A couple electrical questions

R

royce

Member
I am installing a Victron multiplus 3000 and a sterling 60 amp battery to battery charger.
The battery bank is 4ea battle born 100 amp.
I have enclosed a pic of Sterlings recommended wiring and a sketch of my proposed schematic.
My first question is have I satisfied sterlings recommend grounding with the way I am thinking of wiring it?
The second question, is running the inverter case ground to the negative bus acceptable?
Thanks

Royce
 

Attachments

marklg

marklg

Well-known member
I think it looks OK to me. My inverter case ground is connected to the ground bus. You probably should have one fuse per battery on each + terminal. I use Blue Sea battery terminal fuses rated for each battery's max short time current.

Regards,


Mark
 
R

royce

Member
marklg said:
I think it looks OK to me. My inverter case ground is connected to the ground bus. You probably should have one fuse per battery on each + terminal. I use Blue Sea battery terminal fuses rated for each battery's max short time current.

Regards,


Mark
Click to expand...
Thank you Mark,
Battle born rates their 100 amp hour battery for a 30 second surge at 200 amps, so would it need to be 200 amp fuses?

Royce
 
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sparkplug

sparkplug

Well-known member
I might be missing something here as I've never used a B2B (I didn't know that VSRs only charge to around 80% or I would have got a B2B) but....

My set up has the PV coming into the MPPT controller and going to the vehicle battery (not a common bus like your schematic).

The VSR then runs from the vehicle battery to the leisure batteries which have a shunt to which all the load negatives are connected and a fuse box to which all the appliances connect. These circuits are individually fused.

Your diagram seems to have the fuse box leading to a common positive bus so I don't see how you can put different fuse ratings on the circuits that way. Unless they are connecting to the 12v fuse blocks (I also don't understand why you have 2 - but I'm sure you have your reasons!)

I don't have shore power so can't comment on that part of the circuit but I've kept the leisure battery negative separate from the vehicle negative. The VSR is 'one way' so it effectively keeps the leisure circuit completely independent from the vehicle one.


As for the fuse coming off the batteries, surely that should rated to the maximum load you plan to run, rather than the battery amps? My biggest load is 30A and that's the fuse I have off the battery. If something is trying to pull more than 30A then something's gone wrong - the fuse blows and protects the battery.

Battery amps are Amp Hours - i.e. how many hours the battery will run for with a 1 amp draw. Not the maximum amps the battery can supply.
 
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R

royce

Member
sparkplug said:
I might be missing something here as I've never used a B2B (I didn't know that VSRs only charge to around 80% or I would have got a B2B) but....

My set up has the PV coming into the MPPT controller and going to the vehicle battery (not a common bus like your schematic).

The VSR then runs from the vehicle battery to the leisure batteries which have a shunt to which all the load negatives are connected and a fuse box to which all the appliances connect. These circuits are individually fused.

Your diagram seems to have the fuse box leading to a common positive bus so I don't see how you can put different fuse ratings on the circuits that way. Unless they are connecting to the 12v fuse blocks (I also don't understand why you have 2 - but I'm sure you have your reasons!)

I don't have shore power so can't comment on that part of the circuit but I've kept the leisure battery negative separate from the vehicle negative. The VSR is 'one way' so it effectively keeps the leisure circuit completely independent from the vehicle one.


As for the fuse coming off the batteries, surely that should rated to the maximum load you plan to run, rather than the battery amps? My biggest load is 30A and that's the fuse I have off the battery. If something is trying to pull more than 30A then something's gone wrong - the fuse blows and protects the battery.

Battery amps are Amp Hours - i.e. how many hours the battery will run for with a 1 amp draw. Not the maximum amps the battery can supply.
Click to expand...
Thank you Sparkplug,
Regarding the fuse blocks, I neglected drawing the branch circuits coming off the individual fuses.
Please excuse the poor drawing, I am not very proficient with electricity.

There is one fuse block on each side of the van, my thought was to keep the branch circuits shorter to reduce voltage drop.

The main fuse was spec'd by Victron for the inverter load, not that it would ever see that much current with what I would use it for.

