius you have free Toyota roadside assistance for 3 years. Wouldn't it be easier to pick up the phone and give them a call? Why go to all the trouble of trying to charge it yourself when you can have someone come out and do it for you at zero cost?

Springtime

 

if it's a small trickle charger just leave it on overnight and you should be good to go in the morning. Did you, if you have SKS turn it off before you left? Lots have gone more than two weeks and not had any trouble.

 

smart key system. Do you have a black square on the outer door handle to lock the car?

 

I was gone 5 weeks and had no problems whatsoever. Of course I did shut off SKS. Last year I was gone for just over 4 weeks, and had no problems. Again, I shut off SKS.

Admittedly, I have no way of know how close the battery might have been to dead. But I'd suspect something caused your battery to drain. Something left on.

 

Your trickle charger should be set at 12 volts, I doubt that it can be "turned down to 2 volts as I would normally do for a standard battery." The question is how many amps? The Prius battery cannot be recharged as a normal car battery would be. It says in the owner's manual to charge at a rate no greater than 3 amps. So if you have a 2 amp trickle charger you should be OK.

I have a "Battery Tender" by Deltran that charges at 0.75 amps. It takes a lot longer if the battery is needing to be recharged, but it is also less stress to the battery. And the Prius battery is very tempermental. Why Toyota didn't include some monitor for that battery to disconnect if it was drained to a certain level I can't understand.

 

A bit of a technical correction for the 2005 Prius. In the owner's manual, on page 302,it says the battery can be charged at a rate of 3.5 amps. It seems that the 2004 Prius can only be charged at 3 amps, but I'm not sure about that. Either way, they want the auxillary battery charged slowly. So a 1 amp or 0.75 amp trickle charger should work fine.

 

Whatever charger you go with absolutely *MUST* have circuitry that monitors and shuts off charging when the battery is full.. You can get really cheap "trickle chargers", which are basically just a transformer and a diode, but even low amperage versions can cause battery damage if left connected over long periods. There are battery maintainers that are just afew dollars more expensive and contain a simple comparator circuit to shut off charging when the battery reaches its "full" voltage and resume when it falls below a threshold, which is much healthier for the battery than being force-fed a continuous "trickle"..