I just bought a 2002 Prius knowing it had battery issues, insanity is implied. The price was right, $1500 in good shape, engine good, inverter good, body good, everything looked good except the battery was marginal. It would start and drive (triange, etc flashing) but still get 50 mpg for about 7 miles. After 7 miles it would drop into limp home mode. I figured I could fix the batteries, being an electrical engineer I am qualified for this type of work, and indeed drawn to it. We pulled the traction battery today and performed an initial inspection and checked the voltages on each cell. There is much corrosion on the battery, and it looks like some leaking under the batteries, though I am not certain. I plan on pulling the whole pack apart and cleaning it. The following voltages were recorded. 1 - 8.02 2 - 7.96 3 - 7.95 4 - 7.94 5 - 7.95 6 - 7.94 7 - 7.94 8 - 7.92 9 - 7.94 10 - 7.94 11 - 7.92 12 - 7.92 13 - 7.92 14 - 7.91 15 - 7.93 16 - 6.24 ***** 17 - 7.93 18 - 7.91 19 - 7.94 20 - 7.91 21 - 7.91 22 - 7.91 23 - 7.92 24 - 7.90 25 - 7.92 26 - 7.90 27 - 7.92 28 - 7.92 29 - 7.92 30 - 7.91 31 - 7.92 32 - 7.93 33 - 7.93 34 - 7.92 35 - 7.95 36 - 7.95 37 - 7.97 38 - 8.0 I plan to replace cell 16, clean up all the terminals. Should I put the better packs in the middle and the weaker ones on the outsides? Also what type of solution should I clean the terminals with, and the buss blocks? I read baking soda and vinegar works well. Any other solutions that I can use? Also this is a 1st gen pack, and I am going low cost so do I put a new (used) 1st gen cell, or are the 2nd gen cells compatible? Thanks in advance for any advice. Marc in Kennewick
For the past few days, 1st gen batteries were 25 - 30 on ebay, now that I know I need one I cant find any!!! Where do ppl get batteries? Anyone have a good 1st gen cell they are willing to sell?
All of the Toyota manuals refer to mixing up a boric acid solution. If it's too hard to find boric acid, another acid like vinegar would also do the trick of neutralizing the battery electrolyte, which is strongly basic. Mixing in something already basic like baking soda surely looks impressive, but only defeats the purpose. The Gen 2 modules (each module is six NiMH cells) can be made to fit in the Gen 1 case with a bit of effort, but the dimensions are different, so one doesn't commonly hear of mixing both types in one battery. It would be hard to attach the bus bars between modules of the two styles. -Chap
Hi Vanionbb, I had good luck cleaning the modules in my gen1 last month with acetone. The advantage over water- based cleaners is it dries off immediately and you can switch off between cleaning and checking for voltage leakage with a multimeter without the conductivity of traces of water to interfere. In the pic below, you will see I used clipped an alligator lead on one module terminal and am reading over 2 volts on the case near the other terminal. This was leaking voltage module-to-module.. You really have to wipe the lead all over the whole unit casing, then swap terminals and leads and do it again...you can probably do the whole bank in a couple hours. I was lucky and didn't need to replace any modules, I had voltage leaks between modules and broken sensing connectors. Bought my car dead and down last month like you did, now happily pulse and gliding. I found good advice here on Priuschat. I charted voltage leakage between adjacent modules and module to battery rack before taking it apart and used that chart during reassembly, module by module, to ensure that I got it the first time and I did have to reclean 2 or 3, but avoided complete re-teardown. I used and liked the Halogen headlamp trick to check modules for voltage drop under load. The no-load voltage means little. You can find it in postings here. I charted voltage befor load, during, and recovery after one minute. Some other members here look at internal resistance, I hope to learn that trick some day. If your terminal sealant is gooped onto the bus bars, acetone and vinegar will clean them with minimal labor. If you find broken sensor wire connectors, no need for a $100. harness, fixed mine for $2.94 I have a spare cell I got off Ebay last month, voltage is good I have not tested resistance, you can have it for what I paid plus shipping of your choice for speed. Robert
There are a number of things that will clean the copper buss bars. If you want a really cheap/effortless cleansing, mix 4 packets of Kool Aid (lemonade flavor) into one quart of water and let it sit for 8-12 hours, wire brush any stubborn stains/deposits and let it sit for another 8 hours. I cleaned tons of salt water corroded brass and copper this way while serving in the Navy. I works awesome and its cheap. There is a guy on here named ericbecky, he likely has a Gen 1 module and if he doesn't, ask Bob Wilson or scotman27.
