Install a second leisure battery in parallel - or not?

[aandncaravan]

No I couldn't sleep, had too many chargers to fix!!

Writing on the Forum was making me think, so keeping me awake.

 

How fast your batteries charge depends on the technology of them. Gel are the slowest, then AGM and Wet Acid the quickest. The Varta Silver batteries we suggest are more efficient so charge about 25% faster than ordinary Wet Acid and twice as fast as Gel. The difference becomes more marked as the batteries age, with a normal Wet budget battery of 2 years potentially taking 40% longer to charge than when new, yet the Varta Silver/Bosch S5 remains about the same through to 5 years.

 

The voltage delivered to the Habitation battery varies from Charger to Charger. Generally, 14.4v reaches the battery in most German/Italian systems.

 

I too have been the victim of a Noisy generator. I don't advocate Generators. JUST the Honda Eu10i, it really is whisper quiet. When I first saw/heard it demonstrated I thought it had stalled.

 

By contrast the Hyundai copies that are supposedly quiet (still only 63db so much less than most) are quite intrusive. The Honda has a really efficient engine which burns the fuel in a way that gives off less noxious fumes and uses less fuel. The 20i talked about above converted to Gas would have a very clean exhaust as well as being even quieter with double mpg?

Do you run it from the Motorhome Barbeque gas point?

You may find the 12v output is exactly that, about 12.4v which won't charge a battery, it's designed as a 12v Power supply rather than a battery booster on some models?

 

I also seem to have been taken literally as saying don't connect a second battery. If I did it was not intentional, I was trying to say that all charging systems have a limit. If you go over that limit by putting on a second 110Ah battery, it is likely the bank won't give the performance you were expecting as it might not get fully charged. It will also put strain on the charger and shorten the batteries life.

 

However, if your 20a charger supports a 200Ah bank (remember to make an allowance for the Starter battery of about 40Ah if that is simultaneously charged) then you have a safe Habitation capacity of 160Ah. 2 x 85Ah batteries would work a treat, no strain, fully charged, etc,

 

I am just suggesting some thought is given to the design limits. The way it gets configured will depend on the Alternator and charger unit, remember some are only 12amp chargers.

If you do want to 'go big' then many electronics manufacturers supply an upgrade kit, Calira/Lunar have a 30a upgrade charger that will care for a 300Ah bank of batteries. The EBL220 can be uprated to over 500Ah.

 

For example, those with the Sargent 500 box on board, will find it is usually configured out of the factory for a single battery and the 20A charger is restricted to 'half' power. If you add a second battery don't forget to reset it to '2 battery mode' to use it's full 20amps? Many technicians add a battery but don't up the charging rate.

 

Look after you batteries and they will give your charger an easier life. Hammer the Batteries by drawing 280amps on a 3000watt inverter and they will cry.

 

[aandncaravan]

 

Sorry can I just share this email I have just received from James?

 

Message : Hi, I have owned a 2007 Burstner a747-2since 2009 It is fitted with a reich ebox, I installed 4 no 95amp battery's a few years ago, the charging side of the ebox gave up shortly after. I would like to purchase a new ebox, what do you recommend?. Regards James

 

Can you guess what my reply will be?

 

[Tracker]

Sorry Allan, but you seem to be talking predominately about inbuilt chargers which is fine for those who stay put on a site hook up for several days at a time and for whom a battery is just something to smooth out the peaks and troughs of a constant 12 volt supply!

 

Personally we never use our onboard charger from one year to the next because we rarely stay on sites and even if we do I really cannot be bothered to faff about with umbilical cords when I have gas and 12 volt on board! In fact I don't even carry a mains lead anymore so little was the use it got!

 

Interesting points about charge rates though. I must confess that I never really thought about that before as I always assumed that the battery charge rate was determined by what the alternator fed it rather than the battery's ability to accept the charge.

 

So for me, as well as several others who use their vans in a similar way, we are only interested in other forms of battery charging and these seem to be either vehicle alternator - not good enough, solar - suspect regulators, B2B - too much load on the alternator, generator - no space to store one, too much faffing about and very anti social.

