Hymer ML-I 540 - using off grid

[dicksob]

Hi, as I mentioned in a previous thread we are considering the 540 as a potential replacement for our IH. As we spend more time on stellplatz and Aires being self sufficient for power is becoming more important. The Hymer can be ordered with 3 95amp amg batteries, an extra charger and an 1800w inverter, all of which seems to do the trick. However only room on roof for one 100w panel, though it has a 180amp alternator on base vehicle. Having read previous threads on amg batteries, now thoroughly confused!! Our ideal would be to be able to be off electric, charge bike batteries and run our nespresso machine ( I know, I know) and recharge by panel or driving ( not huge distances). Views and advice please.

 

Bill

[aandncaravan]

That is asking a lot of 3 batteries of any technology AGM or otherwise!!

The sort of power you are probably going to draw from the batteries will take a long time to put back with a 100W Solar Panel and an Alternator run for only short distances.

 

If you ration your power draw so the batteries never get below about 12.7v for any length of time it will probably work ok for a while but budget for replacing the batteries every 18 months as they are unlikely to get very highly charged?

 

For example an 1800w Inverter can draw close on 170amps (with conversion losses) so if you run it for 30 minutes (I know that is unlikely, just easier to do the maths) that is 85Ah taken from the batteries. Driving on Alternator will take about 2 hours to put back. Or by Solar Panel around two to three days, depending on time of year.

 

 

 

 

 

[dicksob]

Thank you, yes understand. Would top up regularly on hook up, just want the flexibility when required. What do you think of the Hymer set up, I'm used to the simple one in my IH , a 140amp battery, 100w panel, single charger. Am I going to have future problems with 2 chargers etc?

[aandncaravan]

I can't answer that question as it depends on many factors, like how low you discharge the batteries, how often you connect to EHU, the time of year and where you use the vehicle.

 

AGM batteries are not the ideal for the type of use you propose, AGM are better at supplying lots of amps over long periods of time than Gel, but not as good as a big wet battery.

 

When you do 'top up' on EHU, maybe every 3 - 4 days?, the two chargers will make a faster job of it than one and share the load.

 

However, four batteries (including the Starter battery which the Schaudt Elektroblock also charges) of 4 x 95Ah = 380Ah is still a big ask of 2 x 18Amp chargers if the batteries are in a very discharged state.

 

What does the Nespresso draw in watts and how long does it take this power for?

 

 

 

[dicksob]

Allan, thank you, it's really valuable to get impartial honest advice! I should ask you next what you think of the sprinter short wheel base chassis and if you think I might have any grounding issues, but probably not your topic!!

Again, sincerely, thank you.

Bill

[Wiggy]

Hi Bill

I have sent you a PM re the grounding issues with the Hymer MLT & MLI motorhome range

Regards

Wiggy

[dicksob]

Wiggly, thank you, have sent you a pm.

 

Bill

[Clive]

Nespresso Machine!! Come on, that is taking the mick. You will be saying next that you cannot do without your hair dryer, oh and the pop up toaster and camping electric kettle in the mornings. Seriously though if you are wild camping then don't use 12 volt leccy for any heating purpose. Use gas and your gas locker will in fact take two 14kg Alugas bottles if you like. The MLI 560 has room on the roof for two 80 watt semi-flexible solar panels and a satellite system. Why is yours not similar.?

 

If you are flush then for around £3000 the latest 130AH EZA LiFeP04 battery unit (Roadpro) will charge quite quickly by running the engine, but it will require new cables from it back to the alternator.

 

But nice van especially if you have that 3 litre V6 engine and Alde heating.

 

Enjoy

[Brian Kirby]

dicksob - 2016-08-30 9:08 PM........................ The Hymer can be ordered with 3 95amp amg batteries, an extra charger and an 1800w inverter, all of which seems to do the trick. .........................Bill

In view of the question marks over AMG batteries (seemingly mostly when they are worked hard and re-charged with non-dedicated chargers), can you get the enhanced charging added without the additional batteries?

