Simple solenoid dual battery set up

[86mud]

Hi all

Did a quick search but was unable to find an exact answer...

On my old range rover I had a simple heavy duty solenoid for my dual battery set up and never had a problem in 4 years.

The battery box in my DEF130 is a wiring nightmare with some weird looking dual battery controller that I think has finally died. I purchased new batteries just after I bought the truck in April and my aux battery is now not charging.

I am going to rip out all the dodgy wiring and go back to a simple solenoid.

Can anyone give me the cons of using a heay duty solenoid?


https://www.aulro.com/afvb/images/imported/2009/10/1742.jpg

The two large terminals are for each +ve battery lead, one small terminal is an earth and the other small terminal is to ignition.

Cheers
Andrew

[fraser130]

Andrew, any chance of some details of your existing dual battery device?
Does it have any labels etc?

Fraser

[austastar]

Had one of those when our truck was new.
Be careful you don't parallel the batteries on starting, you can draw 1/2 the starting current from the second battery and fry the contacts in the relay.
I now have an electronic one that charges the second battery once the main battery is at full charge.
You can use that relay, but I would trigger it from a small Voltage Sensitive Relay from Redarc or similar.
cheers

[numpty]

I know it doesn't answer your question, but have you thought of using a large Marine switch. It's what I and a number of others use, mounted on the front of the seat box where it is easy to get at. Everything runs through the battery that's selected. Same with charging.

I have used this system for 22 years with never a problem.

[incisor]

and fry the contacts in the relay.

yep.. that seems to be a common problem with the cheaper solenoids

the marine switch is fine if you have all normal cranking batteries or keep remembering to switch before you crank etc.

i use a traxide (http://www.traxide.com.au/) sc80 as it is set and forget :P

[waynep]

Go to the Traxide site and check out the SC40 and SC80. Much better battery management than a simple solenoid and not that expensive.

No need to connect to the aux/ign switch or anything either.

I've had an SC40 on two vehicles now and works a treat - install and forget. :D

There's others like Redarc, Pirahna but they are dearer.

[buzz66]

Don't waste your time on electronic controllers, they are a waste of money.
Use the solonoid you have there and either make it activated by the Alternator or the Oil Pressure switch.
Mine is activated by the Alternator, so when the engine is running the battery's are in parrallel. It gets a little to tricky to wire it up to the Alternator sence output Terminal D+. You need to use a very small current relay or it kills the self excitation of the alternator. I used to have a drawing of this installation but Yahoo, fixed that. I will do it again and put it up here.

[PhilipA]

And place a fuse in the trigger wire for the solonoid. A friend in WA had a solonoid go short circuit ( must have been to earth) to the trigger wire and burnt out all his underbonnet wiring . Regard sPhilip A

[weeds]

i used this setup for years on my 2 door rangie and worked a treat........i can not see a problem having two differant batteries, well i didn't although i did join them with full size battery cable, there would be heaps of this setup out there

my defender came with a marine controler which works fine

[Vern]

Don't waste your time on electronic controllers, they are a waste of money.
Why is that? I have both and both work fine, prefer the way the electronic one charges the main battery first though!

[rovercare]

Why is that? I have both and both work fine, prefer the way the electronic one charges the main battery first though!

Show off:p

I got a dumb solenoid, via ignition on and a switch on the dash, although it can be kind of embarrasing if you have to jump start yourself if you inadvertantly flatten the cranker enough that it don't pull in the solenoid:D, but I always carry leads and only had to twice, once before my stereo was set up on the aux, the other was my cranker was shagged

[d2dave]

Hi all

Did a quick search but was unable to find an exact answer...

On my old range rover I had a simple heavy duty solenoid for my dual battery set up and never had a problem in 4 years.

The battery box in my DEF130 is a wiring nightmare with some weird looking dual battery controller that I think has finally died. I purchased new batteries just after I bought the truck in April and my aux battery is now not charging.

I am going to rip out all the dodgy wiring and go back to a simple solenoid.

Can anyone give me the cons of using a heay duty solenoid?


https://www.aulro.com/afvb/images/imported/2009/10/1742.jpg

The two large terminals are for each +ve battery lead, one small terminal is an earth and the other small terminal is to ignition.

Cheers
Andrew

There is nothing wrong with this set up. I have been using one of these since 1993. First on my RR and now on my disco.

When I had it on my rangie I had it wired to my ignition switch. I once left my ignition on and flattened both batteries.

When I put it on the disco I connected it to the alternator so it only connects when engine is running.

When I purchased mine it came with a Diode across the small terminals. I was told this was to prevent a spike when ignition was turned on. I'm guessing this would not be necessary when wired to the alternator as it is charging at the same time it is connecting the two batteries.

Can post pics if you want.

Dave.

[isuzurover]

I have an SC40. Quite happy with it.

