# Battery charger query!



## TR5 (Jun 6, 2007)

If you had limited (time wise) availability of mains hook-up, could you connect a second battery charger to the leisure batteries to charge then in a shorter period of time?

Would this work, and would it do any harm to either the batteries, or the chargers?


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## TR5 (Jun 6, 2007)

Bump!
Someone must have an answer.


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## clive1821 (Mar 27, 2010)

Hi.... if for example you had 200AH battery the max you charge them would be 20% of that say 40amp.... any higher than that would start to dammage the plates.... so yes you can charge the batteries with two chargers, you just have to make sure you are charging the batteries corectley, I would just get a 40 amp charger and use that and monitor the charge rate... just my view


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## Mandale (May 18, 2011)

I don’t know if the second charger would damage the batteries or the charger, however the batteries will only accept what current they need. Think of the empty battery as an empty hole and the charger is filling it with water from the bottom, as the hole fills with water the pressure builds up and the flow of water slows down until the filling stops when the water pressure pumped in is equal to the water pressure in the hole.

However if your motorhome has two leisure batteries and they have been fitted properly (using a proper slit charging system and not just connected together) this system usually charges the batteries individually, ie completely charges battery 1 first and then starts on battery 2.

If your motorhome charging system is set up with the split charging system, you should be able to disconnect battery 2 and put the second charger on this battery, thus charging both batteries at the same time. 

Fast charging any battery will have a negative affect on it, (fast charging is basically forcing amp’s into the battery faster that the battery is really asking for them), because the plates in leisure batteries are further apart than on normal vehicle starter batteries they suffer less from damage due to fast charging and draining then to very low levels.


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## HarleyDave (Jul 1, 2007)

Hmmm

My Eura has 2x Leisure batteries (Hab) and 1x Vehicle battery (Cab) with a split charge between Hab and Cab

The Hab batteries are connect simply in parallel with only one set of cables from the Hab batteries to the charge controller

I would be surprised if anyone has two sets of wiring going to the hab batteries from the charge controller (Assuming they are a co-located pair and not situated one in the boot and the other under the bonnet)


Cheers

Dave


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## Mandale (May 18, 2011)

HarleyDave said:


> Hmmm
> 
> My Eura has 2x Leisure batteries (Hab) and 1x Vehicle battery (Cab) with a split charge between Hab and Cab
> 
> ...


Hello Dave,

CBE sell a product for this application. The main charging wire is connected to the CBE split charging device and then separates onto the two leisure batteries. The system then charges the two batteries separately charging one first and then the second. The system then discharges the batteries in the same manner. Therefore the leisure batteries are not connected in parallel or series. This system also prevents a lot of the problems caused by having two leisure batteries connected together, ie: one damaged battery preventing the other form charging / dis-charging correctly.

I can't remember the name of the product but I can find it on Monday and add it to the post

Ps I think the unit costs about £50.00.


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## TR5 (Jun 6, 2007)

I've never heard of one of those devices either.
I suppose one safe solution would be an isolation switch between the two batteries, allow the onboard charger to charge the original installation, and connect a second charger to the additional battery, thereby charging two batteries independently.


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## andrewball1000 (Oct 16, 2009)

TR5 said:


> I suppose one safe solution would be an isolation switch between the two batteries, allow the onboard charger to charge the original installation, and connect a second charger to the additional battery, thereby charging two batteries independently.


this is what I have done for my solar installation. It keeps the two chargers regulators separate and stops their different step charge progammes interfering with each other. It also stops one battery dragging the other down.

A mechanical marine 1,2, both & off switch on the supply side means you can switch them however you want. I also separated the solar input side with a switch as well. I put the money saved by not buying the electronic gizmos into an extra battery.


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## coppo (May 27, 2009)

Our S820 has a supplementary charger under the passenger seat(LHD) Shaudt LAS 1218, which i presume charges the batteries quicker.


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## lgbzone (Oct 8, 2008)

TR5 said:


> Bump!
> Someone must have an answer.


Hi TR5

I have to admit; I didn't post earlier because I don't have the definitive answer but I will offer my thoughts.

First off I don't think you would do any harm to either the chargers or the batteries, unless as stated earlier; it resulted in you charging the batteries at a higher rate than they were designed for, which I doubt.

