Battery to Battery Chargers - Thoughts Welcome (1 Viewer)

[Abacist]

I have 25mm sq cables on my B2B as the cable runs are less than 2 metres so if you are going to upgrade the cables it might be worth jumping straight up to 25 mm sq in case you go for the B2B later then you won't have to re cable again.

 

[DBK]

For a start your Fiat won't have a smart alternator. If you fit a 30 amp B2B as you suggest, you will probably get around 25 amp to start with as soon as the battery starts to take a charge this will drop to around 15 amps.
You could get similar results by upgrading your wiring to the split charge relay to 16mm sq cables. You will need to upgrade the wiring for a B2B anyway.
The latest B2B's are kinder to your batteries as they have a proper charge regium i.e. bulk charge, absorption phase & float.

I would try heavier cables first then if you think you need a B2B, I would fit a 60 amp one.

This thread has made me start to think the existing wiring might need upgrading. I've already found with some of the existing wiring Murvi are a bit mean on thickness.
Thank you.

 

[Wagoneer]

Firstly, it might be worth advising which 12v distribution system you have in your British built van.

Then checkout aandncaravan website regarding the robustness of your system. Allan the webmaster also has views on B2B systems (not all good !!!). He also gives tips on checking the efficiency of your alternator charging system and suggestions to improve it (ie. running cables directly from your alternator to leisure batteries via a 100amp slave relay which is actived from the relay on your 12v distribution board).

Motorhome converters don't normally buy in base vehicles with smart alternators but you can check this with Murvi.

Another source of information can be found on the outandabout forum. Just search for posts by veletron. He has a PVC and is a mountaineer, so spends a lot of time off-grid. He is also an electronics expert and has installed a B2B. He also hosts his own website where you can find details of his modifications.

I've been enjoying highlights from your current trip, keep 'em coming

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[Robert Clark]

If you fit a 30 amp B2B as you suggest, you will probably get around 25 amp to start with as soon as the battery starts to take a charge this will drop to around 15 amps.

Why is this Lenny?

 

[Wagoneer]

Double post !!!

 

[Abacist]

Why is this Lenny?

Robert have a look at the PDF file I uploaded earlier where the 4 stage charging regime is explained - better you do this direct rather than me or someone else tell it differently.

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[hilldweller]

I need a wet weather solution.

Water turbine.

 

[Lenny HB]

This thread has made me start to think the existing wiring might need upgrading. I've already found with some of the existing wiring Murvi are a bit mean on thickness.
Thank you.

What I have seen of Brit built vans all the cabling is way undersize. Lighting probably ok now days with all LED lighting but everything else worth up grading. It will probably be well worth while upgrading the wiring to to heating and the fridge & the main feeds to the distribution unit.

 

[Nasher]

A generator would cost a lot more than a B2B charger though otherwise you have a point. Its all down to personal preferences. A B2B is effectively free once you have bought it as its using the engine power in use already whereas the generator needs fuel to run and service costs etc.

Mine was £180

Review here: https://motor-roam.co.uk/clarke-ig950-800w-generator-review

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[Lenny HB]

Why is this Lenny?

Never seen one that delivers full rated power for more than a minute or so after starting the engine. Once the battery starts taking a charge the voltage across it rises and the current drops.

 

[Abacist]

Wow that is a good price!

 

[haganap]

I know there's a lot of good meaning posts on this thread but I will tell you how it is from a users perspective.

Get a B2B but I am unsure why you are wanting a 30amp one. I have had either a 50 or 60 for over 10 years of Motorhoming with a wife that insists on hair dryers and straighters and kids with laptops. A lot of what I am reading is simply old schools of thought. Your alternator will not have a problem, that I promise, neither will your belts. Your batteries will be better conditioned, they will be higher charged, better balanced and last longer.

Any people with long hair will be happy any lap top users will be happy.

They are extremely easy to fit and they work excellently. I have recommended to so many people over the years that see the benefit. There is absolutely no need for a generator, that's way to old fashioned when you have the generator ready to run at the flick of key.

A stirling is the best IMO although I am after a new one as mine blew up the other week after about a 7 years of use ( 90 nights per year) so after a new one myself

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[Abacist]

When I was getting my solar and alarm done at VanBitz Nick was suggesting a 60 amp B2B and that's what I'd do if I didn't have a 25 Amp one already.

 

[Nasher]

Wow that is a good price!

Yep, electronics tend to get cheaper & better every year

Mine was on special offer from machine mart, currently on sale for £215

And if you sell your moho, you can use it on your new one!!!

 

[DBK]

I know there's a lot of good meaning posts on this thread but I will tell you how it is from a users perspective.

Get a B2B but I am unsure why you are wanting a 30amp one. I have had either a 50 or 60 for over 10 years of Motorhoming with a wife that insists on hair dryers and straighters and kids with laptops. A lot of what I am reading is simply old schools of thought. Your alternator will not have a problem, that I promise, neither will your belts. Your batteries will be better conditioned, they will be higher charged, better balanced and last longer.

Any people with long hair will be happy any lap top users will be happy.

