Battery display -charging/charge levels

[VXman]

I have a 2021 Burstner with a Elektroblock 119.

I wonder if lovely knowledgeable peeps on here can educate me a little.

I have a 175Watt solar panel with an MPPT NDS Suncontrol 2 (SC320) controller (20amps) connected directly to 3 90AH leisure batteries

Both the controller and the Burstner display are a little basic in the info they display. The Burstner display I believe shows the voltage of the battery as it is at the time (resting, charging whatever). Normally in the day it will show up to around 13V and at night 12.7 or less depending on use.

So at the moment it is at 12.7 in full sunlight. I would have expected it to show higher if the solar is working at optimum. The Controller has a red light which means it is bulk charging. The battery would have been a little low at the end of yesterday as I had used it to partially charge an electric bike and accidentally left the outside led/awning light on all night

So the question is - what is the display telling me, currently level of the battery or current charging (input) ?

BTW - I note that the Burstner display is always a level below what a multi meter shows direct from the batteries. 12.7 on the display reads 12.87 on the multi-meter currently and is usually a couple of points above the main display.

 

[autorouter]

The MPPT is trying to imitate a mains charger as best it can. In the bulk stage, a mains charger pushes out its full output amps, and the voltage gradually rises until it reaches the 'absorption voltage', usually about 14.5V. At that point the battery is about 80% charged,and it switches to the absorption stage.

In the absorption stage, the voltage is fixed at the absorption voltage, and the amps gradually reduces from the full output amps to a preset level, typically about 1/10 of the full output amps. The charger then decides the battery is 100% full, and switches to the 'float stage'.

In the float stage, the voltage is set to about 13.5V, which is just enough to stop the battery from discharging and compensate for any internal self-discharge.

Your MPPT is trying to imitate this, with the problem that the solar power input is very variable and isn't sustained for hours like a mains charger.

I think I'd trust the multimeter more than the display panel to be more accurate. Whenever I've checked a random multimeter against a calibrated laboratory instrument it's always been quite accurate, at least to the nearest tenth of a volt. The display panel will probably be quite consistent, now that you know what the voltage offset is.

 

[Richard n Ann]

So at the moment it is at 12.7 in full sunlight. I would have expected it to show higher if the solar is working at optimum.

If the battery is quite low on charge the solar charging voltage will be lower to start with. A DC clamp meter is handy to check what's going in

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[Guigsy]

The voltage is the current voltage of the system. If anything is pushing power in, then that will be driving the voltage.

You can approximately measure the charge on a lead-acid battery by measuring it's voltage. But only when there's nothing else trying to charge it and there are no significant loads on it. Even then, voltage isn't that accurate.

A better method is to add a shunt type battery monitor. It watches the current flow in and out of the battery to calculate how much charge is left.

 

[the1andonly]

A better method is to add a shunt type battery monitor. It watches the current flow in and out of the battery to calculate how much charge is left.

£30 not going to break the bank but keeps you in control

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Battery Monitor 50A or 100A versions suitable for Lead acid if Lithium my preference is BMV712 (a display, BT and relay control) cheaper BT only is Smartshunt.

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[Stealaway]

I have a 2021 Burstner with a Elektroblock 119.

I wonder if lovely knowledgeable peeps on here can educate me a little.

I have a 175Watt solar panel with an MPPT NDS Suncontrol 2 (SC320) controller (20amps) connected directly to 3 90AH leisure batteries

Both the controller and the Burstner display are a little basic in the info they display. The Burstner display I believe shows the voltage of the battery as it is at the time (resting, charging whatever). Normally in the day it will show up to around 13V and at night 12.7 or less depending on use.

So at the moment it is at 12.7 in full sunlight. I would have expected it to show higher if the solar is working at optimum. The Controller has a red light which means it is bulk charging. The battery would have been a little low at the end of yesterday as I had used it to partially charge an electric bike and accidentally left the outside led/awning light on all night

So the question is - what is the display telling me, currently level of the battery or current charging (input) ?

BTW - I note that the Burstner display is always a level below what a multi meter shows direct from the batteries. 12.7 on the display reads 12.87 on the multi-meter currently and is usually a couple of points above the main display.

I don't think you need any device except a volt meter to tell you the state of the batteries.
You don't need to know how much charge you are getting during the day as you cant normally change that.
If you simply keep an eye on the voltmeter in the evenings and don't let it drop below 12V it's as good as it gets
If you cant watch TV in the evenings for as long as you want you need to upgrade the solar and or leisure batteries.
The volt meter is only a gauge/rough guide - it shouldn't need to be that accurate

 

[VXman]

I don't think you need any device except a volt meter to tell you the state of the batteries.
You don't need to know how much charge you are getting during the day as you cant normally change that.
If you simply keep an eye on the voltmeter in the evenings and don't let it drop below 12V it's as good as it gets
If you cant watch TV in the evenings for as long as you want you need to upgrade the solar and or leisure batteries.
The volt meter is only a gauge/rough guide - it shouldn't need to be that accurate

Generally it is not an issue. We can be off grid permanently, certainly in sunny climes. The only reason I got wondering is because I had been charging the electric bike and had used the toaster via the inverter so the levels started to dip. Never below 12.2 and that's on the Burstner readout which I reckon is a bit below reality. I was just confused by varying readings from the Burstner/inverter/multimeter. I reakon one more solar panel would sort it.im probably over batteriedand under solared at the moment but as we travel quite a lot -dont stay put for tomany long periods, the engine probably takes up the slack.

 

[Stealaway]

Generally it is not an issue. We can be off grid permanently, certainly in sunny climes. The only reason I got wondering is because I had been charging the electric bike and had used the toaster via the inverter so the levels started to dip. Never below 12.2 and that's on the Burstner readout which I reckon is a bit below reality. I was just confused by varying readings from the Burstner/inverter/multimeter. I reakon one more solar panel would sort it.im probably over batteriedand under solared at the moment but as we travel quite a lot -dont stay put for tomany long periods, the engine probably takes up the slack.

If you tend to drive every day maybe a B2B charger could be an option

 

[nicholsong]

Generally it is not an issue. We can be off grid permanently, certainly in sunny climes. The only reason I got wondering is because I had been charging the electric bike and had used the toaster via the inverter so the levels started to dip. Never below 12.2 and that's on the Burstner readout which I reckon is a bit below reality. I was just confused by varying readings from the Burstner/inverter/multimeter. I reakon one more solar panel would sort it.im probably over batteriedand under solared at the moment but as we travel quite a lot -dont stay put for tomany long periods, the engine probably takes up the slack.

Then you are like us and we have a B2B which charges the hab batteries very quickly when driving. If you do not have one fitted I would suggest that as a priority before more solar because it is more useful when no sun in day or at night.