Dual Battery for Winch set up.

Submitted: Sunday, Jan 04, 2015 at 12:15
ThreadID: 110615 Views:5127 Replies:7 FollowUps:7
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Hi guys. I've done a search and found a few old thread on this topic. But thought things have probably changed in the last few years so am after some of your thoughts.

I am installing a winch on my 2014 D40 Navara. I already have a dual battery isolator running to a 50 amp Anderson plug for the camper.

I am planning in taking the camper down the OTT and know that I will be in for some heavy winching. I figure a second battery to assist the starter will be beneficial for many reasons (back up starter etc).

Here is my plan.. Please share your thoughts!

Install second battery identical to starter battery. Run a second dual battery system between these two batteries. On top of this join the to batteries with a seperate set of large amp carrying cable (00 gauge welding for example). On this heavy duty link put in a 200amp isolator that is linked to the winch so that when the winch starts the solenoid opens connecting both batteries automatically...I figure this may be necessary as there is the possibility of frying the cables on standard isolator set ups that link the two batteries when the winch is pulling 400 amps.. And the standard set up would share amps as quickly as the winch uses them. If I were to get carried away I suppose I could have a on/off switch so the winch could just run off the starter if I want to save the second on lighter pulls.

Apart from your opinions my question is: would the solenoid automatically open when the winch started to draw over 200 amps? Or would I need a switch rigged up to open it if I wanted to use both batteries?

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Reply By: Frank P (NSW) - Sunday, Jan 04, 2015 at 12:49

Sunday, Jan 04, 2015 at 12:49
Shannon,

I did a set-up similar to what you're proposing. I used a manually switched 200 amp solenoid to parallel the batteries for winching, supported by the alternator. If the batteries are not paralleled the winch runs off the Aux battery. Mistake in hindsight, should be off the crank battery so the alternator can support it, but I'm not going to change it now as I always winch off the two in parallel.

Make sure your solenoid is spike-suppressed to prevent possible damage to electronics when switching it. If it is not, the easiest way is a simple 25 cent diode across the coil terminals with the band on the diode on the positive coil terminal. Or use a simple manual isolator.

Personally, I wouldn't bother with the automatic thing, though it is a nice touch :-)

Also, I would install a manual isolator under the bonnet in the winch supply to reduce the possibility of accidental activation or activation by bleep s with the same remote. Mate of mine packed up his winch, clipped the line onto a recovery point and then sat on his wireless remote when he got back in the vehicle. Bent a few bits - he was not happy. As you're not making and breaking an active circuit you don't need an expensive heavy duty (400 amp or whatever) DC switch. Just an isolator that will make or break the circuit when there's no current flowing.

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FrankP

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Reply By: vk1dx - Sunday, Jan 04, 2015 at 13:22

Sunday, Jan 04, 2015 at 13:22
Shannon

Frank's solution with a Redarc 200 amp isolator between the batteries would suit you. Install a switch for the isolator in the cabin so that you can manually switch the second battery into circuit.

Also run the winch off the main battery. We leave the positive lead disconnected until I need the winch. I also have a bright red LED in front of me to show the "switch" is ON and all batteries are in parallel.

We actually have three Allrounder batteries under the bonnet with two in parallel as auxillary/accessory batteries and one as the crank. All 4wd lights, fridges and accessories run off the twin accessory bank. Th winch runs off the crank, or all three, when needed. I used it once for some garding in at home. Waste of money but I bet that if I didn't have it then I would need it. Murphy's Law . . . .

Regarding the OTT. We did it with our two sons came with us in their own cars. All three cars were basic 4.2TDs with minimal mods - basically shocks and one had a small lift. None of us needed winching. It was in July with Nolans the only creek with any "real" depth. It was just up to the bonnet. All three just ambled through. If you do it properly you may not even need the winch.

