Sudden drop in Amp hours

[Sooz52]

Hi collective clever brain,

I’m hoping for pointers.

In my 2004 Hymer B514 I have 2 old panel (~100w) into an old MPPT into the Hymer regulator panel. To be honest I’m not sure it does anything I’m a digital nomad so power is paramount.
A few months ago I put 240w panels into a Victron MPPT directly into a new LifeP04 200Ah battery (in addition to the old set up). It’s been working wonderfully and I haven’t had to think about it.
Until a few days ago....
The panel in the Hymer normally shows 150-160Ah, but it started dropping daily until yesterday it was down to 80Ah.
I download the Victom app and that only confuses me.
I’m armed with manuals, a Fluke multimeter and a desire to fix it.

Can I have a few pointers as to where to look? Can I measure how many hours the battery has using a multimeter - in case the Hymer panel isn’t showing the actual Ah for some reason? I’m thinking of disconnecting the old controller but the mess of cables worries me a bit...
I’m on a mission today as I don’t really like having to plug into mains.

 

[Richard n Ann]

Is it some kind of counter? Our BM2 has got an AH counter on it that you can reset and it counts the AH either in or out.

 

[Lenny HB]

As you are feeding the solar straight to the battery the reading on the Hymer panel is irrelevant as it can't see the current going in from the solar.
Also your solar is giving a float charge I thought LifeP04 don't normally have a reduced voltage float charge, check the settings on your regulators are correct.

 

[Sooz52]

Hmm, I got to the MH to find the panel showing 160Ah again... so that shows that it was the panel not the battery. I’m sure there must be some relation between the battery and the panel as they are connected and the panel reading does change. My boyfriend hit the Battery-off button in the Hymer regulator yesterday (it’s annoying that the boiler empties each time) so I imagine that reset the panel.

Anyway, it looks like the panic is over. What remains is a desire to understand better and ideally not to have to fork out for anything new - much as a battery monitor sounds good, if all is working well I suppose its not needed.
On the job list - get the setting correct in the Victron MPPT for the lithium iron battery; learn how to use the Victron app ok my phone so I understand what’s going on - for instance right now in full on Spanish sunshine it’s showing 0w - I was expecting to see a large wattage in.

 

[Richard n Ann]

Are you in Benidorm?!

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[Sooz52]

Are you in Benidorm?!

Andalucía

 

[Richard n Ann]

Andalucía

Only kidding Enjoy xx

 

[autorouter]

The point where the EBL/Digital panel measures the battery input and output is a shunt which is inside the EBL. So any current that goes directly to the batteries without going through the shunt doesn't get measured. Basically there are two ways round this.

A separate shunt, usually located in the negative wire next to the battery, can measure all the input/output. A Victron BMV type or a NASA BM1 is typical of these monitors. One possibility is a Victron SmartShunt, which has no display unit to wire in. It displays to an app on your smartphone via Bluetooth. An added feature, which you can view as a bonus or a nightmare, is it can communicate with your Victron SmartSolar via Bluetooth, and send it an accurate battery voltage and temperature. That means its charging will be better adjusted for the battery state.

The other way is to feed the solar power from the Victron controller into the 'Auxiliary charger' input of the EBL. It will then go through the EBL shunt, and the display will account for it accurately. There is a 2-way socket on the EBL, marked 'Zusatz Ladegerat', and a 20A fuse with the same label. The connectors are MNL (Mate'N'Lok) type, with crimp terminals that can be crimped with standard NON-insulated crimp pliers.

You need to set the Victron controller to the Lithium setting, because Lithium batteries don't like extended absorption charge or constant float charge like lead-acid batteries do.

 

[Sooz52]

The point where the EBL/Digital panel measures the battery input and output is a shunt which is inside the EBL. So any current that goes directly to the batteries without going through the shunt doesn't get measured. Basically there are two ways round this.

A separate shunt, usually located in the negative wire next to the battery, can measure all the input/output. A Victron BMV type or a NASA BM1 is typical of these monitors. One possibility is a Victron SmartShunt, which has no display unit to wire in. It displays to an app on your smartphone via Bluetooth. An added feature, which you can view as a bonus or a nightmare, is it can communicate with your Victron SmartSolar via Bluetooth, and send it an accurate battery voltage and temperature. That means its charging will be better adjusted for the battery state.

The other way is to feed the solar power from the Victron controller into the 'Auxiliary charger' input of the EBL. It will then go through the EBL shunt, and the display will account for it accurately. There is a 2-way socket on the EBL, marked 'Zusatz Ladegerat', and a 20A fuse with the same label. The connectors are MNL (Mate'N'Lok) type, with crimp terminals that can be crimped with standard NON-insulated crimp pliers.

