B2B

[saxonborg]

Just to answer the Solar Question:
The Majority of the Victron MOT Solar Controllers have one pair of inputs - for the Panels to feed into; and one pair of outputs - to connect to the Leisure Battery.

As far as 'engine' charging goes, the problem with just relying on the alternator to do the charging is that it will rarely be at a voltage level that will allow for full battery charging - either Starter OR Leisure. It is good practice (although rarely done) to periodically connect the starter battery to a good mains charger to give it a proper full charge. Does it matter? usually won't be noticable, but doing that will maintain the battery better.
A B2B Charger takes care of 'proper' Lesiure Battery charging via alternator as they will boost the voltage upto 14.4V or whatever. This is the best option for Split-Charging where funds allow (reckon on around £200 more for a B2B over a basic relay).
If you have a good Solar Controller with a multi-stage charging profile (which the Victron does, of course), then that controller can carry on where the alternator left off the charging and finish the job off, as it were, so your Leisure Batteries will be treated well probably, even if you have a basic Relay rather than a B2B.

If you do have a relay system that is voltage switched rather than engine/ignition switched and is bi-directional sensing, then you will find that the Solar Controller will also start charging the Starter Battery once the Leisure Batteries are at a reasonable charge level - when this happens, your intelligent Victron Solar Controller will give your Starter battery a decent full charge as well. This is a handy bonus of the basic VSR system.
I don't know much about the EBL99 so don't know what that can or can't do in this respect.

Something that could be worth considering as you said you are replacing the Starter Battery ... maybe replace with the same battery technology as the Leisure Batteries if appropriate so the charging profile of the Victron MPPT Controller matches both battery sets for optimum charging. When I replaced my Starter Battery last year I actually used exactly the same model as I had in my Leisure Battery Bank for this reason so when the VSR came on, all batteries got charge profile they needed.
If you don't have a setup where the Solar will charge the Starter Batterty, then a trickle charge device such as a Battery Master can be fitted.

Thank you for your explanation, still trying to get my head around the detail, for info my Victron controller is the smart solar 100/20 unit, there are three sets of connections, solar panel connections, battery connections and load connections, I still need to re-read your posts and it will eventually sink in.

 

[wildebus]

Thank you for your explanation, still trying to get my head around the detail, for info my Victron controller is the smart solar 100/20 unit, there are three sets of connections, solar panel connections, battery connections and load connections, I still need to re-read your posts and it will eventually sink in.

Dave, does the Victron have a load terminal that may be used to charge starter battery or is it not suitable/not present? I have seen people mention this when I was looking at how to do mine but don’t know if it worked for them.

Of course in winter I will rarely get any charge going to my starter battery even though it is set to do this as there is very little sun most days so not 1amp spare to send lol

In the current range of their MPPT controllers, only the smaller capacity models have a load output - upto the 100/20 in fact.
I have never used the load terminal myself for anything myself as haven't worked out what would really benefit.
On the Victrons it seems to be a way to protect the battery from excessive discharge.
You connect the battery to the Battery Terminals and all the loads to the Load terminals - and the load will turn off if the battery goes below a certain value. So essentially in "normal" cicumstances, day or night, on a Victron MPPT Solar Controller, the Load and the Battery are essentially the same - and connecting the Leisure Battery to Battery and the Starter Battery to Load would just mean you would have a constant connection between the two via the Solar Controller - not much difference to having a switch connecting the two except the Load current is limited to just 20A.

I'll post an idea about "Solar Charging your Starter Battery" in a new thread

 

[nabsim]

Where did you get your Votronic B to B for £135?

Hi Eric, had to go back and find where I got it, I stated wrong price, it cost me £143.90 and I purchased from photonic universe, I used the C&CC discount to get it at that price and it was the same at roadpro at the time.

 

[saxonborg]

Hi Eric, had to go back and find where I got it, I stated wrong price, it cost me £143.90 and I purchased from photonic universe, I used the C&CC discount to get it at that price and it was the same at roadpro at the time.

Thanks Neil, looks the biz, I have had a look at the installation diagrams and not sure what you add and what you take away. Did you wire it yourself?

 

[nabsim]

Thanks Neil, looks the biz, I have had a look at the installation diagrams and not sure what you add and what you take away. Did you wire it yourself?

Yes did it with son in law. The only new wire I had to add was from the B2B to the leisure battery negative. You just cut cables going in to the EBL and fit the B2B in before it. In practice we did add some lengths of cable to allow us to fit the B2B where we wanted it but we followed the second diagram. Like I said before I studdied the paperwork wellbefore starting and it made it a quick and easy job on instal day.

 

[saxonborg]

Yes did it with son in law. The only new wire I had to add was from the B2B to the leisure battery negative. You just cut cables going in to the EBL and fit the B2B in before it. In practice we did add some lengths of cable to allow us to fit the B2B where we wanted it but we followed the second diagram. Like I said before I studdied the paperwork wellbefore starting and it made it a quick and easy job on instal day.

Thanks Neil, it’s a bit like measuring twice then cutting once, only in this case reading and studying about twenty times and then making sure I can undo whatever I have done.

 

[nabsim]

Thanks Neil, it’s a bit like measuring twice then cutting once, only in this case reading and studying about twenty times and then making sure I can undo whatever I have done.

That’s exactly it Eric, because they do a diagram it would be easy to rejoin cables if the worst happened. Must say though both of us were surprised how quick and easy it went though on the day

 

[saxonborg]

That’s exactly it Eric, because they do a diagram it would be easy to rejoin cables if the worst happened. Must say though both of us were surprised how quick and easy it went though on the day

I have had another look at the wiring and realised I was looking at the 45A unit, when I looked at the 30A unit it does look a bit easier to install.

 

[nabsim]

I have had another look at the wiring and realised I was looking at the 45A unit, when I looked at the 30A unit it does look a bit easier to install.

I run Bosch and Vatra Powerframe batteries Eric so the 30 amp model was fine for my installation.

 

[saxonborg]

I run Bosch and Vatra Powerframe batteries Eric so the 30 amp model was fine for my installation.

Just bought two Yuasa L36 EFBs for the leisure side and I will buy a Bosch equivalent for the starter , both makes are dual use. Yuasa don’t seem to do a size equivalent to what is fitted in an EFB version. I think I am going run without a B2B to get an accurate picture of my consumption first.

 

[nabsim]

Just bought two Yuasa L36 EFBs for the leisure side and I will buy a Bosch equivalent for the starter , both makes are dual use. Yuasa don’t seem to do a size equivalent to what is fitted in an EFB version. I think I am going run without a B2B to get an accurate picture of my consumption first.

I would say to definitely see if you actually need it before doing it Eric. We used the trip to Scotland in October for our tests. The 4/5 days at the frog we had a fair amount of sun and we were fine for power but when we left there on the Monday the weather changed and we were only managing 2 days without going on hookup (3rd day). Second frog meet in November we needed to use hookup all meet. Current trip seems like we can now do what we wanted, we need to Find somewhere roughly 4 day intervals to empty cassette and fill with water so booking a day on a site works for us, (long shower and wash clothes as well).

We do use more 12v power than a lot though as we hardly use any gas. We may have been able to manage by running big cables and relays but for us the Votronic was a simple for with almost no cable change and we have a proper smart battery management rather than whatever alternator output happens to be. I don’t think there is a single solution that fits everyone unfortunately

 

[dougbobbill]

I've been reading this long thread with great interest and have a question: I don't have solar, and am considering a Sterling 30ah B2B to charge the leisure and engine batteries. My question is if I add solar at some stage in the future will I still be able to keep my expensive B2B or will it need to be replaced with something more suited to the extra charging source?

 

[Trotter]

I've been reading this long thread with great interest and have a question: I don't have solar, and am considering a Sterling 30ah B2B to charge the leisure and engine batteries. My question is if I add solar at some stage in the future will I still be able to keep my expensive B2B or will it need to be replaced with something more suited to the extra charging source?

Not sure about the Stirling, but shouldn’t have thought there’d be a problem. With the ctek,it’s a b2b charger with a mppt controller built in. One problem solved. As you should know by now, I’m no expert, take your advice from others ?

 

[edina]

I've been reading this long thread with great interest and have a question: I don't have solar, and am considering a Sterling 30ah B2B to charge the leisure and engine batteries. My question is if I add solar at some stage in the future will I still be able to keep my expensive B2B or will it need to be replaced with something more suited to the extra charging source?

I had a sterling b2b and separate mppt controller but, after probs with the sterling, I now have the Ring RSCDC30 combined b2b and mppt.

 

[Okta]

I've been reading this long thread with great interest and have a question: I don't have solar, and am considering a Sterling 30ah B2B to charge the leisure and engine batteries. My question is if I add solar at some stage in the future will I still be able to keep my expensive B2B or will it need to be replaced with something more suited to the extra charging source?

I have no problem with a separate BtoB and MPPT. As long as your BtoB is properly wired in with a separator relay (EBL or other) I wouldn’t expect there to be any insurmountable problems.

 

[nabsim]

As others have said, I am running seperateB2B and solar controller. I have a feed from D+ to tell B2B when ignition is on before it will start so all good

 

[edina]

My doubts about running separate charge sources, and I'm probably completely wrong, is that they would compete with each other. i.e. when the solar took the batt voltage up, the b2b would sense this and stop sending a charge and vice versa. Praps one of our learned members could tell me if this is correct?