 

If so, might it pay to get the van without the extra two AMG batteries, and then remove that and install your own choice of batteries? I'd guess that may be cheaper (and probably better) than what Hymer will charge for the two extra AMGs.

 

I'm assuming the additional charger is the Schaudt plug in module for high capacity battery banks? If this is correct and Hymer won't supply this without the added battery, can't it be obtained in UK - for example from A&N Caravan?

[Robinhood]

Brian Kirby - 2016-09-02 6:12 PM

 

In view of the question marks over AMG batteries (seemingly mostly when they are worked hard and re-charged with non-dedicated chargers), can you get the enhanced charging added without the additional batteries?

 

 

Schaudt have had a range of products (including a version of the supplementary charger) for a while now which have an additional (over flooded and gel) charging regime option for AGM.

 

I'd wouldn't be surprised if Hymer have started fitting them (if they are still providing AGM batteries as standard).

 

It would certainly be worth a check.

[Brian Kirby]

Robinhood - 2016-09-02 6:49 PM

 

Brian Kirby - 2016-09-02 6:12 PM

 

In view of the question marks over AMG batteries (seemingly mostly when they are worked hard and re-charged with non-dedicated chargers), can you get the enhanced charging added without the additional batteries?

 

 

Schaudt have had a range of products (including a version of the supplementary charger) for a while now which have an additional (over flooded and gel) charging regime option for AGM.

 

I'd wouldn't be surprised if Hymer have started fitting them (if they are still providing AGM batteries as standard).

 

It would certainly be worth a check.

True, oh wise one, but there seems to be a more general question as to whether AGM batteries are worse suited to relatively slow deep discharge followed by relatively slow (solar)/incomplete (insufficient driving time) charging than other batteries.

 

Off grid motorhoming on a continual basis seems to be what kills AGM batteries, and (as a confirmed non-expert!) I'm not entirely convinced that whatever mains charging regime is applied (on an infrequent basis) would compensate for a seemingly ill-suited battery technology.

 

Ours is AGM, but it is seldom discharged to any significant extent, and is invariably re-charged immediately thereafter. It recently did us for four days off grid, and showed almost no voltage reduction after that time and, as it is now three years old, I'm assuming that our pattern of use doesn't stress it and consequently it will survive for a good while yet. But that is us: Bill's pattern of use is at the other end of the scale, for which I'm assuming AGMs are probably not his best choice. Hence my suggestion that he gets the supplementary charger, disposes with the Hymer fit AGM, and instead sources three batteries more suited to his pattern of use.

[Robinhood]

Brian Kirby - 2016-09-02 7:20 PM

 

True, oh wise one......

 

 

...flattery will get you nowhere ;-)

 

I know you raise a question about AGM batteries' longevity, but I'm far from convinced there is a fundamental issue with the technology.

 

I can accept that there may be some issue with the charging regime used if subjecting the batteries to significant DoD, and, if I were planning on being off-grid for large amounts of time, I'd like to see the charging technology match (hence the comment about the newer Schaudt chargers/Electroblocks). If I were adding solar, I'd also want to ensure an AGM charging regime for that (either via a dedicated regulator, or by checking that the add-on Schaudt controller utilised the new AGM regime).

 

My worry is that, with the exponential increase in use of electronic equipment in motorhomes - some of it high-demand such as e-Bike battery recharging, people are expecting too much of battery installations in general, and that over-demand is proving somewhat punishing whatever the underlying technology. I would factor in to the running cost a periodic replacement of batteries anyway, in this case.

 

IMO, the profile of use of the OP (depending on the time off-grid) may well be an example of this. Charging on hook-up could well be a (short-) periodical requirement, hence my recourse to the point about AGM charging regime.

 

My own use with two AGM leisure batteries is generally light without hook-up, but we do go off-grid with blown-air heating use (and, if appropriate a solar panel) for periods of up to a week.

