The B2B question

[Raul]

DBK, he is saying the vsr on the same path, same wire that feeds the B2B in front of it. Like in cascade. Not a separate route to bypass the B2B.

 

[autorouter]

If the alternator fails the B2B won't flatten the cab battery because a B2B only switches on if it either senses a rise in the cab battery voltage (how mine works) or if it detects a voltage at the alternator - the D+ signal.

This B2B doesn't seem to have a voltage input threshold, it takes charge from the cab battery whenever the D+ signal is active. This is exactly how you would want a B2B to behave when wired to a smart alternator.

Adding a VSR in series with a Renogy B2B gives it a voltage threshold capability, which you may or may not want.

My Sterling B2B runs in 'Mode 3', which disables the voltage thresholds and triggers only on the D+. If the alternator fails, and also the D+ signal is still active (most unlikely) then the B2B will charge the hab batteries from the cab battery, until the cab battery is flat or the hab batteries are full.

Just to clarify the difference between the ignition and D+: when you turn the key, the dash lights come on, including the alternator warning light. That's the Ignition signal. When the engine starts, the alternator warning light goes off. That's the D+ signal. The Renogy manual doesn't distinguish between them, unfortunately.

 

[viridiandan]

Hi autorouter , thanks for that

In my setup (as I understand it) the B2B wouldn't be generating any error messages at low voltage as it won't be receiving anything until the voltage is 13.3v and passes through the VSR en route to the B2B.

And yes it's connected to D+ not directly to ignition. I don't have a smart alternator though.

Surely the VSR will turn on at any voltage above 13.3v so I'm not sure how the trickle charge is an issue (not that I have one installed).

And yes I totally understand your Sterling situation, it seems to be a great unit.

 

[viridiandan]

Raul Yes, that's correct (to my knowledge)

 

[autorouter]

Surely the VSR will turn on at any voltage above 13.3v so I'm not sure how the trickle charge is an issue (not that I have one installed).

A trickle-charger such as the BatteryMaster works in the opposite direction to the B2B, ie it trickle-charges the cab battery from the hab battery. It is used when staying parked for long periods, to stop the cab battery from slowly discharging over time, when the hab battery is kept charged by solar or mains hookup. The engine is not running, and you'd expect that the B2B was not active.

The trickle-charger raises the voltage of the cab battery as it charges it. At some point the voltage goes high enough for the VSR/B2B to switch on. The B2B will then start charging the hab battery from the cab battery, quickly undoing all the trickle-charging.

In your case, the B2B won't turn on because the D+ won't be active, so it won't be a problem for you. Other B2Bs are turned on just by a rise in voltage, even if the D+ is not active. Sterling B2Bs in Mode 1 and Mode 2 for example.

The problem is the same if you just have a VSR, with no B2B, so VSRs are not recommended in complex systems where the cab battery voltage can be raised by many different devices.

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[viridiandan]

autorouter - thanks for that, I agree

Also just on a general point, I did see a post somewhere where someone reminded that vehicles (alternator/regulator) don't attempt to optimise cab batteries to stay at (or near) 100% and experience greater longevity when not kept fully charged (partly because full power isn't necessary to start the vehicle). So when connected to a leisure battery via a VSR, the average maximum charge attained will be a similar 80%, especially when there is distance between the batteries. One of the advantages of the B2B is the rate optimisations of the different battery charging stages in order to take care of the batteries and achieve a higher state of charge (in some cases 100%).

 

[autorouter]

Batteries based on lead-acid chemistry (standard flooded, AGM, Gel etc) are all best taken to 100% charge regularly, at least every few days.

When these batteries discharge, lead sulphate forms in an amorphous state. When charged, the amorphous sulphate turns back into the original chamicals (lead, load oxide). The lead sulphate hardens into crystalline form if left for a few days. It's difficult if not impossible to turn crystalline lead sulphate back into the original chemicals, so the battery effecively loses some capacity.

The upshot of this is it's best to keep a lead-acid battery 100% charged as much as possible, with a small float charge to keep it 100%. If it is discharged, best to recharge it as soon as possible, and not leave it fully or partially discharged for long periods.

'Recombinant' batteries like AGM and Gel need extended periods of higher voltage for recombination to happen at the battery electrodes. Which is why there are different charging profiles for different lead-acid-type batteries. Even if an alternator had proper charging profiles, the fact that cab and hab batteries are often different types would be a problem. A B2B with the correct profile setting is the best way to keep hab batteries running.

