Solar charge controller - load terminals - what practical use in a MH ?

[Deleted member 62288]

'You had a Schaudt regulator fitted' .... that sounds typical of the Motorhome Leisure industry. Apart from total newbies, the customers know more than the Dealers.

Whoever neglected to fit the adaptor was a pillock.

It's usually a job that I would do myself, but I was in the Algarve and sampling my first batch of organic Sativa.
The fella that sold and fitted the solar upgrade was a nice chap and his prices were good (for the solar panels etc)

- I got the Sativa from a gypsy girl in the town.

Overall, he was up on the roof fitting 3 extra panels to the existing single. Installed a Victron battery monitor and routed all the negatives thro a shunt. The system worked well in spite of my LBs being knackered. He fitted the Schaudtt LR 1218 pmw controller also.

But the schaudt pmw controller has a 18A limit (from memory) while the panels were capable of delivering much more. Plus there was zero engine battery charging via the elecktroblok unit.
And I kept running out of 12v when parked up for more than 3-4 sunny days.

The system was insufficient for my daily load.

Once home and learning from 6 months around Iberia, I decided to upgrade the upgrade by removing the upgrade and fitting a Victron mppt 40A controller, which happened to have load terminals available. The schaudt PMW controller was thus redundant (and is for sale).

I replaced the dud 2x 135 LBs with 2x230Ah Victron AGMs.

I was finding the Victron battery monitor to be a fiddly overkill for my needs so this was removed and replaced with a trusty NASA BM1.
(The Victron Battery monitor and shunt are also for sale)

This combination has been meeting my needs for around 3 weeks now with the LBs being fully recharged by midday most days, and that is from English sunshine too. That's living in the van full time.

My last remaining gap to plug is the matter of keeping the engine battery topped up while parked up, hence this thread.

As the Elecktroblok does not charge the engine battery from solar, even with the correct LR 1218 schaudt pmw solar controller plugged in,
I needed to find some way of using the spare power available at the victron mppt solar controller on the load terminals, to maintain the engine battery.

The simplest and cheapest way would be to fit a cheap 20A solar controller, fed by the load terminals and connected directly to the engine battery. But given that my investment on the upgrade to the upgrade is currently around £1,500 I chose the Sterling BB1230 to perform the task.

An added benefit over a simple split-charge relay type of configuration, is that my config will charge both engine and leisure batteries simultaneously rather than either/or. Given my current and expected daily load I should never run out of juice, even if parked up for months.

The BB1230's role is purely to maintain the charge to the engine battery while parked up and off-grid. Maybe an overkill at worse.

But some folks appear to doubt my sanity regarding this intention, but I am unconvinced that this will not work.

I have to finish off the refurbishment of the seat / locker lids and various other chippy type stuff presently.
Then I can clear up the chippy tools and sawdust and get back to the electrics.

Next step is to site the ugly Sterling box somewhere out of sight, route the cables and connect the B2B between the MPPT load output and onto the engine battery..

The Sterling blurb tells me that it is simple to install with just 2 wires in and 2 wires out.

So unless someone actually knows why this will fail,

that is the plan.

james

 

[Deleted member 62288]

Sterling make some good kit (although it looks so dated!) and is festooned with writing all over, but I find the most annoying thing about them is Charles Sterlings constant slagging off of any product that doesn't have his name on it


FWIW, I know you are installing a B2B charger in order to charge the STARTER Battery from Solar, but the usual purpose of a B2B is of course to install the LEISURE batteries via the Alternator.
For that purpose, I am taking a route you may find of academic interest? Rather then installing a B2B in the usual fashion (the most expensive option), or a typical Split-Charge Relay (the most basic option), I am fitting (when I eventually get round to it) a Programmable Digital Alternator Regulator from Sterling (plus standard 200A Switching Relay).
This will change the alternator output from a basic output to a multi-stage battery charger output, tuned to your particular battery type (which is one reason why I installed an AGM Battery under the bonnet to match the AGMs in the Leisure battery bank when replacing the knackered Starter Battery).
One handy thing about this over a Leisure Battery B2B setup is it will charge the Starter Battery using a multi-stage Battery Charger algorithm as well, not just the Leisure Batteries.


(Going in the other direction, my Solar Controller doesn't have any useable Load outputs as the 'virtual' ones are shared with the comms port I am already using so I will just have a 3-way switch on the Relay control line to allow me to manually spoof the D+ signal from the alternator into the relay so when getting good solar charging, can push some excess wattage over)

Many Thanks for sharing your details.

