Hey, guys. Starting from this week, throughout this month, I'd be writing and/or making videos on various Toyota hybrid vehicle battery pack tear downs I have done.

I'd take about,
1. Their chemistries
2. Problems, and how you can,
3. Solve common HV battery pack related problems.

The link below is the video to an article I wrote on my website, some days ago.

https://m.facebook.com/story.php?story_fbid=1895922413822214&id=767933589982123

The video would further enlighten you, on the 2 alternative options we had for fixing the flooded Highlander hybrid discussed in this article:



https://www.nairaland.com/4708149/hybrid-electric-vehicle-maintenance-hate

Pls drop your comments in any of the social handle's comments bar, provided in the link.

PS: For lovers of hiphop or rap genre of music, there's a JZ playing in the background.


Regards,
Joseph
08066643532(call/WhatsApp)
DW Nig Ltd
Isolo,
Lagos
www.dxta.net.ng

Toyota, and other auto manufacturer's employ the use of basically two types of battery chemistries for use for electric propulsions(to drive their various electric motors).
One of such chemistries is nickel metal hydride batteries.
Their capacities are dependent on the the strings of cells arranged in series, nature of electrodes and manufacture of such.
They have a high energy density, and can safety go through several charge/discharge cycles without posing a fire hazard, unlike their lithium ion counterparts.

These batteries are arranged like a stalk of matches in a match boxes in series, and BMS(battery management systems) are designed to monitor and control currents, temperatures, and voltages, pumping in and out of the high voltage battery.

On highlander or Rx hybrid, Prius, and Camry vehicles, various capacities are allocated to these batteries, depending on the applications.

In the picture below is a battery pack for a high lander or Rx hybrid.

Specification:
Has thirty 9.6-volts modules containing 8 cells/module for 240 cells total (nominal 1.2 volts/cell) provide nominal 288-volts, and a capacity of 6500mAh.

Individual modules cannot be replaces as found in Prius and Camry vehicles, because all modules on the highlander packs are stalked and permanently tightened.

In an event of failure, its always better to have the pack replaced, or get some of the pack of stalked modules replaced with another of matched capacity.

Rx400/450/highlander pack on display.
You can see how they are segmented into three portions.

Inspecting the battery's temperature sensor circuitry.
A faulty temperature sensor would give false information to the BMS about the battery's temperature, and cause problems of overcharging/over discharging the packs.

Thanks for sharing boss. Are you saying individual modules on the prius or Camry can be replaced?

What could cause the temperature sensor to fail?

and / or what is it's lifespan

mrtesso. Yes, individual modules can be replaced. Replacing them, isn't a problem. The stems from clients not being patient t enough to have their battery packs balances during battery rebuilding. As you know, Nigerians want their stuff quick!!! A typical pack would take close to a month. But because of the quick attitude of hybrid car owners, packs in some climes are just recharged and put straight back into service. It does not work that way.
We must follow a laid down protocol to avoid "check hybrid system, or big caution lights", when modules are replaced.

If you must replace modules, ensure you get the right capacity, and do the normal charge/discharge cycles of the existing modules, with the replacement one(s).

A failed battery temperature sensor is always as a result of failure of the resistor embedded in the sensor itself, as a result of years of service, or sometimes, due to negligence during pack disassembly.

Just like every other items, they wear also. Electrical stuff they are.
For me, sometimes, I use a 800-1000ohms resistor as a substitute if one fails.
It sure works well.

Hope this answers your questions?



Regards,
Joseph
DW Nig Ltd

TRYGO:
Toyota, and other auto manufacturer's employ the use of basically two types of battery chemistries for use for electric propulsions(to drive their various electric motors).
One of such chemistries is nickel metal hydride batteries.
Their capacities are dependent on the the strings of cells arranged in series, nature of electrodes and manufacture of such.
They have a high energy density, and can safety go through several charge/discharge cycles without posing a fire hazard, unlike their lithium ion counterparts.

These batteries are arranged like a stalk of matches in a match boxes in series, and BMS(battery management systems) are designed to monitor and control currents, temperatures, and voltages, pumping in and out of the high voltage battery.

On highlander or Rx hybrid, Prius, and Camry vehicles, various capacities are allocated to these batteries, depending on the applications.

In the picture below is a battery pack for a high lander or Rx hybrid.

Specification:
Has thirty 9.6-volts modules containing 8 cells/module for 240 cells total (nominal 1.2 volts/cell) provide nominal 288-volts, and a capacity of 6500mAh.

Individual modules cannot be replaces as found in Prius and Camry vehicles, because all modules on the highlander packs are stalked and permanently tightened.

In an event of failure, its always better to have the pack replaced, or get some of the pack of stalked modules replaced with another of matched capacity.

Thanks for the information I have done jobs on camry hybrid pack but never handle highlander hybrid pack only troubleshooting a faulty ABS.I just discovered that individual modules cannot be replace on RX and Highlander.
How can someone handle the caution light without DTC?Regards

Morning. Well done
So from your expose.. It would take a month for the replacement cells to be conditioned for work? Why does it take that long?

Takes that long, because your replacement modules might be sourced from more than a ten year old pack. Those modules have gone through almost hundreds, if not thousands of cycles of charge/discharge. That way, they already have reduced capacity.
Its takes a dedicated smart charger, to carry out those cycles more than three times, in order to exercise the modules, and bring them back to usable life again.
After achieving that, you got to match up the capacities of your replacement modules in terms of IR, voltages, and map with your existing one, then another round of cycling commences.
Its a tedious exercise though.
When you get it right, red triangle light, would never surface again.

Hope this answers your question?

So Interesting, sold out my Camry hybrid because of battery issues, wish I saw this thread then..

Feel your pain Eric!