Fitting a Sterling Battery to Battery Charger

DBK

Jan 9, 2013
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I've just fitted a Sterling BB1260 B2B charger. Things didn't go quite to plan but it is working now so here is a short account of what I did just in case anyone is thinking of doing the same.

For those unfamiliar with them B2B chargers replace the usual split charging system fitted in MHs. A split charger basically just connects the leisure batteries to the vehicle alternator once the engine is running. A consequence of this is the vehicle and leisure batteries are exposed to the same voltage. Now if your leisure batteries are fairly well discharged they need a lengthy charge at a high voltage - typically 14.4 volts for sealed lead acid batteries. The problem with this is the vehicle battery is exposed to the same voltage and could be over charged. Modern vehicle electrics are aware of this so what tends to happen is the voltage is reduced and the time to re-charge the leisure batteries will be extended. This won't generally be a problem if you are driving a good distance every day but on our trip down the Mosel late last year we were struggling on battery power. It was a combination of low sun, a power hungry diesel heater and the short distance between stelplatz!

A B2B can charge the leisure batteries at a higher voltage than the vehicle battery. It does this by placing a load on the alternator to maximise its output and then boosting this voltage and using this to charge the leisure batteries.

They are not cheap but Sterling have a small number of reconditioned units and a 60A model cost me £159 which is about half the price of a new one.

To fit the B2B requires positive and negative connections to both the vehicle and leisure batteries. Sterling recommend for maximum efficiency you don't use the vehicle body as the return.

On the model I chose no connection to the alternator is required. The cables have to be chosen to match the current and lengths of cable run. On my installation this dictated 25mm cables which I ordered from Electrical Car Services who I've used before and are excellent. https://www.electricalcarservices.com/battery-leads-made-to-order/c-p-0-0-535

Because every installation will be different I won't describe in detail where all the cables went but the front part will be common to most Fiat based MHs so I'll describe this.

Here is a shot of the vehicle battery.

OI000006.JPG

The cables to the B2B are the two disappearing under the bottom of the dash at the top. The positive is fused. From here they run under the carpet just below the pedals. They are out of the way of my feet and do not interfere with the pedals.

To get to the rear of the vehicle I used the space behind the trim below the door.

DSC_0076.JPG

Removing this and the part in front of it reveals this.

OI000003.JPG

The two cables can be seen running front to back. There were even two unused cables clips I could take advantage of. :)

I had to run the cables on top of the carpet for about 6" before taking them through holes into the space behind the seat/bed where the leisure batteries are. The cables are out of the way here and do not interfere with the handbrake although it might look as if they do.

OI000007.JPG

The negative cable is connected to the negative terminal of one of the leisure batteries. From these negative terminals I had already run a 35mm cable to the inverter and this I'm doubling up as the return from the B2B. The red cable runs all the way to the B2B which is fitted behind the panel shown below with wires coming out of it for the TV and WiFi booster. You might just be able to see the four mounting bolts.

OI000008.JPG

This photo shows the other side.

OI000010.JPG

The wires and cables coming out of the bottom are from left to right the wires for the leisure battery temperature sensor, the cable from the vehicle battery and a smaller wire connected to the same terminal from the BatteryMaster which I had to re-connect as it was originally wired through the split charging relay which I disconnected by removing the fuse to the relay. The next cable is the black common negative which runs a short distance to the negative terminal on the inverter to join up with the 35mm cable mentioned earlier. The final red cable is connected to the battery side terminal of the inverter isolating switch, making use of the heavy cable running from there to the leisure batteries through a fuse.

The leisure battery temperature sensor is the yellow thing visible below.

OI000001.JPG

It is not essential to fit this but if you do the unit will alter the charging voltages, reducing it when it is hot and increasing it when cold. So without the sensor fitted it will charge sealed lead acid batteries at 14.4 volts but when fitted and in the current cold weather it is doing this at 14.6 volts. All charging voltages can be altered during setup to match your type of battery including lithium.

So what went wrong?

The first problem is when the B2B arrived I couldn't get it to work! I returned it and Sterling tested it and said they could find no fault but would replace it anyway. When this unit arrived I connected it and it worked perfectly! Most curious.

The B2B comes set up to operate automatically when the vehicle battery voltage rises above 13.6 volts. As mentioned in another thread I was a little concerned how this would get on with the BatteryMaster when the sun was shining. My worry was the vehicle battery voltage could be raised above 13.6 volts by the trickle charger from the BatteryMaster and the B2B tricked into starting. I raised this with Sterling who advised this wouldn't be a problem but to be sure I decided to set the unit up so it would only start when the engine was running. To do this you have to connect a terminal on the unit to an ignition feed which is only live when the alternator is running.

