Solar - Battery Voltages - Victron MPPT, Sterling Lithium Leisure, Battery Master

[Kannon Fodda]

After a few days sat outside my house, on solar power only, the Victron Connect software is reporting the Sterling Lithium voltage as 13.57V, whilst the Metatrak monitoring stuff linked with the Strikeback alarm says the engine battery has a voltage of 13.5V. I know fully charged batteries have voltages higher than 12V, but that engine seems very high if a standard lead- acid is fully charged at around 12.6 / 12.7 V according to most tables I see. Even at night, and I'm not on hookup, the Sargent display is showing that both leisure and engine batteries are in charging status, presumably due to these voltages. Do I have a problem?

Current installation is 100A solar panel, now through a Victron 75/15 MPPT, somehow to the Sterling 120Ah LifeP04. There is a Sterling BB1260 B2B with feed from somewhere up front to the LifeP04. A Vanbitz Battery Master is wired through the B2B inputs and outputs to take spare charge from the LifeP04 back to the engine battery. Originally the leisure battery was charged via the combined Sargent EC176 thing that does EHU leisure charging, 230V and 12V habitation, but the connection from the engine has apparently been pulled (12v fuse in the floor unit behind the drivers seat). With Autotrail the leisure battery, controllers and stuff are all at the rear of the van, leaving the engine battery in the floor well to the front of the passenger seat. The wiring upgrades of B2B, MPPT, Lithium were all carried out by Vanbitz so I'm sure the wires are correct, it's just the voltages that seem high as if something may not be cutting out when intended?

The Victron Connect software shows that in the last few days the panel has initially been charging at bulk (I can't see a setting saying what voltage that might be, but manuals imply it focuses on current rather than voltage). It then switches to absorption (14.6V) for a couple of hours before a float charge voltage (13.8V). The Sterling LifeP04 data sheet says max charge voltages are 14.8V, recommended charge 14.6V and float 13.8V. Are the MPPT controller settings correct, and if the solar is trying to float charge at 13.8 does this explain why the Battery Master is trying to also raise the engine? Do I need to change something?

Thanks

 

[autorouter]

If you leave a fully charged lead-acid battery on a shelf, its voltage will gradually fall due to self-discharge, starting at about 12.7 to 12.8 V. Lead-acid batteries degrade if left discharged for a long time due to 'sulphation', which can be prevented by keeping the battery absolutely fully charged. To do this, a voltage is applied that is just enough to counteract the self-discharge, without overcharging. This is called float charging, and the voltage required for this is about 13.4 to 13.6V.

So your starter battery is perfectly fine with a voltage of 13.5V to keep it topped up. The BatteryMaster triumphs again.

Lithium batteries are different in this respect. They don't degrade if left partly charged. If they are overcharged, even slightly, they degrade. So they ideally should not be float charged. However if you apply a voltage that is less than the fully charged voltage, it keeps the battery at that level without overcharging. Because it acts a bit like a float voltage, that's what the charger manufacturers call it.

Your BB1260, MPT 75/15 and probably your mains charger should have a Lithium setting, preferably LiFePO4, which will take care of this. 13.6V sounds like a reasonable 'float voltage' for your Lithium battery.

The 3-stage intelligent charge process is bulk, absorption and float. For bulk charge, there's no definite voltage setting. The charger pushes out its maximum amps, and for a discharged battery that won't be enough to make the voltage reach the absorption voltage. The charger carries on at its maximum amps, with whatever voltage results. The voltage gradually rises until it hits the absorption voltage.

As soon as it hits the absorption voltage, the charger switches to absorption mode. It fixes the voltage at the required absorption voltage, and monitors the amps which will gradually fall. When the amps falls to a pre-detemined level, the charger decides the battery is fully charged, and switches to float mode.

 

[Kannon Fodda]

Thanks for that. The voltages I showed are when off charge, i.e overnight without any EHU, so the engine battery is at 13.5V and the Lithium leisure fractionally higher at 13.57V. The "charging" status is simply the original display panel's interpretation, due to these voltages, but there is no input into the system.

