The B2B question

What a predicament Manufacturers/converters of motorhomes ( and caravans ), designers of 12v electrical systems and manufactures/suppliers of leisure batteries ( not to mention cowboy MH dealers ) have got us into.
With complete disregard ranging from inadequate cabling to a mishmash of charging technologies and battery types and not having made any real effort to ensure a proper working concept to power our second homes.

My 'desire' to incorporate a B2B system into my new Adria Motorhome stemmed from having the factory fitted AGM battery fail during a tour round Greece last year at just 13months old. After investigation ( with help of Leoch technicians who were genuinely concerned this battery had failed so early in its life ) I/we found that the battery ( A Leoch 100ah AGM ) was actually a UPS model not designed for cyclic use at all, and Adria had bought and installed a batch of these ?
God knows how many Adria owners are driving round in their vans with a battery thats going to fail first time they try wild camping without a EHU hookup !. Mine and many others are/was doomed to fail after a few charge/discharge cycles from day one !.

( Any Adria owners with AGM battery fitted check model number - if its Model Leoch LPL-12-100 then its the wrong type of battery and will fail if used for charge/discharge use - this battery is used for backup in computer centres and in equipment that must not stop if the mains power supply fails and is capable of sitting there for many years on trickle charge waiting for time its really needed but if used in a cyclic system like a motorhome, caravan, boat, etc it quickly will fail if used in a repeated charge then discharge use. Mine was fitted in early 2018 and I am aware that Adria was fitting a different, NDS type battery by Dec 2019. Brownhills Motorhomes did check their stock motorhomes in October last year and said they all had this same battery fitted and also that a check of recently sold Adria's also had the same battery as mine, so how could it be a problem ??. They just advised me to contact Adria )

Looking further into why mine failed ( apart from charging and discharging it ) I found that the solar (shaudt ) controller fitted by the MH dealer ( Brown..., Newark ) was only suitable for normal lead acid batteries not AGM, the alternator could not fully charge the battery at 14.4 volts and the Nordelctronnica power supply was set for a Gel battery 14.2v regime ( as the other available regime was lead-acid ) so also could not charge the AGM to its required voltage of 14.7v minimum.
So, after changing the AGM ups battery for a larger 160ah proper 1500cycle advanced lead carbon AGM, the shaudt solar PWM regulator for a Votronic MPPT regulator with 'agm2' setting, switching the power supply from 'Gel' to lead setting (14.7v) despite adria's insistance that the gel setting was more appropreate for the fitted battery ? ,that just left the problem of how to incorporate a B2B into the existing Nordelectonica as the split charge system within was sadly lacking in capability to charge this new AGM.
The story continues with my earlier post putting out feelers for the suggested wiring diagram in which a NC relay across the B2B in and out +ve's and wired in series with the split charge relay ( which I cannot get access to remove ) sounds like a solution to the loss of cab battery charging and voltage measurement when I wire the B2B using just votronics installation instructions.

Sorry for the length of this tale but there may be something useful to someone in it
 
chrish said:
The Victron 30 amp DC- DC charger has a 'control' input that turns the device on and off, if this is connected to the D+ it will turn off immediately the engine stops.
On another note, The Victron Lithium batteries won't charge when they are below 5 degrees C does anybody have any ideas for keeping them above 5 degrees when in storage ?
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I would think it is unlikely to remain below 5C for long enough for the batteries to discharge enough to be an issue.
 
Robert Clark said:
I wouldn’t worry too much about keeping your lithium batteries above 5 deg when in storage as the UK seldom gets that cold for any length of time
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Thanks Robert,
cmcardle75 said:
I would think it is unlikely to remain below 5C for long enough for the batteries to discharge enough to be an issue.
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Thanks cmcardle75,
I was kind of hoping this would be the case , I've not seen any other messages about temperature related charging problems which suggests it's not a real problem, but then I think about the problems I've had getting water to stay in the system when the Alde dump valve is too cold .. It made me think about how long it would take for the core temp of the batteries to warm up if they did get too cold.
Probably going to need to put the heating on the day before we want to use the van.
 
This is what Relion say about cold charging their batteries.
“LiFePO4 batteries can safely charge between -20°C to 55°C (-4°F to 131°F). However, at temperatures below 0°C (32°F) the charge current must be reduced, until the temperature is >0ºC (32ºF), as follows:
1. 0°C to -10°C (32°F to 14°F) charge at 0.1C (10% of the battery capacity)
2. -10°C to -20°C (14°F to -4°F) charge at 0.05C (5% of the battery capacity) LiFePO4 batteries do not require temperature compensation for voltage when charging at hot or cold temperatures.”

I would turn my B2B off if it was cold enough to be a problem but it hasn’t happened yet. My battery compartment is heated so it is only likely to be a problem when I pick it up cold from storage. Discharge is safe down to -20°C so there is no problem using the battery to power the heating.