 

Perhaps I need a wind turbine on the roof operated by airflow when driving along - but only if it has a good enough regulator of course!

 

So in the words of the great prophet Professor Sodde, I seem to be a long way up you know what creek without a paddle!

 

Two x 85 ah batteries might be a good compromise that would work, if only the alternator charge had a bit more oomph but that would then leave me with two decent 110 ah batteries surplus - still cheaper than B2B or solar though!

 

Still confused of Evesham!!

[kevina]

I only tour in winter and also ski for 2 months so hookups and solar are rarely much use.

 

I have gel batteries and the manufacturer (Victron) categorically states that a C/5 charge rate (ie 22A in each of my 110Ah batteries) is fine even without temperature compensation. Not only this but Exide/Sonn'n state that the charge rate of their gel batteries should be between 10A and 35A per 100Ah nominal capacity.

 

The only way to achieve this in a motorhome whilst touring is with a b2b charger. My Votronic b2b is more sophisticated than my 16A CBE mains charger and has settings for gel/agm/wet etc. I have the batteries temperature compensated but have never seen the charging voltage dropped because of warm batteries (by touch never more than ambient). Its maximum output is 45A which is almost optimum for my batteries and is 98% efficient so never gets hot, I've never even heard the cooling fans come on (unlike Sterling units). My alternator is 140A and with a full load (van and hab) can only be running at about 70%.

 

Just about nobody has a charger capable of more than 45/50A in a motorhome so why this red herring about "slower charging gel batteries", it is of no practical concern. Gel batteries being properly charged give me a much greater capacity and much longer life expectancy.

 

Also, the b2b charger will not start until the vehicle battery has recharged a certain amount; unlike a split charge system where heavily discharged leisure batteries can suck a very high current for a short while at the same time as the vb.

 

 

Kev

[Tracker]

kevina - 2015-04-16 12:35 AM

 

The only way to achieve this in a motorhome whilst touring is with a b2b charger. My Votronic b2b is more sophisticated than my 16A CBE mains charger and has settings for gel/agm/wet etc. I have the batteries temperature compensated but have never seen the charging voltage dropped because of warm batteries (by touch never more than ambient). Its maximum output is 45A which is almost optimum for my batteries and is 98% efficient so never gets hot, I've never even heard the cooling fans come on (unlike Sterling units). My alternator is 140A and with a full load (van and hab) can only be running at about 70%.

Also, the b2b charger will not start until the vehicle battery has recharged a certain amount; unlike a split charge system where heavily discharged leisure batteries can suck a very high current for a short while at the same time as the vb.

Kev

 

Thanks Kev. I appreciate the info. I don't think I need as much as 45 amps as my use is far less extreme than yours but this one appeals to me instead as a good compromise to preserve my alternator, my battery and my sanity and at about £210 all in (278 + 11 Euros shipping) it seems reasonable enough to me and less expensive than a similar Sterling unit

 

http://www.wohnkabinen-shop.de/en/Elektronik/Ladetechnik/Votronic-Lade-Booster-VCC-1212-25-IU

 

Unfortunately I don't speak any German so do they come with multi lingual instructions!

[Brambles]

Tracker, your solution to volt drops between you Alternator and Batteries may be easily fixed by checking your wiring from Alternator to battery and slave relays and upgrading to heavier cable to reduce its resistance. Your batteries will eventually charge with what you have but will just take a long time to rise to 14.2 volts because of the resistance of the wiring. Also check your Negative connection from Batteries to the Chassis is not dropping volts. Try measuring the volts directly between the negative posts and the chassis when chargng and see what drop you have.

 

[kevina]

There should be an English version on their website but I have a copy anyway.

[Tracker]

Brambles - 2015-04-16 9:45 AM

Tracker, your solution to volt drops between you Alternator and Batteries may be easily fixed by checking your wiring from Alternator to battery and slave relays and upgrading to heavier cable to reduce its resistance. Your batteries will eventually charge with what you have but will just take a long time to rise to 14.2 volts because of the resistance of the wiring. Also check your Negative connection from Batteries to the Chassis is not dropping volts. Try measuring the volts directly between the negative posts and the chassis when charging and see what drop you have.

