Lithium battery in VW bus – installation in T4 California Coach model year 97
This article describes step by step how the living area supply of a VW T4 California was converted to a lithium supply, which electronics were installed and what needs to be taken into account.
Guest article by Florian:
This article describes step by step how to convert the living area supply of a VW T4 California to a lithium supply was converted. In October 2021, the Supervolt lithium battery will be put through its paces on a one-month road trip through France, Spain and Portugal and reported on.
The VW T4 California is already fitted with camper van equipment ex works. The consumers requiring power ex works are the 3.5 A compressor refrigerator, the auxiliary heater, 2 fluorescent lamps in the interior and a reading lamp in the pop-up roof. The existing wiring can be used for the installation.
Both Supervolt Lithium batteries (100 Ah or 150 Ah) fit into the battery compartment of the VW T4 California, so you can decide which size you prefer. Next to each other fit two Supervolt lithium batteries only in the version of the VW T4 Californias that do not have a gas container next to the battery compartment.
The installation time was approx. 3.5 hours
Note: The installation/conversion was carried out by a hobby craftsman to the best of his knowledge and belief. We recommend consulting an electrician if you wish to rebuild the system. The supply and starter battery were disconnected in advance for all electronic work. No liability is accepted for any reproduction.
Introduction
It should be noted in advance that the installation described here is aimed at self-sufficient camper behavior. This means that without the use of shore power, the consumers in the California can run for 5-7 days. and then only be driven for 2-3 hours (depending on battery size) to keep the Supervolt lithium battery fully charged again with an optimum charging characteristic. For this desired usage behavior and maximum service life of the Supervolt Lithium battery it makes sense to additionally use a charge booster/charging converter.
This is because the supply battery in the VW T4 California is connected in parallel to the starter battery at the factory and both a gel supply battery and the Supervolt lithium battery are never optimally charged by the alternator alone while driving. In addition, you would have to drive significantly longer than 3 hours to charge the supply battery halfway full without a charging booster if the charging characteristic is not optimal.
In other words, it is not desirable to connect the vehicle to shore power for 24 hours once a month to ensure that the battery is optimally maintained. There should also be no dependence on shore power during vacation trips.
The T4 California has a 13.8 A charger installed ex works, which charges the supply battery via a shore power connection. As no shore power is required for the camper behavior described here, the existing charger is not replaced, but will no longer be used in the future. Whoever uses the Supervolt lithium battery with shore power, you will need a new charger for LifePO4 batteries for the optimum charging characteristic and maximum service life of the lithium battery. charger for LifePO4 batteries.
Required accessories and material
- Supervolt Lithium battery 100Ah or 150Ah
- Votronic charging booster VCC 1212-50 with temperature sensor
- 4 x wood screws for charging booster
- 2 x high-current fuse holder
- 1 x 60 A blade fuse
- 1 x 80 A blade fuse
- 3 x tubular cable lug 16 mm²
- 2 x tubular cable lug 25 mm2
- 1 x 50 cm cable 16 mm² in black
- 1 x 40 cm cable 25 mm2 in red
- 1 x 40 cm cable protection for 25 mm² cable
- 30 cm heat-shrink tubing with internal adhesive
- Tools: crimping pliers, lighter, cutter knife, drill, insulating tape, cable cutter, screwdriver, ring wrench
Circuit diagram
To begin with, the installation is outlined using the wiring diagram of the VW T4 California (see next picture). However, the wiring diagram differs from the converted California in one respect, namely that the wiring diagram shows two supply batteries instead of one, as there are, as already described, two variants of the VW T4 California.
The circuit diagram shows that 2 x 10 mm² cables are connected from the starter battery to the cut-off relay, which mechanically ensures that current only flows from the starter battery to the supply battery when the vehicle is in motion. If the engine is off, the cut-off relay interrupts this current flow and the starter battery is not discharged by the supply battery. The cut-off relay uses the D+ cable to detect when the engine is on and when it is off. You can also see that a 16 mm² cable runs from the cut-off relay to the supply battery. An earth cable runs from the supply battery to the earth point on the wheel housing.