Relion do a low temperature series LT which have internal heating. If the temperature is too low for charging the incoming charge is diverted to the heating elements until the battery is warm enough. Of course they cost more.
 
Thanks Pausim.
It is the pick up from storage bit that's concerning me. I've already got the victron batteries and the bms stops the charge when the temp falls below 5C, Discharge is no problem as that can go to -20C and I don't think I'd want to travel if it was that cold 🥶
Exploring the possibility of a low wattage heat pad under the batteries.

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Don't most B2B's and solar regulators have a battery temperature sensor/probe so when set to a lithium charge profile they won't charge if its near zero temperature ?
 
Adriaadventure said:
Don't most B2B's and solar regulators have a battery temperature sensor/probe so when set to a lithium charge profile they won't charge if its near zero temperature ?
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A lot of the supplied temp sensing probes are provided to regulate the charging voltage on the lead acid charging profiles..im not sure that lithium require that regulation..my mppt solar charge controler specifically said dont fit the temp probe if you are charging lithium..
If they are used I think its to prevent charging at temperature extremes as you say..
Andy..
 
andy63 said:
A lot of the supplied temp sensing probes are provided to regulate the charging voltage on the lead acid charging profiles..im not sure that lithium require that regulation..my mppt solar charge controler specifically said dont fit the temp probe if you are charging lithium..
If they are used I think its to prevent charging at temperature extremes as you say..
Andy..
Click to expand...

That depends on the individual device. Some of them do use the temperature probe to prevent cold charging for lithium. Some also have built in thermostats that can work if the charger is in the same compartment as the battery.
 
andy63 said:
Is that not what I said :unsure:
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Yes, sorry, I misread what you said, fixating on the "dont fit the temp probe if you are charging lithium" and not reading the next line!
 
Hi guys.
Here is an update on my lithium project.

My lithium battery is a really cheap model, but with cylindrical cells, so it suppose to work down to -20 celcius. Dont know if that is true. I will find out this winter for sure.

I decided to start with the most simple solution first, and work my way up from there, so my setup is currently just installing the b2b charger paralell to the original system without a Relay to cut the loop. I have used an 16mm2 positiv cable all the way, but only 6mm2 negative to chassis. I only get a 4.5% drop on the voltage.

I have tested the system alot now, and it seems like when the b2b charging Bulk, the voltage on B1+ on the CBS unit is too low to engage the batterysplit.

When bulk charging i have steady 30A-32A charge with my 30A b2b. When im on absorbation charge, the voltage should be enough to engage the batterysplit, but i cant really see it on the Batterymonitor because its going up and down anyway, On absorbation mode i read between 12 and 20A on the monitor. Dont know if it is the b2b or CBS pulling.

Anyway, the bottomline is that it looks like this system works for me. The b2b goes trough its charging stages and i am happy so far. Maybe if i change the startbattery or alternator and get a higher voltage it could mess it up.

It was one issue i struggled with. I live in Norway so its really cold now, and the car struggled when the b2b startet up. The revs dropped and the alternator belt startet squeeking, but i disconnected the ignition wire, and had some tries adjusting the b2b to start on specific voltage and put in a delay. So now the car get some minutes to get warm before the b2b starts. Problem solved.

Thank you so much for all the good help.
 
I'd just like to add my 5p's worth to this, I just fitted yesterday a Schaudt WA121525 B2B along with a Leoch Lead carbon AGM battery LDC12-105-G27-DT I removed the previous voltage sensing relay and ran a D+ wire from a convenient fuse and the whole thing works well, however I did think about leaving the voltage sensing relay in place and running the output from that into the input of the B2B and then supplying the D+ from that input I'm pretty sure that would have worked fine and the only reason I didn't was because the relay was about 10 years old and I thought I might as well do away with it. The little Schaudt worked as it should, the leisure battery is connected to a 300 W inverter I used it to do a bit of soldering, afterwards the battery was at 12.9 volts on starting the engine I got 14.8 volts charging, after a few minutes that dropped to 13.8 volts and on turning off the battery was back to 13.1 volts where it had been before fitting. Time will tell how durable the B2B and the battery will be.
 
I carry a DC clamp-meter with me ( a habit from when I had a large inverter on the last MH ) and use it to check things are as they should be with the leisure battery charging. Its amazing to stick the meter on the +ve to the leisure battery after standing for a few days and then with the engine ticking over and see it charging at an initial 30amps. Was less than10 amps ( and decreasing rapidly ) before the B2B was fitted.

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Hey guys.
Now that i got this fancy apps and batterymonitors in my car, i noticed that the voltage on the startbattery is most of the time between 13.1 and 13.7 volts when running. Sometimes it comes up to 13.9 volts. And this is ofcourse too low to charge it proparly. I changed the alternator two years ago, so i hope its not the problem.

This is maybe far fetched, but if the startbattery is really bad, could that be the reason that the alternator wont deliver a higher voltage?
Or should it deliver above 13.8V regardless the state of the battery?
 