I looked at those as part of my research.

The fundamental difference between your installation and mine seems to be that I have a second source of solar power available and thus I don't need to consider switching between loads, I can charge both simultaneously. Each of the B2B, MPPT and EBL are chargers in their own right and will happily operate together.

I don't have to include alternator charging or EHU/220v options in my calculus as these are already catered for by the Elecktoblock in the normal manner.

I overlaid a huge battery bank and solar charging onto the existing factory fitted arrangements and thus had the opportunity to create free power that easily feeds my daily usage. This is without affecting the original alternator and 220v charging arrangments, which remain untouched and operate happily together.

That is until I start to use the NutriBullet and Expresso machines too much, that will be part of the commissioning and final testing.

Irons are banned, I like to live a bit wrinkly...

james

 

[Canalsman]

On my previous 'van I used this device to achieve what you are seeking and plan to fit such to my present 'van:

12V to 12V BATTERY CHARGER 1Amp 12W DC-DC (Top Up Battery Charger) Part No: E848 | eBay

Works really well, is easy to fit, and is inexpensive

 

[Deleted member 62288]

On my previous 'van I used this device to achieve what you are seeking and plan to fit such to my present 'van:

12V to 12V BATTERY CHARGER 1Amp 12W DC-DC (Top Up Battery Charger) Part No: E848 | eBay

Works really well, is easy to fit, and is inexpensive

Thanks Chris,

That unit on Ebay is only 1A and I've just spent £175 on a Sterling 20A B2B, so I am where I am.

I've gotta stick to my plan at this point in time. I've yet to connect it and see if it works as I expect but some advice I've had tells me that I am a lunatic, I'll update you all at the next full moon then,

james

 

[Canalsman]

However 1 amp is sufficient to offset any load presented by an alarm system, for instance ...

 

[Deleted member 62288]

However 1 amp is sufficient to offset any load presented by an alarm system, for instance ...

I agree that it should be so, but on my van...

I've got a slow drain on the engine battery and I suspect an old battery.

I am targeting the dash area electrics next as previous owners have hung stuff off the engine battery which I intend to transfer over onto the ample leisure batteries.

This way, I should get to the correct situation where very little is using the engine battery and the spare solar will ensure that it is fully charged at all times.

I'll also be re-wiring an existing switch panel on the dash, replacing everything with a splendidly sleek and compact panel, that is manufactured and supplied by Mr Wildebus himself, it fits exactly into the footprint of the sprinter automatic dashboard and covers up a few old sins.

james

 

[wildebus]

Thanks Chris,

That unit on Ebay is only 1A and I've just spent £175 on a Sterling 20A B2B, so I am where I am.

I've gotta stick to my plan at this point in time. I've yet to connect it and see if it works as I expect but some advice I've had tells me that I am a lunatic, I'll update you all at the next full moon then,

james

I can't see a reason why it will not work as you expect.
It is an expensive solution however, but could be worth the money for the results it will deliver (providing a properly managed charge cycle is one bonus for sure)

I wonder if in actual fact you needed to use anything other than a piece of cable ? The load terminals are only active when you have excess power? So can you not just connect direct to a circuit going to the starter battery? The Victron controller will not suck any charge from the Starter when load is off I am sure (and if it would, a diode would take care of that eventuality)
I am not familiar with the model of Victron controller you have and .maybe a flaw in my idea due to the way the controller operates but just a thought?

 

[Deleted member 62288]

I can't see a reason why it will not work as you expect.
It is an expensive solution however, but could be worth the money for the results it will deliver (providing a properly managed charge cycle is one bonus for sure)

I wonder if in actual fact you needed to use anything other than a piece of cable ? The load terminals are only active when you have excess power? So can you not just connect direct to a circuit going to the starter battery? The Victron controller will not suck any charge from the Starter when load is off I am sure (and if it would, a diode would take care of that eventuality)
I am not familiar with the model of Victron controller you have and .maybe a flaw in my idea due to the way the controller operates but just a thought?

While the main mppt battery terminals is a properly profiled charging point, the load terminals are not, as I understand it, they just provide 14v off load which "might" do something at the battery end but it is not taking any feedback regarding what the load is doing, it just makes up to 14A available, full stop.

The load voltage is only available when the main terminals are or have completed the full charge of the LBs or if there is still spare capacity from the mppt even when it is charging the LBs. In practical terms I am seeing charging and load voltage happening at the same time, which is all daylight hours.

