Wiring Advice

Submitted: Wednesday, Nov 30, 2016 at 22:00
ThreadID: 133870 Views:3387 Replies:2 FollowUps:1
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Hi to all . Not a big poster but a keen watcher. Apology for the long lead in to the question)

I have a iveco van set up as a service vehicle and overnight bed all in one. From the waist down it is full of tools etc and above that is a bed , fridge, fan ... good enough for my travels. Currently has dual batteries ( previously set up and well set up i think)... large crank battery and 120 Ah house battery. Redarc sB12, with two VSRs, remote overide for starter and an AC 20 amp Charger.....a 100 amp main fuse and individual smaller fuses on each circuit. ( note not an SB12D dual sensing,,, thus two VSrs???) anyway system was working well in both 12v and 240 volt mode with only long periods at idle shutting down the draw from the second battery ( 75 litre vitrifrigio doing an efficient job now i have insulated it.) BUT...... ( there is always a but)

the SB12 has given up... as no more red light and no clicking of the solenoid... Age could be the culprit , but i could also be the problem, as recently i started using a small portable electric winch to haul my small car aboard its trailer.,,, i attached it directly to the house battery and disconnect immediately , and all up winching is probably two minutes.

My question

How best to wire in a winch to this equation with a possible draw of 70-135 amps (using winch load data and it is only a 600kg racecar)
and if i chose to replace the SB12 with a SB12Dual sensingor similar would i need the vsrs ( they may or may not be working i have yet to test)...

I don't want to spend a fortune, but do want to protect the circuitry. I was thinking remove the VSRs, add a SB12D either 100 or 200D or similar and have a marine type continuous rated isolator switch between battery and winch solenoid> Thoughts appreciated. Anything simpler Would a super large anderson connection be a possibility to the trailer ? (For those who could suggest a simple human powered winch- my problem is sometimes the racecar is not on all wheels-

Disclosure: I don't see a need for a Dc to DC charger, i have a big alternator, some reasonable travel time and am used to trickle topping up all batteries between outings and have several good quality multistage chargers to share around. Cheers Darryl

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Reply By: Allan B (Member, SunCoast) - Wednesday, Nov 30, 2016 at 23:33

Wednesday, Nov 30, 2016 at 23:33
Hi Darryl,

Let's see if I have this right.......... you currently have a Redarc 100A SBI-12 between the cranking and auxiliary batteries which provides the necessary isolation and is defunct and needs to be replaced. ....... but I don't understand where the two VSR's are positioned or their function. Attaching the winch to the aux battery should not have damaged the SBI-12.

The winch would be better powered from the cranking battery and with the engine running at a fast idle to have the alternator contributing. However I guess you would not want to run heavy winch wiring all the way to the crank battery. So you could run the winch from the aux battery but I still would run the engine whilst winching to contribute and avoid flattening the aux battery. As most of the winch current would be drawn from the aux battery, a 100 Amp SBI should be OK as the 200 Amp version is much dearer.
As I said, I cannot see a need for VSR's unless it is to protect from having your fridge run the aux battery too low. Does your fridge not have 'low-voltage cutout' feature?

A Redarc SBI-12 Dual Sensing type isolator is appropriate where the charge current may come from either end of the circuit. i.e. where both batteries are charged from the alternator or alternatively both batteries are charged from the auxiliary end from a solar panel or a mains-powered charger. I see no need for it in your setup.

A 200A 'marine type' isolating switch close to the battery would be good to safely isolate your winch as with that large current draw it is impractical to provide protection by means of a fuse.

Anderson plugs are available in ratings of 50, 120, 175 and 350 amps.

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AnswerID: 606336

Follow Up By: Darryl E - Thursday, Dec 01, 2016 at 09:15

Thursday, Dec 01, 2016 at 09:15
hi allan , thanks for detailed response.

the use of the house battery was due to the length of cable differences. I was (am ) perplexed at the two VSRs..... guessing the 240V 20 amp charger is used to top up both batteries... as i said a guess......

the fridge has a cut out , but maybe the previous owner thought it cut out too late?

I was hedging towards removing the VSrs, as i am happy with the AC charger assisting the house battery, and leave the cranking battery recharging to the alternator.... your post has solidified this idea.

Cheers Darryl
FollowupID: 876078

Reply By: The Bantam - Monday, Dec 05, 2016 at 00:11

Monday, Dec 05, 2016 at 00:11
Waht I have on my 4wd is a VSR betyween the cranking battery and the aux battery.

I also have an A/B/both marine switch that feeds the winch ... bear in mind my winch will pull in excess of 400 amps at stall.

The A/B/ both switch allows me to isolate the winch wiring which can not have a fuse or breaker in it and in the both position it bypasses the VSR connecting both batteries to the winch and the alternator.

If you don't want to wire the winch all the way to the main battery, just fitting a marine battery isolator across the VSR will protect the VSR from overload and connect both batteries the alternator.

the 2 VSRs has me baffled.

AnswerID: 606417

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