Author Topic: Prius Battery  (Read 7068 times)

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dbcollen

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Prius Battery
« on: September 15, 2011, 12:32:58 PM »
I was just given a Prius battery from a 2001-03 prius, it is 38 7.2V cells in series for 273.6VDc (scary voltage) 6.5Ah for 1.778KWh. Looking for suggestions on what to do with it.

Dustin

TomW

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Re: Prius Battery
« Reply #1 on: September 15, 2011, 12:38:34 PM »
Put them on a pallet and ship them to me?  ;D

Build an electric motorcycle?

Otherwise just use them in your current setup, I guess.

Tom

dbcollen

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Re: Prius Battery
« Reply #2 on: September 15, 2011, 12:47:12 PM »
7 cells in series works for 48v close enough (50.2-58.8v) but I already have 1000Ah @48v.   I have a spare 24v sine wave inverter, but can't get near enough to 24v with any combination of 7.2v.
It would make a hell of a mig welder power pack.  ;D

Dustin

TomW

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Re: Prius Battery
« Reply #3 on: September 15, 2011, 01:08:21 PM »
I suck at math but:

4*7.2=28.8 ?

I consider that to be my upper limit on my nominal 24 volt bank. Not sure of the "full" or "empty" voltage on the cells and I have no idea what chemistry they are.

There would be 2 strays using 9 sets of 4  this way and probably not a huge AH rating

Tom

Bruce S

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Re: Prius Battery
« Reply #4 on: September 15, 2011, 03:15:49 PM »
dbcollen;
 These are NiMh type batteries. They can be very good work horses and since they can bounce back from being drained down to as low as 80% empty, they could be used in front of your current 1000Ah setup as the main draining batteries and let the 1000Ah set bring them backup to full charge.
Otherwise I'd look into maybe breaking them up, you can set them, depending on how much work you want to do :-) into 10-cell packs which would give you 12.0Vdc at rest. Actually more like 12.5Vdc at rest, then build up it at nearly any setup you wish.
I'd put my hat in the ring to bribe you out of them , BUT TomW spoke first  ;D
Other idea would be to offer them up on Craigslist or one of the Prius forum in your area, they'd love to get their hands on them.
ONE thing to be checking on....! voltages once you have the back into individual cells, a lot of times the inner cells are going bad due to poor connections from years of being bounced.

Cheers!! Great find/gift!!
Bruce S
 
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dbcollen

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Re: Prius Battery
« Reply #5 on: September 15, 2011, 04:10:25 PM »
each "cell" appears to be a 6 series pack for 7.2v, so getting 10 cells for 12v is not possible. 1.2 is the nominal voltage, they should charge to 1.4v /cell, so 4 series packs would have to charge to 33.6v, which is a little high for my 24v inverter.

Dustin

Bruce S

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Re: Prius Battery
« Reply #6 on: September 15, 2011, 05:40:14 PM »
each "cell" appears to be a 6 series pack for 7.2v, so getting 10 cells for 12v is not possible. 1.2 is the nominal voltage, they should charge to 1.4v /cell, so 4 series packs would have to charge to 33.6v, which is a little high for my 24v inverter.

Dustin
Dustin;
 Yes and no. At 1.4/cell they are at the point where they are getting hot, the rise voltage and end of charge voltages are interrelated.
Resting voltage is the realm that I work in which happens to be 1.3ish. Unlike NiCds, NiMh's don;t have the easy to define voltage dip that a charger can pickup on. The 6-pack sets are very well known in the "used battery" world and If I still have the link where a guy broke his unit down the find the bad cells I'll post it or PM it to you.
a 2-pack of 6 would be 14.4V which is easily handled two together would be 28.8Vdc still high but not that high that a 24V system couldn't handle it. Hooked to a couple SLAs would certainly hold these down to voltages a 24V based system would work with.
Either way still a good find
Bruce S


   
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dnix71

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Re: Prius Battery
« Reply #7 on: September 16, 2011, 09:04:12 PM »
If you disassemble them they will fail prematurely. They MUST be compressed when charging or they will swell and fail. They are sealed with vents that have recombinant disks and those disks require pressure to work properly.

12AX7

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Re: Prius Battery
« Reply #8 on: September 17, 2011, 01:35:05 AM »
I was just given a Prius battery from a 2001-03 prius, it is 38 7.2V cells in series for 273.6VDc (scary voltage) 6.5Ah for 1.778KWh. Looking for suggestions on what to do with it.

