charging prius battery modules

Batteries, Chargers, and Battery Management Systems.
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apyles   100 µW

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charging prius battery modules

Post by apyles » Feb 26 2012 3:38pm

Hi I recently acquired a number of Prius battery modules (Gen. 2)
Each module is rated at 7.2v 6.5AH
(according to: http://www.endless-sphere.com/forums/vi ... =14&t=6726 )

My post is actually a two-part question. Should I (1) throw money at it and buy a good charger, or (2) should I attempt to build something with parts I have laying around (I tend to lean towards the latter )

Buy it:

Can anyone recommend a charging product for these modules? Like an R/C charger? I have no experience with these R/C chargers so any recommendations would be appreciated.

I suspect going this route and just buying a charger is probably better than my home grown ideas ( keep reading)

Build it:

For now I have several wallwarts laying around. Including a wallwart 7.5v, 600mw power supply. Using this along with a timer set to disconnect after ~ 10.5 hours, I could have a crude charger for very cheap.

I also have an old laptop power supply with 16v 4amps that I was thinking of using as well for charging 2 at a time (wired in series ).

I'm thinking of eventually creating a dV based setup as seen here.
http://www.mdpub.com/555Controller/
When the voltage exceeds a tunable threshold, charging is stopped. But will a dV based approach be accurate for these batteries?

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MitchJi   1 GW

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Re: charging prius battery modules

Post by MitchJi » Feb 26 2012 9:12pm

Hi,
apyles wrote: Buy it:
Can anyone recommend a charging product for these modules? Like an R/C charger? I have no experience with these R/C chargers so any recommendations would be appreciated.

I suspect going this route and just buying a charger is probably better than my home grown ideas ( keep reading)
This will be much better than what you build:
http://www3.towerhobbies.com/cgi-bin/wt ... LXTYX6&P=7
Muchmore Racing Cell Master Platinum Charger
Tower's Low Price $74.99

FEATURES: 16bit high resolution super linear current charger charges 1-8 cell
NiCd/NiMH and up to three cell LiPo batteries
Muchmore's own false peak detection algorithm
Six charging memories
Each six charge modes are customizable
Zero-delta peak cutoff
SPECS: Dimensions: 4.9 x 4.5 x 1.8" (124 x 114 x 47mm)
Weight: 17oz (482g)
Number of Cells: 1-8 NiCd/NiMH and 1-3 cell LiPo
Max. Charge Current: 0.1 - 10A adjustable (1A fixed for Lipos)
Discharge Current: 0.1 - 10A adjustable
Cut-off Voltage: 0.1 - 9.9V
Input Voltage: 10.0 - 16.0V
Charging Capability: 10 -9990mAh adjustable
Charging Modes: Peak & CTX charge, Trickle, Flex, Lithium
Trickle Charge Rate (after charge): 0.1A
Voltage Threshold/Delta Peak: Zero, 3 - 99mV
Flex Charge: 0 - 9level adjustable
Thermometer Sensor: 59 - 158 degrees Fahrenheit (15 - 70 degrees
Celsius)
Keys: 4
Cooling: Ball bearing temp controlled dual fans
Best Wishes!

Mitch


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The best quality batteries and lowest priced batteries for DIY EV's are tier 1 OEM Quality Cells from salvaged (wrecked) EV packs. Three examples are Chevy Volt and Nissan Leaf and Tesla Model 3 packs.

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apyles   100 µW

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Re: charging prius battery modules

Post by apyles » Feb 26 2012 9:48pm

MitchJi wrote:Hi,


This will be much better than what you build:
http://www3.towerhobbies.com/cgi-bin/wt ... LXTYX6&P=7
Thanks for the recommendation. I agree 100%. Before I invest in something like this, I need to ensure that these modules are completely functional.
So I think I'm stuck with my homegrown solution at least for now.

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Monstarr   100 W

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Re: charging prius battery modules

Post by Monstarr » Feb 27 2012 5:51am

You can find lots of information In the big Prius battery 'how to make them work' thread 
http://endless-sphere.com/forums/viewto ... ilit=prius
The charger in the previous post will not work...it only charges 8 cell nimh max. Each prius module contains already 6 nimh cells.

