Installation report: Supervolt Polar 200Ah in the Knaus Sun TI 700
In this detailed installation report, our customer Mr. Hermeling shares his experience of installing Supervolt Polar 200Ah LiFePO4 batteries in the Knaus Sun TI 700 motorhome.
Find out how to replace the AGM board batteries in a Knaus Sun TI 700 with 2x 100Ah Supervolt Polar LiFePO4 on a Knaus Sun TI 700.
A big thank you goes to our customer Mr. Hermeling, who created and provided us with this very good and detailed installation report.
Note: No guarantee can be given that the following installation instructions are correct. The installation described should be carried out or checked by a qualified electrician.
Initial situation
The SUN TI 700 (year of manufacture 2020) was delivered from the factory with two 95 AH AGM batteries. Although the energy consumption has so far been limited, we were concerned about how the AGM batteries would behave in winter operation. In addition, the installation of an inverter was planned. So the decision was made to switch to LiFePO4 batteries batteries.
Why Supervolt?
The first decision to be made was between a 150Ah or two 100Ah batteries had to be made. In the end, we opted fortwo 100Ah in the Polar version. On the one hand, the two smaller batteries give us more power and the advantage of double the continuous current draw. Secondly, in the event of a fault, two batteries (and therefore two BMS) would provide greater reliability. However, as I am already convinced of the quality of the Supervolt anyway, the above-mentioned arguments are probably more to “calm the stomach”.
Comparing the technical data with the known competitors repeatedly led us to Supervolt. The heating, active balancing and 5-year warranty were particularly important to me. In addition, the price is reduced when you buy two batteries – I don’t know of any other provider that does this.
I find the transparency and access to information very good: all questions that may arise about LiFePO4 batteries are already answered comprehensively on the website. Even when I had questions, Mr. Bauer always responded quickly and in detail. The delivery of the two well-packaged Supervolt Polar batteries were delivered within two days of ordering. We are therefore also impressed with the nature and speed of the service.
Note:
With the introduction of our new battery series at the beginning of October 2025, the POLAR 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 POLAR series can now be offered at a lower price.
The PRO series however, still has the corresponding interfaces.
>> Discover our LiFePO4 POLAR batteries directly in the online store <<
Configuration/Overview
Replacing the batteries is easy with a little technical knowledge. However, there are a few things to bear in mind: The charging components installed in the Knaus SUN TI 700 are already suitable for Supervolt operation, but must be converted accordingly. Specifically, these are the following devices, which I will discuss in detail later:
- Schaudt booster WA 121525
- Dometic MCA 1225 charger
- WCS Solar Controller SR 12-20
As the installation of a Dometic 1800W inverter is planned, the cross-section of the cabling must be increased in this case. However, this step is not necessary if the batteries are replaced 1:1 and the power consumption is the same.
In addition to increasing the cross-section to 50 mm2, a battery isolating switch, a measuring shunt, a main fuse corresponding to the cable layout and new plus and minus distributors are installed. The existing installation is then connected to these distributors.
The following overview shows the configuration:
Necessary tools
A socket wrench set or even just the appropriate open-end wrench is sufficient for simply replacing the battery. The extension described here also requires the following:
- Screwdriver
- Hot air gun
- Crimping pliers for tubular cable lugs
- Cable shears
- Stripping knife
Necessary material
It is essential to pay attention to the quality of the material used. This is particularly noticeable with fuses and cable lugs: Cheaper versions simply lack material or contact surface, which can lead to problems during installation and later operation.
Example: 200A high-capacity fuse – comparison of two different versions/qualities:
The following material was used for installation:
- Hella battery terminals M10 bolt
- Battery disconnector BEP 600A (alternatively Victron Energy 275A)
- Mega Fuse fuse holder
- Mega Fuse 250A and 200A fuses
- Busbar 300A red
- Busbar 300A Black
- Tubular cable lug 50mm2( Klauke or brand manufacturer)
- Insulating hose red and black
- Cable ties
- Screws for fastening the components
- Victron 500A/ 50mV Smart Shunt
- Cable FLY 50mm2 red and black
The implementation
1. Establish the same charging level for the batteries
Before installation, the batteries must have the same charge level. If you do not have an external charger available, I recommend first connecting one battery in the motorhome and then alternately connecting the second battery. This way, each of the Supervolt batteries batteries are charged individually before being connected in parallel.
We used the NOCO Genius 10 charger:
2. choice of installation location
In the Knaus SUN TI, most of the technology is housed under the seat bench. The batteries are located in an external compartment. Both compartments only offer limited space.