 

Thanks Jon.

I take your point but I am unenthusiastic about meddling with the existing wiring not least due to the difficult access to the devious route the cables seem to take but also because I don't really consider that I have the expertise for this.

It had not occurred to me but I will check the negative earth side for voltage drop as you suggest.

Over the years I have never seen any alternator output above 13.9 volts into any leisure battery and so I had always assumed that using thin cabling was a design limit to avoid possible gassing of the leisure batteries and that not fully charging was always going to be the result?

 

[747]

Steve928 - 2015-04-15 9:31 AM

 

Interesting stuff. Must admit that I hadn't realised that leisure battery charging was so poor whilst driving.

I had naively assumed that once the starter battery had been replenished then all that alternator power would be available to top-up the leisure batts at the full voltage. You live and learn.

 

Solar isn't a viable solution for everyone. Our heaviest power usage is over Scottish winter weekends with long nights inside followed by short days with the sun (sometimes..) low in the sky. I doubt that panels would contribute much at all. Conversely, when the sun is high in the sky and the days long and hot we use very little power and could probably leave the leisure batteries at home and run the whole shebang off the vehicle battery anyway.

 

It is a common misconception to think that it takes time to recharge the starter battery first and then the leisure batteries get their turn. The leisures batteries are normally charged at the maximum power the charger can supply. If these batteries are greatly discharged, then the charger is working flat out for a considerable time. This is why I am a big fan of solar power because they can take some of the load off the charger. They also prolong battery life by preventing deep discharges. The 2 Numax batteries on my last van were 5 years old when I sold the van and there was no discernible difference in performance.

 

The one and only time my low voltage alarm was activated on my EBL99 was because of 3 days of Fog. :-( We decided to move early from the Lancashire Coast to Hexham in Northumberland. The leisure batteries were still partly discharged by the time we arrived but at least the Sun was shining. :D

 

If you have an ammeter fitted, then check it just after starting the engine, it will be supplying power to the LB's. The engine battery only carries a heavy load for less than one second (under normal circumstances) and the amp loss is negligible for a healthy, charged battery.

[Casimir]

Casimir - 2015-04-11 5:25 PM

... but then I thought - what if there was a way to use the batteries in sequence with some sort of switch between them? That way the age of the batteries would not matter.

My original question back in April (about fitting a second leisure battery in sequence rather than in parallel) prompted a lot of interest and at times lengthy and heated debate.

Thank you to all who contributed even if I did not understand all the highly technical bits.

We tend to stop in a mix of both campsites and aires roughly 60/40, depending on location and facilities. We are unlikely to stop in an aire for more than a few days at a time before moving on to a campsite with EHU so I do not think I can justify the cost of a solar panel (say £400) or an LPG generator (say £900).

Steve928 - 2015-04-14 10:04 AM

Getting back on track..

 

When I installed a second leisure battery (the van has a dedicated space and a parallel connection kit is available) I chose to use a 1-both-2 battery master switch. This gives you the choice of having individual batteries connected and of course of using both in parallel. This is the common method in the boating world and allows the use of batteries of different age or even capacity, allows you to have total battery capacity above the capabilities of your charging systems, and to keep a fresh battery with high plate voltages - useful if you have devices that need a high voltage to start them such as Eberspacher heaters. It does of course require that you remember which battery/batteries are connected at any one time, but I don't find that a problem. Plus of course a turn of the switch disconnects the leisure batteries if required.

I used this a Durite 0-605-09 switch, about £20.

For my particular purposes this was the best suggestion and I will be fitting one of these switches in the near future.

A special thank you to Steve928 for "getting back on track".

 

 

 

[dorant]

Hi All,

 

There is a lot of useful information on this forum, thank you all for contributing.

 

My single 80Ah lead-acid battery is showing signs of age, so time to replace.

 

I spend up to 6 months in the camper / yr, and working on the computer is important for me, so installing two new batteries is not a question.