Given that the Sterling will be hopelessly underworked and should have the engine battery full by midday, every day, I see this approach as my best bet, albeit expensive, but I've spent so much on the system so far, I'm not going to take shortcuts at this stage.

The Sterling will allow me to set the battery type and then simply take what I shove up it's inputs and profile the output to suit the battery type and charge state as a proper battery charger should do.

Well that's my theory and working assumptions anyway.

If anyone thinks it won't work, rather than just attack the theory, please provide some actual facts and offer me working alternatives.

Many Thanks to all

james

 

[YeoBlade]

On my previous 'van I used this device to achieve what you are seeking and plan to fit such to my present 'van:

12V to 12V BATTERY CHARGER 1Amp 12W DC-DC (Top Up Battery Charger) Part No: E848 | eBay

Works really well, is easy to fit, and is inexpensive

Similar charger here
SOLAR WIND SPLIT CHARGE LEISURE & ENGINE BATTERY CAMPER MOTORHOME BOAT 12V | eBay

£25 , as soon as L batts are charged sends charge power over to Cab battery.
Had this on my last 2 vans with a 250w solar, works perfectly and easy 5 min fit.
My cab radio/android headunit is off the cab bat so need to be topped up, never had a problem.

KISS (Keep It Simple S....) is how I work

 

[Deleted member 62288]

Similar charger here
SOLAR WIND SPLIT CHARGE LEISURE & ENGINE BATTERY CAMPER MOTORHOME BOAT 12V | eBay

£25 , as soon as L batts are charged sends charge power over to Cab battery.
Had this on my last 2 vans with a 250w solar, works perfectly and easy 5 min fit.
My cab radio/android headunit is off the cab bat so need to be topped up, never had a problem.

KISS (Keep It Simple S....) is how I work

Yes indeed KISS, its part of my life philosophy.

What you describe is a good approach and is certainly a cheaper option. My solution doesn't bother with switching or relays, each battery bank will have it's own properly profiled charging circuit, dedicated to its own particular needs. both can be charged simultaneously.

The LBs are AGM while the engine battery is standard wet lead-acid, so it would need more than a switch to satisfy the different profiles.

 

[Canalsman]

You think so? A simple diode on a heatsink in a box for almost £50? You could buy a suitable diode for just a few pounds.

Something like Vishay VS-12F20, Rectifier Diode, Stud Cathode, 200V, 12A, 2-pin DO-4 | eBay (which is less than £2) would seem suitable, from a quick glance at the spec.

You haven't read the spec of the device I have recommended.

If whilst the leisure battery is being charged it reaches a voltage 0.4V greater than the engine battery, then the Top-Up Charger transfers charge from the leisure battery to the engine battery until the voltage difference is 0.2V, it then terminates the transfer.

If you can achieve that with a diode I would be most surprised.

Please will you stop trying to pick holes in suggestions made in good faith. It is very tedious.

 

[Nabsim]

I am surprised the Victron units dont have connectors for the starter battery as well as the leisure batteries, would have made this a lot easier for you. Do they have a suggestions section on their website

 

[wildebus]

I am surprised the Victron units dont have connectors for the starter battery as well as the leisure batteries, would have made this a lot easier for you. Do they have a suggestions section on their website

They have actually removed the load terminals from all but the smallest MPPT Controllers as well. I suspect that while the Lesiure (RV and Boating) market is large, it is not their primary one. I think they do sell some kind of B2B trickle charger along the lines of the device POI Chris linked to or the Battery Master.
A very good all in one unit, but aimed at smaller installs of 200W PV or less is the Amperor Associates PI25C. This provides a split charge B2B function for alternator charging, an MPPT Controller for upto 200W of Solar, a starter battery trickle of 1A, a display to tell you Voltages and charge current, all for around £150 - AND it is a British Product!

 

[Nabsim]

You would have thought they would keep some made for the RV/Motorhome/Boat class as everyone says its is growing. Maybe decided they have a different market though but none of that will help here unfortunately. I know my voltronic has the output for lb and starter but you need to get the Duo range for that option.

@ James, when you have charge going in to your leisure batteries does it show on your original control panel? My DT101 does not have an input for the controller like later ones do but it shows whatever voltage is on leisure battery bank and starter battery along with + or - amps on leisure batteries. I 'think' you only get that if you connect through the EBL but interested to know if it can display when not going though like yours is.

