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New system needed

OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
Have you measured the space you have for batteries?thats where you need to start and do you have an inverter to charge your laptop
Hi, yes yes and yes 👍
 
OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
The idea is not to exceed the voltage and current limits. For a 100/50 regulator, 100 is the voltage input from the panels, and 50 is the current (amps) output to the batteries.

If the panels are in parallel - as usual on motorhomes - the voltage will be the same as a single panel voltage of 20 to 40V, so voltage is never a problem.

To work out the current, take the nominal panel watts and divide by the BATTERY voltage, then take about 70 or 80% of this if in Europe with the panel flat on the roof.

Example: three 120W panels: 360/12 = 30 amps, 80% of that is 24 amps. So if the choice is a 100/20 and a 100/30, it would have to be the 100/30.

Don't be misled by the 'max power current = 5.45A'. That's the PANEL output current, at the max power voltage of 22.0V. When the regulator steps down the voltage to feed the battery, it steps up the current to keep the power (volts x amps) the same.

So a 100/30 regulator can manage about 400W of panel if feeding a 12V battery, but can manage 4 x 400 = 1600W of panel if feeding a 48V battery. That's one reason for using higher battery voltage on a house installation, where the only thing connected to the battery output is the inverter.
Thanks, really helpful. It looks like I need 100/50 with the set up I’m planning
 
OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
Ditch the gel and get half of that capacity in lfp. You don’t need bmv 712, a 702 will suffice.
It’s just sooooo expensive!

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Dec 2, 2019
221
349
Amersham
Funster No
67,145
MH
van conversion
Exp
I'm a newbie
Look at ultramax 480 quid for 100ah, bms inside. What’s not to like? You can have as many as you like in paralel. They based in London, UK vat invoice, ebay shop free delivery mainland uk. Still expensive? I don’t think so.
 
OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
Look at ultramax 480 quid for 100ah, bms inside. What’s not to like? You can have as many as you like in paralel. They based in London, UK vat invoice, ebay shop free delivery mainland uk. Still expensive? I don’t think so.
I am waiting for a call back from them, thanks 👍 (although I am in Spain)
 
OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
Ultramax 200Ah ordered!! Woohoo. I note that they include a charger so an MPPT isn’t strictly necessary... I’ll leave my exiting MPPT on the old panels which will look after the car battery and also plug into the new battery. Do I really need another MPPT (victron 100/50) to manage my power effectively?

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Dec 2, 2019
221
349
Amersham
Funster No
67,145
MH
van conversion
Exp
I'm a newbie
Congratulations, the charger that comes with it, if is a 20a charger it stops at 14.4v if is a 10a charger it stops at 14.6v to high. Note, these chargers are mains plug in. From the solar you still need a configurable MPTT or PWM. I do not use the main charger except for the first charge, there after I don’t charge to full never. I stop charge at 13.70- 13.80v max. On ehu, I use the victron inverter charger to charge from mains, limited to 0,2C rate. On your 200ah you can charge up to 40a rate, to keep it sweet. I got two of those in the picture, paralleled with a 100a blue sea cube fuse on terminal and 35mm cables.
 

Attachments

OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
It is with a large touch of embarrassment I post this. I was going through the fuses checking why my wardrobe and above passenger seat lights aren’t working and found that the fuse labelled “solar” had blown. Can anyone tell me what function this fuse serves in the solar set up? Possibly I’ve only been getting charge from the alternator... Separate tests in 2 workshops have told me my batteries are pooped anyway so the new lithium is going to be fab.
 

Attachments

Aug 30, 2011
45
19
North Norfolk
Funster No
17,967
MH
Hymer B678 A class
Exp
5 years
Any fuse in the system is a safety device against damage to the system. For instance, if working on your batteries or disconnecting them. I’m sure damage to your regulator and even the panels could occur if the charge from the panels was not disconnected when removing or disconnecting the batteries. your system should be checked to find the cause of a blown fuse...if not immediately obvious. Obviously, if not running the engine your batteries would soon flatten if no current getting to them because of blown fuse.
Members with greater knowledge will expand on this, I’m sure.