Bore1 said:
Hey guys.
Now that i got this fancy apps and batterymonitors in my car, i noticed that the voltage on the startbattery is most of the time between 13.1 and 13.7 volts when running. Sometimes it comes up to 13.9 volts. And this is ofcourse too low to charge it proparly. I changed the alternator two years ago, so i hope its not the problem.

This is maybe far fetched, but if the startbattery is really bad, could that be the reason that the alternator wont deliver a higher voltage?
Or should it deliver above 13.8V regardless the state of the battery?
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Sounds like it could be a smart alternator doing what a smart alternator is supposed to do.
 
Hi...how long have you actually watched the voltage for.. if its a smart alternator the voltage can fluctuate...
Another point..you said earlier that you did nothing to isolate the cbe loop when the battery to battery is running..what is the float voltage of the battery to battery charger...could it be feeding back and presenting the alternator with a healthy voltage and therefore its not seeing a need to charge the start battery..
Just a thought..
Andy..
 
Yes its a smart alternator. I assumed it could have something to do with the b2b so i turned it off. Still same. I am watching the voltage everytime i take a ride now. Im addicted to it :P I just thougt the voltage should be higher. I know the startbattery isnt good so im thinking to replace it, but if there is a problem with the charging, the new one will turn bad aswell
 
If the loop was engaged, the voltage would be over 14. Not 13.2 i think

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If there is a loop then neither the B2B or ECU/alternator can monitor the voltages correctly so anything could happen and neither will work properly.
 
Put a load on the alternator lights fans etc the alternator will adjust output to suit. Remember not all equipment shows accurate readings. Only kit that calibrated will show true accuracy.
 
It is no doubt that the alternator works. It delivers enough power with the 30A dc dc on. I just worried the voltage is too low to charge the startbattery properly. It could be a bad connection between the alternator and the battery, but it is a pain in the but to getbto the alternator connections to check it
 
A lithium battery once full and off charge will drop back pretty quikly to somewhere in the region of 13.4V. If you have a loop the voltage at the engine battery could well be being held in the 13+v range, remember there will be a voltage drop through the linking relay and return wiring. This level of voltage will be more than enough to tell a smart alternator that it can shut down. Together with the smart alternator there is probably regenerative recovery when you are braking or slowing down to make use of what would otherwise be wasted power. The ecu may be trying to keep the resting engine battery voltage down to somewhere around 12.4V, to leave room for regenerative power. A loop will very likely just be confusing it, the engine battery and leisure battery need to be separated when the B2B is running.
 
I may have missed this in the treads- but has anyone sucessfully fitted a B2B charger to a Sargent ec600 system ( mines on a 2017 Swift Bolero) - two questions - did you keep the exisiting Sargent charging system connected and did you use an isolated or non isloated charger - I'm thinking of fitting a Victron Orion 30a

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Lissimore27 said:
I may have missed this in the treads- but has anyone sucessfully fitted a B2B charger to a Sargent ec600 system ( mines on a 2017 Swift Bolero) - two questions - did you keep the exisiting Sargent charging system connected and did you use an isolated or non isloated charger - I'm thinking of fitting a Victron Orion 30a
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It might be useful to look at the manual for the Votronic 30A B2B model as it shows 3 different diagrams for incorporating their B2B into existing system types. I would also suggest looking at a diagram of the Sargent ec600 to determine if it has the existing split-charge relay built-in ( and what current it can carry ) as you may decide to make use of this by connecting the B2B in series with it.
You could always ring Sargent for advice about using a B2B with their ec600 as they have always been very helpful in the past.
 
Thanks- I did call Sargent but they said they could not confirm if I could use the ec600 alongside the B2B and that that my auto electrician would need to confirm!
 
Lissimore27 said:
Thanks- I did call Sargent but they said they could not confirm if I could use the ec600 alongside the B2B and that that my auto electrician would need to confirm!
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I installed mine behind the EBL unit according to Votronic‘s instructions. I can’t see how others would be different if they have a big enough relay and wiring as standard.
 
I am not sure that this would apply to Fiat/ Citroen but on Iveco euro6 to disable the smart facility on the alternator you can by disconnecting the small plug on the negative battery terminal the alternator then works as normal.
 
WARNING!

I think i have stumbled upon this "loop" you are talking about. I see the alternator charging indicator for the leasurebattery is going on and off and flickering like crazy. I asume It is because the original split relay switch on when its high enough voltage on startbattery, but when it does, the voltage drops so it turns off again. This happens so fast that i cant measure it. But now i got a whining sound from either the alternator or the turbo. I will find out later, but if it is the alternator its probably because of this.
If thats the case i will name it "The loop of death":roflmto:

As Andy63 and others recommended, a NC relay is probably the solution on this, but if anybody know how, i would love to just disable the original charging system.

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