 

[Deleted member 62288]

Yes, my suggestions presupposed a rational approach. I was mistaken about that, so those suggestions were no use to you at all. I have already apologised for that.

I'll tell you why I think your whole approach is wrong:

Instead of thinking about what outcome you want to achieve, and the best way to achieve it, you are choosing to reinvent the wheel, using a mixture of soft cheese and wire wool. Yes, you could make a wheel that way, but it is not a good approach, even though it could be puncture-proof.

My advice to you is to start by clarifying your objectives. I don't think you have done that at all. You have stated your indended way to reach those objectives. Not the same thing at all.

Thank you HD.

I will try to clarify my objective(s) as they have changed slightly since my original posting.

Initially, I wanted to understand what use I could get from the Victron MPPT controller's extra LOAD terminals. I initially thought that they were pretty useless and would remain unused.

As I progressed with the bigger project, of upgrading the solar charging and leisure batteries, it became apparent that my original assumption that the Elecktroblock EBL-100-1 is managing both sets of batteries is in fact incorrect.

The EBL-100 will NOT charge the engine battery if the only source of power is from the solar controller.
Even when I was using the correct schaudtt PWM solar controller plugged into the correct port on the EBL unit.

The EBL-100 will only manage the engine battery when on a 220v ehu or when driving via the alternator. never via the solar input.

So I was at the point where I had plenty of solar power to manage the victron 460Ah leisure batteries but I had an engine battery with a drain and no re-charge facility from the solar system.

So my current objective is simply this :

Use the 14v / 14A available from the Victron mppt controller spare LOAD terminals to manage the engine battery, in the simplest method possible.



I looked at many possible solutions and settled on the Sterling BB1230.

As I have 2 solar charging sources, it won't be necessary to complicate matters by trying to use switching or split-charge options because I am not trying to switch a single charging source between 2 battery banks, there is a potential to assign each charging source to each battery bank and thus charge them independently of each other.

The Victron MPPT controller provides 2x outputs:
A) A properly profiled charging system from the main BAT terminals - configured for 2x Victron AGM LBs
B) Non-profiled / raw 14v / 14A available from the Victron MPPT LOAD terminals which needs to charge a standard wet lead-acid starter battery.

If I intend to use the raw 14v/14A outputs, I will need to insert some device that is configurable for various battery charging profiles, eg a charger that operates from a 12V DC (nominal) voltage as a source.

The Ugly Sterling BB1230 is now purchased and I intend to use it in a non-standard way between the Victron mppt LOAD terminals and hooked directly to the engine battery. The specs say that this is possible. I believe that the BB1230 will see the 14v / 14A given out by the MPPT load terminals as a source battery and it will see the engine battery as the battery to be re-charged.

I can't get any clearer than that for you.

I am thinking outside the box. which seems to be taken as a sign of incompetence or technical ignorance, which is far from the truth.

Thank you for your interest.

james

 

[wildebus]

Thinking outside the box is how new ways to use existing products happen so good for you and I am sure it will work.

From my own personal side, I think your solution is rather on the high side price-wise considering the small amount of current you want to move, and would have probably gone with a permanent variation of what I had in place temporarily for a short term while I still had my poor starter battery installed (and what some people do as an alternative to a 'normal' B2B system install as well)
Namely a small inverter connected to the load output terminals and a small smart battery charger. Those two Combined, with mid-range branded items used, would deliver a good solution - a higher price then the battery master type solutions, but a much higher power capability - and the small energy losses from the DC-AC-DC conversion process is coming from free power anyway.

But everyone has their own ways and sees alternative options which is good and as said, discovers new ways to use products.
If you did nothing to address the starter drain, no doubt it would cost you more than the sterling product in replacement battery installation, so in the longer term you are saving money even with the B2B solution

 

[Deleted member 62288]

Thinking outside the box is how new ways to use existing products happen so good for you and I am sure it will work.

From my own personal side, I think your solution is rather on the high side price-wise considering the small amount of current you want to move, and would have probably gone with a permanent variation of what I had in place temporarily for a short term while I still had my poor starter battery installed (and what some people do as an alternative to a 'normal' B2B system install as well)
Namely a small inverter connected to the load output terminals and a small smart battery charger. Those two Combined, with mid-range branded items used, would deliver a good solution - a higher price then the battery master type solutions, but a much higher power capability - and the small energy losses from the DC-AC-DC conversion process is coming from free power anyway.