And this is where I hit a problem. The unit would start but not turn off properly when I switched the engine off. It just repeatedly went through a cycle of flashing LEDs, beeps and re-booting itself. I spoke to Charles Sterling and sent him a video of it happening. His answer was he couldn't explain what was happening, never having seen it before and could offer no solution!

I couldn't be bothered to return this one so I've switched it to automatic operation, which it does perfectly and see how it gets on in the summer when the sun is shining strongly. In the worst case I could just disconnect the BatteryMaster or fit an isolating switch.

As to whether fitting this device is going to help only time will tell. We may have to revisit the Mosel in the autumn. :)
 

Robert Clark

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Jul 12, 2014
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Hi John

I’d be interested to know if the unit delivers the quoted output, and for how long.

Thanks
 

Youlostoo

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Nov 10, 2014
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DBK in the last photo the positive lead looks like it is rubbing on the neg of the other battery. Worth checking out.
 
OP
DBK

DBK

Jan 9, 2013
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Hi John

I’d be interested to know if the unit delivers the quoted output, and for how long.

Thanks
You can get a remote control unit for them which will show the charging current I believe - but they cost up to £100 so I'm sucking my teeth on that. :)

Weirdly the battery monitor is showing a charging current.

DSC_0097.JPG

The voltage will be correct but the current is measured from the shunt in the negative cable - which I've by-passed! I can't get my head around this. The monitor doesn't show anything when the inverter is running as it has its own cables which are the ones I'm using.

It's all very odd but I may look at getting one of the cheap monitors off eBay and fit that instead, installing the shunt in the inverter cable.
 

Robert Clark

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Jul 12, 2014
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You can get a remote control unit for them which will show the charging current I believe - but they cost up to £100 so I'm sucking my teeth on that. :)

Weirdly the battery monitor is showing a charging current.

View attachment 280599

The voltage will be correct but the current is measured from the shunt in the negative cable - which I've by-passed! I can't get my head around this. The monitor doesn't show anything when the inverter is running as it has its own cables which are the ones I'm using.

It's all very odd but I may look at getting one of the cheap monitors off eBay and fit that instead, installing the shunt in the inverter cable.
Surely if you’ve bypassed the shunt it won’t correctly report the battery state?
 

eddievanbitz

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Oct 4, 2007
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why did you by pass the shunt? also did you remember to isolate the existing split charge relay? If not your measuring the charge from the "old" system if you have by passed the B2B connection
 
OP
DBK

DBK

Jan 9, 2013
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Surely if you’ve bypassed the shunt it won’t correctly report the battery state?
The voltage will be correct but I think some of the return current may be passing back through the vehicle body and this is what it is showing.

But I've just bitten the bullet and ordered the remote from the people above. It should arrive next Monday.
 

Robert Clark

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Jul 12, 2014
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The voltage will be correct but I think some of the return current may be passing back through the vehicle body and this is what it is showing.

But I've just bitten the bullet and ordered the remote from the people above. It should arrive next Monday.
I’m not sure what additional info the remote control will do that the battery monitor won’t
The only way the battery monitor will work is if ALL inputs and outputs pass through it
 
OP
DBK

DBK

Jan 9, 2013
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why did you by pass the shunt? also did you remember to isolate the existing split charge relay? If not your measuring the charge from the "old" system if you have by passed the B2B connection
Good question! When I first connected it I used the shunt terminal for the common negative but I subsequently decided to use the inverter cable. Why did I do this? Seemed like a good idea at the time but now you've raised it I'm having second thoughts! I'll try the shunt terminal tomorrow and see what happens. I can cancel my order for the remote if it works - which it should I think. Thank you. :)

The split charge relay is definitely disconnected as I ran the engine after removing the fuse and there was no charge.
 
OP
DBK

DBK

Jan 9, 2013
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What fuse holders did you use? and what rating fuses? I can't see them in your pictures
There is a 100A mega fuse on the vehicle battery which you can't see as it is under the plastic cover. This is bigger than I wanted but the remaining slot was mega fuse sized and they only seem to come in sizes from 100A upwards. I think I can fit smaller midi-fuse and will look at this again. The unit itself has fuses built in though they are soldered in place so it is protected. For the leisure batteries I'm using the inverter fuse but I will fit an inline one of a more suitable rating if I use the shunt terminal.
 
Aug 7, 2017
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Great thread John and very informative (y) I've certainly learnt a few things from the write-up.
 
Oct 20, 2015
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The left hand end of the plastic channel between the van floor and carpet, visible in your photo of the cab step with the step panel removed, is a conduit that runs all the way across the cab floor beneath the seats to the nearside cab step, where you can route cables through the longitudinal section of the channel directly to the vehicle battery box. It might be a little tight for 25mm2 cable, but as my leisure batteries are located beneath the driver's seat and my B2B alongside it, I was able to use less bulky cable and that was the route I chose.
 