If you have a single battery or a bank connected in parallel that appear and act as a single battery; I would only use one charger, if need be I would upgrade the charger to something with a higher output and always ensure that the batteries support the charge rate. something to keep in mind is that on EHU the total amps supplied is limited, so you may not see an improvement from this.

From my understanding of how many chargers work (which isn't guaranteed to be correct or complete), whilst the charger is charging it outputs a higher voltage (at a particular amperage) than what is in the battery, but periodically it polls the battery/bank to ascertain the voltage and charge state of the battery, then adjusts it charge rate and charges again, repeating this until the battery is deemed full.

therefore if you connected two chargers to one battery/bank, I would have thought you may have a situation whereby when a charger polls the battery, it doesn't see the (real) voltage of the battery, but instead sees the higher voltage of the other chargers output, so may decide the battery is full and not add charge at all. for example if I had a battery at 12v, I would expect a meter across the terminals to show 12v, but if I put that battery on charge and immediately put the meter across it, i'd expect it to show a higher voltage. this is evident in that I have seen my solar system putting a small charge into my batteries (almost full), which has then stopped when i've connected the EHU, they are totally separate systems so I assume the solar cut off because it thinks the batteries are full.

If you have two batteries that act as one but they can be isolated from each other; isolating them and having one charge through the EHU and the second from another charger and source, would give an improvement in the charge time, the problem here though is that before the isolation is removed, both batteries need to be in the same charge state to stop a surge from one battery to the other. so this is something I wouldn't like to do.

Not 'the' answer, but 'an' answer and only my thoughts/opinion, i'm far from an electrician or anything.

HTH

<edit>
OK, ignore me as three other people have posted since i last read the thread :roll: 
</edit>


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## HarleyDave (Jul 1, 2007)

Mandale said:


> HarleyDave said:
> 
> 
> > Hmmm
> ...


Hi There Daniel

Well - I live and learn - Thanks

I can see the advantage of that system and in my mind would liken it to having a reserve tank on a motorbike (albeit equal sized to the "main" tank

When one empties you can switch to the other (or have it done automatically presumably with some warning) thus avoiding emptying one big tank with no real warning.

I have been in that situation on a previous Harley when the fuel valve came apart inside the tank and I was still waiting to have to go on reserve when I ran out of fuel on the A420...

But I digress...

It sounds like you know your way around the CBE product range?

Could you advise me please what device I need (from CBE) to connect between an 80W solar panel and the CBE DS 500 socket J12 pin 6 to charge batteries by solar with the control panel C2015 monitoring the charge process?

I have a pdf copy of the electrics installation for my Eura that I can send you if that would help.

Cheers

Dave

Edit to use first name instead of nickname


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## Mandale (May 18, 2011)

HarleyDave said:


> Mandale said:
> 
> 
> > HarleyDave said:
> ...


I can ring our supplier on Monday for you with your enquiry.

Hopefully they can help. I have not had much to do with solar panels as yet, but have seen the pin connections on the PC100 system for them. I only know of the split charging system because we plan to fit them as part on a second battery upgrade pack on our vans.

if you email what you have I can find out for you.


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## clive1821 (Mar 27, 2010)

For every ones info this is CBE's site and have a look and it just mite help you answer any questions...

http://www.cbe.it/en


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## nicholsong (May 26, 2009)

Another solution may suit you.

I am rarely on EHU, mostly wild-camping, but do not do many miles a day.

Thus the alternator spent most of its time recharging the engine battery and only gave a little charge to the habitation batteries.

I have fitted a Sterling Battery-to-Battery charger which effectively causes the alternator to make available maximum output to both engine and hab batt simultaneously. That is simple explanation, but it has lots of protection 'whistles and bells' and like all Sterling products is a professional bit of kit.

Fitting is easy as it is simply connected between the engine and habitation batteries, with a couple of extra sensor wires to battery and alternator.

Have a look at their website for further info.

Geoff


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## Mandale (May 18, 2011)

Cheers Clive,

The Battery split charger is in the site that Clive has Kindly provided,
its called a BDS-150 and its listed under 

products - energy line - battery devices


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## HarleyDave (Jul 1, 2007)

Hi Daniel

This is the text of an email I sent to CBE having seen some of their stuff on their web site last week

_ I have a 2005 model Eura Mobil motorhome (810 HB) with CBE electrical 
components

I have the control panel C2015, The battery charger CD516 and the fuse panels 
DS321 and DS500

I would like to connect a PV solar panel into the system so that I can manage 
the charging from solar using the installed system and showing charging etc 
on the C2105

Will you please send me wiring diagrams for the DS500 and DS321 so that I may 
make the correct connections?

