100W panel for charging chassis battery

[zeekwad]

Hi all, my Interstate 24X has a 100W panel dedicated to topping off the chassis battery. But, often when I get into the van after a couple weeks of sitting, the Mercedes indicates that the battery is low (and that the engine should be started). What is the best way for me to check that the 100W panel Airstream installed for this purpose is sending wattage to the MB battery?

Thanks in advance!

Z

[StogieMan]

I'm not sure how the solar panels are set up on the 24X roof but if the chassis solar roof panel has an entry gland for itself - remove it and test the solar panel there or through the MC4 connectors.

If not, then you can test it at the SolarMinder. Remove the wires from it and test it there. I kinda copied their setup but also installed an inline fuse/circuit breaker before the SolarMinder and can test mine here. I believe that they also have one somewhere but sometimes they're built into the back of the solar panel and that won't help you.

Your SolarMinder should be located either underneath your drivers or passenger seat as this is what others have said and what the diagram says but again this is Airstream and they can put it anywhere.

However, testing near the SolarMinder would be better as you know that you have power all the way to it and no issues in between which would be a PITA to find. You can also test the wire going to the battery from the SolarMinder if they marked it though.

[zeekwad]

Originally Posted by StogieMan

I'm not sure how the solar panels are set up on the 24X roof but if the chassis solar roof panel has an entry gland for itself - remove it and test the solar panel there or through the MC4 connectors.

If not, then you can test it at the SolarMinder. Remove the wires from it and test it there. I kinda copied their setup but also installed an inline fuse/circuit breaker before the SolarMinder and can test mine here. I believe that they also have one somewhere but sometimes they're built into the back of the solar panel and that won't help you.

Your SolarMinder should be located either underneath your drivers or passenger seat as this is what others have said and what the diagram says but again this is Airstream and they can put it anywhere.

However, testing near the SolarMinder would be better as you know that you have power all the way to it and no issues in between which would be a PITA to find. You can also test the wire going to the battery from the SolarMinder if they marked it though.

Thank you for this! You're a great contributor of knowledge to the forum.

In your experience, getting to the items under the seat requires removing the seat, yeah?

[StogieMan]

Unfortunately yes. I think that even if you could see it and access it from the side seat base panels for the fuses and awning, it would probably be too tight to do any work around it.

The one thing to remember when removing the front seats is to disconnect the battery disconnect near the gas pedal area and wait about 15 minutes before disconnecting the cables to the seat(s) or you can get an error code when you plug it back in and you’ll need to schedule a trip to the Mercedes dealer to get it cleared. When you’re done and going to connect the wires again, first connect them back and then reconnect the battery.

Actually, the battery area might be easier but you’ll probably need to chase the cables back to the SolarMinder if not marked. I think that your unit also has a regular BatteryMinder connected to it too. If you do have a regular BatteryMinder as well and disconnect this one by shutting off shore power, you’ll know which one is the SolarMinder one at the battery as if it’s working correctly, you be able to detect voltage there.

A nice set of Torx star sockets/bits and screwdriver sets are necessary tools in the tool bag when owning a Sprinter van as they come in handy. The Torx sockets are very handy when removing the seats.

Hope this helps.


CASOMAN 11 PC Female E-TORX Star... https://www.amazon.com/dp/B07JFJD53J...p_mob_ap_share

Anytime Tools 11 pc 5-Point Star... https://www.amazon.com/dp/B0026WMIV4...p_mob_ap_share

NEIKO 01377A Magnetic Torx... https://www.amazon.com/dp/B09LZ9J2DM...p_mob_ap_share

[wulfraat]

I have 200w on the camper shell of my pickup truck for keeping the 2 chassis batteries charged.

The best way to tell if it’s working is on a sunny day, turn off the vehicle, pop the hood (or maybe your chassis battery is under the seat in the sprinter I forget) and put a volt meter on your battery and you should see 13.2-13.6 volts coming from the panel.

If it’s only 12.8-12.9 volts or less then the panel is not sending a charge or there is a disconnect switch in the system somewhere.

[DavePDX]

We bought a 2022 Interstate 19 in August, which only had a 50 watt panel to charge the chassis. From day 1 the chassis battery showed between 12v and 12.5v, regardless of how much is was driven, and on a couple of occasions, after sitting for 5 - 10 days, Mercedes Me would give a "partially charged" warning. Both Mercedes and Airstream claimed there was nothing wrong, but since we don't drive the vehicle regularly, it made me a bit uneasy.

I finally decided to add an additional 50 watt panel, and the difference ever since has been night and day. The battery now always shows between 12.5v and 14.38v.

Even without a battery tester, I can look at the CZone Monitoring, and see the chassis voltage increase significantly (when there's some sun) between early morning and noon.