# Battery to Battery Charger



## drewdt3 (Feb 15, 2013)

After much pondering as to whether to get a solar panel or a b2b charger fitted I have decided to go with the b2b charger with the option of adding a solar panel at a later date. We are nearly always wilding and the leisure battery isn't getting fully charged and where we park it we can't put it on charge either. What I am getting to is does anyone know of someone in the Cheshire/Stoke area that can fit one of these for me, I'm sure I could do it myself but as I treasure my van so would rather leave it to someone in the know.

Cheers

Drew


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## sparrks (Feb 15, 2013)

Dunno if you've purchased it yet, but make sure you search well on the net as they do vary in price enormously.


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## drewdt3 (Feb 15, 2013)

Thanks for that. I'm going to purchase today if you have any recommendations,  I was thinking of one of yhe Sterling units?


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## sparrks (Feb 15, 2013)

With a quick look, just on my way out, this is the cheapest I can find, here - purchasing from a yacht chandlers seems to be the best bet. You may get it as low as £250 incl if your lucky.

Great bit of kit - got one myself.


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## AndyC (Feb 15, 2013)

A B2B charger isn't necessarily a magic solution to charging problems.

Your first action should be to thoroughly check out your current (sorry!) arrangements, often a rewire with heavier duty cable, a high capacity split charge device, and quality connectors makes a big difference and should be cheaper than a B2B charger.

However I fitted a Sterling B2B charger on our van, the reason being that the engine side is 24v and I wanted an efficient way to charge our 12v leisure battery bank. The Sterling does this very well.

AndyC


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## shortcircuit (Feb 15, 2013)

I fitted a Ctek D250S and am delighted.  It provides multi stage charging up to 20A from the alternator.  In addition I have a 90w solar panel connected to it which keeps the trickle charge going.  What I have now found that if I put the Sergent charger on, on hookup to charge the vehicle battery it will also supply the Ctek and I gain multistage charging.  I appear to have leisure batteries fully charged all the time.


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## mrbigglesworth (Feb 15, 2013)

I would go for the panels first as they will ensure your battery is topped up year round and while you are wildcamping (most of the year).

The sterling is easy to fit.  I have both and consider the solar best for my wildcamping.

Mr B.


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## drewdt3 (Feb 15, 2013)

Thanks for all your replies so far. I will definitely get a solar panel fitted eventually for the summer months but as we park our vehicle indoors it won't give us any help when stored. I was thinking of getting a b2b charger that has the option to wire a panel into it to give me the option at a later date. I have been quoted 499 for a 90 watt panel fitted which appears a bit on the steep side to me but my wife doesn't want me to start cutting holes in the roof myself, (she has loads of faith in my abilities....not!)

Drew


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## shortcircuit (Feb 15, 2013)

My panel cost under £100 so it pays to shop around.


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## bmb1uk (Feb 15, 2013)

Hi does the b2b work when you are ticking over or do you have to go for a drive


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## drewdt3 (Feb 15, 2013)

Should work when ticking over


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## mrbigglesworth (Feb 15, 2013)

bmb1uk said:


> Hi does the b2b work when you are ticking over or do you have to go for a drive




I thought alternator output increased with revs.  Iv'e never checked mine but give Charles Sterling a bell on 01905 771 771 and he will put you straight.  I'd like to know too.

Mr B.


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## sparrks (Feb 15, 2013)

bmb1uk said:


> Hi does the b2b work when you are ticking over or do you have to go for a drive



Works fine on tickover. If the starter battery is connected to a bench charger then the B2B will charge the leisures as well


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## AndyC (Feb 15, 2013)

I've been doing a bit in the van this afternoon so I checked mine out.

The leisure batteries were showing about 3Ah down, on tickover the Sterling B2B put in around 20A, increasing the engine speed made no difference.

Now, this is probably not typical, normally the leisures would be more than 3Ah down so it's possible in that case that the charge current might rise with increased engine speed. The B2B I have can output up to 50A.

The other factor that makes a difference on my engine is that it's slow reving, only just over 2000rpm max, so the pulley sizing is likely arranged to spin the alternator quite fast on tickover (about 700rpm) anyway.

Be interesting to see figures from others with B2B chargers.

