B2B Chargers - Question for aandncaravanservices

[arthur49]

Hi Allan

 

I'm intrigued by this page on your website and can't see any further details.

 

http://www.aandncaravanservices.co.uk/battery-to-battery-chargers.php

 

Specifically this paragraph interests me

 

"QUOTE We can offer faster charging from the Alternator with a B2B that works in harmony with the existing Motorhome electronics, not against it.

Our units stick rigidly to the voltages and currents recommended by the battery manufacturers. The faster charging is achieved by optimising the power from the Alternator by ensuring that whatever the input voltage into our B2B, the optimum is applied to the batteries"

 

I have been a Sterling B2B user for several years. I use remote monitoring so that I can control charging whilst the engine is running as it has its flaws in my view and no way do I want to inflict 40A+ on my 2 leisure batteries! (You and I had dialogue ages ago on this ..... and I support and respect your view/expertise on all things electrical)

 

So, when the time comes for me to change my van I want to instal B2B capability. Can you provide more detail of make/model/output/installed cost, as I thought that previously you did not rate this method of 'fast charging'?

[aandncaravan]

Hello Arthur, I have seen batteries that have been 'Boost Charged' and they suffer from it.

Battery manufacturers say that boost charging a battery will both cause deterioration and shorten their life.

You have probably used your B2B intelligently, gaining the advantage of zero voltage drop, without the short battery life because I seem to remember you manage the voltage?

 

So you are right I don't approve, as they are often counter productive.

Once a battery has been fast charged a few times two things will develop : Internal Corrosion and slower charging.

 

The corrosion will slow future charging and as the battery deteriorates it will become less efficient, etc. This negates the B2B very quickly.

 

To me an old fashioned B2B is about paying an 'Arm and a Leg' to have installed and then shortening the battery life by a factor of up to 4. On a big 4 x battery bank that has to be replaced every two years (to maintain maximum efficiency rather than because they have 'expired') that is a heck of a running cost.

 

Someone on here once wrote in a thread that they would think twice before installing a Stirling B2B again (was it Veletron?) but would put in big fat cables to reduce voltage drop, so that the batteries charged at the best rate that was possible 'naturally'.

 

'Our' solution is all about delivering the optimum voltage and current to the habitation battery, not the reduced 14.1v caused by voltage drop they often 'see'.

It might seem small but as little as a 0.3v drop can make quite a difference to habitation battery charging time.

 

So where an Alternator might be down a bit of voltage due the Voltage regulator being a bit tired, or cabling not up to the job, or whatever it is, the Schaudt B2B will always deliver 14.4v, or whatever the battery technology requires.

Even if connected to a Mercedes Euro 6 'Intelligent' alternator that tries hard to deliver only 13.2v for as much as it is able, the Schaudt unit will deliver a rock steady 14.4v.

 

 

As our advert used to say, "Our units stick rigidly to the voltages and currents recommended by the battery manufacturers".

 

It also works with the existing electronics, supplying the charge that the battery manufacturers recommend.

It doesn't connect Battery to Battery, but Alternator to the Sargent EC328, or Alternator to Schaudt Elektroblock or whatever is installed.

 

Sterling Battery to Battery chargers were designed for boats that have very simple systems, sometimes nothing more than a Gauge and a relay, that are safely sidelined by running 'Battery to Battery'.

 

Motorhome electronics are becoming more and more sophisticated where it is becoming harder to connect anything directly to the battery without causing issues.

The most famous one being the Sargent EC325/EC328 18v charging systems, the high voltage of which can damage many 12v designed gismos.

 

 

 

If you want an example of just how punishing a B2B can be on battery life, the chart below shows how Gel/AGM battery life is shortened massively by quite small increases in Plate temperature.

 

Victron state that if the charge rate rises above 20amps per 100Ah battery the battery life can be shortened by half. A 20 degree rise at the paltes drops it by more, down from 10 years to just 2.

 

They quote :

"15. Charge current -

The charge current should preferably not exceed 0,2 C (20 A for a 100 Ah battery) otherwise the temperature of a battery will increase by more than 10°C".