 

In 18 months, I've noted no downside (even without a dedicated AGM charging regime) though my batteries are Varta, and not the oft-criticised Banners.

 

Empirically, from longer-term past use, I would choose Gel technology, since, fit and forget, a pair of these has been proven to meet my requirements for getting on 5 years, but, for convenience and neatness of installation, I don't think I would necessarily dismiss a well-integrated, factory-fit AGM solution. (of course, depending on how any vehicle were ordered/obtained, one might actually find the end-solution was a dealer-fit "lash-up").

 

If a DIY solution were envisaged, the (supplementary) LAS 1218-2 and similar chargers aren't too difficult to obtain as aftermarket units, particularly from Germany.

 

 

[aandncaravan]

Hymer do still fit AGM batteries along with the latest AGM optimised charger units like the EBL119 (replacement for the older EBL 99) but the downside is the longer charger time.

 

If you look at Schaudt's own document, see bottom of this page : http://www.aandncaravanservices.co.uk/agm-batteries.php, it shows that.

As soon as the voltage AT the battery reaches 14.7v (usually achieved within less than 30 minutes from flat on a discharged 100Ah battery) a timer starts in the charger. After 16 hours on the 'Wet' setting it drops down to a 13.7v 'trickle' charge. On the AGM setting it drops to 13.7v after just 4 hours. Just as AGM don't like long sustained discharges, so their life can be compromised by long charges.

One of the reasons Sterling say don't use AGM or Gel for 'fast' charging, and that 'Wet' is their battery of choice.

 

So the overall result of charging an AGM battery on a Motorhome optimised charger is a pretty slow charge rate. In some instances twice as long as a Powerframe battery. And that is with an 'optimised' charger!!!

 

An AGM battery does have a faster charge acceptance (short term only) than an ordinary wet battery, but little faster than a Powerframe Varta LFD which matches an AGM when new. A Powerframe battery will outperform an AGM after around 2 years.

 

 

It isn't just the life time of an AGM that goes against it when used in a Motorhome, it is it's ability to give real world power and susceptibility to degradation from long, high current discharges/charges.

 

 

However, another issue that has cropped up, is damaged wet Starter batteries from being charged at 14.7v by the new breed of AGM optimised chargers. The Schaudt EBL 119 also charges the Starter battery, if you set the charger on an AGM's 14.7v, that is what is supplied to the Starter battery. Obviously not ideal for most wet Starter batteries.

Likewise if you fit one of the new LAS1218 AGM optimised auxiliary chargers to bring an 'old EBL 99' up to AGM standard, it is again the AGM's 14.7v that is thrown at the Starter battery.

 

This can also apply to Solar Regulators that are optimised for AGM, as the same voltage can reach the Starter battery. We are not aware of a single Solar regulator with the ability to set individual battery technology settings for either battery.

 

Some Starter batteries will cope better than others, a Powerframe based Bosch or Varta probably won't really degrade as they don't suffer corrosion at the Positives plates at higher voltages/Temperatures as other batteries do.

But some 'Wet' Starter batteries will have a very short life at 14.7v..

 

I don't know how the CBE 'Battery Master' device works, but if it passes to the Starter battery the same voltage it 'sees' at the habitation battery, there might be issues here as well if the Habitation batteries are receiving an AGM charge?

 

 

 

[Robinhood]

...we've been here before, haven't we Alan.

 

I would certainly bow to your greater empirical experience of actual installations (especially those that fail, which as I've averred before will be a small percentage of those out in the wild), but some of the technical background is open to different interpretation.

 

For example, rather than the different "Full Charge" phase timings demonstrating slower charging of AGM batteries, I think it demonstrates the expected greater charge acceptance (meaning that, like-for-like, it takes less time to pump the required charge into the AGM battery before you can throttle back to a maintenance charge) i.e. it does or is expected to, charge more quickly.