AndyC


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## hextal (Feb 15, 2013)

Why not just use a split charge system between the van and leisure batteries? Costs about a tenth of the price and does pretty much the same thing


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## sparrks (Feb 15, 2013)

hextal said:


> Why not just use a split charge system between the van and leisure batteries? Costs about a tenth of the price and does pretty much the same thing



A bicycle does pretty much the same thing as a motorbike at a fraction of the price.


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## Teutone (Feb 15, 2013)

I have one of these fitted Power Integrator
and a 100W solar panel. 
Keeps the starter battery topped up and has a display panel included showing you how much charge either alternator or solar panel is charging the system. Very easy to wire up


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## hextal (Feb 15, 2013)

sparrks said:


> A bicycle does pretty much the same thing as a motorbike at a fraction of the price.



Ok, so the B2B is a little kinder, but is there really much in it.  I read about lots of reliability issues with the B2Bs whereas a couple of relays and some wire doesn't have much to go wrong. Plus, you can carry a spare relay for 15notes.  Alternators are fitted to cars to charge one battery (without lots of TLC) so why not just use it to charge a few more.

Yes - I get that if money was no issue then performance wise the B2B would probably be the one.  But reliability wise i'd still have my concerns.

I like to keep things fairly easy and fixable.

Another way to look at it would be that the money saved on the B2B could go towards a couple of batteries


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## sparrks (Feb 15, 2013)

hextal said:


> Ok, so the B2B is a little kinder, but is there really much in it.  I read about lots of reliability issues with the B2Bs whereas a couple of relays and some wire doesn't have much to go wrong. Plus, you can carry a spare relay for 15notes.  Alternators are fitted to cars to charge one battery (without lots of TLC) so why not just use it to charge a few more.
> 
> Yes - I get that if money was no issue then performance wise the B2B would probably be the one.  But reliability wise i'd still have my concerns.
> 
> ...



Speed of charge and a more complete charge does it for me - less time the engine needs to be running. Only ever had 1 problem in 6 years, fixed and returned from Sterling for less than £40. If I had room for a couple of Solar Panels that would take it up another notch.





> I like to keep things fairly easy and fixable.



As you say a split charge is a fraction of the price, does a reasonable job, realiable and easily fixed and used by thousands.


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## hextal (Feb 15, 2013)

Actually that's a fair point - I was making the assumption of running it with a couple of solar panels so it's always getting a trickle charge through the day even when sitting around.


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## Tony Lee (Feb 16, 2013)

hextal said:


> Why not just use a split charge system between the van and leisure batteries? Costs about a tenth of the price and does pretty much the same thing



Only if you normally do the Scrabster to London drive every week or so. 

OP normally  has no mains supply and no solar as yet so if he wants to get his batteries up to 100%, a decent DC-DC charger is the only sure way BUT and it is a big BUT, you still need a lot of time to put 100Ah into a half-discharged 200Ah battery so it may very well turn out to be an expensive device that doesn't do any better than a normal split charger with decent size wiring.


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## drewdt3 (Feb 19, 2013)

I've opted for a Sterling unit and see how it goes I've read good things about b2b chargers on this and other forums. I shall update this thread once Ive fitted and tried it.

Thanks for all the input.

Drew


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## drewdt3 (Feb 19, 2013)

I've not even received the sterling B2B charger yet and I've now seen on another forum that there may be problems using it with the autotrail Sargent EC200 charger. Not sure what the problem could be, has any any information on this?

Drew


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## drewdt3 (Mar 3, 2013)

Started the fitting process today, although it's not a big job I like to take my time and do a proper job.  The first problem was were to put it as its quite a big piece of kit. I have opted to put it behind the front bumper.  My next problem was that the wires aren't long enough so I have contacted sterling to see if it is ok to cut these wires and splice in a new piece between the fuse and charger. Can anyone suggest how best to join these thick wires would it be by terminal block?


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## n brown (Mar 3, 2013)

crimped joints are neat, but terminal block is ok too.can't see any problem cutting and extending the wires unless you make them long enough for significant voltage drop.only thing with crimped joints is they're best done with a proper ratchet crimper.


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## Bigpeetee (Mar 3, 2013)

B2B should be as close as possible to the leisure batts otherwise you will get an excessive voltage drop and loose the benefits of the charger. A longer cable from the starter batt is OK as the B2B will compensate for this loss.


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## sparrks (Mar 3, 2013)

drewdt3 said:


> Started the fitting process today, although it's not a big job I like to take my time and do a proper job.  The first problem was were to put it as its quite a big piece of kit. I have opted to put it behind the front bumper.  My next problem was that the wires aren't long enough so I have contacted sterling to see if it is ok to cut these wires and splice in a new piece between the fuse and charger. Can anyone suggest how best to join these thick wires would it be by terminal block?



