My 12v battery decided to crap out on me and I was wondering if a 750 mA battery tender would be able to charge the battery at all. Or would I be better off buying a real battery charger? Also, is it okay to idle the prius for several hours to charge the battery? I am leaning toward buying another battery but I want to make sure this one is truly dead before doing so.
Also: If this acceptable, should I remove the battery to do this? 750mA is so low that I feel it wouldn't charge the battery faster than it would discharge with the security system.
(1) Nothing wrong with trying this tender, if that is what you have available, but it will take a very long time compared to a real charger. If the security system is drawing enough current to make a noticeable difference, then it is a problem in itself and may be the reason your battery died. (2) Idling the car for multiple hours is fine, as long as it is safe from theft, and you and others are safe from carbon monoxide poisoning. Once you can get the car started, the car's charging system will be much faster initially than the tender, though a bit wasteful of gasoline later due to the car's relatively slow charge rate later.
$30 battery-maintainer is what I use to do the job, it's smart enough to charge the battery according to its needs and go into "maintenance-mode" when it just needs to be topped-up. (Sears Die-Hard Model 28.71219 6V/12V Battery Charger & Maintainer (for those who care)) Good luck!
welcome! i would try it connected, and if no luck, disconnected. if neither works, buy a smart charger.
So I let the prius run a couple hours then hooked it up to my battery tender and it's fully charged. Here's to hoping it doesn't need replaced!
(1) Good, that got it going, for now. Consider keep using the battery tender occasionally to keep the battery topped up. The Prius charging system is rather slow and doesn't keep up during short trips. (2) Bad, you shouldn't have gotten a healthy battery fully charged this quickly with this equipment. So is likely down to a fairly low capacity, and is likely a short-timer. Be ready to change it out, hopefully at your convenience, not when it makes a sudden demand. But with regular tending, it might go quite a while, such as to next winter.
Just because a "tender" indicates a full charge does NOT mean that the battery is healthy. Given what happened to you already, I think you should start shopping for a new one NOW. It will likely fail again soon. And 750 ma is OK for use with a healthy battery during long periods on non-use. Trying to use ANY charger to extend the useful life of a dying battery is not worth the trouble. Doing that tends to leave you stranded when it decides to fail somewhere away from home.
If you want to be "on top" of battery maintenance: 1. Solar BA5, or at the least, a decent digital multi meter 2. Smart charger, in the 4 amp range 3. Last but not least: read up