Lithium batteries are entirely different. They don't have a sulphation problem, and don't deteriorate if left partly charged. They deteriorate if overcharged or allowed to discharge very flat. They are best used in the 10% to 90% charge range.

 

[Ava the Adria]

Hi everyone, we're looking for a relay as in the wiring diagram from the OP to follow their method of isolating the VSR built into the NE237. Asking on here as it seems the most relevant place to, but happy to start a new thread if not. Our Q; can anyone suggest where we can get an 80A 12v NC (normally closed) relay - all the higher power ones seem to be NO (normally open). Quite rightly, the fitter doesn't want to use anything less, but they can't find one anywhere?

Our Adria has an NE237 and did have AGMs, but we fitted a pair of 100Ah LiFePo4 fed from a Renogy 40A B2B. The problem has been not getting the full power from the Renogy, presumably due to it feeding back through the NE237's VSR. Not to mention the problem with the Renogy only being D+ activated and flattening the starter battery a couple of times until we realised that the alternator wasn't "waking up" to charge until the engine had revved up and kicked the alternator in to life. Hence the need to 1) bypass the VSR and 2) fit a voltage sensitive B2B (bought one of the new Sterling B2Bs). So we're aiming for the wiring diagram above. We've also fitted a Victron mains charger with lithium settings and have unplugged the NE237's mains kettle lead so we charge the lithiums fully.

 

[autorouter]

Our Q; can anyone suggest where we can get an 80A 12v NC (normally closed) relay - all the higher power ones seem to be NO (normally open).

Have you looked at a changeover relay - 5 terminals - which have both NC and NO contacts? Then just ignore the NO contact if you don't need to use it. 5-terminal changeover relays are more common than NC 4-terminal relays.

 

[Pausim]

I found I had to use a changeover relay to get one with NC connections. I think it may have been one of these.

12V Mini Extra Heavy Duty Change Over Relay - 80/100A | 072872 Durite - Leaders in Vehicle Safety & Auto Electrical Parts | Durite.co.uk

Product Description and Specification for 12V Mini Extra Heavy Duty Change Over Relay - 80/100A | 072872

www.durite.co.uk

A D+ activated B2B should not flatten the engine battery. Indeed I would have thought it far less likely to do that than a voltage activated one, which might be triggered by other charging sources that could raise the engine battery voltage when the engine is not running.

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[Ava the Adria]

Have you looked at a changeover relay - 5 terminals - which have both NC and NO contacts? Then just ignore the NO contact if you don't need to use it. 5-terminal changeover relays are more common than NC 4-terminal relays.

Thanks for the rapid reply - do they go up to the 80A we need?

 

[Ava the Adria]

I found I had to use a changeover relay to get one with NC connections. I think it may have been one of these.

12V Mini Extra Heavy Duty Change Over Relay - 80/100A | 072872 Durite - Leaders in Vehicle Safety & Auto Electrical Parts | Durite.co.uk

Product Description and Specification for 12V Mini Extra Heavy Duty Change Over Relay - 80/100A | 072872

www.durite.co.uk

A D+ activated B2B should not flatten the engine battery. Indeed I would have thought it far less likely to do that than a voltage activated one, which might be triggered by other charging sources that could raise the engine battery voltage when the engine is not running.

Hi, thanks for the reply.
I know, in theory it shouldn't, but ours did! Killed one engine battery.
With a voltmeter across the battery terminals, fired her up. Sat at (from memory) 12.5v, or so, as long as the engine was idling. It wasn't until the throttle was blipped that the voltage raised. So we found that early morning manoeuvres around the Aire or campsite filling and draining tanks has a bad effect on the starter battery as we don't like to rev a cold engine/make noise etc. Now we know it does it we've managed it with a switch in the D+ line to the Renogy to turn it off unless we're running, but the process needs to be automatic, hence going to voltage sensitive. If we're getting 13.5+ volts out of the alternator then it can suck its 40A out of the starter battery, but not if we're not!

 

[Ava the Adria]

I found I had to use a changeover relay to get one with NC connections. I think it may have been one of these.

