Installation report: 2x 100 Ah lithium batteries in the Sunlight Cliff 540 Camper
Installation report of two Supervolt 100 Ah LiFePO4 batteries in the Sunlight Cliff 540 model year 12/2020 Ducato, which was provided to us by our customer.
Guest article: Installation of 2x 100 Ah LiFePO4 batteries in the Sunlight Cliff 540 camper
Our customer Mr. Rohark has sent us a field report on the installation of our 2x 100 Ah Supervolt LiFePO4 battery set in his Sunlight Cliff Camper. In this article, he explains the details of the installation and what to look out for when converting.
Table of contents
Vehicle equipment Sunlight Cliff 540
- 2 x Varta AGM LA95Ah
- EBL 31 from Schaudt (under the driver’s seat)
- Solar system 100W with Büttner charge controller MT230PP (behind the EBL 31)
User behavior
- Mainly long weekends (Thu-Sun) self-sufficient with approx. 200-500 km driving distance
- Occasional longer trips, then on camping sites or pitches
Reason for converting to lithium batteries
After more than 4 years, the two AGM batteries reached their limits during a long weekend with heating operation (Truma) and dropped to 50%. (Truma was running and there was no sun)
Preparation
- Fully charge both SX 100Ah lithium batteries,
- give the BMS time to detect the state of charge,
- Pair the app with Bluetooth.
- If you have to work outdoors like me, you should choose a sunny day.
- Have tools ready,
- a helper on call (the front passenger seat is easier to lift out of the vehicle with two people),
- Consider clean storage areas for screws and trim parts.
- Remove the ignition key and put it aside.
- Disconnect shore power!
- Switch EBL 31 to lead/gel (see operating instructions)
- Remove the fuse from the solar charge controller and set the charging characteristic to LiFePO4 (see operating instructions)
- Remove all four trim parts from the base of the front passenger seat (be careful! the gray plastic parts are sensitive to scratches)
- Remove the fuses from the body batteries. In my case 1 x 10A, 1 x 2A, 1 x 40A
I removed the seat and swivel console separately as they were too heavy together.
- Move the seat and loosen the 6 screw connections,
- Move the backrest slightly forward.
- The front screws can only be loosened with the bit positioned at a slight angle, possibly place a cloth between them to protect the plastic of the seat.
- Disconnect the belt tensioner plug connection,
- I cut the seat ground cable and re-routed it before reinstalling it.
- If you want to retain the seat ground cable, you may have to remove the seat together with the swivel console, otherwise the cable will not be exposed due to the installation.
- Call helpers,
- Carefully lift out the seat (watch out for the belt tensioner cable) and put it down.
The rotating console is now freely accessible.
- Remove all 4 screws from above,
- Remove the nuts of the stud bolts from below. (Ratchet with 13 mm socket)
- Loosen the stop bolt with hexagon SW 20 and remove upwards through the opening.
- Lift out the swivel bracket and put it down.
Attention! The voltage of the batteries is still present at the battery terminals!
The two AGMs stand on a molded base plate, with a folded bead at the front, a steel bridge on threaded rods between the two batteries and two brackets holding the battery from behind.
- Unscrew the rear brackets and twist them slightly to remove them completely.
- Remove the battery terminal covers and disconnect all 4 terminal connections and carefully set them aside one by one.
- I wrapped them with cleaning cloths to avoid accidental contact.
- Only now loosen and remove the steel bridge.
Note:
With the introduction of our new battery series at the beginning of October 2025, the SE series models no longer have RJ45 interfaces to external devices (e.g. Victron, Truma iNet, etc.), as these are not required by all users.
Due to the elimination of these interfaces, we can no longer offer the SE seriesat a lower price with immediate effect.
The PRO series however, still has the corresponding interfaces.
>> Discover our LiFePO4 SE batteries directly in the online store <<
Replacing AGM batteries with LiFePO4 batteries
- The batteries jam slightly, lift out the rear one first and put it down.
- Then lift out the second battery. (Now comes the aha moment in the weight comparison with the SX-100 😉
- The compartment is free and can still be vacuumed or cleaned if necessary.
