12 V battery Voltage

That battery's only just barely hanging in there Eug. I'd say replace it soon.

The cold temperature will be making the voltages a little bit lower. Since it made it through the winter you could probably hold off until the start of next winter if you really want to stretch it.

 

You could try putting it on a charger overnight, at 4 amps or less, and see if that improves anything. RE the Optima, you can buy the terminal kit from elearnaid for $20 and perhaps source the Optima battery itself in Canada for cheaper.

 

Today after driving for a while I tested again.

Maintenance mode: 12.1 - 12.2 V
Press power again: 11.9 - 12.0 V

I'll definitely ride out the spring and summer. Perhaps I'll think about replacing it before winter. I will try to find that battery locally in the meantime. Shipping just that $20 installation kit for $3.96 makes a lot more sense…

P.S. I (stupidly) jump started a van with it this winter. Perhaps that helped speed up its deterioration.

 

It's a little low but OK; maybe not good if the temperature were to go well below freezing. Is the car exhibiting any problems or odd behaviour?

 

That certainly didn't help. I don't think this battery is capable of starting a regular starter without doing some damage but I certainly could be wrong.

 

As I wrote in another thread, the Signal Check screen is a convenient approximate indicator of battery voltage, but the only way to know for sure, is to measure directly on the battery posts with a meter that has an accuracy of .1 Volt or better.

Low voltage measured elsewhere could possibly result from other causes, such as a poor connection. ...

For example, in my 2007 Prius the voltage drop from the battery to the fuse box in ignition on (not ready) with AC fan low, is .2 Volt.

 

That definitely would have drained it and left it at lower SoC. Seriously, put it on a charger and see what happens.

 

what mileage are you getting? how long have you owned the car? is the mileage you are getting now normal for this time of year? has there been any major change in driving patterns?

although it plays a much different role, the 12 volt battery replacement scenario should be the same as any other car. replace it when it becomes a hassle to not replace it.

now, not starting is the obvious thing, but a bad 12 volt battery will reduce your mileage. that is the criteria you need to use to determine when to change

 

Never had a problem at all with the car starting. No funny behaviour either, and gas mileage is the same as it's always been (more or less). My mileage is poor, but that's mainly because of my driving habits and the fact that I live in Toronto and park outside in the winter.

I will have to find myself a good volt meter. I do have one somewhere but I'm not sure how accurate it is.

 

ok, so no symptons, no events. so why the concern?

 

Because the battery is 7 years old and is reading low (at least with the Prius service menu check). I don't want to park at the airport next winter and find my car won't start after I get back from my 3-day business trip.

 

a valid concern. i am now wondering what you are waiting for? am also wondering if you had this concern with any other car you have owned. i have had many many many cars. some batteries have lasted the entire life of the car a few extending beyond 10 years. some lasted as little as a year but they were used cars.

now, i have little experience with new cars beyond the Priuses i have owned. i have a ford i bought near new (was leftover model year thing) bought in 1991 and the original battery is still in the truck. and no, its not in good shape. it has to be jumped everytime we use it, but that was not an issue when it was driven on a regular basis (that ended in 2004). it currently sits mostly. between 3 households, its probably been used about 3-4 times in the past year.

now, why would one battery last 20 years when another would not last 3 years? good question. i am not sure i would go thru as much as you are now when a battery costs what?? $150

now, my 2006 has been jumped probably 4 times because of end user error. at times, i have put a jump box in the car for times i thought it might be necessary, but i have no plans on replacing the battery unless i find it to become unreliable.

 

Well, shipping to Canada is killer ($72 just for the shipping) for the battery recommended in this thread. So after shipping, handling fees, and taxes it'd be around $300. As recommended by someone else maybe I can find it locally, and just get the install kit shipped to me. In the meantime I have the spring and summer, because I think the battery will be fine during that period.

Yes, I've had this concern with my other cars. Except with the other cars I just went to the local hardware store and spent $75 on a standard battery.

 

yep definitely a chunk of change and one i would not spend until i knew the battery was no longer reliable. a jump box at $40 is pretty cheap insurance.

now they are cheap even if you go out and buy them for that reason only. but i already had 2 of them, used for camping as only way to have cell service for greater than a day. got them because i thought it counter to my values to run the car just to charge my cellphone

 

A Battery Minder or similar float charger would eliminate that problem

I have a couple of vehcles, collectors, that are driven just in summer. Perhaps 20-100 miles total. I pull the battery while in storage, leave the battery plugged into a Battery Minder

The oldest battery I have is from 2002. I left it off the Battery Minder for a week, according to my Fluke DMM, the resting voltage was still 12.93

 

I am testing out a BatteryMinder on a small 12V battery that measures something like 11.7 or 11.8V. After two weeks treatment by the BatteryMinder it still measured similarly after the surface charge is dissipated. I am letting it run another two weeks and will see.

 

like steve said,,,

if you have an AMG proceed with caution or after reading the inst for charging these batterys

 

Well it did not revive the small 12V battery and I haven't seen any effect on the Prius 12V battery either.