 

This greater charge acceptance is exactly the reason car manufacturers are fitting AGM batteries to vehicles with smart charging systems and/or start-stop. The difference in timings implemented isn't far off the quoted ratio of charge-acceptance that I can (quickly) find.

 

Given that there will have been very few UK motorhomes so far with AGM-regime on-board chargers, I'd also be surprised if there were widespread evidence that they were damaging vehicle batteries, not least because the current delivered to that battery is constrained to low-level at all times, whatever the voltage.

 

It certainly isn't unusual, however, for leisure or vehicle batteries to go belly-up early in their life if the vehicle has been on-show. (I've lost count of the number of times I've had to turn items off in such vehicles that are not on hook-up).

 

There are lots of other factors that could come in to play, like under-provision of charging capacity for the installed battery bank, etc., but I see little reason to question the difference in "Full Charge" phase timing.

 

I suspect we will continue to interpret differently, and thus to differ. ;-)

[dicksob]

Thank you chaps for all responses. The additional batteries, charger and inverter all come as part of a "power package" option in the 2017 Hymer price list (£1770), so definitely factory fitted. Brian, no separate charger listed in options so looks like all or nothing.

 

I have perhaps overstated our desire to be self sufficient though! As an example, we are off to Germany for a week leaving next Saturday, intention is to stay on stellplatz in Xanten, Bad Benthein, Bocholt and Bedburg and enjoy some cycling on our electric bikes. All stellplatz have provision of electric but not for all vans. So our desire is that for the occasions when we can't get electric or for when the views etc are better away from the points that we can be self sufficient. No intention of doing it all the time or for long periods or when heating is required in winter months. Hope that's a bit clearer!

We cope ok at the moment in our IH, 140amp wet battery, 75amp solar, cbe electrics but no inverter.

 

Clive, agree on the 3litre v6 and auto box, both superb! Definitely going for alde heating this time too. Biggest concern is the issue re grounding due to placement of the water tanks, well discussed on other thread. Derek has been very helpful with advice, may be that we will have to reconsider and go for a DL version on the Fiat/Alco chassis, though would mean going to7metres. Trying to convince myself it will be ok, but worried I make an expensive mistake.

[aandncaravan]

As we state, AGM do have greater charge acceptance, but not in the order of magnitude of 2 to 1. It is a relatively small difference, especially if compared to a decent wet battery as opposed to the 'worst of the breed' normally used for comparison.

 

AGM batteries are prone to degradation if the temperature at the plates rises, solely because the Acid is not able to move so freely, being absorbed in a Glass Mat.

This same 'loss of fluidity' is exactly the reason why Gel batteries degrade when fast/prolonged charged/discharged.

While charging can be relatively fast initially as soon as the Acid warms up the charging rate has to be reduced to prevent potential degradation. The extent of that degradation will depend on several factors, but to play safe, those chargers with out temperature compensation, will back down the rate.

While AGM is better than Gel in this respect, the slow transfer of heat in an AGM battery is still a major issue.

 

 

The primary reason AGM batteries are used in Stop Start is not because of the greater charge acceptance, which is not that much better than a good wet battery. But because they have reduced susceptibility to damage from repeated discharge/charge cycles. An AGM battery will typically have double the discharge/charge cycle rate of a good wet battery.

 

They are also the battery of choice on many regenerative Braking systems as they are more tolerant of being held in a partially charged state. The reason we think they are being adopted by Dealers and Motorhome manufacturers.

 

On a vehicle using 'Alternator' based braking regenerative technology, the ECU controls the Alternator. The Alternator will not recharge the battery after starting but remain in a passive state, not drawing power from the engine, thereby saving fuel.

When the driver 'lifts off' the accelerator the ECU triggers the Alternator to charge the battery which places it's load on the engine, helping to slow the vehicle and getting 'charging power' for free in the process.