I myself bought a prius gen. III battery 2 months ago. All 28 modules were in perfect shape. Sold half of it.
The lasting 14 modules will be used in a 7s2p configuration, giving me about 50V / 10-13Ah.

In one of the last pages of the Prius thread someone used a 36V NiMH all-battery charger to charge his 36V battery. So far this worked out for this guy. So i bought the 48V version of this charger to charge my pack. Too bad i havnt received it yet ... the shipment from the US takes a while.. :( (shipped on feb 16th.) http://www.all-battery.com/tenergynimhb ... 01017.aspx
Normally the 48V is a 40cell battery and 7s prius module means 42 cells series so i hope this just leads to a tiny bit of less charging instead of blowing up...anyone has an idea about this??

Here is a pic of my scooter with the modules already build in. They are bolted to the frame so they cant move. Sturdy rubber floormats used for isolation of the battery connectors 8)
Image

I am planning to charge in parallel and monitor the first charges closely.

So cheers!

Here is a bit of more information about a guys who parallel charges 42cell NiMH batteries. Tnx to rjoe (the 36V prius pack guy).
http://www.ferromit.com/1000w%20bike.html

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Tom_D   100 mW

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Re: charging prius battery modules

Post by Tom_D » Feb 28 2012 2:30am

Monstarr wrote: Normally the 48V is a 40cell battery and 7s prius module means 42 cells series so i hope this just leads to a tiny bit of less charging instead of blowing up...anyone has an idea about this??
Monstarr,
I wouldn't trust any NiMh charger to catch the - delta v for this battery. This is not like other typical NiMh batteries. The plastic will start to melt and puff the module if the voltage exceeds 1.39 volts/cell, so 7 modules with 6 cells each (42s) can only take about 58.5v. Any more and you will puff them. Ask me how I know :shock:
MAYBE the charger will catch the rise in temp for shut-off, but I would be standing there watching to see a good cutoff, before I felt safe. IMHO, these Prius are very sensitive to over-voltage charging.


-- Tom_D
Bike: wally world 26" Roadmaster mtn
Trailer: Bob
Motor: front Clyte 5305
Controller: LYEN 124115 HV
Charger: Soneil 4808 SRF (onboard), parallel charging (4) 48V blocks, NO BMS
Batt: 84s2p Toyota Prius Gen III
Dashboard: Cycle Analyst

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Monstarr   100 W

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Re: charging prius battery modules

Post by Monstarr » Feb 28 2012 8:08am

I am aware of that issue. I will just put it to the test and go with it.
Whats your charging solution btw? I see you use a 48V SLA charger. Manual cutoff?

This is how we gonna do it..

- hoping nimh charger picks up the delta v in the first place, this is the case with rjoe who uses a 36V 5module/30S prius batterypack,
- if not, the temp sensor will shut the charger down prematurely
- if not, an AC outlet timer shuts it off automatically after a given time which has been put in by me regarding the remaining SOC,

and, i will never charge it unattendedly and will use dealextreme temp sensors at each batterypack so i can check temperatures myself.
http://www.dealextreme.com/p/digital-co ... nsor-15553

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rjoe   10 W

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Re: charging prius battery modules

Post by rjoe » Feb 28 2012 10:07am

Tom_D wrote:
Monstarr wrote: Normally the 48V is a 40cell battery and 7s prius module means 42 cells series so i hope this just leads to a tiny bit of less charging instead of blowing up...anyone has an idea about this??
Monstarr,
I wouldn't trust any NiMh charger to catch the - delta v for this battery. This is not like other typical NiMh batteries. The plastic will start to melt and puff the module if the voltage exceeds 1.39 volts/cell, so 7 modules with 6 cells each (42s) can only take about 58.5v. Any more and you will puff them. Ask me how I know :shock:
MAYBE the charger will catch the rise in temp for shut-off, but I would be standing there watching to see a good cutoff, before I felt safe. IMHO, these Prius are very sensitive to over-voltage charging.


-- Tom_D
My 36V Tenergy charger (discussed above) catches -dV at around 1.45V/cell. I really recommend compressing the cells, especially when charging. That is the way Toyota does it.