They are extremely easy to fit and they work excellently. I have recommended to so many people over the years that see the benefit. There is absolutely no need for a generator, that's way to old fashioned when you have the generator ready to run at the flick of key.

A stirling is the best IMO although I am after a new one as mine blew up the other week after about a 7 years of use ( 90 nights per year) so after a new one myself

Many thanks, you've confirmed my feeling if I go down this route I need one around 60A but I'm going to investigate the existing wiring first to see if there are any obvious choke points.

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[haganap]

Many thanks, you've confirmed my feeling if I go down this route I need one around 60A but I'm going to investigate the existing wiring first to see if there are any obvious choke points.

your current wiring will be more than sufficient, it's going to end up irrelevant, your cabeling that you choose between the battery the B2B and subsequent battery will be all that matters unless you are telling me your van is pre 1990.

 

[Stanbrook]

Hi I fitted a 60a battery2battery from Sterling in April. Costing 125 pounds on auction site. I would recommend it for its amazing performance.

 

[JJ]

Despite our Blessed Leader's (may his name be praised forever) faith in using his B2B charger, driven by a huge Yank engine, to charge up his batteries when parked, I will always, ALWAYS believe that a small, Honda 1000 genny is a much, much, much more economic, environmentally friendly and efficient way...

...and remember, my olive trees are bigger than his tiny ones.


JJ

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[nicholsong]

John

We have had a Stirling B2B for 5 years. From memory ours is 80A(could be wrong) and is feeding 2 x 90A lead acid.

It is excellent even on 20-30min runs for topping the batteries up.

Our B2B is wired directly from alternator to the leisure batteries with heavy cable, keeping well-away from the Schaudt panel, because Stirling themselves have told me they cannot make theirs compatible with Schaudt's technology. The Schaudt ammeter reads fine on engine start but soon shows a negative charge, which is erroneous. This can be solved with a shunt, but since that is an expensive solution I just rely on the higher voltage as evidence it is charging - usually 14+v on the leisure batteries.

How suited it is to your style of MHing depends on how often you move. We are not often in one place for more than 2 days, but even a quick run to a supermarket tops things up, but maybe with one battery that would not be enough, without solar, if you had used a lot of amps. Anyway the engine can be used as a generator when static and the fuel used would not be much for the time needed.

Like most other posters I am very pleased with our B2B and worth it for the cost, especially if you can install it yourself - not too difficult to follow the instructions.

Geoff

 

[haganap]

When I was getting my solar and alarm done at VanBitz Nick was suggesting a 60 amp B2B and that's what I'd do if I didn't have a 25 Amp one already.

not sure why you would want a 25amp one to be honest? your charger will be rated at similar level anyway? alth

John

We have had a Stirling B2B for 5 years. From memory ours is 80A(could be wrong) and is feeding 2 x 90A lead acid.

It is excellent even on 20-30min runs for topping the batteries up.

Our B2B is wired directly from alternator to the leisure batteries with heavy cable, keeping well-away from the Schaudt panel, because Stirling themselves have told me they cannot make theirs compatible with Schaudt's technology. The Schaudt ammeter reads fine on engine start but soon shows a negative charge, which is erroneous. This can be solved with a shunt, but since that is an expensive solution I just rely on the higher voltage as evidence it is charging - usually 14+v on the leisure batteries.

How suited it is to your style of MHing depends on how often you move. We are not often in one place for more than 2 days, but even a quick run to a supermarket tops things up, but maybe with one battery that would not be enough, without solar, if you had used a lot of amps. Anyway the engine can be used as a generator when static and the fuel used would not be much for the time needed.

Like most other posters I am very pleased with our B2B and worth it for the cost, especially if you can install it yourself - not too difficult to follow the instructions.

Geoff

Geoff, then surely you have a A2B charger and not a B2B charger? probably would explain why its 80 amps and more difficult to fit.

 

[Ivory55]

I guess it’s like anything it’s how much you want to spend. For the small amount of time we needed extra power it was cheaper to go the generator route. If you have got the money and want convenience b2b sounds good for you.

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[Abacist]

not sure why you would want a 25amp one to be honest? your charger will be rated at similar level anyway?

Sorry I have not explained this so must seem odd.
My old van had 2 battery banks one fed by solar and the normal split charge relay. The other bank fed the inverter and was powered by the B2B charger. The 2 systems were interconnected by a switch so that the main bank could be supplemented by the 2nd bank if required.

On the N+B it has been easier to replicate what I had before whilst I have 2 pairs of incompatible batteries so far as charging and making one battery bank is concerned.

So the "old" 25 Amp B2B charges the "spare" battery bank which can be brought into use on the main system if the batteries suffer in the winter. These will also be used when adding additional 12 volt accessories.

In the fullness of time when the batteries need changing I will get it all into one bank and get a much bigger B2B at that time. I might as well get use out of what I have at the moment as I doubt I'll get their real value if I sell them.

 

[nicholsong]

Geoff, then surely you have a A2B charger and not a B2B charger? probably would explain why its 80 amps and more difficult to fit.