 

A wet battery will suffer less direct damage, but still take a hit from loss of fluid and corrosion.

 

[arthur49]

Thank you Allan. If/when we change van I'll be in touch

[aandncaravan]

Just reread my reply of last night and I obviously enjoyed that bottle of Wine with my Chinese more than I realised!!

 

What I was trying to say was that all battery manufacturers state that while a battery can be Fast charged or Boost charged at a higher rate than the ideal, their life can be significantly shortened and the battery compromised if you take that option.

 

I have never seen any manufacturer recommend anything other than LOW current and voltage charging as the optimum for long life and battery efficiency.

 

 

The likes of the Stirling B2B, generally, boost the charge to a higher rate than an Alternators normal output, to fast charge a battery. Some B2B's increase the voltage by upto 0.5v more than a standard Alternator's 14.4v.

 

As can be seen from the Victron Energy charts in my first post this can shorten a batteries life dramatically. But remember the exact same process that shortens a batteries life impacts efficiency and capacity.

So a battery bank that is subject to 'Fast charging' will rapidly deteriorate, in the process they will take longer to fully charge as well as lose capacity.

In a worst case, after just a year on a Stirling B2B a 300Ah battery bank could be down to 200Ah real capacity and take longer to charge than undamaged batteries on a standard Alternator.

 

It is at this point that the batteries will then start to place an abnormal load on the other charging systems putting them at risk of failure. The load on the Alternator may be way above it's design.

 

The Stirling is aimed at boats where such a compromise is acceptable, because you can't exactly connect up to EHU in the middle of the Atlantic.

 

 

The loss of efficiency is not generally understood by many who run B2B's, who often also do so in association with Solar Charging.

If you compromise a batteries efficiency, it will take more Solar amps to get fully charged and because the compromised battery is shrinking in real terms you also get back less Solar amphours.

 

Ask anyone in the know out on the web, they will all tell you fast charging will accelerate Internal battery corrosion and that corrosion not only restricts a batteries ability to accept charge, but also give it up.

 

Have a look at the picture below from Bosch, it shows a battery that has corrosion on the Grid and one that hasn't.

This is a layer that sits between the Grid and the Paste through which electricity has to flow.

You can see why the 'reduced corrosion' Bosch and Varta Powerframe batteries have a claim of 70% better electrical flow than conventional corroded batteries.

 

Why would anyone deliberately want to accelerate this Corrosion/'Grid Growth' with the potential end result of 70% less Electrical efficiency??

 

The B2B's out there do what they say 'on the Tin', but the marketing forgets to mention it is only for 6 weeks.

 

 

The other aspect, sorry to go on but might be of interest to one of you, is the Alternator loading.

It might say 150amps on the label, but this is about peak, short term output.

 

Alternators in most older vehicles spend their lives doing little. Only on a really severe Winters day will the wipers, Heated rear window, heater blower, Electric heated seats, head lights, etc be all taking power from the Alternator, and then only for a short drive. (We think that this will change as Stop Start 'matures')

 

 

This is how the majority of Motorhome Alternator Designers view an Alternators use. Few realise that Motorhomes like a Stirling B2B equipped Motorhome, might stress the Alternator to the maximum on almost every drive they take.

So not surprising that Alternator failure on Motorhomes is more common than on any other vehicle category.

Amazing considering the small Motorhome numbers and low annual miles, isn't it?

Lorries covering millions of miles rarely suffer Alternator failure. When they do it's not the burnt Coils/Regulators/Rectifiers overloaded on a Motorhome, but Bearing or Brush failure caused by the vast number of miles covered.

 

 

The product we used to market, does not artificially raise the charge rate at all. It is about ensuring that there are no loses in the cabling, earth connections, etc. so that the Alternators power is delivered to the batteries exactly as the designer intended.

 

By aiming to provide the Optimum charge to the battery set-up, the batteries stay at their best longer, producing the best charge rate without compromising life or efficiency.

 

 

Think of it as a Garage that will help get the best from your Toyota Yaris by making sure the tyres are the optimum pressure, the Brakes are perfect so create zero drag, that the Oil is new and providing maximum lubricity, etc.

