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How are you measuring the voltage? Are you just reading what the software says or are you physically measuring them with a meter? If you are reading the software, what condition (Ready on, ignition only)? I'm guessing you are physically measuring them yourself since the software looks at blocks.... I have replaced cells in at least a dozen Toyotas, Prius and Camrys. In every case, the good cells were all within tenths of volts of each other (.1V or .2V difference). Anything over about .5V difference when loaded indicated a possible problem. You are saying there is over a Volt difference. I would definitely recommend replacing the two low ones.
In my experience, if they don't hold voltage, they're done. Before I put some in that have been sitting around, I top up the charge to get them close to what the other cells read. The system will do it, but I worry less if I do it first. I am sure there are all kinds of ways you should charge them properly... but I have never had a problem by just hooking up a 12V trickle charger and leaving it on for 20 or 30 minutes at about a 2A rate until the voltage comes up. My charger (an automatic Black and Decker from Lowes) has a function to tests the voltage. I just run the charger for a bit, switch it off and test the voltage until it is where I want it, usually about 8 volts. As I said, never had a problem. The cells charge really fast, so don't leave them alone. Oh, yeah, and they swell when charged so I always put them in a vise with wood blocks on both sides to keep them in line. Don't know if it matters, but I do it anyway.
I have heard of companies that "refurbish" the cells. I have no idea how they do it or if it's bogus. Again, if the voltage drops too low, I put cells in. Sometimes they'll last for years, sometimes not so much, but I have never had a cell that I replaced fail...it's always the other ones.
You can clean the copper connectors up to drop the resistance, but lately I have seen the sensor wires break in some Camrys... I don't know why. The entire connector with the sensor harness down that side is only about $40 and well worth the investment. I've got one on order right now. In my opinion and experience, to really do it "right," replace the low cells, carefully clean all the ends of the cells, replace all the connector assemblies and replace all the nuts. Yep, the nuts. They are about $1 apiece and they do corrode. All of that will be around $200 plus the cells. All your connections are then new, and the battery should last for years!
Last edited by Protech; 02-24-2016 at 09:15 PM.