main battery rebuild

I used an inexpensive ($25) [FONT=&quot]Supermate DC6 charger/rebalancer and a 12v 5amp computer brick ($10) to rebalance my 27 good Gen2 modules. I set the charge limit to 7.25 amp-hours at 5 amps to protect the cells and it worked fine. Three cycles got all of my modules to better than 6.5 ah but it took 5 weeks to get them all done (the Supermate is limited to a 5w discharge rate o 0.7 amps at 7-8 volts). Having multiple setups would speed up the process.

One note: power failures are a pain as you loose stored data so think about running it all on a good UPS.

Do you need any more modules? I am selling my 27 Modules (the 28th had a bad cell) for $30 plus shipping each. You need 38 good ones and you should use Gen2 modules as they are a better design.

JeffD
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The low power is why it takes 32 hours to do a 3 cycle (discharge at 0.7A/charge at 5 Amps) balancing protocol. It balances the 6 NiMh cells in one module in about 32 hours, but it can be purchased for only $25.

The Supermate DC6 is set up to use a car battery as it's power supply (there is another model that includes an AC supply). I bought a 120v ac to 12v DC, 5 amp supply that was made to power a laptop computer and used it to power the Supermate.

JeffD

 

Rebalancing is done with all 6 cells in series so the two terminals are all you need. In the charging cycle, the module is slowly and (if you have set things up correctly) safely charged to slightly beyond full charge. the stronger cells in the module dissipate the excess energy as heat while the weaker cells get some extra charge. After the third charging cycle, all of the cells will have gotten a full charge.

The module voltage will drift down from the 8+ volts right after the charging cycle to just under 7.8 volts in a week or so and stabilize (if the module is sound). Before you hook up the bus bars to connect your 38 modules in series, you should carefully discharge every module to the same voltage level (about 7.6 volts, use a digital voltmeter and a 10 ohm, 10 watt power resistor) so that all of the modules are at the same State Of Charge (SOC).

It is important to clamp the module while it is under charge as internal pressure builds up that can make the module case bulge which ruins the module. I kept my modules clamped in the battery case during the whole process after taking off the bus bars for my safety.

JeffD

 

For those of you not interested in rebuilding the hybrid battery pack yourself, if you are located anywhere near Nashville, Tennessee, give Tommy Roller a call. He owns Roller Salvage in McMinnville, TN. Telephone number - 931-939-2971.

Dealership wanted $4,000. I only located two companies in the entire Southeast that would tackle the job - one in Melbourne, FL - Mellors Automotive and the other in Savanah, GA

Both wanted over $1,000. Tommy Roller rebuilt my battery for $550. Great country guy who's not interested in making a killing. He saved me $3,500 and my Prius is back up and running again!!

 

Lots of good info! Thanks! I'm in the process of fixing a friends bad pack in a 2003. When I got it it had been sitting for about 5 months. Last 4 batterys (away from battery ECU) were dead. zero, or very close. The next 4 were low, 6.88v, all four the same voltage. Then the rest all were the same at 7.66v with 4 or 5 being 7.67v. Bought a Supermate DC6 and some replacement "good" batteries. Set up the charger to charge at 5 amps, discharge at .7 amps to 1v per cell or 6v. Cycled the replacements 3 times. Amp hour for discharge was very close to 1500ma, and charge was very close to 3000ma. I'm starting a charge cycle on one of the low originals and will see the readings on that one. I'm guessing I need to do them all, then match the highs with the lows till I get to the middle. Also which one is the amp hour rate of the battery, Charge? Discharge? The rest of the pack looks clean, its only got a few spots of corrosion.

Thanks!
Gerry

 

This set of 8 are of questionable usefulness as the probably have a faster self discharge rate than the others.

These should still be good ones as long as they still have sufficient capacity.

You may want to consider getting more than one. It will take more than a month to do the job with only one.

Using modules with noticeably lower capacity than the others will cause you to have to do the job again when one of them reverses a cell when the total battery SOC drains to to lower limit.

Gerry,

The discharge milliamp-hours is the available capacity and you want all of your modules to have the same capacity. When I rebalanced the modules in my 2004 battery, all of the "good" ones (27 of 28) measured above 6500 milliamp-hours for the third cycle discharge (the first cycle discharge is always low as the modules start at a low SOC). The Supermate DC6 records all three cycles. I hope that you are reading the data on all three cycles.

JeffD

 

Thanks Jeff! Yeah, it is going to take me forever with one charger! I checked on the original low battery (one of the 4 that were 6.88v) that I'm cycling and when it finished just the first discharge it showed 1399ma where the other two purchaced "good" ones were in the 400ma range. So I'm not getting a warm and fuzzy on the batteries I bought. I do have 6 more to test (bought 8).

I'm recording everything! I need to with it taking so much time. It takes a long time even at 1500ma, how long does it take to discharge 6500ma at .07!

Gerry

 

0.7, divide; about 10 hours per cycle. Remember, the reading that counts is the third discharge cycle, not the first.

JeffD

 

Okay, finished the first charge and it stopped on 6500ma, guessing this is why you set the upper limit at 7250ma. I caught it between cycles, set a 30min rest time (is this to much or to little?) Changed the upper limit and set it to 2 cycles to finish this battery.

Gerry

 

I set the limit at just above the assumed capacity to charge it enough that the higher SOC cells have to burn the excess as heat giving the lower SOC cells a chance to catch up.

5 or 10 minutes is enough rest time.

JeffD

 

Okay, charged a known good original, ended up with 1393ma for the last discharge. Guessing the one that went to 6500ma charge on the first one needed balancing (it was an original that was low at 6.88v) The last 2 charges were in the 2500ma range with the last discharge being 1383ma. The ones I bought, three are 1399ma, and the other 1395ma. Is it common for Gen 1 batteries to have this low of amp hour rating after 100K? Bought the "good" ones from Taylor Automotive in NC. Looks like they will "fit" the amp hour rating of the rest of the pack.

Gerry

 

Okay, learning curve on the charger. Found that its got a safety timer that was set at 120 minutes and the default is on. The manual told you how to figure it out for the amp hour and rate you're charging at. Figured it and it was 121 minutes. Thing I found out was that it works for the discharge side to. (don't know if this is normal) I found this out when I checked on it and noticed it was between cycles before a charge and the voltage was 7.65V. Stopped that battery and started another and checked it after discharging for 2 hours and watched it stop and move on. So I'm starting over, shut off the safety timer. Will the ones I charged to full 3 times benefit from another 3 full cycles? Should have wondered why it was going so fast (if you call 5 or 6 hours fast). Now its going to take forever! Wanted to buy a few more chargers but the places that have them for $23 are all sold out!

Gerry

 

Hang in there trseven. You'll be happy you did when its all over.

 

Using a triton eq charger..Is .7amps the fastest you can discharge? or can I go at a higher amp ? Thanks Mark

 

Not trying to thread jack, I'm in the process of charging and discharging an hv batt and have a quick question. Nearing the end of the charging cycle I'm experiencing cell expansion. All the modules are still clamped in the case, is this normal? Charging at 3-5a, discharging at .7a.

 

You need to provide a flow of air to avoid overheating of the modules under charge.

How do you have the limits set on your charger? You may be going too far into overcharging. A little overcharging is required to bring the weaker cells in each module up towards better balance, but too much generates too much heat.

Which generation of battery module are you recharging? The Gen1 modules are not very good. The Gen2 modules rebalance well and the Gen3 modules are even better (lower series resistance).

JeffD