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Re: charging prius battery modules

Post by rjoe » Feb 28 2012 4:50pm

This is my clamping system:

Image

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Monstarr   100 W

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Re: charging prius battery modules

Post by Monstarr » Mar 01 2012 5:20am

rjoe wrote:This is my clamping system:

[img]image[/img]
Any expanding seen so far? And will the modules puff when they can't expand due to the clamping? When does the temperature rise kick in? before or after expanding?

Waaah can't wait for the charger to be delivered.

apyles   100 µW

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Re: charging prius battery modules

Post by apyles » Mar 01 2012 1:02pm

rjoe wrote:My 36V Tenergy charger (discussed above) catches -dV at around 1.45V/cell. I really recommend compressing the cells, especially when charging. That is the way Toyota does it.
Rjoe are you wiring 4 modules in series? Can your charger also handle a single module at a time?
(Assuming 4 in series) Have you had any problems with over/under charging any single module?

And for the newbie question of the day: Can you explain what "-dV" means? My understanding on how to charge these things, is to charge until a peak voltage is reached (from some posts I've read that ranges from 8.2V- 8.4V).
If I understand your 1.45V/cell -dV your charger stops at 1.45V*6 or 8.7V. Somehow I feel I'm missing something.

The specifications of the battery are linked here. However, I'm confused on how to decipher "Charging Termination".
From:
http://endless-sphere.com/forums/downlo ... p?id=47166
Charging Termination (Consult GP for other charging conditions) : -ΔV : 0mV/cell to 10mV/cell
Can someone explain to me what this means in layman terms?

apyles   100 µW

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Re: charging prius battery modules

Post by apyles » Mar 01 2012 1:06pm

Monstarr wrote:
Here is a pic of my scooter with the modules already build in. They are bolted to the frame so they cant move. Sturdy rubber floormats used for isolation of the battery connectors 8)
Image

I am planning to charge in parallel and monitor the first charges closely.

So cheers!

Here is a bit of more information about a guys who parallel charges 42cell NiMH batteries. Tnx to rjoe (the 36V prius pack guy).
http://www.ferromit.com/1000w%20bike.html
Monstarr, Looks like a great setup! I'd like to find out how that charger works out for you.

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rjoe   10 W

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Re: charging prius battery modules

Post by rjoe » Mar 01 2012 1:34pm

Monstarr wrote: Any expanding seen so far? And will the modules puff when they can't expand due to the clamping? When does the temperature rise kick in? before or after expanding?
I have some "bad" prius modules that I tried to charge with this charger without clamping. They puffed in about 15 minutes, but they were still cold.
The good cells will not puff if they are clamped. I haven't really tried it on good cells without clamping, just to be safe.



apyles wrote:
rjoe wrote:My 36V Tenergy charger (discussed above) catches -dV at around 1.45V/cell. I really recommend compressing the cells, especially when charging. That is the way Toyota does it.
Rjoe are you wiring 4 modules in series? Can your charger also handle a single module at a time?
(Assuming 4 in series) Have you had any problems with over/under charging any single module?

And for the newbie question of the day: Can you explain what "-dV" means? My understanding on how to charge these things, is to charge until a peak voltage is reached (from some posts I've read that ranges from 8.2V- 8.4V).
If I understand your 1.45V/cell -dV your charger stops at 1.45V*6 or 8.7V. Somehow I feel I'm missing something.

The specifications of the battery are linked here. However, I'm confused on how to decipher "Charging Termination".
From:
http://endless-sphere.com/forums/downlo ... p?id=47166
Charging Termination (Consult GP for other charging conditions) : -ΔV : 0mV/cell to 10mV/cell
Can someone explain to me what this means in layman terms?
I have 5 cells in series for 36V nominal. -dV means negative change in voltage. So, this charger works by charging at a constant current until the voltage of the pack starts to decrease, i.e. the change in voltage of the pack is negative 3-5 millivolts. That means it reached its maximum. It makes sense -- there's no point in charging anymore if the voltage is going to go down. Consult the last page of this manual for a graph and explanations, which should really help:
http://www.all-battery.com/productimage ... manual.pdf

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Re: charging prius battery modules

