# Alternator to Battery Chargers



## Snow (Dec 22, 2008)

I have just looked at Sterlings Web site and they feature a 80amp (and higher) Alternator to Battery charger/control unit. I think the principle of this is to maximise the alternator output. Is this the answer to our flat leisure battery problems or is it to good to be true? 
- Has any one used this equipment in the motorhome enviorment??
Snow


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## nicholsong (May 26, 2009)

Some replies here

Tech / Mech Chat » Electrical » Sterling Battery charger


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## bigcats30 (Aug 13, 2012)

£330 quid

http://www.shop.sterling-power.com/acatalog/Alternator_to_Battery_Chargers_.html


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## erneboy (Feb 8, 2007)

We have a Sterling battery to battery charger and it's a good piece of kit.

DAB posted the following links in reply to a similar query some time ago.

http://www.motorhomefacts.com/ftopicp-601034.html#601034 
http://www.motorhomefacts.com/ftopicp-651721.html#651721 
http://www.motorhomefacts.com/ftopicp-587885.html#587885 
http://www.motorhomefacts.com/ftopicp-217582.html#217582 
http://www.motorhomefacts.com/ftopicp-211763.html#211763

http://www.motorhomefacts.com/ftopicp-651725.html#651725

http://www.vanbitz.com/product/Battery_Master_BMaster 
http://www.outdoorbits.com/Brochures/Battery_Master_Customer_instructions.pdf

http://www.motorhomefacts.com/ftopicp-798960.html#798960

http://www.roadpro.co.uk/retail/pro...erling+Pro-Charge+"C"+20A/12V+Charger&id=1063

http://www.roadpro.co.uk/retail/product_detail.aspx?prod=CTEK+Multi+XS+25000+Battery+Charger&id=289


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## nicholsong (May 26, 2009)

Snow

Had my Sterling B2B for 2 years in MH - very pleased.

You have plenty to read on the links above - from some very knowledgeable people.

I am not sure if this point is made there somewhere, but by keeping your batteries charged and well away from half-charge it will prolong their life and thus offset some of the initial outlay.

The only problem I have(not Sterling's fault) is that the ammeter on my Schaudt Electoblok panel will not accept the feed from the B2B. However from the high voltage going in there is evidence of a high charge.

You did say 'flat leisure battery problems'. If you mean the batteries never come up to charge, it is a 'knackered battery' problem so solve that first before spending money. If you only mean keeping batteries charged fully that is a different matter.

Geoff


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## Antonia (Apr 27, 2008)

A simple answer is yes, very much a good piece of kit.
We've used a Stirling B2B charger for 5 years, wonderful !
In retrospect I should have installed an Alternator to Battery charger as they can charge BOTH cab and house batteries and look after both of them at once. Still, live and learn.

Regards

Antonia


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## nicholsong (May 26, 2009)

I have just realised that the OP was asking about Alternator to Battery chargers and I mistakenly thought he was talkiing about B2B chargers.

I have just looked at Sterling's website and see there are two different products.

Can anyone well-versed in the technical difference please explain, in layman's terms please, the difference and pros/cons? Are the Alternator-Battery chargers new products?

Geoff


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## organplayer (Jan 1, 2012)

*organplayer*

Have Sterling batt to batt charger. Had considered a Sterling alternator to battery charger 80 amps. Ascertained that the alternator output was 150 amps max, and Sterling informed me that although the alt charge would rarely reach 150amps output, 130ish could be put out. Therefor, I was informed, the alternator output would blow a diode(whatever one of them are)in 80amp Sterling alternator to battery charger. VanBitz did a super intallation of the Sterling batt to batt charger 50amp. A really super bit of kit and so well installed.


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## cabby (May 14, 2005)

I am not sure if I am getting this correctly, but my existing alternator charges the engine battery and also the leisure batteries when the engine is running, is this NOT the norm.
My solar panels charge either the leisure or the engine battery by way of a manual switch, that is the way I asked for, rather than having to have the engine batt charged only after the others were fully charged.
When on hookup it also charges both engine and leisure batteries.
I assumed that this was standard.

cabby


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## airstream (Jan 7, 2009)

*This one?*

Hi,
Most common in use on the waterways where battery banks are larger and engine revs lower

http://www.foxsonline.com/acatalog/Adverc-Mark-1Va-Alternator-controller-12v-Negative-1AA01KM.html

Ray


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## nicholsong (May 26, 2009)

cabby said:


> I am not sure if I am getting this correctly, but my existing alternator charges the engine battery and also the leisure batteries when the engine is running, is this NOT the norm.
> My solar panels charge either the leisure or the engine battery by way of a manual switch, that is the way I asked for, rather than having to have the engine batt charged only after the others were fully charged.
> When on hookup it also charges both engine and leisure batteries.
> I assumed that this was standard.
> ...


