BMS Wires To The Front

I decided to run the 20 BMS wires up to the front box via the "tunnel" using nine feet of non-metallic 3/4" flexible conduit. There are rubber plugged holes behind the rear seat and in the front battery box that perfectly fit the water-tight connectors. The conduit has plenty of anchor points where the exhaust system would have been in the tunnel. The conduit is 3" to 4" higher than the power cables you see running under the driver's side floorpan.


I used the lower gearbox mount to attach a loose guide/clamp to keep the conduit away from the driveshaft and steering bootie. With everything exposed this was a good time to change the gearbox fluid.

Where To Mount The Charger?

I'm looking at building a diagonal mount for the Zivan NG3 charger. The manual says vertical mounting is preferred but the unit is too tall. I had it mounted horizontally last year but now the BMS needs to sit somewhere nearby so going diagonally looks like the best option. The wires will easily miss the trunk hinge and the fans/vent openings can be clear of obstructions this way.


The Hardy BMS-48 has mounting tabs on it's outer casing that exactly line up with the two stock rubber mounts from the Solectria charger. I think that's a sign telling me to use the existing rubber mounts.

Filling The Front Battery Box

I thought I'd follow Reed's advice and see how much weight I could shift to the front battery box. At this stage it's easy to try new arrangements. It turns out that 24 of these 100Ah cells will fit snugly into the stock steel front box. It was tight enough that I had to wiggle two of the packs back and forth a few times to get the last one to settle in, no pounding required. This is without any foam on the ends so there's no insulation there from the chilly winter roads or from vibration.

** Note: The arrangement in this picture is not a good arrangement because it positions two terminals right next to each other that have a fairly high voltage between them (where the big negative cable attaches). Even with insulated wrenches (mine are just wrapped with layers of electrical tape) it's best to orient things to avoid having high voltages this close together. You can guess what would happen if I accidentally dropped one of the copper connecting bars! Once I start hooking up connectors I'm planning to use a thin rubber mat over the cells I'm not working on. **

The front battery box in this configuration has 154 lbs. less than it did with the 5 big lead batteries. I wound up moving one of these 4-packs into the rear box and you can see the layout in later pictures.

Fitting the Puzzle Pieces

With all the cells in their compression plates I had to re-arrange things a little. I tried several different arrangements and this one looks like the best. The positive cable connects to the upper left, the negative connects mid-way on the left so the stock cables in the Force easily reach the terminals. The Solectria fused cable will make the jump from the middle five sets to the rear two sets. The stock battery box lid fits nicely. I'm making this lead-to-lithium switch as simple as possible.





The warming pad is under the front batteries and the little black box with the temperature control is next to the cells. I like the idea of having a fuse in the front compartment so I'm using the stock Solectria fused cable to jump between these two packs instead of using the copper bar. I reversed the orientation of the four cells on the passenger side. The pink foam sheet is easy to work with if you use a new knife blade. My local hardware stores don't stock 2" thick sheets anymore so I used 1" foam.

Learn Something New

I just learned that the prismatic LiFePO4 cells need to stay banded together with the compression plates on the ends so that they won't swell in the middle. Swelling can shorten their life expectancy. Thanks to the guys on the Solectria Drivers list I just avoided a costly mistake. So tomorrow I get to re-band some cells back into their handy 4-pack arrangements.

This means that I'll need to use that front battery box after all. Oh well, at least it's clean already :-).

Empty The Front Battery Box

Since the new lithium batteries all fit in the rear box this front box can now be empty.

With everything unplugged it's easy to remove the controller and set the A/C pump gently on the towel that protects the fender. I'm careful not to move the vacuum lines for the brake system when I set the pump assembly down on the reservoir.



BIG CAUTION HERE! - I always unhook the short wires between battery #1 and #2 first. The same thing on battery #4 and #5, remove the short wire FIRST! If you don't and instead you try to take the bolt out of the opposite end first, be ready for sparks, fire, and/or expensive replacements. The same concern applies in the rear battery box in several places.



The last picture shows that the stock cables are long enough to make a solid connection in the middle of the newly emptied front box. I coated the cable ends and bolt parts with anti-corrosive, then heat-shrink wrapped the connection. Then to make sure the connection never touches anything metal I taped and zip tied two layers of flexible foam padding around the connection. I should not need to open this front box ever again.

With 340 pounds of old lead removed the front end now sits 3/4" higher.

Let's See If They Fit

Just for fun I unhooked everything and removed the eight old lead batteries from the rear compartment. Then I placed the new 4-packs into the empty compartment. I was pleasantly surprised to find that by unstrapping three of the 4-packs I could fit all 48 of the new Thundersky 100Ah lithium cells into the rear compartment. There's even room for one or two more cells! I had expected to need to place some of the new cells in the front battery box. This all took about 30 minutes from start to finish.

I notice that Ellie's rear end now sits about an inch higher than it did with all the lead back there. When I get the five front batteries (340 pounds) removed I'll post a note of how the front height changes.

The Lithium Arrives

The crates arrived and I couldn't wait to put them into the car. I noticed that the shipping weight was about 40 lbs. more than I expected. That was partially because the new cells came strapped in stainless steel and aluminum "4-packs".

In The Beginning

I started out in 2007 with a 1997 Solectria Force that had a dying AGM (lead/acid) battery pack. I replaced the thirteen 12 volt AGM's with thirteen new AGM batteries. The new batteries only lasted two years because I was using about 50% of their available energy to climb a 2,700' high, 16 mile long hill to get home. The leisurely 16 mile uphill drive took about 30 minutes. This was apparently too hard on the lead/acid batteries, even with a full charge.

In January of 2010 I removed the 884 pound lead battery pack and replaced it with a 350 pound LiFePO4 pack that has more available energy.