 

What we wouldn't do is fit a Turbo to the engine. That might work for a while, but just as likely to give negative effects.

Nor would we work on one that had 'Forced Induction' added as an after market option as that is clearly going to affect reliability long term.

 

 

 

 

 

[aandncaravan]

Arthur, before you consider fitting a B2B to your next vehicle, have a look at our web page 'How does a Battery Charger Works' : http://www.aandncaravanservices.co.uk/how-does-a-charger-work.php

 

Near the end there is a 'Tips' section on improving the efficiency of Alternator charging to cope with extended battery banks. Tips like fitting a bigger Split charge relay (for less Voltage Drop not current handling), fatter cables, etc.

The improvements suggested, on some British built Motorhomes, can improve Alternator charging by up to 50%.

 

 

 

 

[arthur49]

Thank you Allan.

 

Just for info my battery bank is 2 x 110Ah sealed acid. Mains charger is EC155 which has straight 13.8v charge voltage. Never gets to 14.4v and only reduces below 13.8v is we apply a load to mains.

 

So, I know my charger will never (or will take forever) to get 2 batteries to 100% charge, and thats why I fitted an isolator switch so that I could isolate one battery from the other and charge/load each one independent of the other.

 

Three years ago I did have a Sterling 40A B2B fitted BUT most importantly I wanted remote monitoring and that sits besides the drivers seat so that I can switch off B2B when I think battery has had enough! (No complicated algorithm, I just think thats enough)

 

One flaw I don't like about the B2B is when the engine is first started the B2B starts at 14.4v ..... but if I stopsay 90 minutes later to stretch my legs/coffee, when I restart the engine off the B2B goes again at 14.4v. So on a say 6 hour journey with 3 stops a B2B could never change from 14.4v!!

 

So I use my B2B with extreme care as I don't want to wreck my alternator or batteries. I have NEVER run my batteries down so far that its running at higher than 27A ..... and that only for a short time, maybe 10 minutes or so.

 

With care, I think B2B is a decent charging option in my case since the EC155 is weak 8-)

[aandncaravan]

Hello Arthur, We would agree with your assessment of your mains 230v charger.

 

The Cabling from the batteries to/from the Fuse Board is also not the best either for optimum battery charging. So understand you opting for a B2B as that was the advice going around at the time.

 

 

Surprised you are only seeing 14.4v out of the B2B, most we have seen run more like 14.6v/14.8v for Wet Acid batteries?

 

Maybe you have sensibly chosen the lower voltage setting of 'Sealed', which restricts the charge quite a lot?

That might also explain the low 27amp (assuming it's across two batteries so just 13amps each?) charge rate.

 

So a good setting, your battery degradation should be much less, but your charge rate not that different to an "uprated cables, Big Split charge relay, etc" option?

 

 

The 'Flaw' you mention is a feature of many charger units and Solar regulators.

Some solar regulators will 'wake up' each morning at 14.4v full charge voltage for several hours, even if the battery was fully charged when the Sun went down the night before.

One we saw stayed at 14.4v for 4 hours till it settled down to 13.8v Float. Did that every day, 'overcharging' the battery. Some nasty Solar Regulators being used out there!!

 

 

[david lloyd]

Allan, just on that point about 'nasty' solar chargers our newly acquired 2015 Hymer B544 has three Vision Plus 40w solar panels linked together and rung through the standard Vision Plus regulator. I have no details/instructions for any of these and cannot find anything useful on the internet but did wonder how good the regulator would be. I quite like the three panels and the literature I have seen sats the emulator can take a fourth 40w panel if I need to expand. Have you come across these and have a view on how good they are?

 

Sorry to hijack the thread.

 

David

[arthur49]

Thanks Allan.

 

Yes I deliberately chose 14.4v setting.

 

If/when I change the van, depending on mains charger fitted etc I'll look at enhanced charging then .... and maybe a trip to N Wales B-) B-)

[emmerson]

On the subject of charging, have I discovered the secret of endless free power?

Let me explain; I use a 350w inverter in my car to keep Herself's mobility scooter charged up when travelling.

So, I bought another inverter to use in our camper van.