Apart from the extra capacity the batteries will be strained less (I hope they will last longer then 2x), and there will be less efficiency lost (and strain on other electronics) due to voltage drop.

(BTW the single 80Ah with 200 W of solar was almost always enough during the summer, I can only recommend solar to everyone )

 

I took the same route as Tracker, and bought a Votronic 25A (moderate strength) B2B charger, I think it's worth the long-term investment, saves the batteries and the alternator too. Has instructions for EBL.

I have also bought the "remote control" instrument panel, which apart from monitoring enables me to switch off the charge altogether.

The alternator will be happy not having to work when starting at already 30 degrees heat in the morning, full AC, headlights, and initially low revs.

In the summer the solar can charge on the road as well, so saves some fuel too.

I will also add a temperature sensor both for the solar and the B2B charger - I want my expensive battery bank to last.

 

Deciding on the battery type took some research, there is so much misinformation out there.

 

As the battery is under the seat (which needs to be removed to refill), another deep cycle flooded battery is the last thing I wanted.

 

Although the Varta LFD 75 or 90 are relatively cheap, at 200 cycle (at 50%) lifetime it's really only enough for occasional users.

BTW I don't think they have the PowerFrame (look at the company page and the missing stickers).

 

AGM would've needed the new AC charger modul, and AGM can die in high heat, etc, so Gel is the answer for sure. May not charge quite as fast as AGM, but I mostly charge from solar anyway, it seems to be good fit for that.

 

Now I need to decide between Exide G80 (ES900) or the Victron 90 Ah Gel.

 

Though the Victron is higher capacity, the ES900 (in Hungary), and the G80 seems to be easier to source.

Also the ES900 seems to be more robust, 1 kg heavier than the Victron for 10Ah less rated capacity.

Unfortunately also a bit bit bigger.

 

Since the passenger seat holds the toolkit (jack, towing eye, etc.), it would be really nice if both batteries could remain under the driver's seat. (also less cables and cable loss for solar)

Is it a good idea at all (cooling) ?

 

I will be charging at max at 0.16 C for the Exide or 0.14 for the Victron (in the cold days with B2B, even less with solar) - so hopefully not too bad next to each other regarding heat ?

 

Regarding size - has anyone tried to fit 2 pieces of G80 under the driver seat in a Fiat Ducato 250X ?

(mine is from 2013, LH drive)

Would I need the Victron to fit - if it does ?

 

(apologies for such a long winded post)

[aandncaravan]

Tracker, Just re-read this whole thread and I think that Brambles highlighted something about your low voltage charge rate, that we didn't pick up on 13 months ago.

Brambles says your Alternator charger rate should be higher than 13.8v, more like 14.4v, and talks about poor connections?

What if it's a poor Earth strap?

 

We saw quite a few 'low charging rate' issues during the Summer and earlier this year that we reported on as being fixed by an additional earth strap.

 

 

 

 

[Tracker]

aandncaravan - 2016-05-25 10:27 PM

Tracker, Just re-read this whole thread and I think that Brambles highlighted something about your low voltage charge rate, that we didn't pick up on 13 months ago.

Brambles says your Alternator charger rate should be higher than 13.8v, more like 14.4v, and talks about poor connections? What if it's a poor Earth strap?

We saw quite a few 'low charging rate' issues during the Summer and earlier this year that we reported on as being fixed by an additional earth strap.

Thanks Alan, the alternator output to the engine battery is good at 14.4 volts and I am all too well aware of the earth strap issues of Sevel vans so adding a supplementary as per Nick's (Euroserv) advice is always one of the first jobs I do when I get a different van.

However it is not uncommon for the alternator output voltage to the leisure battery to be less than 14.4 volts and that does limit the charge rate and gassing.

When checked with an ammeter in the past I have not often been lucky enough to see much more than 5 to 10 amps going into the leisure battery and that does mean a lot of miles to get a decent charge.

I have not checked this van recently, but I will now so many thanks for the reminder!

