Member Since: 12 Oct 2007
Location: In the cack
Posts: 6485
Leisure batteries charging with the D3
I'm fitting 2x220Ah batteries to my off-road trailer and wondered if it would be wise to charge them direct from the D3 alternator via an Anderson plug from the rear end as I already have the Traxide kit fitted? The batteries are Lucas lead/acid type and would be connected together in paralell. What options are available?Any advice appreciated.Club Exped trailer
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5th Apr 2009 9:50 pm
Bodsy Site Sponsor
Member Since: 06 Nov 2006
Location: In the Clubhouse
Posts: 21361
I'd have thought they would be fine for keeping charged up and general running, but if they were quite flat, wouldn't the drain be too much for the alternator?Bodsys Brake Bible
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5th Apr 2009 9:53 pm
Ent
Member Since: 12 Oct 2007
Location: In the cack
Posts: 6485
Ian
I dont know enough about "in rush" currents to gauge wether or not the D3's alternator could cope. I'm hoping the Traxide 8mm cable will be up to the job as I'm sure if both batteries were flat they would pull quite a few amps for a short period. I have my auxillaries connect via breakers instead of fuses so I'm pretty safe but I think I will have to do some test in the garage first by discharging both batteries and then using a clip on ameter when charging to see the current draw. Its all at drawingboard level at the moment so Ill see what other people with similar requirements have done.Club Exped trailer
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5th Apr 2009 10:08 pm
Bodsy Site Sponsor
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Tbh I think you'd be best off dropping Tim (Drivesafe) an e-mail as he knows his onions istr you had the sc80 Bodsys Brake Bible
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5th Apr 2009 10:17 pm
Ent
Member Since: 12 Oct 2007
Location: In the cack
Posts: 6485
No I made a school boy error and ordered the SC40, doh! I didnt realise that ownning a D3, or any other LR, is like trying to fill a bottomless pit. Originally I only intended a few pieces of additional kit like a fridge, couple of rear headrest monitors, but now I find myself with a pair of Waeco 80ltr fridges, off-road trailer, TV's, projector and a Mrs Ent who insist on bringing Vidal Sassoons entire range of electrical products away with her when we go camping. I will drop Tim an email if he doesn't pick this thread up.Club Exped trailer
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Last edited by Ent on 7th Apr 2009 12:02 pm. Edited 1 time in total
5th Apr 2009 10:35 pm
caverD3
Member Since: 03 Jul 2006
Location: Oberon, NSW
Posts: 6922
Tim is very helpful and I am sure he'll know.“There are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely gamesâ€
Ernest Hemmingway
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6th Apr 2009 1:47 am
Roel
Member Since: 16 Aug 2008
Location: home
Posts: 1215
I am not a speciallist but I think that the length off cable from the front to the rear will give enough resistance to reduce the current so the altenator can handle it. Make sure the cables are thick enough.
My camel had 2 completely flat batteries and I have a set cheap so thin starter cables and when I connected them between the cars I had a 1 1/2 V drop acros the starter cable.
The D3 Voltage did go below 13 1/2 V. It toke about 10 min to get enough juice in the Camel to be able to start it.
The cables became handwarm so some current went through them.Roel
1997 Camel Trophy Disco ex-P101JWK (traded it for a Britains 42101)
1984 90 TD5
2005 G4 Disco 3 BN55WPT
Also member of club MTR
and Club Faultmate
Interested in my 4x4 history see my website: www.mudmachine.webklik.nl
Sorry it's in Dutch and with google translator it gets funny.
6th Apr 2009 8:17 am
TallPaul
Member Since: 03 Jan 2008
Location: Near Reading
Posts: 1214
As long as you have a correct fuse or breaker for the cable you should be safe.
But you know what happens in the end, you run 25mm^2 from front to rear of D3 with 175A Anderson, why not just get it out of the way and do that now?
6th Apr 2009 11:52 am
xtc
Member Since: 27 Mar 2007
Location: Hampshire
Posts: 1072
I would use min 16mm cable, ideally 25mm. Votage drop and maybe heat on 8mm could well be to high! Maybe use the output of the SC40 to power a 200a relay as 2 flat batt's of that size could draw a great deal of current initially. Also use a breaker at the engine end of 100a min. We always use these :-
Lots of good quality 12v goodies also on that site.
We also use their voltage sensitive relays for split charging but I'm keeping well out of that discussion / argument apart from saying it works for me!
Cheers, Richard.Off Roading is OK.... But I'd rather be Boating!
6th Apr 2009 6:44 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Ent, you have a number of options and unfortunately, all will cost you money.
While you won’t harm the SC40-LR control module as it is current protected, the 8mm2 cable that is supplied with the SC40-LR is specifically sized to charge a single battery in the engine bay and this cable size is intended to help regulate the current to that single battery, so the system can never be over loaded and as such, and as such, it’s not thick enough to be able to charge two batteries in your camper trailer.
