Strange starter battery voltage on EBL227 of over 20v

[fred_jb]

I thought that is what I said. I don’t think anyone is suggesting leaving the original split charge relay operating alongside the booster, we know it creates a loop.

Edit. I probably misread your post, sorry.

No problem, the reason I was wittering on about this was that some of the things Roger was saying implied a direct connection between starter battery and EBL in an installation which is using a booster.

 

[autorouter]

Sounds a bit suspicious as a booster normally sits in series with the starter battery feed to the EBL. With a booster the EBL should never see the original starter voltage, only the boosted version, otherwise there is a danger that you will connect the output of the booster to its input!

I think you need to look at the actual wiring diagram of the EBL 227, it is not the same as most other EBLs in this respect. There is a starter battery input, with a 50A fuse - so far so normal. There is a pair of 'Booster' (= B2B) connections (input and output) and a D+ connection on Block 1, a 3-way Minifit connector on the EBL front panel. The B2B is connected to this connector.

Obviously this could be ignored and the B2B wired directly to the batteries if that's what you decide to do.

There is a switch to select between using the split charge relay and the B2B, labelled 'Booster-betrieb: Ohne (= without) / mit (= with) Booster'. This can be used to enable or disable the split charge relay, and send the starter battery supply to the B2B.

Unfortunately there is only a German version of the EBL227

https://res.cloudinary.com/lci-cloudinary/image/upload/v1694803226/lippert-eu/support/power-on-board/pdf/anleitungen/911/9110268/8110268_2021-08-06_EBL227_BA_DE.pdf

Also the usual way of reading the starter battery voltage (via a separate cable to the starter battery) is not used in this EBL. So if you simply disconnect the main starter battery feed (with the 50A fuse) you lose the starter battery voltage reading facility. It will still read some random voltage - 20V sounds a bit high but possible I suppose.

 

[RogerIvy]

All the EBL's I've seen have a seperate feed for the fridge direct from the starter battery via a 20 amp fuse, the same wire that does the mains trickle charge.
But I don't know if they have changed that with smart alternators.

I’d say this is true of the more modern motorhomes, with quite a few of the older ones there was often a single feed from the starter battery into the EBL that was shared by the split charge and the fridge. When we used to install the old 30A DC-DC it was disappointing when half of the 30A was “wasted” running the fridge. Of course, there was always the possibility of feeding the fridge directly from the starter battery by making a few more changes. These days with the 50A XS it’s more palatable to lose 15 out of the 50 to the fridge.

 

[Peavy]

Unfortunately there is only a German version of the EBL227

Sometime ago I uploaded an English version in the resources section

 

[fred_jb]

I think you need to look at the actual wiring diagram of the EBL 227, it is not the same as most other EBLs in this respect. There is a starter battery input, with a 50A fuse - so far so normal. There is a pair of 'Booster' (= B2B) connections (input and output) and a D+ connection on Block 1, a 3-way Minifit connector on the EBL front panel. The B2B is connected to this connector.

Obviously this could be ignored and the B2B wired directly to the batteries if that's what you decide to do.

There is a switch to select between using the split charge relay and the B2B, labelled 'Booster-betrieb: Ohne (= without) / mit (= with) Booster'. This can be used to enable or disable the split charge relay, and send the starter battery supply to the B2B.

Unfortunately there is only a German version of the EBL227

https://res.cloudinary.com/lci-cloudinary/image/upload/v1694803226/lippert-eu/support/power-on-board/pdf/anleitungen/911/9110268/8110268_2021-08-06_EBL227_BA_DE.pdf

Also the usual way of reading the starter battery voltage (via a separate cable to the starter battery) is not used in this EBL. So if you simply disconnect the main starter battery feed (with the 50A fuse) you lose the starter battery voltage reading facility. It will still read some random voltage - 20V sounds a bit high but possible I suppose.

That is interesting information, so thanks for that. It certainly explains why you might have both a direct connection to the starter battery and one via a B2B going to an EBL 227 and possibly other EBL models too. Not something I would be keen on as I have no requirement to bypass the B2B, and possibly the additional complexity might make it more prone to faults.

The EBL 31 I have addresses the fridge power requirement by an internal relay which switches the fridge over to the starter battery via a 20A fuse when the engine is running, so the full output of my Renogy B2B (50A) goes directly to the leisure battery.

However, I'm not sure that maximising use of alternator power is a good strategy in any case, especially if you have a decent sized leisure battery and can use solar and/or EHU to recharge it, as any energy you get from the alternator is derived from burning diesel - probably with an energy conversion efficiency of no more than about 30% taking into account both engine and alternator losses. Use of a B2B is basically subverting the Euro5/6 alternator management which is designed to save fuel, so will impact fuel consumption - there is no such thing as a free lunch!

