Solar panel and battery status display

[jens.zollhofer]

Hello Campers

Because we often camp for one or two weeks on a beach in New Zealand I have connected a solar panel and controller to the leisure battery in the back cabinet of the T5 SE. We only run the fridge (and sometimes the electric sliding door, and minimal lighting). According to my math, the solar panel should generate more power than what we use. However, the battery status display above the mirror indicates that the battery (or better both batteries, I trust they're wired parallel) is steadily draining 10-20%. On day 4 (battery: 40-50%) I get nervous because I don't want to ruin the two new batteries.

I start the engine - and the display shows battery: 100% (whiskey, tango, foxtrot)??!!

Has anyone else experienced similar nonsense? What am I missing here? Which reading is correct?

 

[Azteccamper]

Hello Campers

Because we often camp for one or two weeks on a beach in New Zealand I have connected a solar panel and controller to the leisure battery in the back cabinet of the T5 SE. We only run the fridge (and sometimes the electric sliding door, and minimal lighting). According to my math, the solar panel should generate more power than what we use. However, the battery status display above the mirror indicates that the battery (or better both batteries, I trust they're wired parallel) is steadily draining 10-20%. On day 4 (battery: 40-50%) I get nervous because I don't want to ruin the two new batteries.

I start the engine - and the display shows battery: 100% (whiskey, tango, foxtrot)??!!

Has anyone else experienced similar nonsense? What am I missing here? Which reading is correct?

I believe your reading is accurate after starting the vehicle, i.e. 100%. The panel doesn’t read the ongoing input of solar on your batteries. There is a way of doing it - @WelshGas - will explain the best. Does your controller have a read out? That tends to be accurate and always up to date. My T5.1 California SE is exactly the same.

 

[Ch1pbutty]

Hello Campers

Because we often camp for one or two weeks on a beach in New Zealand I have connected a solar panel and controller to the leisure battery in the back cabinet of the T5 SE. We only run the fridge (and sometimes the electric sliding door, and minimal lighting). According to my math, the solar panel should generate more power than what we use. However, the battery status display above the mirror indicates that the battery (or better both batteries, I trust they're wired parallel) is steadily draining 10-20%. On day 4 (battery: 40-50%) I get nervous because I don't want to ruin the two new batteries.

I start the engine - and the display shows battery: 100% (whiskey, tango, foxtrot)??!!

Has anyone else experienced similar nonsense? What am I missing here? Which reading is correct?

Ignore the VW display. Get a cheap plug in voltage monitor and plus it into one if the 12v cig sockets powerered by the leisure battery.

Or fit a switch to a victron Bluetooth unit, then you can see full solar charging/battery data on your phone.

 

[WelshGas]

Hello Campers

Because we often camp for one or two weeks on a beach in New Zealand I have connected a solar panel and controller to the leisure battery in the back cabinet of the T5 SE. We only run the fridge (and sometimes the electric sliding door, and minimal lighting). According to my math, the solar panel should generate more power than what we use. However, the battery status display above the mirror indicates that the battery (or better both batteries, I trust they're wired parallel) is steadily draining 10-20%. On day 4 (battery: 40-50%) I get nervous because I don't want to ruin the two new batteries.

I start the engine - and the display shows battery: 100% (whiskey, tango, foxtrot)??!!

Has anyone else experienced similar nonsense? What am I missing here? Which reading is correct?

The % display on the T5 control panel is calculated on amps used and not very accurate. It takes No Account of amps in from your Solar
panel.
The voltage displayed is accurate. Once the engine is run the % display resets to 100%.
Use this voltage table to determine the true charge state of your batteries.
NB, the fridge or Parking Heater will switch Off if the battery voltage drops to 11.5v to protect the batteries. The lights will continue to work.
If you have a full electric sliding door, it runs off the engine battery only and could drain this with repeated use. Your solar panel, unless wired to the engine battery will not charge it.

 

[jens.zollhofer]

Awesome information! Thank you for your responses! I’ll print that table and keep it handy
That made my day.
Cheers Jens

 

[RockinNRollin]

I was thinking about this last night; doesn't the "voltage method" to estimate charge level rely on the battery being wholly at rest (and "rested" for a little while) and therefore presumably also with no charge going to it either? Does that mean the only way to know what's going on is to measure it at night (i.e. no charge current) and with the fridge/lights off (i.e. no draw)?

 

[WelshGas]

I was thinking about this last night; doesn't the "voltage method" to estimate charge level rely on the battery being wholly at rest (and "rested" for a little while) and therefore presumably also with no charge going to it either? Does that mean the only way to know what's going on is to measure it at night (i.e. no charge current) and with the fridge/lights off (i.e. no draw)?