I connected it up to my spare battery to check that it worked ok, and plugged in the 24v charger: all ok. So I connected my 12v battery charger to the spare battery, and plugged it into the inverter, and it all worked!

So the 12v battery is charging itself through the inverter.

Have I made a momentuous discovery? Should I sell it to the power companies, or just keep it to myself?

Or am I just being daft? If so, how long would it take to flatten the battery?

[aandncaravan]

Not come across the Vision Plus regulator before, so know little about it. But do know it is a single battery device (won't properly charge the Starter battery) and that it is not the item recommended by Hymer or Schaudt ?

What Elektroblock do you have?

 

 

Emmerson, If I understand correctly, you have an Inverter running from the battery powering a Mobility battery charger and have plugged into the 230v socket of the Inverter a charger that is charging the battery back up? If so, sorry to disappoint but it the battery will eventually run down.

 

The better Inverters will typically be around 85% efficient and the best battery chargers around 89% efficient, the worst as bad as 70%.

So each device will be 'wasting' power and the battery slowly drop.

 

 

 

 

 

 

[emmerson]

aandncaravan - 2017-04-15 10:25 PM

 

Not come across the Vision Plus regulator before, so know little about it. But do know it is a single battery device (won't properly charge the Starter battery) and that it is not the item recommended by Hymer or Schaudt ?

What Elektroblock do you have?

 

 

Emmerson, If I understand correctly, you have an Inverter running from the battery powering a Mobility battery charger and have plugged into the 230v socket of the Inverter a charger that is charging the battery back up? If so, sorry to disappoint but it the battery will eventually run down.

 

The better Inverters will typically be around 85% efficient and the best battery chargers around 89% efficient, the worst as bad as 70%.

So each device will be 'wasting' power and the battery slowly drop.

 

 

Damn! I thought I was going to make millions! :-D :-D

[david lloyd]

aandncaravan - 2017-04-15 10:25 PM

 

Not come across the Vision Plus regulator before, so know little about it. But do know it is a single battery device (won't properly charge the Starter battery) and that it is not the item recommended by Hymer or Schaudt ?

What Elektroblock do you have?

 

 

 

 

Hi Allan,

 

It's an Elektroblok EBL29 fitted in a 2015 Hymer. The Vision Plus regulator is capable of being wired to the starter battery but this one has not been. There is, however, a Battery Master fitted which takes care of that.

I am waiting for a call back from Grade UK to ask what the LED's mean as there are no instructions with the van and the only online information doesn't mention anything much about the regulator. It's really a question of whether I should invest in a better regulator that would maximise the 120 watts available or is the Vision Plus doing the job.

 

Just on your other thread about BMW endorsing the new Powerframe technology, you may recall I replaced the Banner Energy Bull on our previous van with two Varta LFD 90's and were very pleased with them. The Hymer has two Varta LA95 batteries that I think are AGM - the starter battery is the same size but I can't make out what make. I have been monitoring their levels this week as I know the motorhome was at the dealership for a few months but they seem to be holding their charge well. I just wondered what your advice would be to keep them in good condition fo as long as possible with regard to charging at home. We do a mixture of camping on sites and other spots like CL's, Temporary Holiday Sites or, on the continent, Aires without EHU.

 

David

[aandncaravan]

The Vision Plus Regulator, is not capable of charging a Starter battery properly, the instructions that are supplied with it are wrong.

 

On the instructions, the second output is a 'Load' output, not a battery charging output, yet the instructions show wiring heading off to the starter battery. It is likely to damage the battery. I suspect your installer has realised this and fitted the Battery Master instead?

 

The Battery Master works by 'watching' the Starter battery and when the voltage drops by more than 0.75v (a pretty much damaged battery!!) it then starts taking power from the habitation battery.

 

It also monitors the Habitation battery and when the voltage at it's terminals (not necessarily the battery voltage) goes higher than 0.75v of the Starter battery it will begin stealing power from the Habitation battery.

 

Because it is constantly monitoring both batteries it consumes power from both, only small amounts but obviously not the ideal when Solar in Winter is about tiny amounts of power.