A little confused as to the problem here, the only cables that are supplied with the B2B are the Battery temp sensor and the Alternator temp sensor. All other cabling can be as long or short as you like, as long as a cable with a suitable csa is used. As others have suggested crimping would be preferred (assuming a ratchet criping tool is used) although a suitable sized terminal block would be suitable.


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## drewdt3 (Mar 3, 2013)

I thought that was the case until I read tbe leaflet that came with it which said to install it as close to the starter battery as possible and it only cones with short leads from charger to starter battery?


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## drewdt3 (Mar 3, 2013)

Sorry Sparrks posted at same time as you. This is a sealed unit which comes with all the wires molded in to it along with molded in fuse carriers. (Not sure "molded in" is even a term).


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## mikejay (Mar 3, 2013)

Unless sterling have changed the design they are not waterproof mine is a big black heatsink with fans on the sides a one in the center and it is not sealed for fitting outside maybe the newer ones are.Also as been said the closer you can get it to your LB the better i mounted mine on its side under the seat next to the LB i used heavy starter type cable witha 50amp maxi fuse at the end as it connects to the main battery and used big soldered on ring terminals.


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## sparrks (Mar 3, 2013)

drewdt3 said:


> I thought that was the case until I read tbe leaflet that came with it which said to install it as close to the starter battery as possible and it only cones with short leads from charger to starter battery?



Which B2B do you have? Mines the 50A and never had any leads supplied to connect from charger to starter. The cable lengths on mine are roughly 1.75m from Starter batt to charger and another 1.2m from charger to leisure batts.


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## drewdt3 (Mar 3, 2013)

Hi its this one 
Sterling Power Waterproof 12-12v battery-battery 25A digital charger PN:BBW1220
It's waterproof to ip68. It has to be fitted in a cool place. U suppose I couldofit it in the cupboard with a fan on  it.


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## sparrks (Mar 3, 2013)

drewdt3 said:


> Hi its this one
> Sterling Power Waterproof 12-12v battery-battery 25A digital charger PN:BBW1220
> It's waterproof to ip68. It has to be fitted in a cool place. U suppose I couldofit it in the cupboard with a fan on  it.



That explains a lot! I did wonder about fitting it behind the bumper, I was thinking of one of these BB1250 especilly when you said about how large it is.


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## drewdt3 (Mar 17, 2013)

*fitted and working*

I eventually got to finish fitting this unit today. Setting the battery type is a bit fidly but now its set that's it. Only taken it for a short 10 mile run and everything seems fine and cool. I've fitted it behind the front bumper. It's putting 1 more vault in the battery than the split charger was just  before I swapped over but not as much as it says on the sterling leaflet maybe it doesn't need the full whack at the moment.  Will update once I've done a good run and weekend on battery. Should be easter weekend.  Can't wait, just need to choose somewhere!


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## sparrks (Mar 17, 2013)

drewdt3 said:


> I eventually got to finish fitting this unit today. Setting the battery type is a bit fidly but now its set that's it. Only taken it for a short 10 mile run and everything seems fine and cool. I've fitted it behind the front bumper. It's putting 1 more vault in the battery than the split charger was just  before I swapped over but not as much as it says on the sterling leaflet maybe it doesn't need the full whack at the moment.  Will update once I've done a good run and weekend on battery. Should be easter weekend.  Can't wait, just need to choose somewhere!



What voltage is it charging the batts at?


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## Deleted member 13867 (Mar 17, 2013)

Deleted irrelevant post


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## drewdt3 (Mar 17, 2013)

Is my grammar off Dr Dave?
It was putting 13.77 volts in Sparks. 

Drew


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## sparrks (Mar 17, 2013)

drewdt3 said:


> Is my grammar off Dr Dave?
> It was putting 13.77 volts in Sparks.
> 
> Drew



That does seem rather low, what battery type is it set for?

I usually have mine set to Sealed lead acid (14.4v) and when wilding set to open Lead Acid (14.8v)

I'm just wondering if it's your meter not reading accurately as you said it's about 1v more than the split charge (12.7v ?) approx, I would expect the split charge to give about 13 - 14v.