12V Mini Extra Heavy Duty Change Over Relay - 80/100A | 072872 Durite - Leaders in Vehicle Safety & Auto Electrical Parts | Durite.co.uk

Product Description and Specification for 12V Mini Extra Heavy Duty Change Over Relay - 80/100A | 072872

www.durite.co.uk

A D+ activated B2B should not flatten the engine battery. Indeed I would have thought it far less likely to do that than a voltage activated one, which might be triggered by other charging sources that could raise the engine battery voltage when the engine is not running.

Thanks for the link, I'll share it with the fitter - although I do know he was looking for the ones with the M6 terminals as the cables are quite heavy duty.

 

[autorouter]

we're looking for a relay as in the wiring diagram from the OP to follow their method of isolating the VSR built into the NE237.

To avoid any possible confusion, the relay built into the NE237 is a standard relay, with a coil activated by the D+ signal from the alternator. It's not a Voltage Sensitive Relay (VSR) which turns on and off when the voltage on the main contacts is above or below the threshold. voltage.

If that relay is ON, it connects the B1 and B2 terminals directly with a metallic contact. If the B2B is also connected to the B1 and B2 terminals, it will effectively be short-circuited by the relay. That will nullify any possible benefit the B2B will have. That's why that relay needs to be disabled or worked around somehow.

 

[Pausim]

Hi, thanks for the reply.
I know, in theory it shouldn't, but ours did! Killed one engine battery.
With a voltmeter across the battery terminals, fired her up. Sat at (from memory) 12.5v, or so, as long as the engine was idling. It wasn't until the throttle was blipped that the voltage raised. So we found that early morning manoeuvres around the Aire or campsite filling and draining tanks has a bad effect on the starter battery as we don't like to rev a cold engine/make noise etc. Now we know it does it we've managed it with a switch in the D+ line to the Renogy to turn it off unless we're running, but the process needs to be automatic, hence going to voltage sensitive. If we're getting 13.5+ volts out of the alternator then it can suck its 40A out of the starter battery, but not if we're not!

If you are using voltage sensing you will need to ensure that any other chargers that keep the engine battery topped up do not raise the voltage sufficiently to turn the B2B on, which will do far more harm than a minute manoeuvring around a campsite. If it were me I would use the throttle. Revving a cold diesel engine is better for it than letting it tick over when cold which can cause damage. The opposite of a petrol engine which is designed to run at a cooler temperature than a diesel.

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[Ava the Adria]

To avoid any possible confusion, the relay built into the NE237 is a standard relay, with a coil activated by the D+ signal from the alternator. It's not a Voltage Sensitive Relay (VSR) which turns on and off when the voltage on the main contacts is above or below the threshold. voltage.

If that relay is ON, it connects the B1 and B2 terminals directly with a metallic contact. If the B2B is also connected to the B1 and B2 terminals, it will effectively be short-circuited by the relay. That will nullify any possible benefit the B2B will have. That's why that relay needs to be disabled or worked around somehow.

Yes, correct, I’m incorrectly calling it a VSR!
The NE237 circuit diagram shows it has a D+ activated 70A relay between B1 and B2. (See attach) My intention is that by installing a NC relay activated by the D+ feed between starter battery and B1will disconnect the NE237 from the starter battery when the engine is running. (See other attach). Thus only allowing the lithium habitation batteries B2 to charge from the B2B at a controlled 40A rate, also protecting the NE237 and the alternator from the lithiums power hunger - they would happily take 50A each and we don’t want to stress the system. Does that achieve what you are saying about disconnecting the NE237’s internal relay?

As an aside, the new 40A Sterling B2B allows a return of up to 20A back from the hab batts into the starter battery when the hab voltage is above 13.5 eg when the solar is plentiful or on mains hookup. (20A sounds a lot, but presumably the starter battery won’t take it if it doesn’t need or want it…)
The VictronConnect mains charger we now have floats at 13.5v, but this could be adjusted down or up, to suit what, if any is put back into the starter battery if it is too much.

 

[Pausim]

As an aside, the new 40A Sterling B2B allows a return of up to 20A back from the hab batts into the starter battery when the hab voltage is above 13.5

I think you might have other issues from this with the lithium batteries having higher resting voltages than lead acid ones. autorouter probably knows more than me about this so he may be able to reassure you that it will be ok.

 

[Ava the Adria]

If you are using voltage sensing you will need to ensure that any other chargers that keep the engine battery topped up do not raise the voltage sufficiently to turn the B2B on, which will do far more harm than a minute manoeuvring around a campsite. If it were me I would use the throttle. Revving a cold diesel engine is better for it than letting it tick over when cold which can cause damage. The opposite of a petrol engine.