Dustin

I must be missing something here.    Does the prius have more than one set of these batteries?  1.78KWH doesn't sound like enough power to move the car down the road for any great distance/speed  1.78KWHs   is it correct/possible to some how equate KWH s to horse power/hours?  In other words is 1.78KWH about 2.3 horsepower/hour? 

It is getting late here.....Maybe tomorrow I'll come back to this and say..  duh!   

ax7

dnix71

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Re: Prius Battery
« Reply #9 on: September 17, 2011, 02:44:53 AM »
12AX7 that's the correct size for a Prius battery. They are not intended to power the car very far. In stop and go city traffic this works well, on the open road an ICE does just as well.

offgrid1

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Re: Prius Battery
« Reply #10 on: December 18, 2014, 12:22:07 AM »
Two 12v batteries under construction from the Prius if I can get the picture attached. While the individual modules are quite rigid I suspect dnix71 is correct that the modules should be compressed, which is s good way to keep the modules together, anyway. I use three modules in series for 24v and two for 12v.   

offgrid1

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Re: Prius Battery
« Reply #11 on: December 19, 2014, 11:46:19 PM »
Here's a 12 v battery! 160 pounds of NiMH. All the negatives on one side. Copper sheet to join the two batteries vertically on each side is at the lower left, ready to be cut and drilled.

Mary B

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Re: Prius Battery
« Reply #12 on: December 20, 2014, 05:27:07 PM »
Need higher rez pics...

dnix71

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Re: Prius Battery
« Reply #13 on: December 20, 2014, 05:48:14 PM »
NiMH makes for an odd 12v battery. Your modules are 7.2v nominal under load. Powerstream has a good article on charging.
http://www.powerstream.com/NiMH.htm   Charging at C/10 or less for 15 hours or less will give you a full battery with a charging efficiency of 2/3's [66%].

Fully charged, NiMH has 1.41v/cell. That makes your "12v" double pack 16.92v, which is too high for safety on a 12v system. 16v is the normal rating of 12v car system capacitors. One less cell gives a full charge pack of 15.51 and nominal 13.2 under load. I don't think you can break the modules down to do that.

For a 24v system, three modules fully charged is 25.38v. A resting 24v lead acid stack would be 25.2. Under load though, 3 packs would be 21.2v which is too low for most 24v systems.

At 48v nominal NiMH works. Seven 7.2v packs is 50.4v under load - exactly what four '12v' lead-acid batteries in series would be. Charged, seven 7.2v packs would be 59.22v, just under the legal limit for "low voltage systems" Charging 4 lead-acid to 14.5 gives 58v.

Build 7-in-a-series module stacks and get yourself a 48v inverter and you should have no trouble.

offgrid1

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Re: Prius Battery
« Reply #14 on: December 22, 2014, 01:04:15 AM »
Thanks Dnix71

Overcharged 2 or 3 modules on 24 v bank. Tops fractured and dripped KOH. 12 V bank finished today. I suspect these modules are more like thoroughbreds than regular horses and require careful limiting.

Simen

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Re: Prius Battery
« Reply #15 on: December 22, 2014, 01:33:39 AM »
I got 20 blocks of 5-cell 100Ah NiCd in my (old) electric car (a Citroen Saxo Electrique from 2000), and these blocks come with integrated water cooling. (The blocks are: Saft STM 5-100MRE) The integrated charger in the car, overcharges the cells with 10% of the last discharged Ah at C/20, and that makes them hot. (Normal discharge current are 100-150A continuously , and that also makes them hot. ;) )

I don't know if the same charging scheme could apply to your NiMh cells, but you might find some documentation about handling on the net? :)
« Last Edit: December 22, 2014, 01:40:07 AM by Simen »
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dnix71

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Re: Prius Battery
« Reply #16 on: December 22, 2014, 06:44:32 PM »
One more warning about charging NiMH and Nicad batteries. The internal cell resistance drops way off when the cells get charged. If you have a dumb charger you need a timer to shut off the pack when it should be full, whether full or not, and to limit the voltage and current to a safe level and put some kind of thermal cutoff on the stack just in case everything else fails. NiMH and nicads won't catch fire like LiCobalt will but they will still cook internally and short out.

If you have to cycle your pack every day, then c/10 for less than 15 hours won't hurt the pack. If you don't need to cycle daily, c/40 is enough to keep up with self-discharge but low enough to avoid cooking the cells.