Also the Battery Master will not be 100% efficient, so will sap some of the power it is transferring between the batteries. Typically these types of devices are only 80% efficient, so in addition to taking power from both batteries it will typically sap 20% of all it transfers.

 

The Battery Master also short circuits the EBL 29 functionality, taking control away from the unit that the manufacturer put in to control everything.

 

A Battery Master is probably the least efficient way of getting Solar to the Starter battery.

Also likely the installer will have disturbed the EBL 29 and cut into the main wiring loom instead of using pre made cables that just plug into the EBL. Check this won't impact your warranty as your installation is not how the Motorhome manufacturer or the electronics supplier recommend.

See here for more info : http://www.aandncaravanservices.co.uk/lr-1218.php

 

Check they have installed the safety fuse up near the roof where the cables enter the vehicle, often not fitted on older installations.

 

All in all, I would say an installation done by someone who didn't have a clue?

 

I can't advise you, but I think you know what I would do?

 

 

.

[david lloyd]

Thanks for the comprehensive reply Allan.

 

I have now received the information sheet from Grade UK and, as you say, the solar charge controller isn't really for charging a second battery but I didn't realise the Battery Master would not be a good option either. Further reading of your website also seems to point to the two AGM batteries not being the best choice either.

 

As far as the installation is concerned it was undertaken by the supplying dealer for the original 1st owner when supplied new in September 2015. The dealer in question is a main Hymer dealer and, as such, would be expected to follow Hymer guidance on fitting 12v and solar power so I am surprised it doesn't seem to. Especially if Hymer have built in solar power handling capabilities. That's a bit worrying.

 

I think for now I'm stuck with the AGM batteries until such time as they need replacing but, providing the EBL29 has the capabilities, may have to seek out a suitable replacement regulator but, as I have very limited knowledge of 12v wiring and solar fitting, will have to locate a suitable installer to wire the existing panels to a new regulator using the original Hymer wiring and EBL29.

 

David

[aandncaravan]

I don't know, but didn't think your Solar charger was optimised for AGM, so the AGM's may not have had the ideal charge regime?

 

 

 

 

[david lloyd]

aandncaravan - 2017-04-18 7:01 PM

 

I don't know, but didn't think your Solar charger was optimised for AGM, so the AGM's may not have had the ideal charge regime?

 

 

 

 

You may be absolutely right Allan, I have no idea but will ask Grade UK. The system does seem to be working in the sense that all the batteries have maintained a full charge (according to the main control panel) but if the EBL 29 and Hymer circuitry are designed to run the solar charging and starter battery top up then it may be wise to get that old regulator out and a proper one properly wired into the Hymer system.

 

David

[david lloyd]

aandncaravan - 2017-04-18 7:01 PM

 

I don't know, but didn't think your Solar charger was optimised for AGM, so the AGM's may not have had the ideal charge regime?

 

 

 

 

Allan, I have bought a 30amp Solrelectronica regulator that will comfortably cope with 180 - 250 watts of solar and can be set to cut out at any battery voltage level. As supplied it was at 14.0v but should this be 14.4v for my two Varta LA95 AGM batteries?

 

I am going to see how I get on with the three 40w Vision Plus panels but I can easily add another panel if required.

 

Thanks

David

[aandncaravan]

I have not seen this unit before, so know nothing about it.

Not sure what you mean by 'cutoff' voltage, is that the top end as in 14.7v for AGM or the bottom range for maintenance of 13.2v?

 

 

 

 

 

 

[david lloyd]

aandncaravan - 2017-04-21 8:31 PM

 

I have not seen this unit before, so know nothing about it.

Not sure what you mean by 'cutoff' voltage, is that the top end as in 14.7v for AGM or the bottom range for maintenance of 13.2v?

 

 

 

 

 

 

No, I'm not sure what I mean either - which doesn't make it any easier to give me any help!

 

But the regulator cab set to stop charging at any level within a certain range. It was set at 14.0v but I changed it to 14.4v thinking that was the correct maximum voltage for the two AGM batteries. So, i was just needing to know what the correct maximum voltage it should be set at. As you may be able to detect, I don't have much knowledge of these things.