[86mud]

Thanks for all your responses.

the current unit that is in my truck comprises of two components - one looks like a type of solenoid and one looks like a type of controller all connected with wires going everywhere. I will take a photo on Saturday to explain.

It currently has a lead coming from the alternator which I take it activates the control unit.

In my old Rangie I had the ignition from the coil and never had a problem in four years.

I looked at the SC40 & SC80 on the Traxide site. I also looked at the Baintech units. So now I have 3 choices!!!!

Cheers
Andrew

[buzz66]

Why is that? I have both and both work fine, prefer the way the electronic one charges the main battery first though!

Why.... Most Alternators are more than capable of charging both Batteries at the same time.
So your controller is charging the main battery first while the Alternator ticks along with 30 AMPS of more of spare capacity. Like I said electronic controllers are a waste of money.

Here is the best Aux battery setup coming from an Avionics Engineer...;)

.
https://www.aulro.com/afvb/images/imported/2009/10/1681.jpg

[roverrescue]

Out of interest Andrew,
what are your requirements?

For our style of weekend camping / touring / week long fishing trips I have no need for isolated batteries but a need for maximum winching current.

In the 130 I run two N70 marines parralleled with heavy cable. All accesories including fridge run off the two batteries.

Weekend camping, no worries, engine will always be started before the battery bank is even close to being discharged. Touring same thing, from two big marines our SS40 Engel will go 2.5 days and the fender wont even stutter on start... most touring stops for us are less than that, and the longer ones always require a firewood run or some such. And on week long fishing camps, well no dual battery system will simply allow for that so you need external power. We use a honda.

BUT when winching is required, two parralelled N70s will give more poke than any isolated system, besides a complicated system where you put in a manual switch to join them for winching.

I use to use a rotronics with one cranker and a deep cycle batt, but get more fridge run time out of two N70 marines. Just have a voltmeter you can check on until you know the current draw of the fridge.

Simplicity

S

[86mud]

Requirements are:

80 litre waeco
Roof mounted DVD player for the kids
two Burn Bright fluro lights http://www.burnbrite.com/pdf/TNB8%20Portable%20Fluorescent%20Lead-Light.pdf

and a shower pump made using a small bildge pump.

The lights would only be used for say 4 hours at night and the pump would be running continuously for say 20 minutes (2 kids + adults) max at night.

Cheers
Andrew

[86mud]

here are some pics of the current set up/mess...

once I position the new solenoid, I might get myself a fuse block and tidy up the wiring as well..

[Vern]

Why.... Most Alternators are more than capable of charging both Batteries at the same time.
So your controller is charging the main battery first while the Alternator ticks along with 30 AMPS of more of spare capacity. Like I said electronic controllers are a waste of money.

Here is the best Aux battery setup coming from an Avionics Engineer...;)

.
https://www.aulro.com/afvb/images/imported/2009/10/1681.jpg
didn't really tell me why an electronic one is a waste of money

[isuzurover]

Why.... Most Alternators are more than capable of charging both Batteries at the same time.
So your controller is charging the main battery first while the Alternator ticks along with 30 AMPS of more of spare capacity. Like I said electronic controllers are a waste of money.

Here is the best Aux battery setup coming from an Avionics Engineer...;)


So just because an engineer says you should do it you believe it???

There are quite a few engineers on here, who I am sure would have a range of dual battery systems.

Personally, I would use a marine switch before a solenoid. And probably will use an HD marine switch on the IIA, as it will mainly be used for short trips and winching...

I like the electronic system (SC40) on the 110 because:
(1) it will draw power from both batteries until the main battery voltage drops to a set threshold
(2) it will charge the cranking battery first - I only have a 40A alternator, so I am sure it is flat out running the electrics and charging 1 battery at a time, let alone two.

[HangOver]

i found a solenoid to be a good cheap solution the only drawback for me is remembering to flick the swich on/off.

[drivesafe]

Don't waste your time on electronic controllers, they are a waste of money.

i found a solenoid to be a good cheap solution the only drawback for me is remembering to flick the swich on/off.

This is the main problem with using a manual set up and why they are called idiot switches.

You only have to forget once and you can easily stuff a battery and then you end up paying more than one of these electronic controller would have cost you in the first place.

[rangieman]

This is the main problem with using a manual set up and why they are called idiot switches.