No it is a B2B and maybe it is not 80A and maybe it is more than 5 years because i think the A2B was not on the market when I bought mine.

I have to go down to the MH later so I will check.

Geoff

 

[haganap]

No it is a B2B and maybe it is not 80A and maybe it is more than 5 years because i think the A2B was not on the market when I bought mine.

I have to go down to the MH later so I will check.

Geoff

trust me Geoff. if it's running from the alternator and its a B2B you're doing some weird stuff there.

see here for installation. the B2B has been around as long as I've been around





Also an old post from @jonandshell about fitting his and that was back in 2012. https://www.motorhomefun.co.uk/foru...rnator-to-battery-charger-on-a-transit.55212/

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[two]

One or two on this thread have suggested that a B2B produces ‘cheap’ electricity. Unlike solar, the power from a B2B comes from the fuel going into the engine and has to be paid for when it’s replaced. I believe that the cost of the energy available in fuel is roughly the same as the domestic rate for electricity (about 14p/kWh). However, the internal combustion engine is no more than 20% efficient at converting that energy into power, after which you need to account for other losses in the alternator and B2B itself. So, in simple terms, I think a B2B provides rather expensive electricity, albeit at times when there may be no other source.

As for the current available, I’m not sure it’s a good thing to charge too rapidly. 20A may be all that’s required, whereas 80A may be excessive (patience is often rewarded). Hopefully the B2B ‘intelligence’ would only provide what it considers necessary.

 

[NickandClair]

B2B charging is by far a great alternative to safe and reliable rapid charging to your leisure battery banks. We regularly fit the B2B's when installing the Lithium Batteries, but deal with all different battery construction types and in nearly all cases, a direct battery to battery connection including dealing with Euro6/Regenerative Braking/Smart alternator issues.
I have used them on my vans since 2008 and find them a great back-up when using the van during the winter months, when solar just doesn't cut it. It also is great to use when supplementing the inverter's use when the wife is using the hair dryer off the inverter. She'll start the engine and leave it on idle speed, switch on the inverter and use her hair dryer, then leave the engine running for a further 10mins after to add a bit of extra oomph back into the leisure battery bank.

 

[DBK]

One or two on this thread have suggested that a B2B produces ‘cheap’ electricity. Unlike solar, the power from a B2B comes from the fuel going into the engine and has to be paid for when it’s replaced. I believe that the cost of the energy available in fuel is roughly the same as the domestic rate for electricity (about 14p/kWh). However, the internal combustion engine is no more than 20% efficient at converting that energy into power, after which you need to account for other losses in the alternator and B2B itself. So, in simple terms, I think a B2B provides rather expensive electricity, albeit at times when there may be no other source.

As for the current available, I’m not sure it’s a good thing to charge too rapidly. 20A may be all that’s required, whereas 80A may be excessive (patience is often rewarded). Hopefully the B2B ‘intelligence’ would only provide what it considers necessary.

Cost of the electricity isn't a factor I'd considered so thank you for raising it. But when the batteries are low and the sun isn't doing anything then my options at the moment are to drive several hours every day or stay at aires with EHU which is what I'm doing now and it is costing me about ₤€10 a day.
If I need to produce say 100Ah of power to recharge the batteries as an example that's about 1.2KWh of energy. Allowing for the 20% efficiency you suggest that's 6KWh of energy in total. At which point my mental arithmetic fails me but I suspect this might only be a pound or so of fuel.
But the bottom line is if I need to recharge the batteries a half hour drive is going to be cheaper than a four hour drive.
The charging rate was a concern but no one has raised this as an issue and if B2Bs wrecked batteries I think it would be something well known.

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[haganap]

B2B charging is by far a great alternative to safe and reliable rapid charging to your leisure battery banks. We regularly fit the B2B's when installing the Lithium Batteries, but deal with all different battery construction types and in nearly all cases, a direct battery to battery connection including dealing with Euro6/Regenerative Braking/Smart alternator issues.
I have used them on my vans since 2008 and find them a great back-up when using the van during the winter months, when solar just doesn't cut it. It also is great to use when supplementing the inverter's use when the wife is using the hair dryer off the inverter. She'll start the engine and leave it on idle speed, switch on the inverter and use her hair dryer, then leave the engine running for a further 10mins after to add a bit of extra oomph back into the leisure battery bank.

completely agree, Had our first in 2008 and always have had and will do. If I want to use the microwave or Nikki dries her hair I simply run the engine and balance it out. Solar panels have never given me the power I need especially wilding in ski resorts in the winter

 

[hilldweller]

The charging rate was a concern but no one has raised this as an issue and if B2Bs wrecked batteries I think it would be something well known.

This is so hard to spot. How long will a battery last ?? How long will a battery last with b2b ?? We are talking year/s to find out and anyway who has, say 5 years of non b2b followed by 5 years of the same batteries with b2b. Stirling might.

 

[eddie]

The charging rate even with a B2B will always be lower than the engine battery, and there is no concern about the charging rate buggering engine batteries

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