# A B2B charger question



## cliffhanger (Jun 27, 2008)

Hi

A question about B2B chargers, as Sterling state that any charging source can be used. 

The generator I'm going to use(no alternator)delivers a CONSTANT 22amps. With the 'input' already charged, can a B2B charger cope with this as the output(leisure batteries) reach full charge and the float is implemented, i.e how are excess amps be dealt with?

thanks

MAC


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## weldted (May 1, 2005)

*B2b charger*

Hi I had a 50 amp b2b charger, when they state any charging source, I take it you will connect your generator to the engine battery, then the b2b will handle that input and distribute it between the batteries allowing the starter battery to reach it correct level of charge before sending the surplus to the leisure battery or batteries. When you say you charger puts out a constant 22 amps, will the charging rate not decrease as the battery level come up? If it does not the you will run the risk of bamaging the batteries, do you know at what voltage the charger puts out the 22 amps, ideally around 13.8 volts much higher than that rill cause the batteries to star gassing?


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## safariboy (May 1, 2005)

Will not the voltage rise to a dangerous level? A constant current generator sound more suitable for welding, certainly not battery charging.
Perhaps I have misunderstood the spec?


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## cliffhanger (Jun 27, 2008)

No, the charging rate would not decrease as the leisure batteries come up, I had assumed the B2B would handle that, but it seems not?
The excess charge has nowhere to go.

But the genni would cut out at 14.4volts, but that's not going to happen as the input will be pulled down by the B2B. Again, I hoped that the B2B would balance the charge.

MAC


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## cliffhanger (Jun 27, 2008)

Okay it's not going to work

Will take a diffferent route. How does a B2B charger work alongside an Electrobloc assuming it is wired directly to the leisure batteries? In theory there are two charges taking place.

MAC


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## erneboy (Feb 8, 2007)

There are plenty of posts about the B2B and electroblok combination. Some say it may be damaging to the Eb. Schaudt were not interested in discussing or investigating it when I asked about three years ago. All they would say was that the Eb couldn't handle that level of charge so it must not be connected through it.

I went ahead anyway wiring the B2B direct to the leisure batteries. I found that, for me, it worked OK except that the readings on the Eb were completely inaccurate till full charge was reached. The Eb recognised that and reset to the correct readings as soon as the B2b was finished charging, Alan.


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## cliffhanger (Jun 27, 2008)

Many thanks may email Schaudt. I use a Nasa BM1 so any panel readings wouldn't matter, will post result.

MAC


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## WildThingsKev (Dec 29, 2009)

I have a German Votronic b2b charger, if you go to their website product page and clickon the downloads tab you will find the owners manual. Page 12 has an installation diagram for use with an Electroblok. I would imagine this is the same for a Sterling b2b charger.

There is an English language manual somewhere on their website but is not the latest version.

Kev


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## cliffhanger (Jun 27, 2008)

Many thanks for that website, looks like a good call.

MAC


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## erneboy (Feb 8, 2007)

> I have a German Votronic b2b charger, if you go to their website product page and clickon the downloads tab you will find the owners manual. Page 12 has an installation diagram for use with an Electroblok. I would imagine this is the same for a Sterling b2b charger.
> 
> There is an English language manual somewhere on their website but is not the latest version.
> 
> Kev


That's an interesting link and the diagram completely contradicts what Schaudt told me when I asked.


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## cliffhanger (Jun 27, 2008)

I would be connecting to a EBL 99 and don't fully get that diagram, where are B1 and B2? I assume one has to trace wires?

MAC


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## pippin (Nov 15, 2007)

I will post here the info that I sent to Cliff in a PM.

I have an EBL99 & a Sterling B2B.

"Separate from the EBL there is a a relay which is the split-charge jobby. 

The coil is connected by wires to chock-bloks (I think) marked "A1" & "A2" on the rear of the EBL. 

Disconnect the wire that goes to A1 and insulate it. 

There is another chok-blok marked "E20-3F" on the diagram, again at the rear. 

A3 is the negative connection for both the Starterbatterie & Wohnraumbatterie. 

It may, confusingly have brown wires connected to it. 

The middle one is the hab battery and the other end one is the engine batt. 

Now, here I get a bit hazy. 

I am pretty certain that I connected the B2B i/p to the starter batt connection and the o/p to the hab batt connection. 

Use hefty wire! 

The B2B does not require a huge earth connection - mine gets it from the mounting screws to the chassis. 

E&OE!!!!!"