But everyone has their own ways and sees alternative options which is good and as said, discovers new ways to use products.
If you did nothing to address the starter drain, no doubt it would cost you more than the sterling product in replacement battery installation, so in the longer term you are saving money even with the B2B solution

I have a huge list of work, repairs and upgrades to complete so that I can get un-SORNED and mobile again and I don't want to waste too much time experimenting if I can buy something off-the shelf.

The inverter / 220v car charger method is certainly an option, but I want something that is fit & forget that will not need any manual interventions or switching.

I've spent the cash on the sterling unit, so that is my destiny - unless it fails, then I'll eat crow.

 

[Deleted member 62288]

That's not an objective. It's a method.
Objectives are things like "Reach Birmingham by noon", not "Use my unicycle hesdlight to light the road so that I can reach Birmingham by noon"
Or "Keep both banks of battery charged without having to use the engine" but not "Use a mirror to reflect the sun onto the solar panel to increase charge to the batteries"
You have confused objective with method, and as a result you are going about it in what I've consider an inside way.
Powering the B2B charger from an intermittent supply may work (but don't depend on it) but it will prevent the charge controller in the B2B from keeping track of where it has got to, so if it works at all over time the engine battery will get cooked.
It's daft. Extra complexity and misuse of kit.
The rational approach is to simply charge the engine battery with the solar controller, then let the B2B charge the aux battery from there. All power is used properly and the battery is looked after using a four stage regime.

I am not confused about my objectives or the definition of the word "objectives" and your constant and irrelevant nonsense such as this posting serves only your ego and offers zero practical help or advice.

You have not taken onboard the details that have been carefully provided all of the way through this thread.

The B2B is designed for an intermittant supply - that is precisely what an alternator is, as it is never going to be running 24/7 is it ?
The mppt load terminals will offer a charging source all of the time that the sun is shining.

If the sterling b2b operates as per the spec, it won't cook the engine battery, that is a dramatic figment of your imagination, you are projecting your wish of failure.

It is not adding extra complexity, it is as simple as 2 charging sources and 2 properly profiled charging outputs.

You have also ignored the fact the the Sterling B2B needs to have the battery type configured, how do you suggest that it is configured to charge 2 totally different battery types? I have a 460Ah AGM bank as my Aux batteries and I have a standard lead-acid starter battery of around 95Ah - so, how do you address this difference ? by ignoring it ?

You have suggested inappropriate solutions based on switching a single source between 2 batteries .

Misuse of kit ? If I choose to use the sterling b2b as a door stop it won't be a misuse of kit, I own it and can use it for any purpose that I choose.

Your suggestion of your rational approach, ignores the fact that I am not needing to use the B2B to charge the aux batteries they are fully managed already. I need to ONLY address the engine battery so no relays or switching is required under any circumstances.

I genuinely welcome constructive inputs from those with a real interest, but your advice, frankly is useless and ill intentioned it is not being given in good faith.

I say again, I do NOT NEED to use the B2B to manage the aux batteries, I need to ensure that the ENGINE BATTERY ONLY gets charged by the B2B via the solar system.

In my installation, the aux battery bank of 460Ah is the main job for the solar system with the engine battery being a secondary priority, I have a second charging point available which I intend to use to also manage the engine battery simultaneously to the aux charging.

This is the least complex solution albeit expensive.

james

 

[Deleted member 62288]

It will be a couple more days before I can get the Sterling B2B unit wired in and once it is fully operational, I will be happy to report on the result.

I anticipate that the results will be splendid, with all of my charging and battery management needs being met with the design that I have implemented.

Full charging of all of my batteries from solar panels will be the result.

Hopefully this will convince the nay-sayers that I am not a lunatic , but that hope is doubtful, given the nature of some of the nonsense that has been thrown into the discussion.

james

 

[Deleted member 62288]

The B2B charger is designed to work with varying input voltage, but with constant power.
You clearly don't understand what I am suggesting.
The whole point of a B2B charger is to charge one battery from another of a different type, and it is designed specifically to do what I am suggesting.
I'm sorry that you have led yourself so far up the garden path that you think helpful suggestions unhelpful.
I wish you luck with your hare-brained project. You'll need a lot of luck.

sorry but I have elected to ignore any information that you provide, you are simply stuck in the wrong paradigm and you don't appear to have the capability of flexible thought.

I've stated several times that I intend to use the B2B in a non-standard way, which appears to you to be lunacy, but to me is simply thinking outside the box.

The results will prove who is really the lunatic.

james