For this reason I have a switch to disable the D+ input to the B2B for occasions where I have no need to charge the battery using the diesel powered alternator. I may also disable the starter battery feed to the fridge, though my compressor fridge seems quite economical on power, so probably not worth bothering with that.

^{_{Subscribers  do not see these advertisements}}

 

[fred_jb]

Any progress on this interesting problem?

It is difficult to envisage how this could be due to the leisure battery and starter battery connecting additively. Reading the original post again it seems that a more likely scenario is that the output of the booster is connected to its input, adding the two voltages together, either because it is misconnected externally or because a fault in the EBL is connecting them together internally.

I kind of feel that this model of EBL is asking for trouble by allowing both the starter battery and the output of the booster to be connected simultaneously!

 

[Raul]

Any progress on this interesting problem?

It is difficult to envisage how this could be due to the leisure battery and starter battery connecting additively. Reading the original post again it seems that a more likely scenario is that the output of the booster is connected to its input, adding the two voltages together, either because it is misconnected externally or because a fault in the EBL is connecting them together internally.

I kind of feel that this model of EBL is asking for trouble by allowing both the starter battery and the output of the booster to be connected simultaneously!

Are you referring to ''booster'' as in B2B? if that's the case, it will only show when b2b is active. If I remember rightly, this was not mentioned on the opening post. I still believe the EBL, has a H bridge. If this bridge fails, it can reverse polarity, hence ending with two sources that meet in series; the two sources are starter and leisure, when no B2B active.
To confirm my theory, you need two man testing. One takes the 25v reading, while the second disconnects the negative of the starter battery, if voltage drops to the value of the leisure voltage, you got your answer. The EBL combining the two batteries ability is gone.

 

[fred_jb]

Are you referring to ''booster'' as in B2B? if that's the case, it will only show when b2b is active. If I remember rightly, this was not mentioned on the opening post. I still believe the EBL, has a H bridge. If this bridge fails, it can reverse polarity, hence ending with two sources that meet in series; the two sources are starter and leisure, when no B2B active.
To confirm my theory, you need two man testing. One takes the 25v reading, while the second disconnects the negative of the starter battery, if voltage drops to the value of the leisure voltage, you got your answer. The EBL combining the two batteries ability is gone.

Yes, DC-DC, B2B, and booster seem to be terms that are used interchangeably. Good point about whether this fault is there when the booster is not active. If it is then it would seem to rule out the booster, though I don't know whether a B2B typically has no output when the D+ signal is absent or whether it passes through the starter battery without boosting it. Probably not, though I have only ever observed charging current levels, not voltages with the B2B on and off so I don't know for sure.

What is an H bridge? My starting point is that if the negatives of the two batteries are bonded externally to the EBL, as seems to be recommended by Schaudt, it is hard to see how their voltages can add up.

In the case of a B2B I imagine the voltage converter involves a transformer in which case there will be isolation between input and output voltages which would allow them to add.

 

[Raul]

There is NO isolation transformers in DC, only AC. The DC buck or boost is done only by semiconductors, diodes transistors etc.
Even your alternator produces 3 phase AC then gets converter to DC via a bridge rectifier made out of diodes. Anything DC is handled by semiconductors, and any AC can be Up-Down via transformer.

 

[fred_jb]

There is NO isolation transformers in DC, only AC. The DC buck or boost is done only by semiconductors, diodes transistors etc.
Even your alternator produces 3 phase AC then gets converter to DC via a bridge rectifier made out of diodes. Anything DC is handled by semiconductors, and any AC can be Up-Down via transformer.

I know that there are no isolation transformers in purely DC circuits as primary and secondary windings in a transformer are only coupled by AC. I am also well aware of how alternators work.

However, switch mode power supplies chop DC into AC at which point it can be converted to a higher voltage via a transformer, then rectified and smoothed back to DC. This also provides isolation between input and output.

Typical B2Bs and MPPT controllers may not use transformers as such, I really don't know or care, but I believe they still work by using transistor or MOSFET switches to chop up the incoming DC into AC and may then achieve similar voltage transforming effects to an actual transformer by means of inductive and/or capacitive coupling of this AC into the output circuitry where it can be turned back to DC.

The point I am trying to make, which admittedly may be irrelevant to the matter at hand, is that for two voltage sources to be connected additively they must be floating with respect to each other. I expect the input and outputs of a B2B must be effectively isolated from each other by some form of AC coupling, regardless of the technology used to achieve that, otherwise they could not be at different DC levels.

