[dddrrr]

Hello Jeff ,Once I pressed "Menu" then "Displaly Check"field then "Signal Check"field my reading was 12.1V. When I pressed the power button again it dropped to 11.8V Then I went to "Ready Mode" and it read 14.3V then droped to14.2V then to 14.1. Do I need a new battery or is the Charging system not working properly?
Thank you very much for your help

[asewan]

Usually my 2010 Prius will read 14.5v or 14.4 v. It has been constant ever since I connected a Scanguage II to the car 5 months ago.


Prius 2010 II

[jdenenberg]

dddrrr said:

Hello Jeff ,Once I pressed "Menu" then "Displaly Check"field then "Signal Check"field my reading was 12.1V. When I pressed the power button again it dropped to 11.8V Then I went to "Ready Mode" and it read 14.3V then droped to14.2V then to 14.1. Do I need a new battery or is the Charging system not working properly?
Thank you very much for your help

Your charging system is working. Do you do a lot of short trips? If so, the Prius charging system is not getting enough time to fully recharge your 12v battery (The charging system - "Constant Voltage" - is quite slow to avoid overcharging the 12v battery). If not, either your 12v is getting old (5 years is old) or it has been drained a few times which shortens it's life.

If you need a new battery, consider getting an Optima Yellow Top as they are more robust than the one Toyota supplies. A source for one with an adapter kit (The Prius uses Japanese style terminals, not the SAE standard terminals in most cars) is: http://www.elearnaid.com/12vo1topraub.html

If you do drive a lot of short trips, consider getting a "Battery Minder" (http://www.batteryminders.com/batter...--p-16151.html) which will maintain your battery at full charge as well as desulfate the lead plates which can actually bring a weak battery back to life.

JeffD

[dddrrr]

jdenenberg said:

Your charging system is working. Do you do a lot of short trips? If so, the Prius charging system is not getting enough time to fully recharge your 12v battery (The charging system - "Constant Voltage" - is quite slow to avoid overcharging the 12v battery). If not, either your 12v is getting old (5 years is old) or it has been drained a few times which shortens it's life.

If you need a new battery, consider getting an Optima Yellow Top as they are more robust than the one Toyota supplies. A source for one with an adapter kit (The Prius uses Japanese style terminals, not the SAE standard terminals in most cars) is: http://www.elearnaid.com/12vo1topraub.html

If you do drive a lot of short trips, consider getting a "Battery Minder" (http://www.batteryminders.com/batter...--p-16151.html) which will maintain your battery at full charge as well as desulfate the lead plates which can actually bring a weak battery back to life.

JeffD

Hello JeffD, I was driving and the warning lights came on so I cleaned the battery post and the warning lights went off until the next day ,after about 2 hours of driving. I ran the battery test and my battery failed so I bought a new battery on 5-17-10. All the warning lights went off. On 6-4-10 I was driving and all the same lights came back on. I ran the battery test and the battery tested ok. Before I take my Prius in to Toyota, I would like your opinion on what you think my problem might be. The lights are the Master warning light ,Check engine. When the lights come on nothing changes in the cars performance or handling ,no lose of power, braking or anything else. Thank You

[jdenenberg]

You need to know the error codes that are read using an ODB2 scanner to diagnose faults. Ask your dealer for the codes and report them. A group of talented technical Prius owners can help you in the Yahoo discussion group "Prius-Technical-Group"

JeffD

[Myprius]

Hi JeffD,
I have followed your instruction and got 10.5v on step 7 then went through the step 8 and the battery went to 13.8v. Do I need a new battery? I don't know how significantly from 12-10v means to your guild check. I have failed to start 2 times. How much would it cost to replace?
Thank you for your assistance.

[jdenenberg]

10.5 volts is too low and indicates that either your battery has not been fully charged or a new one is required. The 13.8 volt value is the charging voltage supplied by the "Inverter" in your Prius that both provides 12v power to the various components that need 12v power and slowly charges your little 12v battery (it is very slow).

Our 12v batteries are special in two ways:

1. They are Absorbed Glass Mat (AGM) lead acid batteries that are "sealed" to prevent acid and vapor leakage into the passenger compartment of our car.
2. There is a pressure release valve that will let vapor out if something goes wrong (very rare). This needs to be vented to the outside of the car.

There are only two standard sources of batteries that meet the requirements of our Prii. Both are more expensive than the normal "flooded" lead acid batteries in most cars (VW also uses AGM or its close cousin a "Gel Cell" battery).

1. Toyota - They have two models of battery that fit well. One has a slightly higher amp-hour capacity (for Prii with the SKS-auto entry system) so it is the one to get. Many Toyota dealers severely overcharge for a battery, but some will install a new one for under $200.
2. http://www.elearnaid.com/12vo1topraub.html which sells the Optima "Yellow-Top"" battery (size 51). This is also a higher capacity battery and is more tolerant of deep discharges than the Toyota battery. It is the better choice. ElearnAid provides an adapter kit (also sold separately if you can find an Optima locally) to fit your Prius and installation instructions that any garage mechanic can follow easily at a low cost. It is $180 and shipping is free.

Installing either of these batteries should fix your starting problems.

JeffD

[Mckenzie500]

More or less it's the same method, But I would suggest you to not to try on your own, better consult dealer or service centers.

[tumbleweed]

The ZVW30 Prius 12V battery has two charging voltages, 13.8 and 14.6 +or- a tenth or two. After the battery is fully charged it will drop to the lower voltage. Of course it is current limited so if the battery is really low it will start out charging at a lower voltage than 13.8.

Optima now sells a Yellow Top that is a direct replacement for the Prius NWH20 and ZVW30: http://shop.optimabatteries.com/prod...56.0.0.0?pp=8&

It lists for $200 but I understand you can get a better price if you shop around or get one of their coupons.

[jdenenberg]

I just replaced the OE 12v battery in my 2004 Prius at 214k miles (after over 7 1/2 years and it still holds a charge!) with the new "Drop-In" Optima (I paid $170 for it using the offered coupon when it was introduced). I didn't bother to keep the 12v bus powered so I needed to reset the radio, clock, and auto window functions.

One other problem occurred; the AC stopped working! The MFD said AC off and the steering wheel controls couldn't change temperature. It turned out that some of the electronics got out of sync. I noticed that the steering wheel controls for the defrosters still functioned so I hit the steering wheel AC mode switch which caused the MFD to say AC off. Then hitting the AC mode switch again got everything working again.

JeffD