Recommended equipment for working with battery packs?

Hi All -

I'm new to the forum, and new to DIY solar and DIY electrical. I've recently come into a Ford C-Max PHEV that the owner intends to scrap. Apparently it needs a new transmission, and the cost is more than the vehicle is worth.

Anyway, I'm planning to yank the hybrid battery pack out of it and work my way through making a DIY powerwall hooked up to a solar array.

According to info I have found, there are 84 cells, 3.7v each or 310v total. The battery pack itself seems to be rated at 2.6kWh.

Are there recommended/suggested tools for working with and testing these batteries? Basic stuff I have, multimeter, etc but I am wondering about more extensive testing if I am going to rely on these cells for backup power at home.

Will just posted a video about BMS with an impressive list of monitoring and features. Including a coulomb meter, to track energy flow and capacity. That would be good.

johnzilla said:

Hi All -

I'm new to the forum, and new to DIY solar and DIY electrical. I've recently come into a Ford C-Max PHEV that the owner intends to scrap. Apparently it needs a new transmission, and the cost is more than the vehicle is worth.

Anyway, I'm planning to yank the hybrid battery pack out of it and work my way through making a DIY powerwall hooked up to a solar array.

According to info I have found, there are 84 cells, 3.7v each or 310v total. The battery pack itself seems to be rated at 2.6kWh.

Are there recommended/suggested tools for working with and testing these batteries? Basic stuff I have, multimeter, etc but I am wondering about more extensive testing if I am going to rely on these cells for backup power at home.

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2.6 isn’t very much power. 8.3 amphours... just doesn’t seem like much for a hybrid vehicle.
a single bank from a Tesla is over 5kwh... and they have 16 of them! Wild to think a hybrid uses so little.
Do you have safety equipment? 310v is a huge dc voltage to deal with. I would want good rubber gloves, and safety glasses, or a face shield before I started tearing into a pack.
will pointed out plastic ratchets available at harbor freight as a good idea. Maybe plastidip some sockets, and extensions etc...
Safety first of course.

There were early hybrids where the battery system was only ever intended to be supplementary to the petrol / diesel engine, give the car more oomph taking off from stand still that sort of thing. ffcossag on youtube recently did a video on one of them where he pulled the battery apart and discovered the fault was simply no battery balancing so that the cells had drifted severely limiting storage.

A car battery without cell balancing. Yes, it really happened!

That may be small in EV terms, but it is nearly the size of 2 battle born batteries. So it is decent.

Yeah the two things you will need to use that battery:

1. BMS that can provide safety features for your battery cells, for your specified application (low temp cut off, current rating etc)

2. all in one unit that works in the voltage range of your battery (or you can buy a inverter/SCC/ATS/Fuses etc, but all in one is easy way to do it and what most second use battery guys use)

And some electrical tools. Really hard to give a true direction of "where to start" with second life batteries. I would watch some battery building tutorials first and try to install a bms first. That is a safe way to get started. Then when you have a good voltage at your battery, hook up an all in one unit and you will be set! add some solar panels and you would be good to go

That is a high voltage pack that WILL kill you instantly. You should build a basic lifepo4 or NMC pack first, then read an electrical safety manual on high voltage systems, then add a bms to a high voltage battery, then build a full size system. If you touch the wrong terminal, your organs will fry. Very dangerous stuff

Thanks, everyone, for the replies. I mistyped. It is 7.6kWh. At least, based on this:

Manufacturer: Panasonic
Rated Pack Energy/Capacity: 7.6 kWh / 26.0 Ah
Type: Lithium-ion
Min/Max Cell Voltage: 3.00/4.20 V
Number of Cells: 84
Pack weight: 272 lb
Nominal Cell/System Voltage: 3.7/310.8 V
Thermal Management: Active - Forced Air

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The vehicle specs state "EV-only" mode for up to 17 miles at highway speeds (70mph in the US).

Agreed 100%, safety is my number one at all times. I have been following the Ford OEM instructions for emergency responders and tow truck drivers which details step by step how to safely approach the battery pack and get it out of the vehicle.

I won't try anything with the hybrid pack except getting it to a safe storage location until I am comfortable that I understand what is going on and can be safe. I just thought it was a pretty good deal to get that battery pack just for the work of pulling it.

The 300v definitely is throwing me off as all of the Tesla vids and DIY powerwall vids seem to be talking about 24v. So my first task after safety seems to be understanding how to get that stepped down to something usable.

Are there any other tools, monitors, dischargers/sinks, etc (apologies for newbie terminology) that you guys recommend having? I have Will's lists (thanks, Will!) and added the mentioned BMS. I also have a basic o-scope, a good multimeter and the other infrastructure typical of a small farm. I can do homesteader-level electrical and thanks to Will's videos I feel pretty good about a basic solar setup. The DIY battery pack stuff is totally new.

And extra thanks, Will, for the focus on safety throughout your posts and videos! The learning continues.

The Tesla cell banks are 24ish volts... but the full pack is 400ish volts!

I would cover the positive lead side with wood or plastic/rubber when taking the negative side apart. Be ABSOLUTELY CERTAIN you know what all terminals feed, and where the voltage potential is before touching one screw. Test with dc meter DC= sign on most meters...

Know what you are doing before you start...

Supervstech said:

The Tesla cell banks are 24ish volts... but the full pack is 400ish volts!

