Help please re correct size cable for Victron IP22 20a charger

[bartman]

I have just purchased this charger, with the intention of using it to charge 2 100ah Expedition lead carbon gel batteries. After pondering for some time over the different versions of Victron chargers I settled on the IP22 - I obviously didn't pay enough attention because I didn't realise that it doesn't come with DC cables.
I'm trying to find out which size is required, but now find it confusing. The information I can find indicates that a 2mm² cable is rated at 25a, which I thought would be sufficient. However on a Victron community forum, the same question was asked, admittedly for a 30a version, and the recommendation was 10mm² which seems excessive.
If I install the charger in the upright position as Victron suggest, the cable run would be no more than 3m. Otherwise I could install it in a less easily accessible place (under seating) with a cable run of less than .5m.
Any advice would be much appreciated

 

[wildebus]

10mm is OTT (people love to quote insane cable gauges!). If you are buying cable specifically, I'd probably go for 4mm2, but if you have 2mm2 of suitable length you could use that.
these chargers work in pretty well any position, so why not under the seat

 

[Admin]

I have just purchased this charger, with the intention of using it to charge 2 100ah Expedition lead carbon gel batteries. After pondering for some time over the different versions of Victron chargers I settled on the IP22 - I obviously didn't pay enough attention because I didn't realise that it doesn't come with DC cables.
I'm trying to find out which size is required, but now find it confusing. The information I can find indicates that a 2mm² cable is rated at 25a, which I thought would be sufficient. However on a Victron community forum, the same question was asked, admittedly for a 30a version, and the recommendation was 10mm² which seems excessive.
If I install the charger in the upright position as Victron suggest, the cable run would be no more than 3m. Otherwise I could install it in a less easily accessible place (under seating) with a cable run of less than .5m.
Any advice would be much appreciated

If it is 3m away, then I would use 6mm cable to reduce the voltage drop to 3.14% (0.377 volts)

 

[bartman]

Thanks for that. As I suspected the suggested size was OTT. I agree it doesn't need to be easily accessible as it has Bluetooth, but one of the advantages of putting it on the wardrobe wall (which is where the solar controller is) is that it leaves slightly more storage space for other stuff under the seat!
Anyway, many thanks, good advice as always

 

[wildebus]

If it is 3m away, then I would use 6mm cable to reduce the voltage drop to 3.14% (0.377 volts)

If you were limited with the cable size and run, you could also simply slightly raise the charge voltage to compensate for the drop. One of the great advantages of the Blue Smart IP22 chargers is the ability to fine tune the settings.

 

[merl]

If you were limited with the cable size and run, you could also simply slightly raise the charge voltage to compensate for the drop. One of the great advantages of the Blue Smart IP22 chargers is the ability to fine tune the settings.

The problem with raising the voltage to compensate for the cable volts drop is that it could easily lead to overcharge when the current drops toward the end of the charge phase and also float stage.
The thing about wiring resistance is it has what's known as a 'current limiting' effect, the battery won't charge up quite so quickly but both the battery and the charger will have an easier life. So it really depends on what you want to achieve, if you want the absolute fastest charge rate then use fat cable and/or keep the output leads short, if you don't mind charging taking a little longer and the idea of not being so demanding on the charger appeals then go for 4mm.

 

[wildebus]

yup, but there is the ideal - which is what you go and buy if you need cable, and the ok - which will work fine but with some minor compromises and what you use if you happen to have it available to hand. (I've just come back from buying some 35mm2 cable - £6.50 a metre! but the 16mm2 cable that is in place right now is perfectly safe to use, just not optimum).
What does annoy me is when people say things like "you MUST use this size cable or that size cable" when it is a load of tosh. 10mm2 cable for a 20A charger? or similiarly you get (usually on Motorhome Fun) people saying "use 10mm solar cable" when connecting up a Victron Solar Controller. you never need cable anywhere close to that. And that controller does not even accept a cable gauge larger than 4mm2. I run one of my 100/20 20A chargers with 40 foot of cable smaller than 1.5mm2 to a 300W array and it works just fine with no real losses.

 

[merl]

Some of the 'Knowledge' on Fun really makes me laugh!

 

[bartman]

Some of the 'Knowledge' on Fun really makes me laugh!

Well I must admit when I first browsed that site years ago I quickly realised how spoilt we are here with the wealth of knowledge available from our members - I haven't been back there since

 

[Pudsey Bear]

I'll flex my sparky muscles and ask is the 3m mentioned in a straight line or electrically.

 

[Nabsim]

yup, but there is the ideal - which is what you go and buy if you need cable, and the ok - which will work fine but with some minor compromises and what you use if you happen to have it available to hand. (I've just come back from buying some 35mm2 cable - £6.50 a metre! but the 16mm2 cable that is in place right now is perfectly safe to use, just not optimum).
What does annoy me is when people say things like "you MUST use this size cable or that size cable" when it is a load of tosh. 10mm2 cable for a 20A charger? or similiarly you get (usually on Motorhome Fun) people saying "use 10mm solar cable" when connecting up a Victron Solar Controller. you never need cable anywhere close to that. And that controller does not even accept a cable gauge larger than 4mm2. I run one of my 100/20 20A chargers with 40 foot of cable smaller than 1.5mm2 to a 300W array and it works just fine with no real losses.

Now see, I would probably have run a second 16mm2 if I thought I needed to uprated before spending £6.50 a metre

 

[wildebus]

Now see, I would probably have run a second 16mm2 if I thought I needed to uprated before spending £6.50 a metre

Have you seen the price of 16mm2 cable!!
It was an option but starts to get a bit messy

 

[bartman]

I'll flex my sparky muscles and ask is the 3m mentioned in a straight line or electrically.

I've made up my mind to site it as close as possible to the batteries, it's little further than the .5m I suggested earlier, nearer to 1m. With one bend, 90 degrees...... to the left!
Not sure what "or electrically" could be a typo for

 

[yeoblade]

Some of the 'Knowledge' on Fun really makes me laugh!

AFAIK Many (not all) 'Fun' users just post what they think is (Possibly ) a good idea, though often have little or no experience, always good for a laugh!!

 

[merl]

I'll flex my sparky muscles and ask is the 3m mentioned in a straight line or electrically.

Straight line is always best for electrons but more importantly down hill

 

[merl]

Straight line is always best for electrons but more importantly down hill

JOKE!

 

[yeoblade]

Straight line is always best for electrons but more importantly down hill

Funster!

 

[wildebus]

Straight line is always best for electrons but more importantly down hill

I find it is a good idea to make a little loop in the cable at the bottom and put the cap of a spraycan underneath to catch the loose electrons. You can then undo the caps on the top of the Banner Bull batteries, take the spraycan cap and pour them back in the battery so they are not wasted



Ok... I'll admit it. not my idea. I got it from another forum that will remain funless. opps, nameless.

 

[merl]

Great idea, My battery doesn't have screw caps but now I understand what that little plastic pipe coming off the top of the battery is for, just need a small funnel

 

[gasgas]

. . . .and don't forget that red electrons go down the + wire, and black electrons go down the - wire.

In A Level Physics at school we were introduced to the Cathode Ray tube. As the voltage on the anode was increased the green phosphors on the screen glowed brighter. The Teacher asked the class what we could conclude from this. One of the more intelligent pupils stuck his hand up and said 'Electrons are green'.
It's the sort of thing you never forget.

This is why 230v mains wires are brown and blue. They carry both + electrons and - electrons, very quickly and alternately so they can't be red and black any more since Brexit.