You only have to forget once and you can easily stuff a battery and then you end up paying more than one of these electronic controller would have cost you in the first place.
I know what your saying and i use one of your controllers and are more than happy with it:D

What Hangover is saying is right as much as you are , i used to run the old solenoid set up with a switch to isolate the 2 batterys and were more than happy with the job it did (if you remember the switch , which i never forgot it)
Some people live in the past and are scared or cant afford a flash electronic jobbie or maybe not happy with all this electronic stuff , each to there own :cool:

[austastar]

I did have a problem with a Rotronics isolator when I had a strange wiring in my truck.
I had wired the headlights into the domestic battery, which worked fine for years using a diode isolator between the two batteries.
The diode isolator got 'accidentally' cooked on one trip when a battery was put in the wrong way round, and very expensive lesson on why wires should have fuses was learned as all the smoke escaped from the circuitry.
That is when I wired in the Rotronics, and was happy with it for a long time, till the domestic battery started to fail.
Syptoms:
Start vehicle, turn on headlamps.
No headlamps till vehicle battery was charged then headlamps would come on.
Then the load of a dicky domestic battery and the headlamps would pull the voltage on the vehicle battery below the critical level - then no head lamps again.
Repeat ad nauseum for hours.
Moving the headlamp circuit back to the main vehicle battery fixed the problem till I could replace the domestic battery, and have left them there.
The idea was to have some insurance against leaving the headlamps on, but it turned out that the cure was worse than the problem.
cheers

[d2dave]

I know what your saying and i use one of your controllers and are more than happy with it:D

What Hangover is saying is right as much as you are , i used to run the old solenoid set up with a switch to isolate the 2 batterys and were more than happy with the job it did (if you remember the switch , which i never forgot it)
Some people live in the past and are scared or cant afford a flash electronic jobbie or maybe not happy with all this electronic stuff , each to there own :cool:

I am not scared of, and can afford a fancy electronic isolator I just can't see the point in spending a lot of money on a device when a $30 solenoid does the job just as well.

Dave.

[slug_burner]

Why do you guys have an aversion for electronics and want to use huge ugly mechanical switches? We all have accepted that we turn the key, the relay/solenoid pulls in and the starter motor cranks. If you are so concerned about the reliablity of relays and electronics, I have a big push button on the floor of an old mini you could use to replace the solenoid and ignition switch.

[rovercare]

Why do you guys have an aversion for electronics and want to use huge ugly mechanical switches? We all have accepted that we turn the key, the relay/solenoid pulls in and the starter motor cranks. If you are so concerned about the reliablity of relays and electronics, I have a big push button on the floor of an old mini you could use to replace the solenoid and ignition switch.

Yea, your right, although having spent massive amounts of time in my life, working with PLC/SCADA/various types of HMI automation, automated prot., wiring EFI engine conversions, I have a stoopid Isuzu RR with a dumb solenoid, why? cause it works everytime I need it to:D albeit, without the finesse:)

[d2dave]

Why do you guys have an aversion for electronics and want to use huge ugly mechanical switches? We all have accepted that we turn the key, the relay/solenoid pulls in and the starter motor cranks. If you are so concerned about the reliablity of relays and electronics, I have a big push button on the floor of an old mini you could use to replace the solenoid and ignition switch.

When you refer to big ugly mechanical switches I assume you are talking about the solenoid, yes?

Dave.

[Rosscoe68]

I have a big push button on the floor of an old mini you could use to replace the solenoid and ignition switch.

just dont mount it on the floor like leyland did in the mini. my old mini would die totally for about 10 seconds every time i hit a puddle of water. took me ages to work out it was the starter switch in the floor that was getting wet and must have been shorting out cutting all the electrics.

at least a D2 TD5 ecu if it gets wet you can blow dry it and put it back and away you go.

my HID lights played up one time after i had a laser car wash. turned out the mechanical relay in the control unit had water in it. the rest of the electronics still worked fine, just one relay latched on even thought the dashboard lightswitch wasn't on. relay needed replacing due to water and corrosion after a while. electronics still going good after a dose of pc board cleaner.

so much for reliable old switches and solenoids.

[slug_burner]

When you refer to big ugly mechanical switches I assume you are talking about the solenoid, yes?

Dave.

No, the big Marine Switch

[Blknight.aus]

check your alternator you may find that it has a second output which is isolated from the one that currently charges your batteries. IF it does just plumb the second battery up to that and you're set.

[adonuff]

Hi Andrew I have one of the electronic controllers think it cost me around $100.00 it has worked really well for 3 years now and been fitted to two different vehicles. It is simple to wire in requires one wire to + on main battery and one wire to + on the aux battery the - on the aux batt then goes to the nearest suitable earth.

Would reccomend when you tidy up around your battery get rid of all the crimp terminals and use a soldering iron with heat shrink for insulation of any joins or live terminals.

Send you a few pics of mine if you like.

Andrew

[incisor]

crimp terminals done with a proper crimping tool can give you much better service in a world filled with vibration than a soldered fitting...

each has their place IF done correctly....

[fraser130]

crimp terminals done with a proper crimping tool can give you much better service in a world filled with vibration than a soldered fitting...

each has their place IF done correctly....