The SX 100 are slightly shorter and fit well in the compartment. Make sure that the positive terminals are in the same place as those of the AGM batteries. The wiring was flawless and was left unchanged.
The pole terminals can now be fitted and tightened one after the other. Check the insulation of the cable eyelets and the tightness of all screws. I fixed both carrying handles of the SX 100 with some tape, which is only intended to prevent rattling in the event of vehicle vibrations.
During the conversion, the decision was made to retrofit a 300W inverter. The two cables of the inverter were attached to the connection poles with cable eyelets and M8 screws.
Observe torque!
Function test
- Reinsert the 3 body battery fuses and take a look at the control panel.
- Switch on the on-board power supply,
- Voltage is displayed as 12.3V.
- Then plug in the fuse of the solar charge controller and observe the start of charging on the control panel. The day was sunny and after 2 hours both batteries showed 100%.
- The voltage on the control panel showed 13.5V.
- Test of the inverter: the load from the inverter can be easily read in the Supervolt app.
Once all the cables have been properly routed and secured, the battery terminal covers are fixed in place and the installation of the passenger seat can begin.
The black ground cable between the seat and the swivel console is intended to dissipate static charges from the seat. I attached it to the seat console when I reinstalled it. The hole was already there, remove the paint with some sandpaper and fasten the cable lug with an M6 screw.
Plug the belt tensioner cable back in, fit all the covers, check between the seat base and the swivel console, there should still be enough space between them, even during the swivel movement… done!
Note on the conversion itself
At 12V, we speak of low voltage, which is not dangerous for humans. However, batteries supply a very high short-circuit current, and an accidental short-circuit of the battery terminals can lead to an electric arc and melting of the conductor causing the short-circuit. This is dangerous!
Metal bracelets, finger rings and free-hanging necklaces should be removed during the conversion.
Reversing the polarity, i.e. reversing + and -, can cause damage to the device. Wires and cables should not be laid across sharp edges, as vehicle vibrations can wear through the insulation of the conductors over time and cause short circuits.
It is commendable that the manufacturer Sunlight has fixed everything that can vibrate and that cables that run close to metal are protected with self-adhesive felt or cable protection tubes.
There are various manufacturers of swivel brackets, you should find out the tightening torque of the fastening screws of your swivel bracket and tighten the screws to the specified torque.
Some manufacturers also recommend securing the screws with a locking lacquer, such as loctide.
The conversion is not “witchcraft”, basic knowledge of electrical engineering and a practiced handling of tools should be available.
Conclusion after two long weekends with normal use
Batteries each 98% on departure, 100% on arrival
Heating for 1 hour in the morning, satellite TV, TV, cell phone and tablet recharged.
1 x e-bike battery charged and 1 day home office with laptop on charger.
The Supervolt app displays the data from the BMS, the capacity displayed is an estimate!
On departure after 3 nights of self-sufficiency, the batteries were each at 63%. After approx. 4 hours of driving (according to the app, charging was done with 22A from the alternator), both batteries were full again on arrival. The app’s capacity display is therefore quite useful.
The conversion was a success for our usage behavior, we can now stand self-sufficiently for 5 days without hesitation.
R. Rohark
05 / 2025
👉 You can access our LiFePO4 SE batteries in the online store here
Acknowledgments
We would like to take this opportunity to thank our customer Mr. Rohark for the great contribution! By publishing these instructions, we hope to be able to help you replace AGM batteries with our lithium batteries in the Sunlight Sunlight Cliff 540 model year 12/2020 Ducato.
With the new battery, nothing stands in the way of your next vacation. We wish you a safe journey and unforgettable trips.
If you are also planning to convert your vehicle yourself, please write to us ([email protected]). We will be happy to give you a discount on the purchase of your battery for a report.
Supervolt LiFePO4 batteries and accessories
You can find all our LiFePO4 batteries in our store. Whether for motorhomes, boats or solar systems – our batteries can be used anywhere.
You can also find suitable installation accessories such as solar regulators, charge boosters and inverters directly from us:
