What input Amperage to set Votronic 50A BtB?

[Adrianlle]

I’ve now assembled all the kit to convert my James Cook Sprinter to Lithium ( Sterling Lifepo4 on sale at moment ). I’d like some views please on what max input current draw to set the Votronic BtB at. The set up will be my 200ah alternator, 50A max output on the Votronic BtB, 2x 100ah Sterling Lifepo4. 25mm cable except for a short stretch of 10mm between existing disabled in/out terminals of the existing split charge relay( so as to get cable into Votronic ) , 100a fuse output from there and either a 60 or 80A fuse on input from 100ah Starter battery. No EBL or anything- power at moment goes straight from the split charge relay to the batteries.
The Votronic blurb doesn’t say what the max current draw in is but there is a switch to limit to 68A max. So I’m pondering whether to leave it at max or limit it to 68A? Presumably limiting it will have a corresponding effect on output? Also presumably either way it should be an 80A fuse rather than the 60A! Awkward to get at the Votronic so want to get settings right first time. Thanks

 

[Spriddler]

The Votronic blurb doesn’t say what the max current draw in is but there is a switch to limit to 68A max. So I’m pondering whether to leave it at max or limit it to 68A

Maybe I'm being a bit dim but you said that 68A is the max..................

 

[Adrianlle]

Sorry, wasn’t clear. The switch is either max current draw ( and don’t know what that is) or limited to no more than 68A current draw.

 

[Adrianlle]

Sorry Spriddler, I’m having one of those senior moments! Just reread the Votronic manual yet again and you are quite right. The options for the dip switches are input current draw of 68A max or 49A or 42A or 33A. So with a 200A alternator think I’m reasonably safe going for the 68A max with an 80A fuse in the supply side. Thanks

 

[autorouter]

So with a 200A alternator think I’m reasonably safe going for the 68A max with an 80A fuse in the supply side.

I have a 70A Sterling B2B, and found that it blew a 100A Maxi blade fuse, twice, on the first two excursions. I replaced the fuseholder with a Mega fuseholder and 100A fuse, and had no further problems. Don't know why, but thought it might be useful to know.

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[Adrianlle]

Thanks for that. See how it goes then!

 

[arthur49]

I have the same B2B as you but in a 2019 Renault Master ie smart alternator, rated at 180A, so not far off your alternator. Personally I think the 68A max draw from the alternator, to produce a steady 50A is too high. If you add a 3 way fridge running at 15A say whilst travelling thats 68A + 15A = 83A.
I have throttled back my B2B so max draw from alternator is 49A, giving me 45A approx into batteries. I have 2 x Sterling 100A LifePo4's as well

 

[Adrianlle]

Thanks Arthur49. As it happens I was wondering overnight about doing that. I don’t have a smart alternator and the compressor fridge is fed from the leisure batteries. But nonetheless think I will at least start with 49A and see how it goes. Thanks.

 

[arthur49]

Thanks Arthur49. As it happens I was wondering overnight about doing that. I don’t have a smart alternator and the compressor fridge is fed from the leisure batteries. But nonetheless think I will at least start with 49A and see how it goes. Thanks.

I think that makes a lot of sense. The strain on an alternator at tick over - traffic lights, congestion etc - is not worth the risk IMHO. Tick over = reduced cooling for alternator as its not spinning so fast yet is still delivering the load requested by B2B

 

[Adrianlle]

Arthur 49, can I ask whether you have your Votronic 50A set to D+ and if so whether you then have the Starter battery sensor switch set low or high? Low seems to activate charging by the unit when Startrer battery voltage exceeds 11.7v; high when starter battery voltage exceeds 12.5v. I’m wondering whether the lower v is to accommodate smart alternators and whether a non smart 200A like mine and a100A battery will be ok with the 12.5 threshold? Any thoughts welcome.

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[Lenny HB]

Arthur 49, can I ask whether you have your Votronic 50A set to D+ and if so whether you then have the Starter battery sensor switch set low or high? Low seems to activate charging by the unit when Startrer battery voltage exceeds 11.7v; high when starter battery voltage exceeds 12.5v. I’m wondering whether the lower v is to accommodate smart alternators and whether a non smart 200A like mine and a100A battery will be ok with the 12.5 threshold? Any thoughts welcome.

I think your assumption is correct when your alternator is charging it will be at 14 to 14.5 v.

 

[Old Gibber]

All batteries, no matter what the type, prefer a longer slower charge to a fast charge.

 

[Pausim]

Arthur 49, can I ask whether you have your Votronic 50A set to D+ and if so whether you then have the Starter battery sensor switch set low or high? Low seems to activate charging by the unit when Startrer battery voltage exceeds 11.7v; high when starter battery voltage exceeds 12.5v. I’m wondering whether the lower v is to accommodate smart alternators and whether a non smart 200A like mine and a100A battery will be ok with the 12.5 threshold? Any thoughts welcome.

On my VCC1212-45 the instructions say that if using D+ activation the voltage sensing wires Vs+ and Vs- are not required. It shows the 2 dip switches set to D+ and Low. That is how I have set them but always assumed that without the voltage sensing wires the High Low setting probably doesn’t matter either way. I have also assumed that adding the voltage sensing wire is more likely to confuse things than help.

 

[gerry mcg]

I have the VCC1212-50 wired as per this diagram
so I have the B2B connected directly to the leisure battery (not using the EBL) on a Euro6 non smart alternator Ducato chassis
I have the switches set to setting 3.
I have a D+ signal wire and the Starter V+ and V- signal wires connected.

and I have the in limit set to 68A, as I am bypassing the EBL

 

[Adrianlle]

That’s all v helpful - thanks. Setting 3 is what I was intending to use with sensor wires to the starter and leisure batteries - which is reccomended for setting 3. I will start the input A at 49 max and subsequently take a view as to whether it is necessary/ prudent to increase to 68 A max. I’m mindful that I also have 200w solar via a Victron mppt so when the sun has his hat on there is that also to be added to the output from the Votronic. What what we do without this forum! Thanks

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[arthur49]

Because we have a smart alternator I use setting 4. in the table above ie I use a D+ signal

 

[Pausim]

Because we have a smart alternator I use setting 4. in the table above ie I use a D+ signal

I use 4 without a smart alternator because it is the most straightforward set up. Saves running the Vs+ and Vs- wiring back to the engine battery.

 

[Adrianlle]

Run the sensor cables now - you’re right it’s a bit of a task not so much the wiring but seats out and panels off etc.- but tested with the existing gel batteries and all as it should be. Now I’ve tested with the old gels , tomorrow I will swap them for the 2x Sterling 100A Lithium that have arrived and change the settings fir Lifepo4 14.4v. Then put the replacement solar panels up and then ready for a tour of Western Scotland using sites as little as poss.