I've crimped, then soldered, then heatshrunk all my connections.:D

Fraser

[garciaj]

buy a marine set up like a BEP brand, fully automatic and doesn't cause any issues. I brought a flash opposite lock set up for my disco and wasn't really happy with it at all but I brought a marine set up for my boat from BEP and its work excellent. I'll be buying the same for the disco.

[ScrubPleb]

Another problem with operating the solenoid directly from the ignition is that it can mask the condition of the main battery. When the main battery is reaching the end of it useful life it will have enough capacity to operate the solenoid when the ignition is turned on but may not be able to deliver enough current to crank the engine. The aux battery will be supplying the cranking current. This will not become evident until the aux battery has been used to supply an aux load while it is isolated from the main. If the aux battery voltage has dropped too low you will find yourself with two flat batteries.

[vnx205]

I've crimped, then soldered, then heatshrunk all my connections.:D

Fraser

So, not just a "belt and braces" man then.

More of a "belt and braces and keep the hands in the pockets" man.:D

[86mud]

Job done

Ended up going with a BEP Marine - Voltage Sensative Relay

Cleanup the wiring as well..

[slug_burner]

looks neat

[d2dave]

Another problem with operating the solenoid directly from the ignition is that it can mask the condition of the main battery. When the main battery is reaching the end of it useful life it will have enough capacity to operate the solenoid when the ignition is turned on but may not be able to deliver enough current to crank the engine. The aux battery will be supplying the cranking current. This will not become evident until the aux battery has been used to supply an aux load while it is isolated from the main. If the aux battery voltage has dropped too low you will find yourself with two flat batteries.

I had a similar problem when I had the solenoid in my Rangie.

When I changed to the Disco I wired it to the alternator so the solenoid does not kick in until the engine is running which eliminates the above and virtually makes it idiot proof.

Dave.

[drivesafe]

I’ve watched this thread and not posted much but I’ve just posted some of this info on another thread and it has a place on this one as well, because there is a case of horses for courses and you really need to know what's available and what will best suit your needs.

Idiot switches ( and this is not a derogatory term but a commonly accepted term to describe this type of set up ) are cheap, depending on how you intend to use them.

If you want a simple system that is only on while the motor is running, they are fine but they are not suited to being used while the motor is of because they require a fair bit of current to keep the solenoid powered.

Again this is not a problem with the motor running, but if you want some extra power while you camping, my SC40 and SC80 because of the way they work ( and is unlike any other DBS on the market ), you not only increase your auxiliary battery’s stored usable capacity by at least 50%, turning say an 80 Ampere/Hour ( A/H ) battery into a 120 A/H battery, but because it does this by using the surplus capacity of the cranking battery, you get a bigger battery at no extra cost. This actually works out cheaper than an idiot switch and you don’t have to remember when to operate it.

There are a number of other advantages, the obvious one is the automatic increase in stored capacity at no extra cost.

Because you are spreading the load over two batteries, you will help extend the operating life span of your auxiliary battery, another cost saving.

Again, because you are spreading the load over two batteries, so you will not need to take either battery down as low as you would have to do with any other set up, including an idiot switch set up and this means because the batteries weren’t as low when you start your drive, you will actually charge them in a much shorter drive time between free camping sites.

So, fitting the RIGHT Dual Battery Controller can actually work out much cheaper, immediately and in the long term, than fitting an idiot switch.

[jx2mad]

I have one of these solenoids on my defender dual battery setup and it works well. With the ignition off the batteries are isolated from each other . On initial startup the motor is fired off the main battery and when the alternator kicks in the solenoid parallels both batteries. If the starter battery is low I have a non locking button on the dash which pulls the solenoid in , parallelling the batteries and allowing the motor to kick off the secondary battery. Jim

[up2nogood]

I have no real idea how to hook these things up, so any help appreciated!
And sorry if this is a wee hijack..... I was planning on running the winch from the aux battery. Is this wrong?

I have 400A marine switch for making the two connect if mega voltage required. Does an aux battery actually connect poles with a main battery? I'd hate to think what would happen to a bettery controller caught between the two when winching.

I have an SC80 I've not yet fitted, are they for charge management only? Should you connect your aux and main batteries in extreme conditions (winching in the poo).

[alien]

I have no real idea how to hook these things up, so any help appreciated!
And sorry if this is a wee hijack..... I was planning on running the winch from the aux battery. Is this wrong?

I have 400A marine switch for making the two connect if mega voltage required. Does an aux battery actually connect poles with a main battery? I'd hate to think what would happen to a bettery controller caught between the two when winching.

I have an SC80 I've not yet fitted, are they for charge management only? Should you connect your aux and main batteries in extreme conditions (winching in the poo).

This thread ran not long ago and it might help you..http://www.aulro.com/afvb/technical-chatter/84032-best-dual-battery-setup-winching.html?highlight=whinch
Plus it saves me saying my 2 cents again.

Cheers, Kyle.

[up2nogood]

Sweet, thx!