I would cover the positive lead side with wood or plastic/rubber when taking the negative side apart. Be ABSOLUTELY CERTAIN you know what all terminals feed, and where the voltage potential is before touching one screw. Test with dc meter DC= sign on most meters...

Know what you are doing before you start...

Click to expand...

Good advice, absolutely. I have to investigate a little more on the primary connection. The first step in the emergency responder instructions says to disconnect the high-voltage service using the clearly marked lever. That's done, though I understand completely that the battery pack itself is still charged at 300V DC.

I bought Will's book (thanks Will!) and amd reading through it. I also need to find a copy of the service manual for reference. All I will do until I am a lot more comfortable is get the battery pack out of the vehicle safely and stored safely in our workshop.

I pulled the battery pack today. It was not easy (it weighs over 100 kg/230 lbs), but it is done. The learning continues....

Can you post a photo of the name plate on it? Maybe the manufacturer has a wiring diagram?

What about getting a manual from ford?

Does this battery charge from the vehicle alternator, or only from grid power/plugged in?

In the car floor - what was the other side with the fan doing?

If the battery is in good shape, at a cell level maybe you could add a BMS and use the factory input and outputs (need to save the connectors from the donor car?)

woha, you've got lucky!
Early this year, I bought four panels and 4 110A lead acid batteries for my home project. I did the math and I'm two panels and 4 batteries short, but since the economy in our country is meant to explode in a few weeks, nobody is willing to sell until that happens. I wish I could get my hands into something like this!
Anyway, that battery pack is amazing! I will be watching your project as it progresses.
You might also want to scavenge the fuse box for fuses and relays, that could be useful in this or future projects.

best regards

welnat said:

Can you post a photo of the name plate on it? Maybe the manufacturer has a wiring diagram?

What about getting a manual from ford?

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See below for more pics. There is no nameplate on it that I can find though I haven't tried to disassemble it yet. I'm not aware of a battery pack-specific manual from Ford. Knowing auto OEM processes as I do (I live in SE Michigan), the OEM gives a spec to a supplier and as long as the supplier meets the spec, it is "hands off". There could be a million tiny monkeys on treadmills in there for all an auto OEM would care as long as the pack met the spec.

Does this battery charge from the vehicle alternator, or only from grid power/plugged in?

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Both. The C-Max has a "EV only" mode as well as "hybrid" and "auto". The original spec allows for 18 miles in EV-only mode, give or take a mile or two depending on average speed. After that, the hybrid pack acts as typical hybrid powertrain. There is also re-gen braking. The pack doesn't fully charge back to "EV-only" capacity unless hooked up to a charger. The home charger is standard US 110v/120v.

In the car floor - what was the other side with the fan doing?

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There is a pretty extensive cooling setup all around these packs. Part of the disassembly instructions tell you to remove all of the ducting and one fan in the far right rear corner. The tray in the floor to the right is for the regular 12v auto battery.

I found someone else who has already worked through a bunch of this and they have additional pics:

If the battery is in good shape, at a cell level maybe you could add a BMS and use the factory input and outputs (need to save the connectors from the donor car?)

Click to expand...

Good point about saving the connectors, though I am sure there are plenty of wires in the harness that are vehicle-specific and not just power IO. I'm not sure if I have the expertise to figure out which wires in a harness are the wires I need to worry about as they are all wrapped in high voltage bright orange.

I also found someone who has re-assembled the cells and posted some videos. So it appears that, while unusual compared to Tesla, Nissan Leaf, etc, I am not doing anything too crazy or off in the weeds.

Deno said:

how do you hook an oscilliscope to a cow?

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Very carefully.

My goal would be to figure out how to balance the cells, and then charge and discharge in simplest way possible, ideally using what is there for cooling, etc. It sounds like the pack has the capability to take dc in or ac and transform to dc. If figured out, you could charge from grid power or from solar...

Then you have to figure out your output.

Or you have to take it all out and build it again from scratch.

Sounds like alot of fun either way... doing it safely. No family pets can walk across it accidentally when you are not around can they? Thinking cat mostly.

welnat said:

My goal would be to figure out how to balance the cells, and then charge and discharge in simplest way possible, ideally using what is there for cooling, etc. It sounds like the pack has the capability to take dc in or ac and transform to dc. If figured out, you could charge from grid power or from solar...

Then you have to figure out your output.

Or you have to take it all out and build it again from scratch.

Click to expand...

Is there a preferred tool to discharge cells correctly/safely? Or is it old school where you have to hook up a load like a space heater or hair dryer or something to it and let it run?

Sounds like alot of fun either way... doing it safely. No family pets can walk across it accidentally when you are not around can they? Thinking cat mostly.

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No worries...there is an outer metal casing, you can lay your hands directly on it, no problem. Lift it, etc. All of the connectors are blocked off with foam and wrapped with duct tape.

ARISE Zombie Thread!

I have 7 of these packs.

12pt nuts are 7.5mm. Yeah. Good luck with that.

5/16 hex socket works very well if you carefully break it loose by hand.

Cells made by Panasonic rated for 150A with internal fusing.

28 modules. Each module will retain the 21 cells, but all will be in parallel for a giant 21P "cell".



14 modules in series.

2X batteries, so:

21P14S2P

Rated capacity, 53.2kWh

First 21P14S battery "dry fit" on rack: