B2B

Phil

Forum Admin
#21
Hi jacking, sorry. Would every B2B unit need to be in a ventilated location ? I was hoping to shove it in the locker with the batteries with all the other electrickery gubbin's. Out of sight,out of mind.
The ring and the Sterling do need ventilation but the CTEK does not.

Both the Ring and CTEK have an MPPT solar charger built-in, the Ring is 30A and can accept voltage inputs up to 50 volts, so it can be used with a wider range of panels. The CTEK is simple as it is fully automatic. The Ring requires setting up but this makes it better non-standard batteries where charging characteristics need to be altered.
 


nabsim

Full Member
#22
Hi jacking, sorry. Would every B2B unit need to be in a ventilated location ? I was hoping to shove it in the locker with the batteries with all the other electrickery gubbin's. Out of sight,out of mind.
Del some of these units are a fair size and I doubt you will fit one on with everything you have in there now. What space is left in that locker?

I haven’t found one yet that takes more than 300W solar although the Sterling stuff is clear as mud.
 

Phil

Forum Admin
#23
Del some of these units are a fair size and I doubt you will fit one on with everything you have in there now. What space is left in that locker?

I haven’t found one yet that takes more than 300W solar although the Sterling stuff is clear as mud.
The Ring B2B will take 360 watts of solar.
 


nabsim

Full Member
#24
If I add another panel Phil it will be minimum 150W so total would be minimum 450W
 

Trotter

Full Member
#25
Del some of these units are a fair size and I doubt you will fit one on with everything you have in there now. What space is left in that locker
Still got about 20x 30x 30cm It could go where I was going to put the trickle charger, if it doesn’t need ventilation. The Ctek would fit there nicely. Let’s hope I can sort the vehicle charge problem. Changed sizes by 100. cm not mm
 
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#26


nabsim

Full Member
#27
Prices jump when you go above the 30 amp huh :(
 

nabsim

Full Member
#28
Looked at those Ctek ones and couldn’t work out if you just need the D250SA or if you need the 56-676 Smartpass 120 as well?
 

Okta

Full Member
#29
My choice of B2B was restricted by needing one with a range of charging profiles, including LiFePO4 ones. I chose a Votronic 1212-45 because not only did it have very good range of profiles but could also be set up to work with a Schaudt EBL and existing wiring. If you have an EBL I would recommend you consider Votronic.

So far as installation position is concerned the instructions state:
Install the charger near the board supply battery to be charged (for short charging cables) at a clean, level and hard mounting surface, which is protected from moisture, humidity and aggressive battery gases. The unit can be installed in any position. Despite the charger's high efficiency, heat is produced, which is brought out of the casing by means of the built-in fan. The vent holes at the unit rear should never be covered (minimum distance 10 cm) to ensure full charging capacity. Ensure sufficient ventilation in the environment of the unit so that the heat can be dissipated. Otherwise, in the event of overheating, the charger will reduce its charging capacity.
 


nabsim

Full Member
#30
I use Votronic for my solar controller Okta and am very impressed with it and like the brand. From what I could see yesterday though the Votronic units didn’t work as a solar controller as well as a B2B but I didn’t check every model number so will have a look at the one you mention above :)
 

Okta

Full Member
#31
No nabsim I haven’t seen a Votronic with built in solar controller. If you already have a solar controller do you need a combined unit? I quite like keeping them separate, if one stops working you haven’t put all your eggs in one basket.
 


nabsim

Full Member
#32
No nabsim I haven’t seen a Votronic with built in solar controller. If you already have a solar controller do you need a combined unit? I quite like keeping them separate, if one stops working you haven’t put all your eggs in one basket.
The reason for going for a combined unit is the B2B would always know if the voltage on the starter battery was coming from the solar so not start drawing from the battery just because it sees >13 volts. Plus it makes cabling simpler, actually not sure it does make it. Simpler as you still need the same input, one less output set though?
 

Okta

Full Member
#33
The reason for going for a combined unit is the B2B would always know if the voltage on the starter battery was coming from the solar so not start drawing from the battery just because it sees >13 volts. Plus it makes cabling simpler, actually not sure it does make it. Simpler as you still need the same input, one less output set though?
Presumably the same would happen on ehu. Best to use D+ and disable voltage sensing. The Votronic wiring diagram suggests a separating relay is needed but I have wired through my ebl which performs this function, again D+ controlled.
 

Trotter

Full Member
#34
Still got about 20x 30x 30cm It could go where I was going to put the trickle charger, if it doesn’t need ventilation. The Ctek would fit there nicely. Let’s hope I can sort the vehicle charge problem. Changed sizes by 100. cm not mm
Just checked the space in the van's battery box. The space available an is L shape so depending on were it would be fitted would be either 25x12x20 or 25x25x10
 

nabsim

Full Member
#35
The reason for going for a combined unit is the B2B would always know if the voltage on the starter battery was coming from the solar so not start drawing from the battery just because it sees >13 volts. Plus it makes cabling simpler
Just checked the space in the van's battery box. The space available an is L shape so depending on were it would be fitted would be either 25x12x20 or 25x25x10
del do you just need the one ctek part or two?
 