Good point.

Below is from Sterling;
“Charging modes
In default mode, the BB needs to see 13.5V on the input terminal to begin charging the output battery. When the input then drops below 12.8V the BB will stop charging.
Charging modes
Input voltage
Charger on - 13.5 -> 16V Charger off - <12.8V
Input voltage + ign feed.
Charger on - 11.6V -> 16V Charger off - <11V
Input voltage + vib. sense.
Charger on - 11.6V -> 16V Charger off - <11V

Reverse Charging Feature -
There is nothing to setup with regards the reverse charging feature. Provided there is over 13.8V on the leisure battery and the starter battery is below 13V the BB shall allow approximately half current (~20A) to flow back to the starter battery up to about 13.6V (float voltage). It simply allows the starter battery to remain topped up when there is surplus energy in the domestic battery. This feature will NOT drain your domestic battery - it simply takes surplus. Once your alternator / engine turns on or you provide the BB with an ignition signal the BB revert to normal charging of the leisure battery. To disable this feature hold button down to 30 seconds and let go”

My concern with the D+ activation is that it kicks in as low as 11.6v and stays on down to 11.0v, with which previously we have had starter battery failure. We also get alert Texts from the tracker that the vehicle battery is low, so I have developed an aversion to this method of activation! However, looking at the Sterling blurb, the voltage activation seems to fit how this vehicle seems to operate. We’ll have to watch it.

I think you might have other issues from this with the lithium batteries having higher resting voltages than lead acid ones. autorouter probably knows more than me about this so he may be able to reassure you that it will be ok.

Yes, good point and I was worried about this too, but if you see the Sterling blurb re reverse charging above, they give the reverse charging voltage parameters, which should be ok. Again, will have to monitor.
Interesting that they set the float voltage for the starter at 13.6v, when the voltage activation is set to 13.5v. Wonder if it then drains the starter down to 12.8v, at which it switches off? Then reverse charges it back up, then repeats?

 

[Lenny HB]

My concern with the D+ activation is that it kicks in as low as 11.6v and stays on down to 11.0v, with which previously we have had starter battery failure.

But with D + activation it will only turn on with the alternator running, if was down at 11v the alternator would be dead.
Also with the basic voltage sensing setup it would never work with a smart alternator.

 

[Ava the Adria]

Thanks for the link, I'll share it with the fitter - although I do know he was looking for the ones with the M6 terminals as the cables are quite heavy duty.

Yes thank you, we’ve decided to go with one of these. (In the absence of anything else and they did have one in stock, but need to get a base in for it). So the jobs been postponed until that arrives.

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[Pausim]

I couldn’t find a suitable N/C relay with threaded terminals either so I resorted to a spade type one and a bulk head socket. It has worked without a problem interrupting the B1 connection on my DS300 for 3 years now.

 

[Ava the Adria]

But with D + activation it will only turn on with the alternator running, if was down at 11v the alternator would be dead.
Also with the basic voltage sensing setup it would never work with a smart alternator.

But D+ is always live with the ignition on, not alternator generating, on these Euro 6 machines. Isn’t it all governed by the ECU? Our alternator certainly seems to have a mind of its own as to when it generates

 

[Ava the Adria]

I couldn’t find a suitable N/C relay with threaded terminals either so I resorted to a spade type one and a bulk head socket. It has worked without a problem interrupting the B1 connection on my DS300 for 3 years now.

Brilliant, that’s reassuring, will mention to the fitter - as posted above, just waiting for the bulkhead mounting base thing to arrive.

 

[Pausim]

But D+ is always live with the ignition on, not alternator generating, on these Euro 6 machines. Isn’t it all governed by the ECU? Our alternator certainly seems to have a mind of its own as to when it generates

The D+ signal is activated by the the alternator and should only operate when the engine and alternator are both running. If your B2B is activating when the ignition is on but the engine is not running then it sounds like an ignition on connection not a D+ and for me this is a big no no.

Edit. I am beginning to think that you don’t need a new B2B, just the N/C relay and a proper D+ signal. D+ is generally seen as the best way to activate a B2B and is absolutely essential if you have a smart alternator.

 

[Lenny HB]

But D+ is always live with the ignition on, not alternator generating,

The D+ only gives a signal when the alternator is turning.
Sounds you have wired it to a live ignition feed rather than the D+.