My concern is whether the batteries are getting overcharged by the various float and absorption solar levels. I'd expect the inbuilt controller on the LifeP04 to prevent overcharge, but the engine battery wouldn't have a controller.

 

[autorouter]

I'm not sure I'd rely on the inbuilt 'controller' to manage the day-to-day charging process. I get the impression it's more of a last resort, to protect the expensive battery from damage if all else fails.

The BB1260 should have a LiFePO4 profile, which will keep the charging amps and volts within reasonable limits. If not already fitted, you could fit a temperature sensor option to avoid charging when very cold. Or in fact very hot. Although from your description of the locations you may need a very long temperature sensor wire between the battery and the B2B.

Similarly the MPT 75/15 should be set to the Lithium profile. If you want to have temperature monitoring, Victron do a BatterySense module, which literally sticks on the side of the battery, connect a pos and neg wire, and it sends battery voltage and temperature data to the MPT by Bluetooth. This prevents damage to Lithium batteries by charging below zero degrees C.

I'd be fairly confident the BatteryMaster will keep the starter battery topped up without overcharging.

 

[andy63]

Hi..
ill add a few general observations from my set up..which would be similar to yours and is entertaining me in a similar fashion atm..
First thing that I feel is we are in a transition period and are using products that are designed to run with same battery chemistry.. and we are adding lithium to the equation..
The battery master and other makes of battery maintainer will chances are be running nearly all the time as soon as you introduce lithium.. you need to check their specifications to see what will happen..
The battery master works on a voltage differential of approx half a volt between the two banks..
Other makes tend to operate on a threshold voltage.. but most probably with lithium they will be above that voltage more often than not..
With solar and the battery to battery chargers the manufacturers appear to have quickly reacted by adding a lithium profile and selecting voltages to suit and hopefully not damage the lithium while still retaining functions like float which are not needed..
I've been watching how my system behaves and like you at times felt the voltages were running on the high side..for the lead acid , and the lithium appears to be kept at an elevated voltage by the solar..
I have the Stirling battery maintainer fitted which works on a threshold voltage of 13.3 volts... its running all the time since I installed the lithium....
On the Stirling battery to battery ive disabled the regen timer as i noticed that if the engine is started for whatever reason for a short period and switched off the charger can continue to be drawing a very high current for the period that the timer is set for.. default is 4 mins..ive watched mine drawing 45 amps during that period after the alternator shuts down.
Ive also after contacting sterling found a way of preventing the battery to battery charger switching on , on its default voltage sensing mode as the battery maintainer keeps the start battery at a voltage above the threshold operating voltage of the battery to battery charger..so its switching on without the alternator running
it was autorouter pointed out that some of the units come with the facility to only run on an engine run signal but my software version didn't cater for that ..but after changing the operating voltages it appears to have stopped switching on unless the engine is running ...I have an engine run signal wired to the ignition feed provided on the unit.
All rather long winded but I imagine there will be a good few having similar issues atm as more and more install lithium..
One final note..I bought a dedicated lithium mains charger and put that in, and disabled the feed from the cbe mains charger to the distribution board (rather than remove it i just rewired its output to the start battery which is obviously still a lead acid so I can mains charge that battery if the need arises) . so currently on hook up I just run my batteries and manually switch the mains lithium charger on when required..preferably when I'm not running any , or very low loads on the leisure side..
Andy..

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[autorouter]

some of the units come with the facility to only run on an engine run signal but my software version didn't cater for that

Apparently if it has a 'green stripe' on the front, the software can be upgraded (to V69 or later), but that can only be done by Sterling so needs to be returned to them to do it.

 

[andy63]

Apparently if it has a 'green stripe' on the front, the software can be upgraded (to V69 or later), but that can only be done by Sterling so needs to be returned to them to do it.

