When you're working on this thing out of the car there are many ways you could complete a loop. ...And you might not know which loop is closed at any one time. The idea is to ensure you are not part of that loop. The mat will do that.

The bigger hazard is that of dropping a tool that then shorts two terminals. The battery will give up its charge fast. It is capable of welding your tool to the terminals. Then worse things can happen, like an explosion of the battery.

You can get insulating mats at an electrical supply house (Home Depot won't have a clue). Try wrapping your tools in electrical tape, just in case.

 

A plastic hat with a hole is a great way to play it safe. Would 8mm sheet prevent a transfer? Hal

 

Hi all,

I hate to disagree. The matt will do nothing to prevent exposure to electrical current from the battery pack unless one pole of the battery pack is connected to earth or something conductive that you might be standing on. Unless you physically wire one side of the battery to the ground this is not likely to occur.

The danger is exposing your hands and arms to two opposite poles of the battery (positive and negative). With the batteries in series and the bolts exposed and connected to different battery groups, it is difficult without taking the time with a meter, to know which poles (bolts) have enough voltage potential between them to pose a risk. The greatest risk is electrical shock through both arms, placing your heart in the path of the electricity. Our bodies operate on minuscule voltages. Disrupting those charges that work our heart muscles is our greatest risk, not to mention, we always feel really stupid with it happens!

I remember my electronics class instructor telling us we can be killed with only miliamps of current. All it takes is disrupting our circuits, stopping our heart and we die.

So lets just settle with this. Be careful. Take extra precaution. Hold a healthy appreciation for the power this battery holds to move a vehicle at some speed. It has more than enough energy to kill you.

The plastic could work very well. Add to that a pair of dish gloves and I think you are in great shape. You could also wrap the metal socket wrench with several layers of electrical tape in case it was dropped across the battery hat. Wear some goggles to prevent eye injury. Keep one hand in your pocket so you don't expose yourself to shock risk through your heart. You get the idea.

Let's get some more pictures up eh guys?

Regards,

Ross

 

So, let's get this thing back in the car!

The attached pictures show the back seat already removed and the electrical box cover. A bunch of torx screws hold it on. First though, we have to remove the small metal cover centrally located. It exposes the safety switch that opens the circuit inside the battery pack. When this switch is off, it disables the current from flowing to the IMA controller. It makes it a lot safer to work on the battery, disconnecting the power cables from the pack. Turn that puppy off!

A word of caution... even with the switch off, you can stick your fingers in there and get a nasty shock. Let's pretend that every piece of metal around the battery is hot for safety sake. Until both "hats" have been removed and the batteries are disconnected from each other, there is risk of electrical shock and death. Please be careful handling this battery!

I also have a picture of a couple of wires in my hand with red electrical tape over the ends. This is an external connection I made to the battery pack that allows me to trickle charge the battery from a charger I built. It's a very slowwww charge that should not hurt the battery pack but allows me to do a full charge and hopefully balance the pack. More on that later.

Ross

 

Disconnect a few connectors, the battery cables... no big deal. Four bolts hold the battery pack in. Handles make it reasonably easy to remove... but it is heavy... 40-50lbs. It leaves a hole when removed. :-)

 

The pack is out! I have a couple of shots of the cable I made to charge the pack. It's wrapped in spiral wire-wrap for an extra layer of safety. The closeup shows the connection to the battery terminals. These terminals have full pack voltage even with the car key off. It allows me to trickle charge the pack. Also note the bulges in the shrink wrap next to the connections. I have two diodes in series with the connections. Diodes are like one way check-valves for electricity. They allow electricity to flow in one direction and not the other. As long as I feed a higher voltage into the pack than the pack voltage itself, I can push electrons (current) through the diodes. But the pack can't push current through the other way. That keeps the other ends of the wires safe (I wrapped them in electrical tape anyway) I intend to get a connector for the loose end. Someday.

 

So all that's left is to transfer my charging cable over to the twin battery pack and install it!

Last picture shows it installed in the car. I swear the hardest part of the whole ordeal was getting that **** seat back cushion re-installed!

I hope you enjoyed the write up! It was fun but I'm glad it's done. I have started cycling the batteries from the pack I removed. I'll let you know what I find. I'll also keep you updated on how the new pack is doing. It's early to spout MPG numbers but they look good at 44mpg so far. That makes me happy!

Regards to all,

Ross

 

Thanks rossfree for sharing the details- makes me (and many other people) feel better knowing I can always just take matters into my own hands and get the pack fixed.
Have you considered making an instructables tutorial? I'm guessing it may be pretty popular
I am also thinking of building a grid charger. Hopefully for just mildly disbalanced pack like mine, simply running a connector out from the pack without actually taking the whole battery apart, and giving it an occasional top-off charge may be enough.

 

A couple more thoughts- when you took the pack apart, was there a lot of dust/ need to clean the cooling air pathways?
And secondly, are the live battery points fused anywhere between the place you connect the wires and the pack itself? If not, maybe a small inline fuse? I am sure diodes will serve as such in some cases as well

 

Great thread! Enjoyed it from the start. Thanks for taking the extra time to show us the way. Well done, H