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[Ava the Adria]

The D+ signal is activated by the the alternator and should only operate when the engine and alternator are both running. If your B2B is activating when the ignition is on but the engine is not running then it sounds like an ignition on connection not a D+ and for me this is a big no no.

Edit. I am beginning to think that you don’t need a new B2B, just the N/C relay and a proper D+ signal. D+ is generally seen as the best way to activate a B2B and is absolutely essential if you have a smart alternator.

The D+ only gives a signal when the alternator is turning.
Sounds you have wired it to a live ignition feed rather than the D+.

Hmm, we’ve used as the D+ the feed into the NE237 labelled D+ input (JP18, terminal 4), why wouldn’t it be so we now think the D+ is an ignition on live and not D+ ! Will have to check that out.
The next question has to be where to find the D+ on a 2017 2.3 150bhp Ducato?

 

[Raul]

Yes, D+ it’s only life when alternator runs. On some smart alternators you don’t have a D+ only ignition life. In my case vw crafter, there’s nonD+ as fa as I know. What I did is ignition signal with a switch. You can’t flatten the starter only on a short start up, that if I forget the switch. You can flatten the starter via vsr if you have solar toping the starter.
Each to their own, but a vsr on a smart alternator, it’s a really bad move.

 

[autorouter]

Now we know it does it we've managed it with a switch in the D+ line to the Renogy to turn it off unless we're running, but the process needs to be automatic, hence going to voltage sensitive. If we're getting 13.5+ volts out of the alternator then it can suck its 40A out of the starter battery, but not if we're not!

I don't know enough about smart alternators to tell you if there is some kind of fault and maybe it shouldn't be doing this. But if it is working as intended, then there is a solution.

You want the B2B to come on if the engine is running AND the voltage is above a threshold, say 13.5V. The B2B starts working as soon as it gets a signal on the D+ input. So, you could put a relay in the D+ signal path, with the coil triggered by a voltage-sensitive relay (VSR) with a suitable threshold voltage. The VSR should be connected to the starter battery, so it senses the alternator output voltage.

As the Alternator voltage rises, the VSR switches on the D+ signal, activating the B2B if the engine is running. when the alternator voltage falls, the VSR switches off the D+ signal, so the B2B is inactivated.

If for some reason (eg solar power) the starter battery voltage rises when the engine isn't running, the VSR will trigger, but there is no D+ signal so the B2B won't be activated.

The VSR and the other standard relay would be switching a coil and the D+ signal, so they can both be low power, they don't have to be high power types.

 

[Raul]

I don't know enough about smart alternators to tell you if there is some kind of fault and maybe it shouldn't be doing this. But if it is working as intended, then there is a solution.

You want the B2B to come on if the engine is running AND the voltage is above a threshold, say 13.5V. The B2B starts working as soon as it gets a signal on the D+ input. So, you could put a relay in the D+ signal path, with the coil triggered by a voltage-sensitive relay (VSR) with a suitable threshold voltage. The VSR should be connected to the starter battery, so it senses the alternator output voltage.

As the Alternator voltage rises, the VSR switches on the D+ signal, activating the B2B if the engine is running. when the alternator voltage falls, the VSR switches off the D+ signal, so the B2B is inactivated.

If for some reason (eg solar power) the starter battery voltage rises when the engine isn't running, the VSR will trigger, but there is no D+ signal so the B2B won't be activated.

The VSR and the other standard relay would be switching a coil and the D+ signal, so they can both be low power, they don't have to be high power types.

Maybe I’m missing something, but, vsr, with smart alternator will not charge properly. If your batt starter does not need a charge, the ecu will not turn on the alternator. So the vsr can sit there sleeping while you driving, until the starter batt needs a charge. Then you get a rise and vsr connects.

 

[autorouter]

Maybe I’m missing something, but, vsr, with smart alternator will not charge properly. If your batt starter does not need a charge, the ecu will not turn on the alternator. So the vsr can sit there sleeping while you driving, until the starter batt needs a charge. Then you get a rise and vsr connects.

I think you are right, and I think that smart alternator isn't working properly. If the B2B turns on, the alternator should provide power to it, even if it is at a low voltage. But the Ava the Adria says it doesn't, and the B2B takes power from the starter battery, causing it to discharge. The arrangement I described,with the VSR on the D+, would stop that happening, but as you say it doesn't solve the underlying problem.

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