Cabby

I am not an expert, but I think I have leaned (in laymans terms) the following:

You are correct that the alternator charges engine battery and leisure battery, but only at the rate required to top-up the engine battery, to which it gives priority (via the standard automotive regulator, set at 14v.

The leisure battery gets a residual charge, but when the engine battery requires little from the alternator the leisure battery gets almost nothing.

The B2B( and presumably the Alt2B systems) 'kid' the alternator into thinking it is 'not doing its job', by bypassing the normal automotive regulator and demanding a higher charge rate which, after ensuring the vehicle battery is 'full', diverts the alternators high capacity to the leisure batteries.

Somebody might be along to correct me, if so, well and good because I can learn from any of my misunderstandings.

Geoff


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## pieterv (Feb 3, 2009)

Don't forget that

1. both the A2B and B2B chargers came into being at a time when the alternator regulators were set to a much lower voltage than they are today. So with modern regulators the advantage is much less.

2. they only really have an advantage (as Sterling says himself) with wet batteries (not Gel) because the charging voltage makes them gas a lot, so the water needs topping up.

Pieter


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## nicholsong (May 26, 2009)

pieterv said:


> Don't forget that
> 
> 1. both the A2B and B2B chargers came into being at a time when the alternator regulators were set to a much lower voltage than they are today. So with modern regulators the advantage is much less.
> 
> ...


Thanks Pieter

What are the regulators set to now?

Could anyone increase their charge rate by replacing an old regulator with a modern one?

You mention 'gassing' but would not apply to a sealed battery?

Only learning(still)

Geoff


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## javea (Jun 8, 2007)

Geoff,

My Schaudt showed stupid readings once my B2B charger was installed so I fitted a Victron battery monitor (simple job) which now tells me the true state of charge in the batteries.

Mike


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## nicholsong (May 26, 2009)

Mike 

My Schaudt Electroblok still reads OK on the Voltmeter - it is only the ammeter which is the problem. Sterling and Schaudt are incompatible.

I have talked extensively to Sterling, who cannot fix it without a 100A Shunt, and others who say 'don't worry' - since the latter are experts I have gone that route.

Geoff


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## erneboy (Feb 8, 2007)

Yes my Schaudt also gives crazy readings when the engine is running. I spoke to Schaudt about it last year when I was near them and asked if they could have a go at rectifying it. They didn't seem to think they could and said they were not familiar with the B2B.

I don't worry about it as all returns to normal when we stop the engine, Alan.


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## pieterv (Feb 3, 2009)

nicholsong said:


> pieterv said:
> 
> 
> > Don't forget that
> ...


Most, I think, are set to 14.4V (as opposed to 13.6-8V for older ones). You might be able to replace a regulator, but it will be integrated into (soldered onto) the alternator, so not an entirely straight forward job.

Gel batteries should not be used because they are not meant to gas, and therefore water cannot be refilled. I think the Sterling has a setting for Gel, but it won't be a higher voltage and therefore defeats the purpose.

Quote from Sterling: "For best effect use open lead acid batteries, avoid gel, sealed and AGM batteries. " here


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## emmbeedee (Oct 31, 2008)

pieterv said:


> .
> 
> Most, I think, are set to 14.4V (as opposed to 13.6-8V for older ones). You might be able to replace a regulator, but it will be integrated into (soldered onto) the alternator, so not an entirely straight forward job.


Hmm, well for several years I was employed at a factory which made thousands of alternator regulators every week, so we must have made millions whilst I was there. All of them were set to 14.7 volts. These were mostly hybrid (solid state) but some were PCB based & older ones still were electro-mechanical. The hybrid ones were bolted inside the alternator but the others were mounted remotely from the alternator. All of these were for spares & most were for US made vehicles, but that shouldn't make a difference as the laws of physics don't change over there :wink: 
Somewhere I have details of Lucas & Bosch alternator information, I'll see if I can dig it out & find anything useful.


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## pieterv (Feb 3, 2009)

OK, so even higher than the 14.4V I mentioned, therefore even less benefit of A2B or B2B chargers. Although 14.7V sounds very high for an automotive application, unless it is meant for vehicles with an AGM battery.

They can indeed be separate (I know it is on my motorbike, because I just replaced it).

My point is just that the benefit of B2B can be overstated. They had much more of a justification in the past when voltage regulators were set lower.


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## Antonia (Apr 27, 2008)

I think what we need to understand here is the way we use our batteries in our motorhomes.

We often drive miles expecting our house batteries to fully charge to give us a long time watching the TV and such in the evenings.

An advanced battery charging system will maximise the charge going into your battery per mile you drive to give you most charge. 
Not only that but it will also look after your cab battery to ensure it gets what it needs in the way of charge after it has been used to start your engine.
The way an advanced charger feeds your house battery optimises it for not only max charge per mile, but also takes care of the health of your battery. Various alarms and indicators inform you of issues, before you end up with a problem. They help reduce and even remove sulphate deposits, prolonging useful life.
Fast charging however uses water, and so batteries need topping up.