Thank you guys for that excellent advice. I now have koolaid on my shopping list and will start the bus bars marinating tonight Robert, those pictures are awesome. Pictures are worth more than words, and now I have a clear path how to proceed. For load testing, I think I will connect my volt meter across a 10 ohm 10 watt resistor and and measure voltage across the terminals when loaded. Current will be 8v / 10 ohms = 0.8 amps. Wattage is I squared R, so 0.8A * 0.8A * 10 ohms = 6.4 maximum at 8V so the 10 watt resistor should survive (it will get hot though). Test Method 1 - Measure resting voltages again. 2 - Apply the resistor and plot voltage at 5, 10, 15 seconds 3 - Measure new resting voltages I may run steps 2 and 3 again and compare. This should give me a pretty good idea of the internal resistance. Internal Resistance = ((Resting Voltage - Load Voltage)/load) * Resting Voltage I will post data when it is available. Thanks again! Marc in Kennewick
I checked the voltages before and after with a 10 ohm load. The last column is the calculated internal resistance of each cell. V0 = Voltage day 1 V1 = Voltage day 2 (before load) V2 = Voltage day 2 (under load 10 secs stabilized) last column = Internal Resistance Calc I highlighted cell 16 with ***, the rest of the cells look fine. 1 -0.04776 2 -0.05572 3 -0.06352 4 -0.04758 5 -0.04746 6 -0.05544 7 -0.04746 8 -0.04752 9 -0.05544 10 -0.05544 11 -0.0474 12 -0.04752 13 -0.0553 14 -0.0474 15 -0.05537 16 -0.22762 *** 17 -0.0474 18 -0.04746 19 -0.0474 20 -0.05537 21 -0.0553 22 -0.04746 23 -0.05523 24 -0.0474 25 -0.0553 26 -0.0474 27 -0.04734 28 -0.0474 29 -0.04734 30 -0.05537 31 -0.05523 32 - 0.0474 33 -0.0474 34 -0.05537 35 -0.04746 36 -0.04758 37 -0.04758 38 -0.05586
Not hard to find boric acid at all; BORACARE, BORA-CARE - Free Shipping Amazon.com: boracare You're just looking at the wrong place. Most hardware stores carry it for a safe pest control item.
Don't drink the Kool Aid! I'd be leery of using it as a cleaner as well because of the sugar content. Straight lemons in water with no sugar, sure, but pass on the added sugar. SCH-I535
Who said anything about adding sugar? Do not add sugar, just kool aid lemon flavor works the best. And..., trust me it works and works well. I've used it numerous times. I just don't understand why it is that when I give advice here, there's always someone that "knows better" and discounts it. I find it odd that those same people offer no solution. How frustrating.
Someone needs to go to the grocery store and look at Kool Aid packet ingredients Kool-Aid Unsweetened Lemonade Soft Drink Mix (0.23 oz) :: Foodfacts.com :: Find out what's REALLY in your food. :: Kool-Aid Unsweetened Lemonade Soft Drink Mix (0.23 oz) ingredients (11)Citric Acid, Calcium Phosphate, Salt, Maltodextrin, Flavors Natural, Lemons Juice Solids, Ascorbic Acid, Colors Artificial, Yellow 5 Lake, Yellow 5, BHA
The batteries from Eric showed up today, one day early, so I got right on it and swapped out the cells. Voltages were very close and internal resistance was very much the same as the rest of the batteries. I had to solo lift the battery into the trunk, just barely got it in without damaging anything. Got her all hooked up and bolted down, I left the seats out just in case. I put 10 miles on it driving around tonight and it looks to be working well. I will button it all up tomorrow in the daylight. So far I am very happy with the repair, thank you all for your pointers and for putting me in touch with the right people to make this possible. I bought the car on Monday, and on Friday it seems to be fully functional. I am very impressed with the level of knowledge and helpfulness of this community. Thank you! Marc in Kennewick
Hi Kentucky, so your lowest voltage module also had the highest internal resistance. I'm trying to apply the resistance formula to the tables of my voltages, but it looks like I am off by a factor of 100...can you please coach me on the calculation.......the term resting voltage-is this the voltage before load is applied........the asterisk in the formula, does this mean multiply...and load do I enter watts or amps? I think I can interchange them using W=VA. My halogen headlamp, high and low jumpered, draws 100 watts or Bravo! Photo please!
vanion, glad you got the modules in time for the weekend and that they look like they will play nice with your existing ones. Keep me in the loop should you need anything else in the future.
Good job to all. Thank you Eric for being a great resource for us here. I hope I don't need anything from you in the future but, if I do, I know who to call.