2nd Gen Prius PHEV Conversion (Enginer plug-in lithium ion battery kit)

[Daox]

I had planned on charging them and balancing them overnight tonight before installing them in the car since I'll be doing the install on Sunday.

Why the recommendation to cycle the battery before its in the car? Got any links to info on this?

The banding idea is interesting and probably a great idea, thanks!

[mrbigh]

Originally Posted by Daox

I had planned on charging them and balancing them overnight tonight before installing them in the car since I'll be doing the install on Sunday.

Why the recommendation to cycle the battery before its in the car? Got any links to info on this?

The banding idea is interesting and probably a great idea, thanks!

To balance out of the car because these are out of the car and at the same time you can use the vehicle for any need that may arise with out having to drive away with a looong extension cord around town.
In the way these batt are supplied to the end user are basically how they arrived from China from a long sea journey and, unfortunately, we found that the Manufacturer's QC is not the best.
So, you may have in your hands some unmatched cells; better to take care of all issues in a control environment.
Patience is a virtue.
PS.
I saw that you opened a new thread in Prius Chat about the same topic than this.
A good topic on Enginer batteries can be found here

[Daox]

It sounds to me like a lot of people are having balancing issues. It sounds as though cell quality is really an issue. This even more so reinforces the need for individual balancer monitoring for each cell, not two cells in parallel.

What are your thoughts on this mrbigh?

[Matt Herring]

SVO gave me heads up on this...very cool Tim! Can't wait to see what you get out of this kit! I knew once you had the Prius in your hands it wouldn't be long before you started working on it...this is great...congrats!

[mrbigh]

Originally Posted by Daox

It sounds to me like a lot of people are having balancing issues. It sounds as though cell quality is really an issue. This even more so reinforces the need for individual balancer monitoring for each cell, not two cells in parallel.
What are your thoughts on this mrbigh?

As you found, balancing on this type of LiFePO4 batteries is a PITA.
Again, I will recommend you to safely discharge these to a safe level of about 2.55 VDC to a dump load, single cells or by pairs, after completion of this process put them in the charger and let the balancers do their thing until all of them are equally charged, re-start the discharge cycle again on the dump load by pairs or single cells.
Low voltage discharge is the most important factor for a healthy battery pack and will prevent further major problems down the road.

NOTE
The Prius NiMH additional batteries I installed (168 in total) went through the same process 5 consecutive times before I configured the battery assemblies (6), and all of them went through a battery analyzer paired to a computer for graphing representation.
- - - - - - - - - - -
The dump load I use since the las 4 years is an electrical water heater, 220v element rod, installed in the cover of a 5 gallons plastic container filled with water that can be recycled.
It is a safe and inexpensive way to do things like this while the voltages that you will handle do not exceed 40 VDC.

[bennelson]

We should also talk to EL-Camino Tom about what he is using on his Lithium pack.

The last time I talked to him about his Lithiums, he said he had
"..... a BMS which only
monitors all cells, does not balance them. Many feel that the balancers
are wasteful and can even unbalance the packs more. If you are willing
to treat them well, LiFePO4 batteries will return the favor. Keep ALL
cells over 2.7V at ALL times, and you will get along if you have a proper
charger."

We can check what he is using for BMS. As a custom electronics engineer, he knows a few things about it.

[Daox]

Good stuff Ben, I didn't think about him.

As of right now, two of the four packs are on the balancers. When they are both done, I will charge them up and monitor voltages as they charge. We'll see if any of the cells charge faster than the others and if I get any alarms.

Last night I had reconfigured one pack to run in the 'buddy pair' setup. I think I'm just going to setup to run with the two balancers and just run half the pack so I don't have any cells in parallel. This will allow me to monitor every single battery and show if there is any problems.

[mrbigh]

Originally Posted by bennelson

We should also talk to EL-Camino Tom about what he is using on his Lithium pack.

The last time I talked to him about his Lithiums, he said he had
"..... a BMS which only
monitors all cells, does not balance them. Many feel that the balancers
are wasteful and can even unbalance the packs more. If you are willing
to treat them well, LiFePO4 batteries will return the favor. Keep ALL
cells over 2.7V at ALL times, and you will get along if you have a proper
charger."
We can check what he is using for BMS. As a custom electronics engineer, he knows a few things about it.

El Camino-Tom must be using a "Battery Monitor System "and not the common acronym of BMS for Battery Management System, these are two different devices, the later being a more complex piece of equipment.
A "balancer" is neither.

[Daox]

The balancers that come with the Enginer kit kind of monitor the batteries. They have a high and low voltage warning beep that goes off when one of the cells goes too high or low.

[Daox]

Enginer said they'd send me to two extra balancers, but they won't cover anything that goes wrong if I use them. This is BS. The whole point of this is to avoid bad cells. If I can't detect them, they ruin more cells, but if I monitor them all and find bad ones, then I have to pay for their bad product. The thing that urks me even more is their site says its supposed to use 4 balancers, so I had no way of knowing of this until I bought the kit.