If you want an accurate measurement Yes.
Measuring on the fly, so to speak, would give a reading .3 to .4 v lower than the resting level, if No Solar input. So measuring at night would give a good approximation. By day with solar or on EHU would show the charging voltage.
On the T6.1 which has a different battery monitoring system, each battery is monitored separately, I'm not sure how sophisticated the system is, but should be better than the T5/6.

 

[dspuk]

Hello Campers

Because we often camp for one or two weeks on a beach in New Zealand I have connected a solar panel and controller to the leisure battery in the back cabinet of the T5 SE. We only run the fridge (and sometimes the electric sliding door, and minimal lighting). According to my math, the solar panel should generate more power than what we use. However, the battery status display above the mirror indicates that the battery (or better both batteries, I trust they're wired parallel) is steadily draining 10-20%. On day 4 (battery: 40-50%) I get nervous because I don't want to ruin the two new batteries.

I start the engine - and the display shows battery: 100% (whiskey, tango, foxtrot)??!!

Has anyone else experienced similar nonsense? What am I missing here? Which reading is correct?

On top of all the other great replies as well you don't mention the panel/s you have (100/200/300), the controller nor the weather in NZ (sunny, cloudy etc?).

There is a good article on the Solar Campers site that explains how much you need in for how much out - in temperate weather with a 100W panel, you might do 5 or 6 days, not not much more. In nearly constant Spanish sun, you could likely do constant off grid, even with 100W, but for sure with 200W. A lot will depend on the actual power you get from your panel, heat loss and controller efficiency/settings.

 

[RockinNRollin]

If you want an accurate measurement Yes.
Measuring on the fly, so to speak, would give a reading .3 to .4 v lower than the resting level, if No Solar input. So measuring at night would give a good approximation. By day with solar or on EHU would show the charging voltage.
On the T6.1 which has a different battery monitoring system, each battery is monitored separately, I'm not sure how sophisticated the system is, but should be better than the T5/6.

Thanks. Probably a daft question/statement, but as the two leisure batteries on the 6.1 are connected together in parallel, wouldn't this normalise their condition anyway (assuming the cube fuse isn't blown)? I assume the readout (voltage) on the display on the 6.1 therefore should mirror the solar controller (it seems to in my case), but not sure about the "blue bars" - presumably once the sun is down and the voltage has stabilised, should be indicative assuming no big loads?

 

[WelshGas]

Thanks. Probably a daft question/statement, but as the two leisure batteries on the 6.1 are connected together in parallel, wouldn't this normalise their condition anyway (assuming the cube fuse isn't blown)? I assume the readout (voltage) on the display on the 6.1 therefore should mirror the solar controller (it seems to in my case), but not sure about the "blue bars" - presumably once the sun is down and the voltage has stabilised, should be indicative assuming no big loads?

I presume that is how it should work and if the solar output is connected to +tve and chassis earth, so it doesn't bypass the individual battery monitor then should show input of solar amps as well. Voltage should be correct however the solar is wired.

 

[RockinNRollin]

I presume that is how it should work and if the solar output is connected to +tve and chassis earth, so it doesn't bypass the individual battery monitor then should show input of solar amps as well. Voltage should be correct however the solar is wired.

Yeah that's certainly how mine is wired (and how Roger's instructions are set out). It's been down the side of the house pulling 15W (at most) in the shade so far so not really very obvious!

 

[dspuk]

Thanks. Probably a daft question/statement, but as the two leisure batteries on the 6.1 are connected together in parallel, wouldn't this normalise their condition anyway (assuming the cube fuse isn't blown)? I assume the readout (voltage) on the display on the 6.1 therefore should mirror the solar controller (it seems to in my case), but not sure about the "blue bars" - presumably once the sun is down and the voltage has stabilised, should be indicative assuming no big loads?

The V readout does, as you say, as does the A in when solar is chugging away. Anywhere between 1 and 10, sun and time of year dependant.

The blue bars are purely down to VW, so no indication on the MPPT of time remaining in leisures.

Night time V is a good indication of the state of affairs after a day in the sun. Or not if you are in the UK

 

[RockinNRollin]

Cheers @dspuk and @WelshGas . Some interesting information there.

 

[Gliderbee California 6.1]

Ignore the VW display. Get a cheap plug in voltage monitor and plus it into one if the 12v cig sockets powerered by the leisure battery.

Or fit a switch to a victron Bluetooth unit, then you can see full solar charging/battery data on your phone.

I like this one: plug-in . It keeps the socket multi-usable, and you can even kill the 12v outputs with the buttons on top.