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## drewdt3 (Mar 17, 2013)

Yeh I thought it should  be 13+ for the split charger, I'll see if I can get hold of another to try.

Cheers 

Drew


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## drewdt3 (Mar 17, 2013)

Set for sealed lead acid.


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## ivecotrucker (Mar 17, 2013)

Hi Drew. I would check your voltage output with a proper meter, your B2B output certainly doesn't look right, unless your leisure battery is absolutely fully charged already.


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## drewdt3 (Mar 17, 2013)

This might sound like a daft question but if this battery has been discharged to low in the past would that also make it unable to fully recharge or  make the charger think that it id fully charged. It held its charge for a 3 monyh  period over christmas, but we accidently leave a liad on it  last year and fully discharged it.


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## sparrks (Mar 17, 2013)

drewdt3 said:


> This might sound like a daft question but if this battery has been discharged to low in the past would that also make it unable to fully recharge or  make the charger think that it id fully charged. It held its charge for a 3 monyh  period over christmas, but we accidently leave a liad on it  last year and fully discharged it.



I think if it's held it's charge for a 3 month period over christmas then it would appear to be in a pretty good condition.

Try taking a series of volt readings tomorrow, first at the starter battery with the engine off, then with the engine running and see what the altenator is putting out and another at the leisure battery. Starter batt should be around 12.5v with the engine off, with engine running should be about 13.5v and 14.4v at the leisure batts with B2B set to Sealed. If all readings are lower by roughly the same amount it could be the voltmeter not reading correctly.

As per post #41 the batt could be fully charged and B2B has gone to float mode - is there an LED on the unit to show this?

Have fun.


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## drewdt3 (Mar 17, 2013)

Cheers Sparrks!


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## bmb1uk (Mar 18, 2013)

Hi  all been reading all the replies on the b2b chargers, i have brought one from sterling, its a returned one been refurbised £200
anyone looking for one contact Sophie, anyway i want to install b2b at the back of drivers seat ,as batteries are 1 under passenger seat , 1under drivers seat and 1 behind drivers seat in batt box, going to use 35mm cable from starter battery to b2b which is about 3mtr length  and rewire hab batteries in paralel with the same 35mm cable,(35mm cable coming from jump leads of ebay if they are ok ?) should i put a new fuse on the3mtr cable and how big ?. the original cable looks thin, should that be connected as normal, and should i run another earth cable near to habitation batteries, also been told i should remove fuse from split relay. hope that is clear regards BAZ.  :scared:


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## sparrks (Mar 18, 2013)

bmb1uk said:


> Hi  all been reading all the replies on the b2b chargers, i have brought one from sterling, its a returned one been refurbised £200
> anyone looking for one contact Sophie, anyway i want to install b2b at the back of drivers seat ,as batteries are 1 under passenger seat , 1under drivers seat and 1 behind drivers seat in batt box, going to use 35mm cable from starter battery to b2b which is about 3mtr length  and rewire hab batteries in paralel with the same 35mm cable,(35mm cable coming from jump leads of ebay if they are ok ?) should i put a new fuse on the3mtr cable and how big ?. the original cable looks thin, should that be connected as normal, and should i run another earth cable near to habitation batteries, also been told i should remove fuse from split relay. hope that is clear regards BAZ.  :scared:



Which B2B have you bought?

re-reading it must be the waterproof one as they come pre-wired


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## bmb1uk (Mar 18, 2013)

Hi, i have a b121250 12v-12v 50a  baz


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## sparrks (Mar 18, 2013)

bmb1uk said:


> Hi, i have a b121250 12v-12v 50a  baz



Same as mine. My cables supplying the B2B and leisure batts is 25mm csa, I use fine stranded welding cable. 
The cable from starter batt to the B2B has a 60A fuse next to the S Batt.  
The pos cable linking the 2 leisure batts has a 100A fuse between the 2, on the output cable of the leisure batts is the isolater switch and a 125A fuse (was going to use a largish Inverter) Am going to replace it with a 60A fuse.
Two cables each with a 40A fuse feeds two individual fuse boards with lighting and power split equally over the two.


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## sparrks (Mar 18, 2013)

drewdt3 said:


> It's putting 1 more vault in the battery than the split charger was just  before I swapped over but not as much as it says on the sterling leaflet maybe it doesn't need the full whack at the moment.




Just taken a series of volt readings on my van.

                          Engine off        Engine running
Starter Battery         12.1v                14.2v

Leisure Batteries       12.6v                14.8v    11A Input

The volt meter I used is the one built into the B2B remote control unit.