_

They sent me the Eura Mobil specific Operating Instructions which is great and all I need now is to know which solar regulator to purchase and how to wire it

A - to the batteries

B - to the DS 500

Any info much appreciated

Cheers

Dave


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## joedenise (Jul 20, 2007)

Coppo - the Schaudt 1218 is just a solar regulator so that the solar panel can charge both batteries when not on EHU.

Joe


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## coppo (May 27, 2009)

joedenise said:


> Coppo - the Schaudt 1218 is just a solar regulator so that the solar panel can charge both batteries when not on EHU.
> 
> Joe


You maybe correct but why does it only light up when you are on EHU.

I thought it was just a supplementary charger to support the main one because the S820 has a lot of battery power.

I think you are confusing it with something else you have heard about as this is just a supplemantary charger which supports the main one and nothing whatsoever to do with solar.

Paul.


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## joedenise (Jul 20, 2007)

Coppo 

No, I have one myself. You'll find you probably haven't got another regulator for your solar panel. You can tell because if your solar panel is charging the batteries it will show on your control panel. It's the only one that will show on the Hymer control panel.

Joe


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## coppo (May 27, 2009)

joedenise said:


> Coppo
> 
> No, I have one myself. You'll find you probably haven't got another regulator for your solar panel. You can tell because if your solar panel is charging the batteries it will show on your control panel. It's the only one that will show on the Hymer control panel.
> 
> Joe


Joe, we are going to have to agree to disagree on this one, it has nothing whatsoever to do with solar on my MH and is just a supplementary charger which supports the main one.

We need a second opinion on this one to settle it 

Or its daggers at dawn :lol:

Paul.


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## coppo (May 27, 2009)

Maybe needs a separate thread Joe to ask other Hymer owners, i am sure you are wrong.

Paul.


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## coppo (May 27, 2009)

Joe
If you do a search you will see a thread from Jon n Jules who has now sold his S820, but whose LAS 1218 packed in and it is just a supplementary charger to support the main one.

Maybe you can also use it for other applications, i don't know.

Paul.
PS apologies for hijacking the thread.


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## joedenise (Jul 20, 2007)

Coppo

Aha, you didn't say LAS 1218, I assumed you meant LR 1218.

Joe


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## coppo (May 27, 2009)

coppo said:


> Our S820 has a supplementary charger under the passenger seat(LHD) Shaudt LAS 1218, which i presume charges the batteries quicker.


Joe
My original post above.


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## joedenise (Jul 20, 2007)

Coppo

Apologies, have just reread it!  

Joe


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## spatz1 (May 19, 2011)

i have the choice of 4a van charger, 20a boost charger or both together and it charges fine at a 4a, at 2oa on boost or 24a combined and switches to float at 14.7v...

there are 3 problems to be aware of...

if charging on 20a boost only and the hab electrics are used you will be putting the full 14.7v through equipment if its at that point of its charging cycle...

(if you have the van charger on in tandem with boost you will charge at 24a but prevent the above problem occuring because the voltage to the hab is regulated to 13v by the van charger.) 

however, with both chargers on and 14.7v hit they will drop to 13.7v float but charge at double float amps of 2.5a instead of the 1.25a either charger will suply on its own as float if the other is switched off.

the last problem is the fact you re charging at high amperage which raises the temperature of the batteries with no control over the charge rate for temperature ( you will notice nearly all solar controllers have a temperature sensor and the better higher amp tollerant ones a remote sensor to fit on the battery... )

no other problems found with using a boost charger ....


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## nicholsong (May 26, 2009)

Agree with Spatz1 about the temperature issue.

My Sterling B2B booster from the alternator charge, as described in my post above, also has a temperature sensor connected to the leisure batteries to protect from over-temp. 

(It also has provision for a temp sensor for the alternator, but this is for boats where the alternator may operate with little ventilation. Sterling advised it was not necessary for a vehicle.)

Geoff


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## PincherM (Jul 28, 2011)

My leisure batteries have almost completely discharged. I was advised that normally once these batteries get below 9v they should automatically isolate, so preserving them. Would appreciate any advice on this.

Vic


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