Cheers..you covered that with me on another thread..my software version was 66..
I gave sterling a call as mine is supposedly a new version with ghe green stripe and I enquired if it was possible to have mine switch on the engine run rather than voltage sensing.. that way it wouldn't be coming on when the alternator wasn't running..
The work around is to go into settings and rais the cut off voltage to a silly or high level..that in turn raises the charging threshold voltage (there are 4 set voltages which are all linked to the cut off voltage ) to a high enough level to ensure the unit only switches on when the unit receives the engine run signal or the alternator voltage is high anyway..
It seems to be working as it should..
Andy

 

[Kannon Fodda]

I think I'm going to trust that Vanbitz wired me up appropriately, particularly for the B2B (which is right next to the leisure battery at the vehicle rear and heavier cables for the charging were run from the front somewhere to that). It was just the apparent voltages once the solar has finished topping off, and shut down for the night, that seemed high, based on my limited knowledge. Only closely watching stuff as I'm working out how to add a small inverter into the mix.

 

[eddie]

Its all fine! Everything is set to Lithium profile, temperature sensors fitted all checks and balances is place.

Just think, your system's performance is what so many people dream about achieving

 

[andy63]

I think I'm going to trust that Vanbitz wired me up appropriately, particularly for the B2B (which is right next to the leisure battery at the vehicle rear and heavier cables for the charging were run from the front somewhere to that). It was just the apparent voltages once the solar has finished topping off, and shut down for the night, that seemed high, based on my limited knowledge. Only closely watching stuff as I'm working out how to add a small inverter into the mix.

I'm sure it is all fine..and the issues I've mentioned i don't believe will cause a problem..certainly in the short term..
have you monitored your start battery voltages while your solar is on especially..?is it beyond the threshold of the battery to battery..is the battery to battery switching on when the engine is off... its easily missed as the load it can impose on the start battery is such that it pulls the voltage down fairly quickly and it then switches off..and the cycle continues..I just don't think that is desirable if it can be prevented..
Andy.

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[eddie]

I'm sure it is all fine..and the issues I've mentioned i don't believe will cause a problem..certainly in the short term..
have you monitored your start battery voltages while your solar is on especially..?is it beyond the threshold of the battery to battery..is the battery to battery switching on when the engine is off... its easily missed as the load it can impose on the start battery is such that it pulls the voltage down fairly quickly and it then switches off..and the cycle continues..I just don't think that is desirable if it can be prevented..
Andy.

Connecting the D+ on the alternator always eliminates that problem.

To be honest, I don't think that the OP will have an accurate voltage reading of the engine battery anyway as neither the Metatrak app or the existing battery gauge will be accurate.

 

[andy63]

Connecting the D+ on the alternator always eliminates that problem.

But it doesn't.. at least not on my Stirling battery to battery charger..
There are some Stirling battety to battery chargers where the software provides that facility as mentioned above ..ie it only operates on receiving a signal on what they call the ignition terminal but I believe most units are voltage sensitive by default whether its wired with an engine run signal or not...
Whether the various voltage indicators that the op has are reliable or not .. it wouldn't be hard to check to see if the battery to battery charger was running..it looks like a bloody Xmas tree when it turns on
Andy.

 

[Kannon Fodda]

I'm sure I don't know the accurate voltages on the engine battery. I've always been suspicious of the Sargent display as on the old setup it never ever showed fully green leds for the leisure even after a very long run or lengthy EHU. It's even more meaningless now there is Lithium in the mix as the voltage doesn't gradually drop as the capacity is depleted.

For the engine battery last night the Metatrack monitor said 13.5V this morning it was reporting 12.6V. So that has no idea either.

The install of B2B, MPPT (to existing solar) and Lithium was this August so this is the first time I'm starting to be able to spend too much time watching behaviour as we go through Autumn. As it's newer than andy63's Sterling B2B I can't see I would have the firmware version that caused him concern. Most of my wires are concealed and interlinked with so much other stuff of the base vehicle but I would expect Vanbitz would have set the necessary settings to the B2B including any D+ connectors, which is presumably somewhere at the front of the van, despite the B2B being at the rear. As it's all squeezed into a very small space the B2B display is hidden from view. I see the Battery Master occasionally flicker from green to red during the day, so I know that is transferring to the engine as the solar tops off, and can see that is wired through the B2B.