 

[Okta]

My BtoB switches off when the engine stops, it only runs if the D+ Is active. The separator relay then separates it from the battery. An MPPT has to cope with other power sources such as ehu charging so I don’t see why it should have a problem.

 

[nabsim]

My doubts about running separate charge sources, and I'm probably completely wrong, is that they would compete with each other. i.e. when the solar took the batt voltage up, the b2b would sense this and stop sending a charge and vice versa. Praps one of our learned members could tell me if this is correct?

I have heard both sides of this Chris but for me the worry was the starter battery draining if the B2B saw charge going to the starter battery. The B2B I got let me use a sense from ignition D+ so does nothing unless engine is running.

Either solar on its own or the B2B will give me what we need.

 

[wildebus]

My doubts about running separate charge sources, and I'm probably completely wrong, is that they would compete with each other. i.e. when the solar took the batt voltage up, the b2b would sense this and stop sending a charge and vice versa. Praps one of our learned members could tell me if this is correct?

There are a lot of contrary opinions on this subject and there is no definitive answer I have ever seen that trumps others. This is my take on it (the explanation is a bit waffley but can't really describe in much less words)...

The TL: DR version: No real problem having multiple and active Battery Chargers running in a motorhome setup

MY reasoning:
Example: A battery is sitting at say 12.3V and is around 50% full. It is a standard battery that wants upto 14.4V to fully charge and then floats at 13.8V

If you put a charging source on the battery, it will not instantly rise to 14.4V, it will gradually increase, putting as much current as the charger can provide into the battery (until the battery state moves from a Bulk state into an Absorption state)
If you added a second charging source, this again will so the same thing, so what happens is charging current gets increased, so charges faster of course. The voltage itself at that stage is essentially determined by the Battery, NOT the Charger (this bulk charging stage is maybe better described by its alternate name - CC (Constant Current) Mode
I have validated this myself checking the charging current and its changes when I have added a 20A mains Charger to a 35A mains Charger and the current went up, but the voltage itself just continued to rise (albeit at a faster rate), and didn't suddenly jump.

Once the Battery charge is at a higher level and the charger would go into Absorption mode (aka CV - Constant Voltage - Mode) and would be at a steady 14.4V, the current would start to drop. If a second charger was put on, there can be some confusion between the two chargers but essentially they would both work and when the current demands drop they usually both end up working at a lower capacity than they are able but they don't 'fight' with each other.
What I have found in practice with my own setup is that although the MPPT Solar Controller and the Mains Charger are seperate but when both available, both operate at the same time if the battery needs charging, however if just a small amount of 'maintenance' charge is required on a full battery bank, it is the Solar Controller that tends to provide it rather than the Mains Charger. I plan to look into this futher for my own curiosity but I suspect it is by design that the mains charger is slower to respond to the demand (talking just a second or so) to allow a Solar Controller to supply if fitted (both are from Victron so they could have chosen to make this happen between the two)

The above is applicable (IMO) for Smart Chargers i.e. those that adapt their charging profiles for different stages of battery charging.

Where a problem CAN occur is when a Power Supply is used and that can stop a Smart Charger working correctly. An typical Alternator is not a Battery Charger, it is a Power Supply. It just wants to put out 13.4V or 13.8V or 14V or whatever it may be. If the battery is full and should go into float mode (13.8V) or maybe a storage mode (13.4V usually) and the Alternator is putting out a constant voltage higher than the float mode or storage mode, then your connected smart Battery Charger will be defunct and pointless at that time and the battery will not be treated in the best way.
And just to make it clear, a VSR or any other kind of relay is NOT a Battery Charger or 'Split Charger', it is purely an automated way to connect the Leisure Battery to the Alternator.
The same is true for many Motorhome Mains Battery "Chargers" where they are not chargers at all, but again Constant Voltage Power Supplies and do not adapt for the battery needs.
A power supply type of battery charger should not be connected for a long duration (talking long here, not a few hours or just a couple of days) otherwise they can adversely effect the battery. Alternator charging of a battery is fine if there is also a way to 'finish' off the charging job with a proper battery Charger, either mains or solar, as the alternator can put some good bulk current into the battery but is no good once the battery is at around 80% or so (for example, if my battery is lowish, I may have the VSR on to use the Alternator to put in a bulk charge higher than the B2B can put out).
It also cannot really effect the battery in the same way as the mains power supply charger can as it will never be running long enough to do so.

The last bit was a bit off subject but thought it worth mentioning.

All the above is, as I said, MY take on this. Others may agree, others may disagree. No problems with that. Down to the individual to make their decision.