Of course there are many charging boostersthat are suitable for installation. To find the right charging booster 3 parameters are decisive:
- The recommended maximum charging current for the Supervolt lithium battery is 50 A
- The alternator installed in this VW T4 California has an output of 120 Ah.
- The cable cross-sections installed ex works.
The cable cross-sections are 2 x 10 mm² (i.e. 20 mm²) and 16 mm².
The “thinnest” cable is the 16 mm² cable, which is the limiting factor for the maximum number of amperes that can flow through. According to the installation instructions for the charge booster, the cable cross-section of 16 mm² is completely sufficient for a 50 A charge. As the output of the alternator still provides enough amperes for the starter battery when the supply battery is charged to 50 A and the cable cross-section allows it, a 50 A charging booster is chosen. This should charge the 100Ah Supervolt lithium battery in 2 and the 150Ah in 3 hours, which is a sufficiently fast charge for the desired camper behavior. In addition, the charging current is not too high in terms of optimum maintenance of the lithium battery.
The next picture shows the modified circuit diagram including the sketched installation with only one supply battery (instead of 2). The 2 cables from the starter battery to the supply battery are secured close to the starter battery with an 80 A fuse. The cut-off relay is protected by a 50 A charging booster replaced. The blue D+ cable is connected to the charging booster The black/red cable, which is connected to the plug with the D+ cable, is disconnected (red X in the circuit diagram). The charge booster only requires the D+ cable for disconnection, unlike the factory-fitted disconnect relay. An additional earth cable is laid from the charge booster to the earth point on the wheel housing. Officially, this earth cable is connected to the negative terminal of the lithium battery is connected. As the lithium battery gets the earth from this earth point and the earth point is located directly next to the built-in charging booster, the earth cable can be connected directly to this earth point.
The 16 mm² cable leading from the charging booster is secured with a 60 A fuse just before the lithium battery.
Important: The ampere values of the blade fuses used here are the specifications for the Votronic charging booster VCC 1212-50. Another charging booster with a different charging current may have different blade fuse values. Therefore, please always refer to the installation instructions for the charge booster used!
Installation
So much for the theory. Now the practice begins:
First, push the bench seat as far forward as possible. Now remove the rear shelf cushions and the storage shelf. In the next picture, all the screws that need to be loosened to access the supply battery and the cut-off relay are marked with arrows.
The gas cylinder is located in the left-hand compartment, the supply battery in the middle compartment and the cut-off relay (arrow 1), the shore power charger (arrow 2) and the refrigerator compressor unit (arrow 3) in the right-hand compartment.
In the next picture:
Arrow 1 the plug with the blue D+ cable and the black/red cable that is laid dead
Arrow 2 the 2 x 10 mm² cables from the starter battery
Arrow 3 the 16 mm² cable to the supply battery
Arrow 4 Ground point on wheel housing
Attention! Important!
Before working on the electronics, the supply and starter batteries must first be disconnected. First minus, then plus.
In the next picture, the cut-off relay has been unscrewed and the gel battery has already been replaced by the Supervolt 100Ah lithium battery replaced. Due to the different size, it is easier to estimate where and how things need to be positioned later when the battery is already in place.
Now the 60 A fuse just before the Supervolt lithium battery is installed. To do this, sufficiently unwind the black tape that wraps all the cables and cut the 16 mm² cable approx. 10-15 cm in front of the battery with pliers.
The cable is stripped and the tubular cable lug is attached. The tubular cable lug is then crimped using crimping pliers.
The heat-shrink tubing is attached to the cable and heated with a lighter so that the cable is optimally insulated. A heat-shrinkable sleeve with an internal adhesive was specially used for the installation, as the connection achieves a high degree of tightness and durability thanks to the adhesive.