May 7, 2016
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As to whether fitting this device is going to help only time will tell.
My B2B makes a big difference.

I have had no problems with the D+ trigger but it did go a bit loopy when I accidently bypassed the separation relay. However being a Votronic unit it probably has different issues.
 
Oct 12, 2009
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DBK

You have done it but it sounded complicated.

We fitted a Sterling B2B (maybe not same model) about 4-5 years ago.

We kept it separate from all other electrics, partly because Sterling advised they had not been able to integrate their electrical geometry with the Elektroblok.

So the B2B stands alone and is just connected to the engine and vehicle batteries.

It causes the EBL ammeter to show negative after a minute - this could be solved with a shunt, but we just rely on the voltmeter showing a high reading to know that there is a good charge going in.

We are never on EHU(except at home) and the B2B has kept us charged up for these years.

Geoff
 
May 7, 2016
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We kept it separate from all other electrics, partly because Sterling advised they had not been able to integrate their electrical geometry with the Elektroblok.
That is why I chose the Votronic one instead of Sterling. It has wiring diagrams specifically for Schaudt EBL and input and output setting limits to make it compatible with the existing wiring and the EBL separation relay.
 
Apr 2, 2017
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Hi can I ask a question, I’m just about to fit a sterling B2b to my van and looking at the sterling diagram it looks like you need 2 negative cables coming from the chassis battery one going to the unit and one going directly to the leisure battery but looking at your 1st photo you have just one how comes ?
 
OP
DBK

DBK

Jan 9, 2013
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DBK

You have done it but it sounded complicated.

We fitted a Sterling B2B (maybe not same model) about 4-5 years ago.

We kept it separate from all other electrics, partly because Sterling advised they had not been able to integrate their electrical geometry with the Elektroblok.

So the B2B stands alone and is just connected to the engine and vehicle batteries.

It causes the EBL ammeter to show negative after a minute - this could be solved with a shunt, but we just rely on the voltmeter showing a high reading to know that there is a good charge going in.

We are never on EHU(except at home) and the B2B has kept us charged up for these years.

Geoff
That's exactly how mine is connected. It was only when I tried connecting it to the ignition feed it went loopy.

I'm going ahead with the remote control unit which should arrive on Monday. This gives more information and also allows me to turn it off.

More to follow when it's fitted. :)
 
OP
DBK

DBK

Jan 9, 2013
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Hi can I ask a question, I’m just about to fit a sterling B2b to my van and looking at the sterling diagram it looks like you need 2 negative cables coming from the chassis battery one going to the unit and one going directly to the leisure battery but looking at your 1st photo you have just one how comes ?
I've just daisy chained them. The one from the vehicle battery goes to the leisure batteries and from there on to the B2B. There is only one common negative on the B2B.

I think how you do it just depends on what is easiest given the layout of the individual batteries and where the B2B is going to sit.
 
Oct 12, 2009
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DBK

I do not know your style of moving in the MH(days static etc.) nor your electric consumption, but if it is about like ours I bet after a few weeks you stop monitoring as you will know it is doing its job.

Enjoy it.

Geoff
 
Apr 2, 2017
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I’m a real novice at electrics when you say piggy back do you mean take the earth from chassis to leisure battery then a wire back to the sterling unit from leisure battery
 
OP
DBK

DBK

Jan 9, 2013
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I’m a real novice at electrics when you say piggy back do you mean take the earth from chassis to leisure battery then a wire back to the sterling unit from leisure battery
Yes, that's what I did. A cable goes from the single negative terminal to one of the negative terminals on the two leisure batteries. This terminal is already connected by another existing cable to the other negative terminal of the second battery. From this terminal a cable goes to the B2B.

There are schemes to balance the load on each leisure battery and as far as possible I've followed them. The idea is you connect the positive of one battery to the load (or charge) and take the negative from the other battery. It's easy to do this with two batteries and it can be done for more but it gets complex, especially with four or more but if you use thick enough cables the downsides of doing it more simply shouldn't be too bad. :)
 
Sep 16, 2013
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When connecting 3 batteries do you have to have a fuse between each battery ? Cheers
I would say it depends on the distance between the batteries.

If they are next to each other then it isn't imperative. If they are further apart, and there's a chance the cable could be damaged and come into contact with the chassis, then yes (two fuses, as close as possible to each end terminal as installation allows).

Just my opinion of course :)
 

Lenny HB

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I would say it depends on the distance between the batteries.

If they are next to each other then it isn't imperative. If they are further apart, and there's a chance the cable could be damaged and come into contact with the chassis, then yes (two fuses, as close as possible to each end terminal as installation allows).

Just my opinion of course :)
Agree.
 
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