You need to set the Victron controller to the Lithium setting, because Lithium batteries don't like extended absorption charge or constant float charge like lead-acid batteries do.

Thank you, really helpful. I didn’t spot before that I can select the li battery type in the victron app.
I’ll scratch my head over the rest.

A big thing I don’t get is why I get such a varied reading on the solar wattage dial in the victron app. For instance this morning I saw between 0 and 75w. Right now it’s showing 0w on the app (in float state) and although it’s a bit cloudy, I’m in Spain and I was expecting to see 50w+ from my 240w of panels. Maybe it always reads 0 if the battery doesn’t need it and it’s in float mode. I’m reading the manual but can’t see anything about it.

 

[autorouter]

A house solar array always sends out its maximum power for the conditions. Anything surplus to requirements is fed back into the electricity grid. A motorhome solar array doesn't feed back any surplus. The MPPT controller just stops converting the power once the battery is full and there's no loads requiring power.

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[olsgreen]

As others have noted you need to change the battery preset to LiFePo4 in the charge controller...

Todo this, when viewing 'solar wattage dial' in the app click on the cog icon in the top right of the screen, then battery, then battery preset, then select preset, scroll down to LiFePo4 and select it and press ok.

We've got AGM batteries so there is always a small float charge accepted by the battery, thus our dial never reads zero. I think that when the LiFePo4 gets fully charged it's internal battery management system stops it from receiving any more charge, so unless you have a load (something switched on), it will be zero.

Best test would be next time it goes to zero, go and turn a light on and you should immediately see it jump up from zero as the solar controller should be providing power instead of the battery...

 

[Sooz52]

As others have noted you need to change the battery preset to LiFePo4 in the charge controller...

Todo this, when viewing 'solar wattage dial' in the app click on the cog icon in the top right of the screen, then battery, then battery preset, then select preset, scroll down to LiFePo4 and select it and press ok.

We've got AGM batteries so there is always a small float charge accepted by the battery, thus our dial never reads zero. I think that when the LiFePo4 gets fully charged it's internal battery management system stops it from receiving any more charge, so unless you have a load (something switched on), it will be zero.

Best test would be next time it goes to zero, go and turn a light on and you should immediately see it jump up from zero as the solar controller should be providing power instead of the battery...

Fabulous information, just what I was after, thank you!

 

[Raul]

On another note, the presets are toooo high. That Li preset will work ONLY If you have communication from charger to bms. Victron batteries do. If you want any meaningful life out of those LiFePo4, custom settings: float at 13,4v absorb at 13,6-13,8v and max absorb time 30 mins. All this can be done in the settings of the controller. Keeping lithium at high voltage without discharging, it will degrade it four times faster. The float is low enough not to Over charge but to feed the loads while charging. Once it hits the target voltage, if the battery is full, the charger will not pass any current anymore. In this condition you can not overcharge, unless you raise the voltage.

The battery monitor Is a lead type and it can’t calculate exactly for Li, and over time it drifts. Li efficiency is almost 100% at low amps, lead is 70-80% efficient, the panel Is not clever enough to calculate the difference hence the drift over time. Victron BMV could do nicely in your system.

 

[Sooz52]

On another note, the presets are toooo high. That Li preset will work ONLY If you have communication from charger to bms. Victron batteries do. If you want any meaningful life out of those LiFePo4, custom settings: float at 13,4v absorb at 13,6-13,8v and max absorb time 30 mins. All this can be done in the settings of the controller. Keeping lithium at high voltage without discharging, it will degrade it four times faster. The float is low enough not to Over charge but to feed the loads while charging. Once it hits the target voltage, if the battery is full, the charger will not pass any current anymore. In this condition you can not overcharge, unless you raise the voltage.

The battery monitor Is a lead type and it can’t calculate exactly for Li, and over time it drifts. Li efficiency is almost 100% at low amps, lead is 70-80% efficient, the panel Is not clever enough to calculate the difference hence the drift over time. Victron BMV could do nicely in your system.

More fabulous information thank you; I have made those suggested changes. I did ask the battery manufacturer for the settings but they told me to ask Victron...
The BMV sounds a good idea.

 

[peterc10]

Have you cleaned your solar panels lately. they can often get very dirty with the summer dust in Spain.

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[Sooz52]

Have you cleaned your solar panels lately. they can often get very dirty with the summer dust in Spain.

Yes, that was high on the to-do list. I’ve found I can reach all 4 panels with an extending broom handle through the sky lights - bonza! They were filthy, so need washing at least monthly, more if in windy Almeria near a beach.