Fancy expensive batteries for those with little knowledge about batteries consume lots of money and don't work as well as standard lead acid batteries with the advanced chargers.
Irrespective of the type of alternator.

My humble advice, is to choose a good alternator to battery charger to take care of your cab and house battery. Use standard lead acid batteries in the > 100Ahr range, keep them topped up with distilled de- ionised water.
If you have a very high output alternator and cannot afford a Alternator to battery charger of adequate capacity...then choose a Battery to Battery charger 50A or more, as your bank balance dictates.

Use a good battery meter with a shunt to monitor your battery.
Have these fitted by a competent electrical engineer.
Sit back and don't worry about it anymore.

Regards

Antonia

PS: battery info here
http://www.sterlingpowerproductsbam.co.uk/support-faq-2.htmr


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## Snow (Dec 22, 2008)

Thanks to you all for contributing to this thread. After reading every ones commends I am now convinced the way forward is the A2B. The only thing I need to determine is what ampage A2B to go for, and I'll have a chat with Sterling to sort that one out.

Again many thanks
Snow(John)


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## nicholsong (May 26, 2009)

Is anybody still there? as I am a bit late with this post.

Having read about the 'gassing' aspects of the B2B operation, I assume one should be checking the battery cell fluid levels more frequently when the B2B is in use. How often? Every 5 hours of engine running time?

Geoff


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## listerdiesel (Aug 3, 2012)

Some of the figures quoted here worry me a bit.

14.70V ? That's running at 2.45V per cell, what we would class as a cyclic charge rate, but probably OK if only in short bursts with some discharge in between.

Our solar panels have much lower settings, something like 13.40V but they are on continuously.

Our batteries are also sealed types.

It all depends on whether or not you 'need' the extra complexity of the extra stuff or not, but I've tried to keep ours nice and simple with no additional charging from the vehicle charger, which is a 130A Bosch unit.

Peter


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## Corkheader (Aug 25, 2008)

The Sterling chargers are or were fitted to the Romahome R40 as standard. We had electrical problems with ours. It transpired not to be the charger but with the electronic touch screen control panel. In investigating the system I do recall that unless you are very competent in electronics fitting its not a DIY job and that the actual unit has a number of settings, it needs to be set up correctly in he first instance. Its not a simple charger.

My understanding is that the alternator is working under maximum load all the time, something to consider.

John


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## erneboy (Feb 8, 2007)

Corkheader said:


> The Sterling chargers are or were fitted to the Romahome R40 as standard. We had electrical problems with ours. It transpired not to be the charger but with the electronic touch screen control panel. In investigating the system I do recall that unless you are very competent in electronics fitting its not a DIY job and that the actual unit has a number of settings, it needs to be set up correctly in he first instance. Its not a simple charger.
> 
> My understanding is that the alternator is working under maximum load all the time, something to consider.
> 
> John


Sorry but your understanding seems incomplete. Firstly fitting is reasonably straight forward if a little time consuming. Routing the wires etc.

Only a few basic skills are required.

The unit does have some settings which are very easily sorted out.

It's a fairly simple charger but it has sophisticated software controlling it. We needn't worry about that in the same way as we don't worry too much about how our computers work

I fitted my my own three years ago and have monitored it's performance since.

I suspect you haven't.

There are a few possible disadvantages too, Alan.


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## Corkheader (Aug 25, 2008)

Alan -

Thanks for your reply to my post. I am basing this reply on your original post prior to amending it.

I owned the Romahome and did have issues with the electrical system. I have stated that the fault was not with the charger. I have given my opinion based on investigating the fault and comparing the system to others I have owned. The comment around the alternator running at maximum output is again based on ownership, the manual and comments from a technician who eventually rectified the fault. 

I gave my opinions in the spirit of this forum, one of conversation, friendly debate and a common interest. The tone of your response is totally unnecessary.

John


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## erneboy (Feb 8, 2007)

No John, the tone of my immediate response was a little harsh and was very quickly altered so that it became perfectly sweet and reasonable.

You replied to the first draft but make it obvious that you before you did so you had seen the changes I made in order to make my message less strident. 

If your electrician thinks that your alternator will always run flat out in order to keep up with the demands placed on it by a B2B then he does not understand how it works, Alan.


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## oldun (Nov 10, 2005)

I think I am (about) correct in stating that the alternator is controlled by the voltage of the engine battery so that it will drastically lower the output when the engine battery is topped up thus reducing any possible leisure battery charging.

I also understand that the alternator can be rewired to overcome this problem. Is this so and is it easy to do? Will the mod void the warranty?

Can someone who knows something about the subject give a better and more precise explanation?


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