This can sometimes result in the battery getting to a fairly low discharged state before the ECU senses the voltage dropping below at set threshold, so triggering the Alternator regardless of the accelerator position.

 

 

An AGM battery fitted to a car with Stop Start and regenerative braking will stand these stresses better than a wet battery, but that does not mean it is a better overall battery in a Motorhome which is a completely different environment.

In the average Stop Start vehicle the battery won't be discharged very deeply. It goes through a process of repeat slow discharge/recharge cycles. The discharge is neither deep nor the recharge very long and punctuated by rests which allow the battery to cool and the heat to slowly transfer away from the plates, which it handles ok .

 

In a Motorhome, it can be discharged right down to 50% (or even more) and then recharged all the way back up. That is a very different stress for an AGM, especially if the currents involved are hefty, like when paired with an Inverter?

 

 

There have been AGM optimised Solar chargers for almost 2 years.

The LAS1218 AGM aux charger also being available for around 12 months.

The EBL 119 became standard Hymer fitment at the end of 2015.

Normally a Starter battery can be expected to last 7 plus years, not the much shorter intervals we have seen on LAS 1218 AGM and AGM Solar regulators retro fitted to earlier build vans.

 

It is not just the current which causes battery degradation, higher voltage than ideal is as big a problem, regardless of the actual current.

As witnessed by the recent release of Solar charging units with a lower than the 'standard' 13.8v 'trickle' charge since it was recognised that 13.8v was causing issues. The Schaudt LRM1218 has a maintenance charge of just 13.4v. The very good Votronic Solar Regulator units are 13.4v.

Victron Energy's excellent Solar Regulators are 13.2v.

Even some of the budget Chinese ones are coming into line with this thinking.

 

If 13.8v is now recognised as an issue, I can't see 14.7v being a better option?

 

 

Finally go on the German Audi Forums and read the growing criticism of the short battery life on Start Stop systems. People are not getting 5 years life out of AGM.

We suggest it will be a growing trend.

 

 

You are right in that we see things differently, but I don't see that as a bad thing, as it promotes more discussion, sometimes with more depth?

Several times your responses and views have caused me to refine and even change my own.

 

 

 

[Robinhood]

Crikey Alan, that's a bit scatter-gun. I'm genuinely having difficulty picking your argument out of that, quite a bit of which seems to describe factors that would support AGM batteries as being a good motorhome option.

 

I'll stick to just a few points that were at the core of my initial response.

 

The EBL119 you refer to is clearly designed (at least from Schaudt's write-up) to support only Gel (which they describe as Lead-Gel, as they do in most of their documentation, using Lead-Acid for "flooded" batteries), and AGM batteries.

 

Accordingly, it has only two charging regimes, one for Gel (to which the 16 hours applies), and one for AGM, (to which the 4 hours applies). There is no "wet" setting as such, so a 16/4 comparison for wet vs AGM for this unit is rather invalid.

 

It is then useful to compare this with the LAS1218-2 and LAS1218 BUS auxiliary charger(s):

 

The former implements only Lead-Acid (with a 4 hour charge phase) and Lead-Gel, (with a 16 hour charge phase).

 

The latter implements an additional AGM regime, retaining the 4 hour (Lead-Acid) and 16 hour (Lead-Gel) from the above, and also implementing a 4 hour regime for the AGM (consistent with the EBL119).

 

Voltages at each charging stage are varied according to the selected battery type.

 

Accordingly, if you use a combination of charger and battery as Schaudt intend, you will get 4 hours "absorption phase" charging on both "wet" and AGM batteries, and 16 hours only on Gel.

 

Further to this, with your concerns about tailoring charging regimes to battery type, it would appear that retro-attaching a "wet" battery to an EBL119 (without a regime that looks tailored by Schaudt) ought to be giving you some doubts (not least because the AGM regime looks closer to Schaudt's implementation of "flooded" than the Gel one does).