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## drewdt3 (Mar 21, 2013)

Just taken the same readings with my multi-meter:-

ENGINE OFF

Engine  battery 12.16  
leisure battery  12.3

ENGINE RUNNING

Engine battery 14.2
Leisure battery 13.97

I  contacted Sterling at the beginning of the week but as yrt they have not bothered to reply.


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## sparrks (Mar 21, 2013)

drewdt3 said:


> Just taken the same readings with my multi-meter:-
> 
> ENGINE OFF
> 
> ...



It does look as if somethings wrong as the "boosted" value is lower than the "non-boosted"

Try giving Chas a ring, I found on the odd occasions I've rung up Sterling Power Products and have been put straight though to Charles Sterling - be warned he can be rather abrupt! but also very helpfull. Best if you ring up when you are next to the unit as he might get you to run some tests.


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## ivecotrucker (Mar 21, 2013)

I'm stuck for an obvious explanation. Running the engine boosts the starter batt voltage by +2.04V but the leisure batt voltage by only +1.67V, but it does increase it. One possible conclusion is that the B2B isn't actually doing anything  -- the leisure batt boost of +1.67V is just due to the alternator chucking out 14.2V, less some cabling resistance 'tween alternator & leisure batt terminal.
Good advice there from Sparrks, Charles is very knowledgeable & he knows it but has zero tolerance for fools. Have all your details, voltages, make/model details before you phone him.


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## WildThingsKev (Mar 21, 2013)

It doesn't kick in for 2-3 minutes after starting in order to first boost the starter battery; so if you took your reading during this period it will just show what is going in via the split charge relay (which sounds about right).


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## ivecotrucker (Mar 21, 2013)

That's a good point; some power management systems do have a built in time delay; about 5 minutes is the most i've come across but some systems claim to also monitor the starter batt voltage before switching to leisure charging (e.g. SmartBank), regardless of a fixed time delay. I don't know what's inside the Sterling box.


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## sparrks (Mar 21, 2013)

kevina said:


> It doesn't kick in for 2-3 minutes after starting in order to boost the starter battery; so if you took your reading during this period it will just show what is going in via the split charge relay (which sounds about right).



That's possible, I had forgotten they used to do that, I understood they stopped that with new BB1250 with updated software, mine charges straight from start up. 

As you have a different model It is certainly worth waiting 3 or 4 minutes to see if that is the case as Kevina suggested. As ivecotrucker says Charles Sterling has zero tolerance for fools


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## drewdt3 (Mar 22, 2013)

Well if we all had his knowledge we'd make one ourselves, not a good PR attitude to have, hope he doesn't answer when i call as I don't suffer arrogance. 
All the lights did what they should in the sequance they shoul


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## drewdt3 (Mar 22, 2013)

ld. We are going to Llandudno with the granddaughter this weekend, stopping at the POI behind the Orme, I shall test again after that. Thanks for all your input.


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## drewdt3 (Mar 22, 2013)

I meant to mention that I had it running for more than 5 mins and it didn't change. 

Drew


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## Tony Lee (Mar 22, 2013)

Have you still got the old split charge system hooked up


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## drewdt3 (Mar 22, 2013)

I think I have taken the split charger fuse out. What I mean is I have taken a fuse out and hopefully it was the split charger one lol.


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## sparrks (Mar 22, 2013)

I've just been reading the installation instructions, does it complete the startup and charging procedure correctly and what colour LEDs are shown?

Undoubtably this will be one of the first things they ask for.


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## drewdt3 (Mar 22, 2013)

Hi Sparrks

I remember them being correct but not got the book with me as it's in the van which I keep in a barn on a farm (poet). I seem to remember when I set it the leds were both on green for sealed lead acid then went into red and green not flashing which I think means it's first stage of charging and should be putting in 14.4v. I maybe need to be up there as you say when I call them, I will go through it again as well just to make sure.

Cheers

Drew


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## drewdt3 (Apr 7, 2013)

Well it appears to work well anyway. It's now charging at 14.1 volts, still low but when I spoke to someone at Sterling, may have been the chap mentioned above as he was a bit snippy at first, he gave some mumbo-jumbo reason as to why it might not be showing 14.4 volts at the battery. Anyway I left it for 5 days after parking up and put my meter on it and it's showing 12.89 volts so well charged.


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