^{_{Subscribers  do not see these advertisements}}

 

[autorouter]

What is an H bridge?

If you want to easily reverse the polarity to an appliance like a motor, then with mechanical switches or mechanical relays you can have an arrangement of changeover switches. However if you want to do this with a semiconductor device, the problem is it can either be on or off, and doesn't have a changeover mode like a switch does.

A solution to this problem is to arrange the semiconductor devices as in the diagram, with only diagonally opposite pairs on, and the other opposite pair is off. So to apply positive to the left side of the motor, and negative to the right, SW1 and SW4 are ON, and SW2 and SW3 are OFF.

To reverse the polarity, turn SW1 and SW4 OFF,and SW2 and SW3 ON. This arrangement is called an H Bridge.

 

[fred_jb]

If you want to easily reverse the polarity to an appliance like a motor, then with mechanical switches or mechanical relays you can have an arrangement of changeover switches. However if you want to do this with a semiconductor device, the problem is it can either be on or off, and doesn't have a changeover mode like a switch does.

A solution to this problem is to arrange the semiconductor devices as in the diagram, with only diagonally opposite pairs on, and the other opposite pair is off. So to apply positive to the left side of the motor, and negative to the right, SW1 and SW4 are ON, and SW2 and SW3 are OFF.

To reverse the polarity, turn SW1 and SW4 OFF,and SW2 and SW3 ON. This arrangement is called an H Bridge.
View attachment 980531

Thanks for that. However, I can't see how such an arrangement, if it is present in the EBL, could end up adding leisure battery voltage to starter battery voltage unless the negative poles of the two batteries were not connected externally to the EBL in the way they should be. If they aren't properly bonded together and to the vehicle chassis then all bets are off!

 

[Raul]

Thanks for that. However, I can't see how such an arrangement, if it is present in the EBL, could end up adding leisure battery voltage to starter battery voltage unless the negative poles of the two batteries were not connected externally to the EBL in the way they should be. If they aren't properly bonded together and to the vehicle chassis then all bets are off!

Fred, it's only a theory. EBL sits in the system where two sources meet. The only thing that may reverse polarity on a pcb only came across is a H bridge. Arduino guys use this for automation.
In reality it may be something more simple. I wish I had a answer.

 

[RogerIvy]

Any progress on this interesting problem?

The owner is considering binning the booster and installing a Victron Orion XS cabled directly to batteries (as we usually do).
And also considering wiring the MPPT the same way.

 

[fred_jb]

Sounds like reducing dependency on the Electroblock would be a good move. Mine only does 12V distribution now, and is no longer involved in charging, either from mains or DC-DC/MPPT, and this arrangement seems to be working fine for me.

^{_{Subscribers  do not see these advertisements}}

 

[StillGoing]

Sounds like reducing dependency on the Electroblock would be a good move. Mine only does 12V distribution now, and is no longer involved in charging, either from mains or DC-DC/MPPT, and this arrangement seems to be working fine for me.

Mine too!

 

[Clive Mott]

To get excessive volts then check mains charger output voltage and also the B2B output voltage. Something is not right. Did you get all these figures using a seperate multimeter? Another multimeter as a cross check.

 

[fred_jb]

Regarding replacing the Shaudt B2B, I know Victron kit is regarded as the gold standard, but I used a Renogy DCC50S 12V 50A combined DC-DC and MPPT solar controller to replace the previous separate Schaudt and Renogy items, which reduces and simplifies the wiring and takes less space. Can be connected to a low cost Bluetooth adapter to control via the app. So far I'm very happy with mine, and it only cost £209. It now allows you to define a low level of solar output whereby the solar will be ignored and the full 50A of DC-DC used. I think previous versions always gave 50% to each if there was any level of solar input which limited the DC-DC to below its maximum.

DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT(New Version)

Renogy DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT, featuring enhanced heat dissipation, 50V input capacity, versatile DIY connections, optimized charging logic, and smart monitoring via the DC Home app.

uk.renogy.com

 

[growly_bear]

I think previous versions always gave 50% to each if there was any level of solar input which limited the DC-DC to below its maximum.

This is correct and what happens in my set up too

 

[fred_jb]

This is correct and what happens in my set up too

I am OK with using this setting, though I think the highest amount of solar you can set it to ignore is 10A. However, if I want to I can easily force 100% DC-DC by using the breaker I put in line with my panels to disconnect them.

^{_{Subscribers  do not see these advertisements}}