Sorry again, I neglected to state the batteries are 100 amp hour.

Royce
 
sparkplug

sparkplug

Well-known member
No worries royce.

I'm no expert either - I've only ever done one solar installation so I'm learning with you here.

royce said:
There is one fuse block on each side of the van, my thought was to keep the branch circuits shorter to reduce voltage drop.
Click to expand...
I'm not sure it works that way. I would have thought the voltage drop is calculated from the total length of wire from the battery rather than from a fuse block.
 
R

royce

Member
sparkplug said:
No worries royce.

I'm no expert either - I've only ever done one solar installation so I'm learning with you here.



I'm not sure it works that way. I would have thought the voltage drop is calculated from the total length of wire from the battery rather than from a fuse block.
Click to expand...
My thinking is that I only had to upsize the leads to the fuse block rather than all the branch circuits for voltage drop.
It will be interesting to do some measuring when it gets commissioned.

Royce
 
J

john61ct

Active member
Amps are amps, current **rate** instantaneous measure of power.

Ah are energy, stored or used over time.

VSRs do not regulate anything, just an automated switch, so

sparkplug said:
VSRs only charge to around 80%
Click to expand...
makes no sense.

If you drive 7-8 hours your bank should get to 100% just fine with a VSR

if the alt keeps putting out enough amps at the voltage setpoint matching what your batt specs and wire fat enough for the distance.

If not that's when you need DCDC B2B charger.

Also to throttle current when going to LFP if the CAR is too high.
 
M

Midwestdrifter

Engineer In Residence
Those BBs will charge up to the mid 90s SOC at ~13.9V, even with some voltage drop. I see lots of folks installing DC-DCs "because lithium". Really they are not necessary with a 400AH bank, as you won't hit the charge limit with the factory alternator. Lithium also charges fine at lower voltages, with no sulfation risk from partial charge.

It depends on your risk tolerance, but adding a 100A (or 200A) fuse for each battery (or 2 battery sub-group) would provide some additional fault tolerance.

The BBs use a solid-state relay for the BMS disconnect. They sensitive to current surges from starting inductive loads. I would avoid surges over 100A per battery on a regular basis.
 
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sparkplug

sparkplug

Well-known member
john61ct said:
makes no sense.

If you drive 7-8 hours your bank should get to 100% just fine with a VSR
Click to expand...
Yes - sorry, from what I've heard (and as I've said, I'm a very long way from being an expert) a VSR will only charge leisure batteries to 80% from solar alone in the configuration I described.

If I drive for decent periods of time, I do get a 100% charge.
 
autostaretx

autostaretx

Erratic Member
I haven't read the thread for its voltage/current discussion ... but i thought i'd toss in a comment about the "case ground"

That "case ground" is a safety connection for the odd chance that something inside the inverter (or DC-DC) box itself breaks and makes contact with the case. In something like a house, that "case ground" would be tied to "earth" ... a 6 foot copper rod driven into the ground.
("old school" is to clamp it on cold water pipes).
So it should be viewed somewhat as the 3rd pin (grounding) on a shore power connection: the case ground should go to the Sprinter's frame metal, so you don't end up with the case being *different* than the nearby Sprinter metal (lest your body create the "connection" between the two pieces of metal (case and frame)).

Since your proposed wiring does "common" the Sprinter's frame (alternator and starter battery negative pathway) with the negative bus, you're probably safe enough doing the case ground connection there.

But: what year Sprinter is this?
If you're an NCV3, your pencil drawing doesn't show where the Sprinter's "main negative disconnect" (near the pedal) fits into the circuit.

--dick
 
G

Geriakt

2017 View 24J
I would go with 100 or 120 amp main battery fuse be for 220 amp. You can always size up. I do see how you would every have more than 100 amp draw with your 3000 watt Multi Plus even if you start your Air Con with the inverter. I don't think you intend to jump start your cab from your liFePo bank. Install a Trik L start to solar charge your cab AGM. I too have a Multi Plus 3000/24 and run a 120 amp fuse on my 24 volt 2 module tesla system.
 