 

However, the information shown on the LCD display can be cycled through and set individually. The cycled information shows:

pv 1.2 A (at the moment but this climbs as the sun increases and there is an LCD arrow showing power flowing into a battery)

Load 0.0A

pv 1118 ah

Load 0 ah

Load on 10.7v

Load on 12.6v

pv on 14.4v (LCD arrow showing no charge going into battery - five full indicators)

Load on 24h

13.2v

24c

Back to pv 1.2 A

 

So I think the first info is the amount of power in amps flowing into the battery (presently climbing from 1.2A) - the 7th screen is the highest voltage the charger regulator is set at (presently 14.4v) and the second to last figure the maintenance charge - set at 13.2v.

 

Does this sound correct or am I completely mixed up?

 

David

[Brambles]

david lloyd - 2017-04-21 3:19 PM

 

aandncaravan - 2017-04-18 7:01 PM

 

I don't know, but didn't think your Solar charger was optimised for AGM, so the AGM's may not have had the ideal charge regime?

 

 

 

 

Allan, I have bought a 30amp Solrelectronica regulator that will comfortably cope with 180 - 250 watts of solar and can be set to cut out at any battery voltage level. As supplied it was at 14.0v but should this be 14.4v for my two Varta LA95 AGM batteries?

 

I am going to see how I get on with the three 40w Vision Plus panels but I can easily add another panel if required.

 

Thanks

David

 

The Varta recommended Absorption voltage for AGM is 14.8 volts.So this will be your cutoff voltage.

AGM also tend to have higher discharge voltages so where in a flooded 12.1 volts is 50% discharged, it is 12.5 volts for a Varta AGM.

 

 

[david lloyd]

Thanks Brambles so I should change the 14.4v figure to 14.8v to get the best out of the solar charger.

 

David

[aandncaravan]

David, I agree with Brambles on changing it to his higher voltage.

 

I assume the 13.2v is the Float/maintenance setting?

If it is then 13.2v is perfect for a long term 'Storage' setting, but for faster charging when you are using the vehicle 13.8v would be better so long as you don't leave it that setting long term when not in use.

 

 

I am intrigued by the two 'Load' figures as one might expect the 'Load' to be the batteries and in a dual battery version the Starter and Habitation battery values?

Yet 10.7 and 12.6 seems too low for both, suggesting, maybe, the batteries have already tired?

 

 

 

 

[david lloyd]

aandncaravan - 2017-04-22 2:44 PM

 

David, I agree with Brambles on changing it to his higher voltage.

 

I assume the 13.2v is the Float/maintenance setting?

If it is then 13.2v is perfect for a long term 'Storage' setting, but for faster charging when you are using the vehicle 13.8v would be better so long as you don't leave it that setting long term when not in use.

 

 

I am intrigued by the two 'Load' figures as one might expect the 'Load' to be the batteries and in a dual battery version the Starter and Habitation battery values?

Yet 10.7 and 12.6 seems too low for both, suggesting, maybe, the batteries have already tired?

 

 

 

 

Yes, sorry Allan, I may have put those 'load' figures in wrong.

 

The charge controller is not a dual version so the 'load' is in fact a feature to enable another outlet to be wired to the charge controller. - perhaps for a light for example. The 10.7v figure should be when the available 'load' is switched off and the 12.6v reading when it is switched back on again - or in other words when it becomes available for the additional wired 'load'. Both these figures can be configured manually. This is not a feature I intend to use at all so will leave them as they are.

 

Monitoring it today I can now see that (having set the 'cut off' voltage at 14.7v) once the batteries reach the voltage set at the higher rate the solar panel charge is stopped until it settles back to 13.2v where it remains on float charge until such time as the load reduces that voltage and the solar charge regulator then cuts in again until it reaches 14.7 again. I think this is probably right for the type of batteries so will continue to monitor the performance. If I find that the 120w panels are not replacing sufficient power each day I can add another Vision Plus secondary panel quite simply and this will take the solar array up to 160w.

 

David

[aandncaravan]

Then, IMO, you have selected a regulator that doesn't create the most efficient solution.

In Winter you could have a system that is literally 50% worse than the best you could have selected, maybe even worse than that?