 

===

 

As for some of the other stuff, Johnson Controls will claim (I know...) that they can achieve charge acceptance rates for AGM batteries three times that of flooded. Whilst I take claims with a pinch of salt, their published recommended charging regimes show initial charging currents a ratio of 2.5 times higher.

 

AIUI, one of the factors in choosing AGM batteries in cars is the charge acceptance rate. As you point out, energy recovered from regenerative braking is "free", but it is very transient. Higher charge acceptance assists in the recovery of more of this energy during the short periods it is available. My current car uses this technology.

 

===

 

Anyway, as we know, this is still, for all the research, an inexact science, and opinions will vary between extremes.

 

I'm still of the opinion that one of the major causes of battery issues is user-abuse of the installed capacity, whatever it consists of.

[aandncaravan]

That is interesting, I had not picked up on that marketing aspect of the EBL 119 being Gel and AGM only. I had assumed the Lead-Gel meant Wet and Gel, like other chargers, see the Reich e-box in the photo.

 

This was reinforced when I checked the PDF for charging voltages to find they were optimised for Wet batteries at 14.4v/13.7v. Although this is bit of a high/compromise for Gel which normally get a slightly lower 14.2v/14.3v, I had thought it wouldn't be a major issue considering that Gel batteries were becoming less common.

 

As you say the Schaudt documentation states the EBL 119 is targeted at Gel and AGM batteries only and not Wet/Flooded batteries. The AGM based EBL 30 documentation mirrors this.

Yet despite the documentation 'angle', charging a Bosch/Varta LFD Powerframe on the Gel setting will not result in any issues, as the 14.4v and 13.7v are about as perfect as you can get for a wet battery.

 

 

AGM acceptance charge : While they can have a higher charge rate, if it is prolonged the Plate temperature will be raised potentially causing issues. In my post on the 3rd September I wrote :

 

"An AGM battery does have a faster charge acceptance (short term only) than an ordinary wet battery, but little faster than a Powerframe Varta LFD which matches an AGM when new".

 

The AGM marketing bandwagon makes much of this 'higher charge acceptance' but often forgets to state it is for an initial short period only.

Your own statement above tallies with this where you write,

"...their published recommended charging regimes show INITIAL charging currents a ratio of 2.5 times higher".

 

In a real Motorhome environment, the Bosch/Varta Powerframe batteries will be pretty close to the charging time of an AGM.

 

 

Isn't it basic chemistry?

In a wet battery the acid is very fluid, as the chemical reaction of a Discharge/Charge takes place the Acid warms and rises up the Plate due to Convection, bringing in cool acid behind it.

 

This also results in fresh acid being brought into contact with the Plates to continue the chemical reaction. The heat is carried to the outside of the casing where it dissipates.

 

In a Gel battery the acid is almost 'solid', resulting in almost zero movement. As a result the acid at the plate warms quickly with very slow heat transfer away. Where the current being drawn off is high, the Acid at the plate becomes exhausted slowing the chemical reaction and the current drops.

 

When fast charging exactly the opposite happens with the Acid being 'regenerated' at the Plate and stopping charging until exhausted Acid takes it's place.

 

 

While the Acid in an AGM is a little more fluid, because it is trapped in the Glass Mat, acid movement is still quite static. Restricted in both getting the heat away and bringing in fresh Acid that is exhausted or getting away 'regenerated' Acid when charging. When fast charging a fully run down AGM, if the 'regenerated' acid is not replaced by 'exhausted' acid, the charge rate drops down.

 

Such technology only works reasonably well where the current either way might be prolonged but low or high but only short duration. However, prolonged high current either into or out will decimate both Gel and AGM batteries.

 

 

So matching an 1,800watt/ 180amp Inverter with a Gel/AGM battery is just bonkers.

 

Ask those who have tried to run a Microwave from AGM batteries. I have actually witnessed the Microwave struggling to get the power it needs after a few minutes as the Acid at the Plates becomes exhausted and unable to continue the chemical reaction. You can probably imagine the temperature at the Plates by this point??