You can either upgrade the SC40-LR to an SC80-LR + D3 FPC Kit which will give you a full cable set up, including all the hardware and protection, all the way to the rear of your D3 and is designed to allow the D3 to do exactly what you are after and you could then sell off your SC40-LR.
Or you could do as suggested and fit an external solenoid and rewire the SC40-LR controller to use it as electronic trigger to control the solenoid. You will still need to install heavier cable right from the cranking battery all the way to the rear of your D3 and protection devises.
As to the amount of current the two batteries in your trailer will draw, the cable size, more than anything else, will govern how much current your batteries will draw.
If you fit the SC80-LR + D3 FPC Kit, the cable size is set to be able to recharge the trailer batteries in a relatively quick time while not overloading the system.
A short note on, for want of a better word, “OVERLOADING†your alternator. This is a very crude explanation but if you apply a load that is greater than the maximum CAPABLE output of your alternator, you will NOT damage the alternator. All that will happen is the output VOLTAGE will drop.
This sort of operation is actually self protecting because in most DC voltage situations, reducing the voltage to most appliances, reduces to overall current requirements of the system and as such protects everything in the system.
BUT!
With a D3 there is an additional line of defence in that the D3’s voltage monitoring system will go further and in an attempt to protect the system it will start to shut down high current demanding devices like your suspension compressor, sound system and so on.
Ent, in set ups like what you are planning, it is imperative to get the correct cable size or you will have problems. You could fit very thick cable to allow you to charge your trailer quicker but the first time you have to charge them when they are in a low State of Charge, you are going to have D3 system conflicts.2008 TDV8 RR Lux + 2009 D4 2.7
6th Apr 2009 9:36 pm
Ent
Member Since: 12 Oct 2007
Location: In the cack
Posts: 6485
Cheers fellas for the suggestions, my first thoughts were to run 2x25mm cables via a suitable breaker from my Aux Yellow top under the vehicle some how to a 175Amp Anderson at the back. This way my cranking battery would always be charged first but I dont think the SC40 would handle the current if both batteries are flat(I dont intend to run them flat but you never know). I like the look of XTC suggestion of using the SC40 as a trigger for a large 200amp solonoid, I think this would be the cheapest option with the kit I have already installed. I've sent Tim a pm on his thoughts but its like everything in life what you want is not always what you can afford! Dam that Euro lottery!Club Exped trailer
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7th Apr 2009 12:13 pm
TallPaul
Member Since: 03 Jan 2008
Location: Near Reading
Posts: 1214
Ah, but if you use 25mm^2 to the yellow top, then the SC40 is charging them, but the yellow top acts like a large capacitor and so the load of the flat batteries is not directly applied to the SC40. However, unless you also use a relay, your trailer would run flat the yellow top as well when connected.
7th Apr 2009 12:20 pm
Ent
Member Since: 12 Oct 2007
Location: In the cack
Posts: 6485
Paul
I do have a very very limited knowledge on 12v DC systems, in my mind I thought the SC40 would see the three batteries as one large bank of 495Ah seeing as they will be connected in parallel. I knew I would have to disconnect the trailer once parked up or it would flatten the Yellow top but that wouldn't be an issue if I forgot as long as the cranking batttery was isolated when it reached the SC40 cut off point. What is the best way of running 25mm cable from the engine bay to the rear?
LeeClub Exped trailer
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Club National Luna Stella conditioner
7th Apr 2009 12:31 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Ent, you can fit a solenoid to the D3 and rewire the SC40-LR to use it to control the operation of the solenoid.
Leave the existing SC40-LR cable running from the cranking battery to the SC40 but unplug it at the SC40 while you do the rewiring.
Remove the SC40’s positive cable from the Yellow Top and connect it to one of the solenoid’s coil terminals and the other coil terminal should be wired to earth.
You need to run a new thicker cable from the cranking battery via the new solenoid and then to the Yellow Top.
Connect your twin cable coming from the rear of the D3 to the terminals on the Yellow Top.
BTW, you may be able to run the cable to the rear of the D3 inside the chassis rail. There is a hole just below the back of the engine bay and another one at the rear, BUT I don’t know if the hole is big enough for the size of cable you are using.
Don’t forget to put 50 to 100 amp circuit breakers at both ends of the positive cable running between the Yellow Top and your trailer batteries.
In the diagram below, the cable running from the circuit breaker on the side of the SC40 module to the Auxiliary battery is the one to use to control the solenoid.
Cheers and let us know how you go.
2008 TDV8 RR Lux + 2009 D4 2.7
7th Apr 2009 2:26 pm
Ent
Member Since: 12 Oct 2007
Location: In the cack
Posts: 6485
Tim
Once again you have come up trumps. Do I really need to run 25mm or would 16mm be better? I can get hold of both. I'm looking at a 200 amp solenoid is there any specific make or model which stands out? What size breakers will I need as I cant find out how much 440Ah worth of batteries will draw from flat.
LeeClub Exped trailer
Club Timed Climate
Club Flappy paddle steering wheel
Club 300bhp
Club Prospeed test pilot/lab rat
Club National Luna Stella conditioner
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