The 22A that the generator IS ABLE to supply does not necessarily mean that a connected load WILL CONSUME that amount.

Here's a bit more I-hope-I'm-not-teaching-granny-to-suck-eggs information.

The Sterling unit is basically a very clever inverter.

It ups the voltage from the alternator/engine battery (one and the same thing as far as it is concerned).

Why does it increase the voltage (inside itself)? 

So that it can easier control it's output voltage.

Why? So that it can control the charge that it gives to the hab batteries.

The alternator is designed to look after the engine batt.

The split-charge relay contacts directly connect the engine batt and hab batt(s) together. 

That is not ideal because they may be at totally different states of charge and totally different types of battery.

A B2B charger acts as a very clever split-charge relay.

We need to ensure that the crude split-charge relay is disabled.

With the EBL99 the split charge relay is external with its coil controlled from within the EBL99 via connections A1 & A2 - chocbloks on its rear.

Simply disconnect one end of the coil at A1 or A2.

Then connect the B2B I/P to the starter batt connection and the O/P of the B2B to the hab batt connection (on E20-3F) at the rear of the EBL.

If you want to use an external 12V (nominal) generator in conjunction with the B2B then life gets a bit complicated.

First, you would need to disconnect the engine battery from the rear of the EBL (by simply removing the big 50A fuse).

Next you would need to connect the genny to the B2B I/P via a 50A fuse and then both of them to the engine batt I/P on the rear of the EBL.

Not a quick and easy procedure, especially as you will want to revert to alternator charging via the B2B when on the move.

You would need some serious switches to accomplish that without faffing about changing wires over.

Right - now you are all asking me how come I am such a clever-clogs!

It's because I have the circuit diagram of the EBL99 in front of me.

I have been reading circuit diagrams for everything from receivers, transmitters, radars, TV's - you name it - for over 55 years!

Again E&OE (errors and omissions excepted).


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## cliffhanger (Jun 27, 2008)

Many thanks for that complete explanation Bruce. I wasn't trying to keep you up, honest! 

MAC


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## pippin (Nov 15, 2007)

If you follow this link

http://www.schaudt-gmbh.de/de/service-support/downloads.php

you will be able to download the EBL99G manual which includes the block diagram.

It is well worth printing the diagram off and then working out which fuses on the front work which lights/appliances & etc.

Easier to do at leisure by daytime than in a panic in the dark on holiday.

Incidentally, I can't help with questions on how a B2B will affect charge indicator panels as ours is basically just a voltmeter.


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## cliffhanger (Jun 27, 2008)

Had that for some time Bruce. But was under the impression, until recently, that a B2B was not possible with the Electrobloc. 

I've now had a email from Udu Lang that seems to support the method above:


When you put a booster to the system with the EBL 99, the best would be to remove the wire starter battery at the back side of the EBL and use this one as 12V entry for the booster.
Then you put a minus connection from the starter battery to the booster input and from the booster output you connect the minus to the leisure battery.
The booster 12V output you connect the the position starter battery at the EBL (where you have removed the wire for the booster input 12V).

This is possible, when the booster will stay within 45A!
In case there is a bigger current, please disconnect just the wire starter battery at the back side of the EBL and put new wires in your camper like described in the user manual of the new unit.

MAC


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## pippin (Nov 15, 2007)

Woah!!

Just got in and had a beer and read the information from Udo Lang.

DO NOT follow his instructions until I have had a good think about them with a clear head in the morning.


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## cliffhanger (Jun 27, 2008)

He also said this:

When you have an Ampere meter at the panel in your camper, better to connect via EBL.
Then you will see the charging current there.

But accept of the the amps you can see there it doset matter to connect this or the other way with the EBL 99.
For EBL 101 or 220 there is a must to connect to the starter battery wire to the EBL.

Not good English, but better than my German :lol: :lol: 

MAC


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## erneboy (Feb 8, 2007)

Hieke Gronwald was the Schaudt guy who told me not to put it through the Eb, maybe they have now rethought the advice he gave me.


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## cliffhanger (Jun 27, 2008)

What effect do you see on EHU?

I assume the B2B is triggered?

MAC


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## pippin (Nov 15, 2007)

The B2B couldn't care less if you are on EHU.


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## cliffhanger (Jun 27, 2008)

Hi

I thought I would put this out on the site for anyone wanting to wire a B2B through an Electroblock. This was sent by Udo.

I was not altogether clear by the message at the bottom.

Cliff 8)


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