Despite the confined space in the battery compartment, the compact DIN size of the Supervolt batteries it is no problem to store them there.
Existing installation in the Knaus SUN TI 700:
3. connection
A direct connection to the battery would be possible for the inverter.
However, the clearer – but also more complex – solution is to lay a connection from the battery to the main fuse and to the distributors. This makes further subsequent installations easier.
This extension is fitted in the compartment under the seat bench directly next to the factory-fitted technology.
The individual components were installed on a mounting plate. This makes mounting in the motorhome easier and ensures fewer screw holes in the original furniture panel.
Installation of the mounting plate under the seat bench:
4. expansion of the existing batteries
The next step is to remove the AGM batteries. 56kg leave the motorhome!
The original connection cables can be seen in the top corner of the battery compartment. These lead to the main fuse and the main switch (Knaus) under the seat bench.
The following individual steps are necessary:
- Remove the main switch and disconnect the cables.
- Carefully pull the main fuse of the body with the cables back into the battery box.
Now the connections with the fuse holder can be pushed through an existing gap in the footwell of the seat bench.
We have an ALDE radiator installed in the space between the pipes – don’t worry, there’s enough distance to the pipes!
The original cables are exactly the right length to connect them to the distributors.
In the picture, the main cable FLY 50mm2 has already been laid and connected to the battery.
The batteries must be connected “crosswise”! A corrugated tube was also used as protection for the cable feed-through.
As the 100Ah Supervolt batteries is 35 mm shorter than the 95Ah AGM battery, an additional profile rail had to be screwed into the battery box. This ensures that the Supervolt is also securely fastened:
I changed the arrangement of the measuring shunt and negative distributor slightly so that the longer negative cable could be shortened. The installation is as good as finished. The labeling of the fuses, switches etc. is still missing.
Charging voltage
The charging voltage must be adjusted on the following three devices:
Schaudt booster WA 121525
The charging voltage is switched to lithium using the microswitch (charging voltage 14.4 volts).
Dometic MCA 1225
There are four small microswitches on the top left of the front. Switch 4 switches the charger fan to sleep mode. This has no effect on the charging voltage, but the charging power is reduced when the switch is set to “ON”.
For a charging voltage of 14.4 volts and a float voltage of 13.8 volts, the following switch position should be used:
Switch 1 | Switch 2 | Switch 3 | Switch 4 |
ON | OFF | OFF | OFF |
(Image source: Dometic)
WCS Solar Controller SR 12-20
The settings for the LiFePO4 battery can be made directly on the charge controller or via the WCS APP. In addition to the charging voltage, additional settings must also be made.
Setting changes via the charge controller:
…
Settings changes via the APP:
- Connect with controller and press the small “+” at the top right.
- Select Administrator and enter the personal password. (I do not know the standard password, but can be requested from the installing company).
The settings can only be made under the User-defined battery type. I recommend removing the fuse from the solar system before making the settings. Although this is not absolutely necessary, it prevents possible effects in the event of an incorrect entry.
The settings can be changed directly in the input field. Important: Do not use the comma, but the dot as a separator for the decimal places.
After changing the values, tap on Set to save them.
Then close the app and reopen it. To read out the saved values, tap Read and check the values. Correct the settings if necessary.
Conclusion
In summary, it can be said that simply replacing the batteries can certainly be carried out in approx. 1 to 2 hours with a little manual skill. Due to the confined space in the battery box of the Knaus SUN TI 700 – caused by the operation of the inverter and the associated need to upgrade the supply cable to 50mm2– the Supervolt batteries can be advantageous due to the reduced depth. There is simply more space for the thick cable bridges in the rear area.
The Supervolt APP is well designed and offers all the information you need.
Everything else will become clear during operation.
Did I miss something? Yes, a little something 😉
Once the batteries have been installed, unfortunately only the black side panel is still visible. It’s a shame, because I think the Supervolt “presentation” is pretty well done.
Many thanks to the entire Supervolt team for their prompt and competent advice!
Supervolt LiFePO4 batteries and accessories
In our store you will find all our LiFePO4 batteries. Whether for motorhomes, boats or solar systems – our batteries can be used anywhere. Suitable installation accessories such as solar regulator, charging boosters and inverters are also available directly from us.
Acknowledgments
A big thank you to Mr. Hermeling for this really detailed and comprehensive report! We hope that by publishing these instructions we can help many travelers to convert to lithium.
We wish Mr. Hermeling a lot of fun with the new batteries and always beautiful trips with the motorhome!
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.
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