Charging

Charging is arguably the toughest part of an EV build to do right. It’s critical to the safety and usefulness of the vehicle. Without human intervention the charger must evenly and accurately charge the expensive batteries- failures can result in expensive damage to the pack or even fire. In building this car I took a couple of different approaches to the charging equation. From the beginning of the project I planned to use the Manzanita Micro PFC-20 charger. When I planned the project and was purchasing parts Manzanita Micro was not doing a good job supplying their line of “rudman regulator” balancers. At that point it seemed there were no good balancer options on the market- so I elected to build my own. It turned into a semi-functional but deeply flawed system- an expensive but very educational experience. The car runs now with a Manzanita Micro MK3 Lead regulator system. The charging system is composed of multiple parts- so I will describe it in sections.

Cords/Inlet

I followed the traditional route of concealing the charge inlet behind the original fuel filler door- I searched for a nice connector to use- people often use NEMA twist-lock standard connectors of various flavors- but they’re usually code-specified to be used with circuits of a certain voltage and amperage, or in 120/240 split systems with certain rails on certain pins- since none of these standards really fit the charge requirements of the EV (100-250V, 20A) I prefered not to mis-use a standard connector (even though in service it would work fine.) I picked a connector from Neutrik- the PowerCon 32. Neutrik PowerCon connectors are used in the entertainment industry for stage lighting and audio equipment. The ’32 version is a larger 32 amp rated model. They’re not rated for make/break of the circuit under load (although neither are most connectors)- but have proven to be very durable. For the quality and nice fit and finish of the connectors they’re not too expensive- (at time of purchase $10 for the panel-mount side, $18 for the cord-mount side)

  

The “main charging cord” is a 12 foot long piece of 10/3 SO cable connected with a waterproof strain relief to a plastic junction box which contains a 4 hour mechanical countdown timer, a small “wall wart” SMPS and a good sized power relay. The timer switches AC power to the wall wart which feeds the 12V coil of the relay. The relay breaks the circuit to the car. This serves as the “last line of defense” against failures in the charging system causing major damage or fire.

I removed the cable-pull fuel door release in favor of a magnetic cabinet-door style latch, which while light duty has lasted fine and is more convenient. The connector is held in a big piece of aluminum I turned- it’s super over-kill but it’s a nice touch for a special user-interface part of the car.

Under the inlet a short length of 10/3 SO cable runs to a plastic box which has a panel mount PowerCon connector that the charger plugs into and a triple-tap receptacle cord-end wired in parallel. I use the extra receptacles for the power supplies that run the fans for the battery regulators. Everything is suitable for use at either 120V or 240V with no reconfiguration required.

  

Charger

The charger is a standard Manzanita Micro PFC20 charger. I fitted the AC inlet with a PowerCon connector, the output uses a gray Anderson SB50 connector to connect to a set of 8GA wires that run to the front of the car where they are attached to the main battery positive and negative through a 20A fast-blow semiconductor-protection fuse.

The charger is mounted to a 1/4″ thick aluminum plate which is bolted to the floor of the trunk. I turned pegs that fit through the mounting holes in the charger and welded them in the correct locations to the plate- then a piece of nylon webbing strap is captured under the plate and fitted with clips that allow the charger to be strapped onto the plate and removed with no tools.

Battery Regulators

Currently the car is running a set (12) of Rudman MK3 Lead regulators. They’re mounted to aluminum plates which are bent to fit under the battery hold-downs and hold the regulator above the battery. Each reg is connected to the battery with short 14GA cables and Anderson PowerPole connectors to allow easy disconnection. The inter-reg connections use flat phone wire and 6-pin RJ12 plugs. The run front to back in the car uses a piece of CAT-5 cable. The Rudman Reg/PFC charger system seems to work OK but I am not entirely happy with it. The regs require a borderline absurd amount of forced air cooling during regulation otherwise they will shut down. The regs are complex and physically enormous. The modular RJ-12 plugs are not completely reliable and not at all resistant to corrosion. Most annoyingly, during the regulation phase the regs command the charger to provide a rapidly fluctuating output current which causes the lights in the house to flicker unpleasantly. But- it works. And combined with the mechanical countdown timer on the main power it’s pretty trust-worthy and unlikely to burn the house down.

At the time I decided to install the Rudman Regs I also considered buying a set of twelve small Soneil 12V chargers to individually maintain each battery. The downsides to this approach are lack of intercommunication and some reports of unreliablilty stemming from insufficient isolation in the chargers to deal with the large potential from one end to the other of the series battery string. If I were to do it again, knowing the shortcomings of the Rudman Regs I would likely take a closer look at this option.

I installed the regs with right-angle “flag” style faston terminals to minimize height. A total of about 150 watts worth of squirrel cage blowers and high powered computer fans keeps the regs functioning.

  

  

  
A chronicle of my own battery regulator project is here.