G

Geriakt

2017 View 24J
Also you may want to hold off in spending $400 on the sterling BtoB charger because your solar may charge well enough when driving as long as you have sun of course.
Install it later if you find you need it. You can pre wire for it.
 
R

royce

Member
Midwestdrifter said:
Those BBs will charge up to the mid 90s SOC at ~13.9V, even with some voltage drop. I see lots of folks installing DC-DCs "because lithium". Really they are not necessary with a 400AH bank, as you won't hit the charge limit with the factory alternator. Lithium also charges fine at lower voltages, with no sulfation risk from partial charge.

It depends on your risk tolerance, but adding a 100A (or 200A) fuse for each battery (or 2 battery sub-group) would provide some additional fault tolerance.

The BBs use a solid-state relay for the BMS disconnect. They re sensitive to current surges from starting inductive loads. I would avoid surges over 100A per battery on a regular basis.
Click to expand...
Thank you midwestdrifter,
I have been reading and trying to comprehend all I can on the subject.

I had originally bought a VSR and a battery protect from Battle born, but then got scared off with some opinions that charging a big battery bank would put too much load on the alternator.

I guess the idea of limiting the current to 60 amps appealed to me and Battle born was kind enough to let me trade the VSR and battery protect for the B to B charger.

Because of my ignorance, the value of this large investment and having seen a number of pieces of equipment burned down, my risk tolerance is pretty low and I like the idea of the individual fuses at the battery.

Royce
 
R

royce

Member
autostaretx said:
I haven't read the thread for its voltage/current discussion ... but i thought i'd toss in a comment about the "case ground"

That "case ground" is a safety connection for the odd chance that something inside the inverter (or DC-DC) box itself breaks and makes contact with the case. In something like a house, that "case ground" would be tied to "earth" ... a 6 foot copper rod driven into the ground.
("old school" is to clamp it on cold water pipes).
So it should be viewed somewhat as the 3rd pin (grounding) on a shore power connection: the case ground should go to the Sprinter's frame metal, so you don't end up with the case being *different* than the nearby Sprinter metal (lest your body create the "connection" between the two pieces of metal (case and frame)).

Since your proposed wiring does "common" the Sprinter's frame (alternator and starter battery negative pathway) with the negative bus, you're probably safe enough doing the case ground connection there.

But: what year Sprinter is this?
If you're an NCV3, your pencil drawing doesn't show where the Sprinter's "main negative disconnect" (near the pedal) fits into the circuit.

--dick
Click to expand...
Thank you Dick,
That is good to know.
The year is 2018 and the negative feed is connected directly to the sprinter battery.
So, when the sprinters main ground disconnect is open, there is still continuity between the sprinter battery and the neutral bus.
I hope that is not an issue.

Royce
 
gltrimble

gltrimble

2017 170 4x4
royce said:
Thank you Mark,
Battle born rates their 100 amp hour battery for a 30 second surge at 200 amps, so would it need to be 200 amp fuses?

Royce
Click to expand...


So is that 200 amps per battery? My 3000 watt/6000 surge inverter recommends using 400 amp fuse.


Sent from my iPhone using Tapatalk
 
R

royce

Member
Geriakt said:
Also you may want to hold off in spending $400 on the sterling BtoB charger because your solar may charge well enough when driving as long as you have sun of course.
Install it later if you find you need it. You can pre wire for it.
Click to expand...
Thank you Geriakt,
I committed to the B to B, for the lack of sun at this latitude.

Royce
 
J

john61ct

Active member
sparkplug said:
Yes - sorry, from what I've heard (and as I've said, I'm a very long way from being an expert) a VSR will only charge leisure batteries to 80% from solar alone in the configuration I described.
Click to expand...
And as I've said, that is nonsensical, 100% false, cannot even imagine any basis for anyone saying that, unless their system had something seriously wrong with it.

When voltage is high, it connects, when low it isolates, that is all.

Now of course there are many reasons why solar may not refill a bank, but nothing to do with a VSR in between.
 
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