Battery charger wiring

[TandC]

Hello all,

 

Currently installing a Stirling ProDigital 40amp charger. The two output cables (domestic bank and engine battery) are 25mm2, there is a fused negative, individually fused outputs to each battery bank (70amp to domestic, 60amp to engine battery) and i am locating the charger in an area where I can install a small 12v fan (in addition to its internal fan) to provide air circulation as per BSS.

 

The question is how to wire it into the mains - It comes with the usual 3-core cable, stripped to reveal around 4inches of each. Is this to allow it to be wired directly into the consumer unit? In order to test it I have wired it directly into the RCD trip switch within the consumer, the same one which supplies the socket ring.

 

Is this acceptable behaviour.... there isnt scope due to location to have it wired through a plug to one of the sockets and I want it permanently wired in so that when I am on the shoreline it automatically receives power. Do i have to provide it with its own trip switch within the consumer unit - im not sure there is room if so...

 

And finally, am i supposed to be able to isolate it from both the 240v supply and also isolate it from the batteries? Does that mean a seperate isolation switch in each of the positive output cables?

 

With the BSS approaching i'd like to make sure its legit...

 

Thanks

[paulcatchpole]

Hello all,

 

Currently installing a Stirling ProDigital 40amp charger. The two output cables (domestic bank and engine battery) are 25mm2, there is a fused negative, individually fused outputs to each battery bank (70amp to domestic, 60amp to engine battery) and i am locating the charger in an area where I can install a small 12v fan (in addition to its internal fan) to provide air circulation as per BSS.

 

The question is how to wire it into the mains - It comes with the usual 3-core cable, stripped to reveal around 4inches of each. Is this to allow it to be wired directly into the consumer unit? In order to test it I have wired it directly into the RCD trip switch within the consumer, the same one which supplies the socket ring.

 

Is this acceptable behaviour.... there isnt scope due to location to have it wired through a plug to one of the sockets and I want it permanently wired in so that when I am on the shoreline it automatically receives power. Do i have to provide it with its own trip switch within the consumer unit - im not sure there is room if so...

 

And finally, am i supposed to be able to isolate it from both the 240v supply and also isolate it from the batteries? Does that mean a seperate isolation switch in each of the positive output cables?

 

With the BSS approaching i'd like to make sure its legit...

 

Thanks

 

Righty, my opinions on this, having done it for the BSS recently, and doing it again this weekend for our main boat's BSS.

 

On the 12v side, anything 'round' the isolators, connecting directly to the batteries, requires fusing (for the BSS, as close as practicable to the batteries but outside the battery box), which it appears you're sorted with. Unknown as to why you've got a fuse in the negative as well as both positive outputs, but not a problem. What are those, ANL or Megafuses or something similar, or maybe not, if it's only 40A?

 

On the 230v side, if you connect it straight to the RCD, then you're essentially saying the cable it came with (.75mmsq?) will handle 80A (or whatever the RCD's max current is). If you've connected it to an RCBO, then that's of course, different. It should be connected to an MCB rated at less (or same) as the current rating of the cable to the charger. Ours is on its own 6A MCB in the consumer unit. Alternatively, install a 13A socket for it, off one of your other radials/rings, and put a 13A plug on the charger, with a suitable fuse in, to protect the cable. There isn't a requirement to isolate it from the 230v supply in the BSS, AFAIK.

 

The BSS is quite vague on 230v stuff, in my opinion.

 

In reality, on the 230v side, although the above is (IMHO) the correct way to do it, I doubt you'd fail a BSS exam with the way you've got it connected.

 

PC

[WotEver]

Alternatively, install a 13A socket for it, off one of your other radials/rings, and put a 13A plug on the charger, with a suitable fuse in, to protect the cable.

That's what I'd do - in fact, it's what I have done on Wot Ever.

 

Tony

[Scotty]

Make sure you're not powering the charger using the inverter!

 

I have a socket wired to the shoreline which is isolated when switching to the inverter

[TandC]

Hmm... thanks all.

 

Paul - the Stirling comes with a whopping great big marine fuse and case for the negative which they state must be used - polarity protection? No idea - its in there though!

 

This is where my knowledge of the consumer unit things falls down - it has a 40amp RCCB (according to the sticker on the front....) - which in my simple mind is the 'master switch' - then next to it are two smaller circuit breakers, one supplies the 240v light ring and the second the sockets - it is into this second that I have wired the charger - I cannot see any ratings on those smaller circuit breakers - one says B6 (light ring) and the other B32 (sockets) - is that a rating??.

 

In which case - does the above mean that the maximum mains current is 40amp, and the cable supplied can cope with that...

 

While another socket/13amp plug certainly seemed the most sensible way, meaning it could be manually isolated from mains by simply unplugging it. But, its a total pain to fit another socket.... I'll have another look, not sure if the above information makes any difference.

 

Cheers,

 

tandc

[MoominPapa]

- one says B6 (light ring) and the other B32 (sockets) - is that a rating??.

 

Yes. B indicates how fast the breaker will operate and the number is the rated current in amps.

 

I doubt that the the charger and its main cable is suitable for protection as high as 32A.

 

In which case - does the above mean that the maximum mains current is 40amp, and the cable supplied can cope with that...

 

No. The cable from the shore to the boat is protected by the breaker at the shore end. That's very unlikely to be 40A. TBH the 32A breaker is pretty useless: a fault on the socket circuit will blow the shore breaker first and plunge you into darkness. Better to use a 10A or 16A breaker there.

 

MP.

 

Edited to add. the RCCD doesn't trip on over-current, it trips on an earth fault. The 40A rating gives the maximum current it can safely carry, not the current at which it will trip.

Edited August 11, 2010 by MoominPapa

[WotEver]

Put simply, the cable to the charger must be suitably protected. A 13A socket outlet is one way. A fused spur is an alternative. A breaker of whatever size Sterling recommend (probably 6A) within the consumer unit would be another option.

 

Whilst wiring it from the back of the 32A MCB is unlikely to fail BSC (because the examiner probably wouldn't realise) it's dangerous.

 

Tony

[Gibbo]

The fuse in the negative cable is (incredibly stupidly) required by the ABYC (American) regs.

 

It's one of their more stupid blanket requirements. It isn't required anywhere outside the USA.

 

Be careful where you wire up the charger. I've seen lots of people wire it up to the main 230 volt system in the boat. If you have an inverter the loop created simply flattens your batteries.

[FadeToScarlet]

I've used the KISS principle, and put a plug on the end of the charger wire. It simply plugs into a normal 240v socket. The socket happens to be next to the inverter, so you can ensure that it's off when the inverter is on.

 

It also means I can plug it into my gennie directly, using an extension lead, and leave the boat's 240v system unenergised, if I wanted. Came in useful once when I had a 13A extension lead, and a 13A socket on a friend's gennie supplying power, but no 16A adaptor to hand to plug the boat in.

[TandC]

Okay- im getting there!

 

Thank you all for the ever helpful replies - its now down to either trying to fit a seperate low MCB for the charger within the consumer unit (difficult as it is only a small unit) or wiring in a new socket spur to supply the charger - the preferred option as it gives a simple level of flexibility - although its going to be tricky.

[blackrose]

My battery chargers are just plugged into the ring mains with 13amp plugs the same as any ordinary mains appliance. If I want to isolate them from the mains I pull the plug out. As well as the fuse on the DC negative that came with the charger, my output cables are all fused too.

 

Since you are charging only 2 battery banks from 3 output terminals, don't forget to link the two output terminals going to the biggest bank (domestic).

[TandC]

All done... had to remove two side panels to gain access to the ring-main, inserted a junction box (thankfully i'd left a bit of slack in the cable/conduit run) and run another cable in conduit run back to the corner where the charger will be - total pain but now have a shiny new double socket to plug that battery charger in.... a total pain, but its definately a better solution. THanks all.

[Gibbo]

All done... had to remove two side panels to gain access to the ring-main, inserted a junction box (thankfully i'd left a bit of slack in the cable/conduit run) and run another cable in conduit run back to the corner where the charger will be - total pain but now have a shiny new double socket to plug that battery charger in.... a total pain, but its definately a better solution. THanks all.

 

Do you have an inverter?

[waterat]

Hello, have been serching threads on this subject. Ihave just installed a Sterling Pro Charge D 40amp. Have followed the instalation instructions to the letter.

However when I power it up from my genny I only get about 14.3volts max from the charger, I should be getting 14.8. Everything is correctly set.

 

It also seems to go into float mode very quick even though batts are not fully charged. Run charger for about 4 hours today with only 2 110ah that need charging. When I took a SG reading it was about 1.2

Any ideas please

[bottle]

Sorry cannot help but the make and model of generator may help the experts.

[waterat]

I have a Kipor IG2000 so it should be man enough for the job.