 

Clearly a wet battery is going to handle the power draw better, purely because the Acid does move. The Plates themselves might not be happy about the way they are being used, but that won't be very different to an AGM. Both will suffer degradation if the currents are high or prolonged.

 

 

Just because an AGM battery can start a car engine many people believe it will handle major amps. But the reality is that a modern Stop Start Car engine fires up so quickly it takes very little power from the battery.

Also acid that needs 'regenerating' is right next to the Plates, which is restored quite quickly, usually before the next 'Start'.

There is no real heat produced nor any need for Acid to 'flow'.

 

It's a very different scenario to Motorhome use.

[Robinhood]

I'm not sure where this leaves us, Alan, though I'm preparing for disappearing to the Continent tomorrow, so this will be the last (considered) response.

 

I did find it interesting when, in the past you pointed out the lack of an AGM charging regime on the previous electronics, and I could see some point in raising that and the potential issues that might arise.

 

I've already said that, despite not conforming to most of your preferred "guidelines", in many years of using Gel batteries and more recently AGM batteries, I haven't really had any problems with either leisure or vehicle batteries. (in fact, the only battery I've replaced in that time is a (flooded) vehicle battery on a 'van equipped with flooded leisure batteries).

 

Patently, other people may have different experiences, and I am reasonably careful not to exceed the appropriate DoD - choosing to fit an extra battery rather than "cane" a single one, and to manage my consumption (though not, I think, unduly).

 

I'm thus more inclined to live with whatever has been installed by the converter from scratch, subject to the latter point.

 

It does, however, seem fairly odd to me continue to question such provision, and counsel the use of "wet" batteries when the installed equipment is now patently (by the manufacturer and converter) specifically oriented towards AGM or Gel batteries, to the exclusion of the "flooded" category.

 

It is, however, a point of view, and no doubt evidence/interpretation will be brought to bear in the future, once such kit is "out of warranty".

 

Just a few comments on the rest:

 

aandncaravan - 2016-09-04 4:41 PM

As you say the Schaudt documentation states the EBL 119 is targeted at Gel and AGM batteries only and not Wet/Flooded batteries. The AGM based EBL 30 documentation mirrors this.

Yet despite the documentation 'angle', charging a Bosch/Varta LFD Powerframe on the Gel setting will not result in any issues, as the 14.4v and 13.7v are about as perfect as you can get for a wet battery.

 

I'm unconvinced; the "float" voltage on that Gel setting is rather higher than Varta seem to recommend for "wet", and, more importantly, the absorption phase is hugely longer (16 hours vs 4 hours as you have noticed) than Schaudt use, or have used in the past for the "wet" setting on chargers that have this.

 

I think using a "wet" battery on the Gel setting would thus currently (sic) be a huge leap into the dark.

 

aandncaravan - 2016-09-04 4:41 PM

The AGM marketing bandwagon makes much of this 'higher charge acceptance' but often forgets to state it is for an initial short period only.

Your own statement above tallies with this where you write,

"...their published recommended charging regimes show INITIAL charging currents a ratio of 2.5 times higher".

 

I could probably have been more clear in this, but was attempting to keep my post short. The Varta information I have recommends a charging current throughout the first (bulk) absorption phase of charging of up to 2.5 times higher than a flooded battery.

 

aandncaravan - 2016-09-04 4:41 PM

So matching an 1,800watt/ 180amp Inverter with a Gel/AGM battery is just bonkers.

 

...I agree, but I would maintain that, except in the case of a large battery bank and numerous solar panels, this wouldn't be a good idea with any lead-based battery type, except perhaps for extremely transient loads.