Trotter

Full Member
#36
del do you just need the one ctek part or two?
If we go that way, then yes just the one piece. The D250SA. If I've got it right, and I'll be surprised if I have, the other bit of kit, the smartpass is for additional solar. My solar is already taken care of by my MPPT controller ( Wrong... Just read the blurb on the Smartpass. Didn't understand it. I'm confused now, think I'll lie down in a darkened room) The Ctek is under 20x11x7cm so will fit in my existing space, on the condition, if I understand Phil's note, it does not require ventilation.
As you said earlier, we'll only do this if the original split charge has gone u/s.

Just read a bit on the Ctek blurb, it says it should be, "fitted as close to the secondary battery and as cool as possible". Me? I'm going into worry mode again.

Nurse! The screens.
 
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Trotter

Full Member
#37
Saw on a youtube video, that an alternator will only charge a leisure battery to 85%. What is 85% of 13.6 volts ? 11.56 ? I've not allowed my batteries to go that low.
Would this mean, there is nothing wrong with my vehicle charging, my batteries are already above the level the alternator would take over? All this is making my brain hurt.
 
#38
Saw on a youtube video, that an alternator will only charge a leisure battery to 85%. What is 85% of 13.6 volts ? 11.56 ? I've not allowed my batteries to go that low.
Would this mean, there is nothing wrong with my vehicle charging, my batteries are already above the level the alternator would take over? All this is making my brain hurt.
that is not how battery capacity is measured. and also that video has by the sound of it oversimplied things when you are talking leisure batteries and split-charge systems.
Ok. To fully charge a battery, the voltage of the charger need to be typically around 14.4V. Many Alternators - and many standard Motorhome Mains Chargers for that matter - will not sustain or even reach 14.4V. (A Sargent integrated charger will typically put out a steady 13.8V). That is why an Alternator is unlikely to charge a Battery fully - and why it is good practice to put your Starter Battery on a charger on a fairly regular basis to give it a full charge and lengthen its life.

Here is a graph showing the voltage and current levels to charge. The End of ABS (Absorbtion) is when the battery is deemed Full

Victron MPPT Charging Scheme
by David, on Flickr (top line V; bottom line A)
for just about any battery people are likely to have (but some ARE different, so you must check for yourself), that voltage during ABS is 14.4V

So Alternator charging a Leisure Battery.... Depends on the charger.
If using a basic relay system that just connects the Starter and Leisure Batteries together when the voltage hits a certain value or the D+ signal is live, then nope, that won't fully charge the battery. Just the same situation as it charging a Starter battery.
If using a decent B2B charger then YES, it will fully charge a Leisure Battery if run long enough (if battery is at 80% say and a 100Ah, and you have a 5 hour drive and a decent B2B charger, then you will be fully charged well before the journey is up). This is becuase the B2B will boost the voltage output to the required level - doesn't matter if the Alternator is putting out 13V - the B2V will boost the chargers output (NOT the alternator output) to 14.4V or whatever is required for the charging algorithm.

This is why a B2B at say 30A will provide a better charging solution than a 100A Relay
 
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nabsim

Full Member
#39
That’s interesting Dave, that’s the first time I have seen time periods mentioned. In your example of a 5 hour drive to fully charge a 100ah battery is that actually correct or just numbers used to explain? Reason I ask is I have been looking at the Ctek DS250 and it says it’s 20ah output, would that not recharge your example 80% of 100ah battery in just one hour running? I see this unit is often linked to a smartpass unit that can output 120ah and trying to get my head round the various workings.

If it takes 5 hours to recharge a battery then this could explain why Dells 270ah (2x135ah) still had a ways to go to full charge after his drive back from Glasson maybe as well.
 
#40
I just threw in 5 hours as a likely driving length, not a calculation.
People often just do the maths and come up with an answer that is not right? E.G. 100Ah battery is 80% full. So needs 20Ah to fill it? Well, close enough for purposes of this discussion.
So a 20A charger will fully charge it in 1 hour, right? No. It won't. As a battery needs the last 20% or so to fill, the current it will take deminishes all the time (have a look at the chart I posted above).
Near 100% full, a 100Ah battery will only take around 4% or so in current terms - the tail current. So that 20A charger, or a 100A charger will both only be putting out 4A at that stage - hence why it takes a lot longer then people think to fully charge a battery - and why a 40A charger is not twice as fast as a 20A charger for example! (Contrary to the perceived wisdom of so many people).
 

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