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Apr 27, 2016
1,620
1,244
Manchester
Funster No
42,762
MH
A class Hymer
Exp
Since the 80s
Can anyone tell me what function this fuse serves in the solar set up?
A fuse is a safety device. Any wire connected to a battery needs to have a fuse. If no fuse is wired in, then if the metal part of the wire touches the metalwork the battery is shorted, and the wire heats up until it is glowing red-hot and can easily start a fire. To avoid that, a fuse is wired in so that if the wire touches the metalwork, the fuse blows instead, and cuts off the battery current.

In your solar circuits, it depends on whether the fuse is between the solar controller and the battery, or between the solar controller and the panels.

On the battery side it is an essential safety device. On the panel side it is not really necessary because shorting the solar panels does not lead to excessive current like when you short a battery. But sometimes they are fitted anyway, and can be handy if for some reason you want to disconnect the panels from the controller.

You could try just replacing the fuse to see if the battery starts charging. If the new fuse blows there might be a wiring fault.
 
Last edited:
OP
Sooz52
Jan 13, 2020
86
32
Spain
Funster No
67,999
MH
Hymer B514
Exp
6 months in a 10m Southwind in the USA (2014). Just bought a Hymer and embarking on a tour of Spain
A fuse is a safety device. Any wire connected to a battery needs to have a fuse. If no fuse is wired in, then if the metal part of the wire touches the metalwork the battery is shorted, and the wire heats up until it is glowing red-hot and can easily start a fire. To avoid that, a fuse is wired in so that if the wire touches the metalwork, the fuse blows instead, and cuts off the battery current.

In your solar circuits, it depends on whether the fuse is between the solar controller and the battery, or between the solar controller and the panels.

On the battery side it is an essential safety device. On the panel side it is not really necessary because shorting the solar panels does not lead to excessive current like when you short a battery. But sometimes they are fitted anyway, and can be handy if for some reason you want to disconnect the panels from the controller.

You could try just replacing the fuse to see if the battery starts charging. If the new fuse blows there might be a wiring fault.
Thanks... though I know what a fuse does... the question was intended to be - in which part of the circuit does this fuse sit.
 
Apr 27, 2016
1,620
1,244
Manchester
Funster No
42,762
MH
A class Hymer
Exp
Since the 80s
Thanks... though I know what a fuse does... the question was intended to be - in which part of the circuit does this fuse sit.
If the fuse has blown it's almost certainly in the part between the controller output and the battery.

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Jul 3, 2018
812
1,989
Oxfordshire
Funster No
54,729
MH
Wildax aurura xl
Exp
since 2014 camping since1968
I have to say totally confused by all this power people seem to be using I mainly FLT and I have 120w panel which is getting old now and two 110 amp LA's and 85amp vehicle batt I use lap top phones and TV all charged off of leisure system LED lighting and camp here as well as abroad late and early in the season and never once has my system dropped below good ( my system reads very good, good, low, then red light comes on) never seen the other two am I very low usage which I doubt or our people just over worried about power and Hording it:devil:::bigsmile:
 
Jan 19, 2014
3,754
9,720
Derbyshire
Funster No
29,757
MH
Elddis Accordo 105
Exp
since 2014
I have to say totally confused by all this power people seem to be using I mainly FLT and I have 120w panel which is getting old now and two 110 amp LA's and 85amp vehicle batt I use lap top phones and TV all charged off of leisure system LED lighting and camp here as well as abroad late and early in the season and never once has my system dropped below good ( my system reads very good, good, low, then red light comes on) never seen the other two am I very low usage which I doubt or our people just over worried about power and Hording it:devil:::bigsmile:
Agree, we got 150w solar, plenty of power 👌💪
 
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