 

I simply return to my initial premise that much of the bad rep batteries in motorhomes get in general is down to the fact that people are expecting them to perform "unnatural acts" and still to give long life; Something exacerbated by the proliferation of electrical and electronic equipment. Some people even want to run a Nespresso machine, you know.... ;-)

 

I run two e-bikes, both with 540Wh batteries. I have the ability to supplement with solar (albeit not at a huge level). Since I do go off-grid for periods where recharging them would be useful, I did the basic math, without allowing for losses, and quickly decided that, despite a nominal 190Ah of installed capacity, I wasn't going to get anywhere near charging them from the leisure batteries - but some people still try......

[dicksob]

So, I guess the advice is use Nescafé instant, recharge batteries only from mains and save my £1770 as I can run everything else from 12v?.!! ????

 

Bill :-D :-D

[dicksob]

Where did my big smiley faces go to?

[aandncaravan]

RobinHood, I posted on another thread an 'in confidence' conversation with a Hymer Dealer technician He stated that they are aware of premature AGM battery failure, but as they tend to fail just outside warranty it's 'not an issue'.

It is something they intend to 'live with' as the advantage of AGM batteries to both the manufacturer and Dealers is the long shelf life. Many Motorhomes spend weeks waiting for a buyer.

Plus much of the time, an AGM battery that has run down low in a van up for sale, will generally charge up again without too much obvious damage once a Sale is made.

As you are aware it's life will most likely be shortened but, it will appear 'normal' for most intents and purposes to the buyer.

 

There was a flippant remark that, "in any case a failed AGM outside Warranty is usually a failed charger so good on both counts, so you should be promoting AGM batteries".

 

The initial higher cost of AGM is passed on to the buyer so it is a good situation for them all round.

 

 

I understand you questioning our stance because Hymer are a big reputable company who would only do the best for a customer.

So why do they offer an 1800 watt Inverter, which you say "wouldn't be a good idea with any lead-based battery type", in a £1,700 option pack?

 

 

You write, "I simply return to my initial premise that much of the bad rep batteries in motorhomes get in general is down to the fact that people are expecting them to perform "unnatural acts" and still to give long life".

On that we agree, but some batteries handle that abuse better than others. AGM have very tight charging and usage tolerances, more so than any other type.

The LFD range will tolerate wildly varying voltages, as high as 16v and as low as 13.5, wider temperature variations, higher power draw, faster charging, etc.

It most definitely isn't indestructible, but just about every condition that causes issues to other batteries, it will handle better. All down to that very special Grid construction.

 

Only thing that lets it down is the number of cycles being half that of an Exide G80 Gel, but when it is half the price of the G80...........

 

 

 

 

 

 

[Robinhood]

aandncaravan - 2016-09-05 10:09 PM

 

I understand you questioning our stance because Hymer are a big reputable company who would only do the best for a customer.

So why do they offer an 1800 watt Inverter, which you say "wouldn't be a good idea with any lead-based battery type", in a £1,700 option pack?

 

 

I think I'm questioning your stance for quite a few different reasons entirely unconnected with Hymer......

 

...but, to answer the above, you conveniently ignore my caveat: "except perhaps for extremely transient loads"

 

The use envisaged by the OP was (amongst other things) the recharging of E-bike batteries, for which your description of the effect that would have on the battery bank was quite relevant - though your 30 minute example was far from enough to achieve such a task (and, indeed, I've already highlighted I'd myself rejected the notion). With a three battery bank you might just achieve it without exceeding the DoD threshold, but without the ability to fully-recharge, you'd as sure as hell only do it once, and any other consumers would then place you at risk.

 

It is a bit different to, say, the nightly use of a hairdryer for 5 minutes, which, in many circumstances your average Hausfrau might want to do, and a 100W solar panel should have little difficulty in compensating for in a decent, average German day.

 

So, there are (possibly, depending on your stance on ladies and hairstyles ;-) ) valid reasons and valid uses for such an installation, but it in part goes to make my point. If it is there, then it will also often get used for "invalid" reasons; the batteries will be asked to perform unnatural acts, they'll degrade rapidly, and then the user will complain they're cr*p (whatever the underlying technology).