Once the tubular cable lugs and heat-shrink tubing insulation have been attached to both ends, the cable ends are connected and screwed tight in the next step using high-current fuse holders and 60 A blade fuses.
The remaining cables are wound together again.
In the next picture, the ground point with the factory-connected ground cable of the supply battery is clearly visible (arrow 1).
The approx. 50 cm long black 16 mm² cable is fitted with a tubular cable lug and heat-shrink tubing as described above and connected to the earth point in the next step.
Now remove all cables and the D+ plug from the cut-off relay.
The D+ cable is cut just before the plug.
The plug is generously wrapped with insulating tape and is thus rendered dead. It can be put back in the compartment somewhere where there is space.
The 2 x 10 mm² cables and the 16 mm² cable are separated from their cable lugs using pliers.
Now strip the insulation from the 2 x 10 mm² cables, the 16 mm² cable and the D+ cable at the front.
Arrow 1 shows the 2 10 mm² cables connected with insulating tape to the input of the charging bosster.
Arrow 2 shows the 16 mm² cable connected to the output.
Arrow 3 the earth cable that connects the charging booster to the earth point of the wheel housing.
In the next picture, the D+ cable has been connected to the designated point on the charging booster (arrow 1) as well as the 2 cables of the temperature sensor supplied with the charging booster (arrow 2). It is used to monitor the temperature of the Supervolt lithium battery.
Now connect the temperature sensor to the negative battery terminal of the supply battery (arrow 1).
Mark and drill the 4 holes for the mounting screws of the charging booster.
The charging booster can now be mounted on the wall.
Continue with the starter battery. The 80 A fuse must be installed here. To do this, unscrew the 2 x 10 mm² cables (arrow 1).
Heat-shrink tubing is fitted over both cables together. The high-current fuse holder is fitted with an 80 A blade fuse.
As 2 x 10 mm² run together in the fuse holder, at least the same cable cross-section should run out. 16 mm² would be too small, which is why a 25 mm² cable (approx. 40 cm long) was prepared with tubular cable lugs and heat-shrink tubing.
The cable is screwed to the high-current fuse holder and the battery terminal of the starter battery.
A cable protector is now placed over the newly attached cable and the starter battery can be reconnected. First plus then minus.
The Supervolt lithium battery is connected. First plus then minus.
The lithium battery is put back into position and tightened with the factory-fitted tensioning strap.
The engine is started and the charge booster lamps are checked to see if they are working.
Everything works wonderfully!!!
The Supervolt lithium battery indicated via the app that it was 44% charged (44 Ah) before installation. After installation, the car was driven for 40 minutes for test purposes to see whether the battery charge was working. After the drive, the Supervolt app already showed a charge of 77%, which means approx. 72 seconds per 1 Ah charge. In other words: approx. 120 minutes of driving to charge the Supervolt lithium battery 100 Ah after a complete discharge.
In the next picture you can see that the volt display of the Supervolt app differs from the volt display of the Westfalia control panel by only 0.05 V and is therefore very accurate (14.05 V vs. 14.1 V). You can also see that charging takes place at 49.1 A and that the charge booster therefore does its job. When the phone is attached to the windshield, the signal strength of the Bluetooth connection is 91/100 despite the fact that there is no connection between the phone and the charger. Supervolt lithium batterya wooden wall and the sleeping/seating bench.
Overall, these are very promising results.
As described above, the conversion to the Supervolt lithium battery will now be put through its paces on a one-month road trip and the findings will be reported here in the coming weeks:
Conclusion after the trip
Many thanks to Florian for the detailed report! We wish you always nice trips and enough power 🙂
Lithium batteries and accessories
In our store you will find the complete selection of LiFePO4 batteries – ideal for motorhomes, boats or solar systems. Thanks to their versatility, our batteries can be used reliably in a wide variety of applications.
Suitable installation accessories such as solar controller, charging booster or inverters are of course also available directly from us – for a perfectly coordinated system from a single source.