Enjoy it. Lovely country up there.
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Reply By: Shannon I - Sunday, Jan 04, 2015 at 15:12

Sunday, Jan 04, 2015 at 15:12
Thanks guys for the comments. I've done the OTT before and didn't need a winch and barely had water bonnet height. I just want to be sure now given the camper in tow and a young wfamily in the car!

Is there any need for a a switch on the solenoid? I thought that as soon as the winch started drawing amps at the isolator a capacity it would connect both batteries. (say if it was 200amps and the winch drew 400 the solenoid would open)?
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Follow Up By: Frank P (NSW) - Sunday, Jan 04, 2015 at 15:37

Sunday, Jan 04, 2015 at 15:37
Shannon,

There are four ways of doing this as I see it.

1 A simple, manually operated isloator which you use to connect the batteries in parallel when you want to winch.

2 A setup where you would have a "dumb"solenoid (ie, not a smart isolator/VSR device). In this case the two poles of the isolator will each have 12 volts on them all the time, one from each battery. You will need a manual switch to operate the solenoid whenever you want to winch.

3 Use a conventional Redarc type 200 amp isolator. It would work conventionally, ie after starting your car the main battery voltage comes up, activates the isolator and connects the two in parallel until you switch the engine off. BUT THERE IS A POSSIBLE PROBLEM HERE. When winching, even though the batteries are in parallel and the engine running, the 200 or so amps coming out of main battery may pull its voltage down far enough for the isolator to drop out, leaving you winching off just the crank battery. You would need to install an over-ride switch to correct that. No gain there compared to option 2, in fact you'll be out of pocket. 200Amp dumb solenoid about $50. 200 amp Redarc $380 rrp.

4 You could place sensor wires on the winch-out and winch-in terminals of the winch motor, feeding back to the solenoid of your choice. Each sensor wire would have to have a diode in it so that when voltage was applied to one, there was no feedback from the common point at the solenoid to the other winch terminal. Thus, whenever you operated the winch, either winching in or winching out, one of the sensor wires would have a voltage applied to it. That would tell the solenoid the parallel up the batteries. When you stop winching the solenoid would disconnect (dumb solenoid) or revert to "smart" behaviour (Redarc type)

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FrankP

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Follow Up By: Frank P (NSW) - Sunday, Jan 04, 2015 at 16:22

Sunday, Jan 04, 2015 at 16:22
Just thought of a fifth way that trumps the fourth!

If you have the manual isolator in the supply to the winch (I think you should), run a sensor wire from the winch side of that isolator to the solenoid of your choice (dumb or smart, as per option 3).

No diodes needed and winch-mode paralleling is automatically sensed.

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Reply By: Allan B (Member, SunCoast) - Sunday, Jan 04, 2015 at 16:58

Sunday, Jan 04, 2015 at 16:58
Although Frank's five proposals have merit, there is a sixth way...............

As you propose adding a battery "identical" to your existing cranking battery, simply wire them in parallel, i.e. join each battery positive together and each battery negative together with heavy cable. The batteries are now permanently in parallel for both charging and for supplying the winch, with alternator assistance, without the need for solenoids, charging isolators, switches or anything else. You can obtain suitable 'made-up' starter cables with fitted lugs from auto accessory stores.
Maybe a 400A manual isolating switch in the supply cable to the winch would be a good idea to prevent mishaps. Do not be tempted to use one rated less than '400A for 5 minutes' as a winch can draw up to 400A when under heavy load.
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Allan

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Follow Up By: Shannon I - Sunday, Jan 04, 2015 at 17:41

Sunday, Jan 04, 2015 at 17:41
Thanks Allan. I totally get where you are coming from in just wiring them up together but I figured while I was at I can add some redundancy and have a back up cranking battery.

I think I will go with a combination of franks suggestions. I will add a manual isolator to prevent "mishaps".

Remembering in the D40 the second cranking battery will be under the car I will join the batteries and winch with some 00 gauge wire with a "dumb" isolator. I will connect this to the winch so that it activates when the winch goes in or out connecting both batteries.

As then the two batteries will only be connected to each other and the alternator when winching I will put a VSR relay on another circuit connecting the two (I have a dual battery kit with 100amp VSR lying around I got free with another purchase). This can "maintain" the second battery on trips away.

I think this gives the best of both worlds.
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Reply By: Shannon I - Sunday, Jan 04, 2015 at 18:28

Sunday, Jan 04, 2015 at 18:28
I think that this is going to leave us pretty well set up. I've got the two 130AH in the camper for Fridge duties (80L and 40L) and then I'll have the two in the ute to back up the starter and winching duties. That should keep the wife and kids happy and the drinks cold.

I know that the two batteries isn't probably necessary for winching but given the camper and car will come in well over 3 tonne fully loaded I want to be sure if I have to winch the winch has plenty of Amps to pull.
AnswerID: 543739

Reply By: Mick O - Sunday, Jan 04, 2015 at 18:46

Sunday, Jan 04, 2015 at 18:46
Shannon, Redarc have a wiring diagram that will fit the bill for you. It involves a solenoid switched to the cab for manual switching at times of high need like winching (or if your cranker is flat ;-). I'm using the BCDC charger in the equation but there are alternatives.

I've done it in my ute using a 700cca hybrid battery as the auxillary.

Redarc wiring guides

Redarc - ultimate dual battery wiring guide

Building a 12V (DC) power system for your 4x4


Cheers

Mick
''We knew from the experience of well-known travelers that the
trip would doubtless be attended with much hardship.''
Richard Maurice - 1903

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Follow Up By: Shannon I - Sunday, Jan 04, 2015 at 18:51

Sunday, Jan 04, 2015 at 18:51
Thanks Mick. Very useful!

I have a DC to DC charger in the camper but didn't think about it for the car second car battery... Well worth the inclusion I think.
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Follow Up By: Mick O - Sunday, Jan 04, 2015 at 21:21

Sunday, Jan 04, 2015 at 21:21
Shannon, if you have the dollars to make it happen, then I highly recommend the Redarc products (aussie made, great service). I'm using the BCDC1240 at present and it also has an MMPT solar controller built in meaning you can simply hookup a solar panel (open circuit) to the BCDC and you'll get automatic solar charge if the engine is switched off or...heaven forbid...the alternator fails to produce electrickery (as happened to a mate of mine recently when he was 1500 km from anywhere!).

Cheers

Mick
''We knew from the experience of well-known travelers that the
trip would doubtless be attended with much hardship.''
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Follow Up By: Shannon I - Sunday, Jan 04, 2015 at 21:54

Sunday, Jan 04, 2015 at 21:54
Agree Mick. I want that unit for the camper and move the campers to the car. I hadn't ever thought though about being able to hook solar panels up to the car. Looks like I might need two!

The list of Mods is always never ending and it looks like I've just added another to the list!
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Follow Up By: Frank P (NSW) - Sunday, Jan 04, 2015 at 22:19

Sunday, Jan 04, 2015 at 22:19
Shannon,

You might find this of interest.

Cheers
FrankP

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Reply By: Roachie.kadina.sa.au - Monday, Jan 05, 2015 at 06:04

Monday, Jan 05, 2015 at 06:04
Call me paranoid, but I don't like my winch to be wired-up all the time and I DO want my batteries to be hooked together with NO little devices (ie: management system, relay, kill switch etc) in between them.

So, given that winching is something that most of us only do on relatively rare occasions, I advocate physically removing the HOT wire for the winch from the positive battery terminal when not needed. I further advocate either: having the 2 batteries permanently connected with NO devices in between....OR....if you must use some form of management "system" (even a basic relay or kill switch), then have a separate HEAVY cable that you can use to connect the 2 batteries. This latter connection could be made at the same time that you are adding the winch connection to the battery.

Of course, it goes without saying, when you've finished winching please don't switch off your engine (a lot of people do). The engine needs to keep running to enable the alternator to recharge the batteries completely as they will be diminished from the winching process.

That's how I do it anyway.

Roachie
AnswerID: 543763

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