Post by apyles » Mar 01 2012 2:32pm

rjoe wrote: I have 5 cells in series for 36V nominal. -dV means negative change in voltage. So, this charger works by charging at a constant current until the voltage of the pack starts to decrease, i.e. the change in voltage of the pack is negative 3-5 millivolts. That means it reached its maximum. It makes sense -- there's no point in charging anymore if the voltage is going to go down. Consult the last page of this manual for a graph and explanations, which should really help:
http://www.all-battery.com/productimage ... manual.pdf
Ah got it 7.2*5. I was using 8V that others have been charging up to.
Rjoe, thanks for the explanation. That makes a lot of sense. How long does it take for a complete charge (when battery is exhausted) with your setup?

Also, do you use the NTC temperature sensor that comes with the charger?

Finally, if I am reading the spec correctly, these modules should not be discharged below 6V. Have you had any issues with these if they are discharged below this value?

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Re: charging prius battery modules

Post by dnmun » Mar 01 2012 4:26pm

negative delta voltage happens on the other side of 1.41V and that is when heat is released which is the other signal for nicad charging end points. you may not want to overcharge them that much. have you read anything about nicad charging before this or followed dave what's his name at 99mpg.com who does the prius pack rebuilding?

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rjoe   10 W

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Re: charging prius battery modules

Post by rjoe » Mar 01 2012 4:33pm

apyles wrote: Ah got it 7.2*5. I was using 8V that others have been charging up to.
Rjoe, thanks for the explanation. That makes a lot of sense. How long does it take for a complete charge (when battery is exhausted) with your setup?

Also, do you use the NTC temperature sensor that comes with the charger?

Finally, if I am reading the spec correctly, these modules should not be discharged below 6V. Have you had any issues with these if they are discharged below this value?
It takes about 3 hours to charge from LVC on my controller, which is around 31V, so about 6.2V/module and it charges them up to about 8.5 or 8.6V/module. The charge rate I measured at 2.78A. This is for 2 packs in parallel.

I have taken one of the 36V packs down to about 24V by accident twice, and I noticed it had slightly less capacity than the other pack that I didn't abuse. However, it may have regained capacity from cycling; I haven't really checked.

Yes, I always hook up the temperature sensor, but the packs never get any hotter than ambient, so I assume it doesn't matter if I do or not. I just do it "just in case" as a safety measure.

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Re: charging prius battery modules

Post by Monstarr » Mar 03 2012 6:49am

Received the charger yesterday.
Charged both packs seperately. Charger showed green light with both packs @ 58V. This means 1.38V/cell on 42 cells. (Charger specs says it is build for max 40 NiMH cells.)

Im satisfied and guesstimating that the shutoff voltage will be a bit higher when i cycle the packs a few times.
I still have to wait on a few parts like CycleAnalyst, turnigy wattmeter, couple of ANL fuses etc. etc. to complete the scooter and build it all together again.

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Re: charging prius battery modules

Post by Monstarr » Mar 03 2012 7:03am

As an addition to my previous post.
The one thing that bothers me slightly is the fact that the charge crocodileclamps tend to spark when i put them on the positive and negative terminal...charger ofcourse is not plugged in. I'm a bit concerned that this will cause damage to the charger over time.

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Re: charging prius battery modules

Post by Gregor » Mar 03 2012 6:33pm

The spark is common with many RC type chargers also--I don't think you have any worries about that. Just to repeat a thought that I made on the other thread about Prius batteries--the nominal voltage of each 6s module is 7.2v, and the "fullcharge" state is 8.4v (1.4v/cell). It is easy to charge these using a RC type charger by treating each module as a "2S" section of LIPO, i.e., the charger will level off the charge at 8.4v. If you want to charge many bricks of the prius batteries is series, that is also possible, but balancing is NOT possible, so make sure that you have well matched sets of cells and do the first cycles of charge/discharge with all the Prius bricks in parallel. The one downfall of this technique is it can easily take overnight to complete a charge, but I have never had any overheating or major swelling from this (easy to charge now without constant monitoring). One sign that you are doing a good charge is if you are getting at least 6Ahr from each module--I usually discharge down to 6v to check this. Cheers, Gregor

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