There was a reason I got it all installed by professionals. As this thread has proven, I don't know enough about it all. To be honest, I'm going to stop worrying now and leave well alone.

 

[eddie]

But it doesn't.. at least not on my Stirling battery to battery charger..

Speak to Sterling they are very helpful and they will resolve the issue if it a problem. I know that the guys have to reset them to recognise the D+ input

 

[JJ]

Oh My Good God...

I guess it is because it's a passionate hobby but I can never quite understand this massive obsession with volts and amps and watts and chargers and wire thicknesses and mppt and panels and meter readings and on and on and on and on...

Then I worked out that it might be because most folk want everything in their vans that they have in their houses and that travelling around in their motorhome isn't a life STYLE change... it is just sticking to the usual life style but in a van for a few days on holiday.

I used to have the mind set where I wanted satellite dishes and mains electrical equipment and all the nobs and whistles but, over decades of fulltiming, I have discovered that the more simple my lifestyle is, the less need I have for all these modern fad items (coffee making machines and the like) and this leads to a more stress free, less worrying life which in turn leads to more happiness and contentment.

Switch the switch... does the light comeon? My electric is fine.


JJ

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[andy63]

Speak to Sterling they are very helpful and they will resolve the issue if it a problem. I know that the guys have to reset them to recognise the D+ input

I have spoken to Stirling.. ..................................
Ive also after contacting sterling found a way of preventing the battery to battery charger switching on , on its default voltage sensing mode...........


My comments to you were in relation to you saying that connecting a d+ to their ignition terminal solved the problem..
It doesn't on a lot of the units..
Andy.

 

[andy63]

I guess it is because it's a passionate hobby but I can never quite understand

Correct
You might understand if it was magic

Then I worked out that it might be because most folk want everything in their vans that they have in their houses

Couldn't be further from the truth in my case..
Dont do microwaves...coffee machines ..hair dryers etc etc..
Just dry and warm
But that doesn't stop me taking an interest in things shall we say technical ..
I enjoy it.. and a simple life..
Andy

 

[JJ]

You might understand if it was magic

Not anymore... retired for a long time now...

JJ

 

[Kannon Fodda]

Speak to Sterling they are very helpful and they will resolve the issue if it a problem. I know that the guys have to reset them to recognise the D+ input

Interesting that the current installation blurb from Sterling suggests the D+ is often not used as "
ignition feeds are getting increasingly hard to find on modern vehicles", so their default automatic mode is based on voltages 13.3V input on.

Oh My Good God...

I only went for this upgrade, not because I wanted all sorts of bells and whistles and home comforts (actually I don't do a coffee maker thingy at home either), more I just knew I needed more capacity to simply stay put for a couple of nights with a bit of TV and the paltry default installed 75Ah leisure (don't think it was even that looking up manufacturer's spec) was hopeless. But lack of space meant the lithium was far better as I was always restricted to a single battery space.

I'd much rather not get obsessed with voltages, amps and suchlike. For that reason I didn't get any monitor put on the battery. But curiosity is presently getting the better of me, especially when I can be in my living room and the Victron app via bluetooth is telling me what the van is doing whilst I'm sat here getting other wise bored avoiding writing reports.

 

[Sooz52]

I have to say I was wondering a similar thing - I’ve got my Victron for new panels directly into the LiFepo4, but the old controller and EBL don’t have lifepo4 settings, and are also connected to it.

For me it’s a work thing - I’m a digital nomad. So playing around with power is a necessary evil which I’d much rather leave well alone, but needs must...

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[andy63]

There is loads to readon the subject..the more im reading and looking into it the less concerned I am about the old charging sources that are predominantly for lead acid technology and employ float charges in their cycle..
I think as long as you understand the voltages involved and what to avoid with some of the chargers they will do the job ..
Heres another good read on the subject..

How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries

By: Rob Beckers You have just sold your first-born into slavery, remortgaged the house, and bought yourself a lithium-ion battery! Now you want to know how to take care of your precious new purchase: How to best charge lithium-iron batteries, how to discharge them, and how to get the maximum...

www.solacity.com

Andy