[aandncaravan]

Tracker, most of the boxes we fix just 'join' the Starter battery and habitation battery together. Very like the old fashioned Split charge relay.

See the wiring schematic of the Sargent EC200 at the bottom of the Sargent page for an example : http://www.aandncaravanservices.co.uk/sargent.php

 

Very few Power Distribution boxes limit the voltage or current to the Habitation battery. Both batteries should get the same from the Alternator.

.

If the wiring is correctly sized, the connections are good and the relays don't have burnt contacts the voltage at the Habitation battery should be pretty close to 14.4v?

 

 

 

 

 

 

 

 

 

[Tracker]

Thanks Alan, that's interesting, I'll check it again!

 

Having been told by several dealers over the years when investigating the lack of charge to the leisure battery on various vans (all UK built), that the alternator voltage is limited to under 14.0 volts to prevent gassing and that a caravan type of control box is used which favours EHU charging over alternator.

 

Their cure has invariably been a cheap new 'leisure' type battery, usually of dubious brand, which may or may not have helped for a while, whereas my standard 'one size fits all' cure has generally been to add a 2nd leisure battery.

 

We tend to tour a lot and rarely stay in one location more tah two nights so for us mileage has maybe hidden other problems that would have been more of an issue had we been in one location for say a week?

 

Thanks largely to your experiences I am maybe now thinking that I've not always been right and that to look at both the type of battery used and the charging regimes might have worked better?

 

It's not always easy for an interested amateur with no technical expertise but lots of experience of things not working properly to get a grasp on the finer points of motorhome electrics and even more so, electronics!

 

Hmmmmmmmmmmmmmm!

 

 

[Brambles]

Any wiring, connections and relays will have resistance and voltage drops when a current flows.

At say a charge current of 5 amps it would be very easy to drop 0.5 volts by the time you passed through fuses relays contacts and the wiring.

.

[Alanb]

Hi Tracker,

 

From recent posts, I surmise that you have been having charging problems. May I suggest that if not already done, you check the leisure battery earth. This is just as important as the engine earth strap, when trying to charge the leisure battery from the alternator. Or are the two negatives (starting and leisure batteries) joined directly.

[Tracker]

Alanb - 2016-05-26 11:04 PM

From recent posts, I surmise that you have been having charging problems. May I suggest that if not already done, you check the leisure battery earth. This is just as important as the engine earth strap, when trying to charge the leisure battery from the alternator. Or are the two negatives (starting and leisure batteries) joined directly.

 

Thanks Alan, funilly enough I have had no problems as yet with this van and although I started posting to try and help the OP it has developed into others helping me for which I am most appreciative.

 

So at the moment, given how unpredictable these systems can be and without getting overly paranoid I am at the checking and pre-empting stage because it is easier at home than it is 1000 miles away from home!

 

I will check the leisure battery earth as you suggest as they are not directly connected by a common earth - although both being internally located they easily could be. Now there's a thought!

 

I also subscribe to Bramble's view about voltage drop and my understanding has been for years that voltage drop by cable size, without causing overheating, is part of the design to limit charge rate and from that battery gassing.

[Tracker]

I've checked the alternator output and at the engine battery it is as expected 14.4 volts.

 

At the leisure battery it, as expected, gradually rises over a minute or two from whatever it was at rest to13.8 volts, but with the battery disconnected it rises to 14.0 volts.

 

On that basis the leisure battery voltage might rise further when on the road but that will have wait to be checked.

 

I use an inexepensive multimeter but it has generally proven to be with .1 of a volt in the past when compared to a calibrated auto electrician's a few years ago.

 

I added a temporary jump lead extra earth from cab to leisure batteries and it made no difference to any readings and as all the wiring is original and undamaged as far as I can see.

 

As I said, it all works fine now and this is just a pre-emptive check knowing how much grief batteries are capable of causing - but only when you least expect or need it!

[Brambles]

Three scenarios.

1. You are over charging the batteries.

2. you are undercharging the batteries.

3. You are charging fine but your are just using and cycling them and getting as many life cycles as can be expected for the depth of discharge you are giving them.