Split Charging System - Upgrades!

[mahon257]

So, I thought I'd share my latest mini-project with you chaps... A split-charging system "upgrade".

Here's the deal... I have an "IBS" split charge system, which is based around a 100AMP relay - whose job is to join the main battery, to the aux battery, and protect the state of charge of the main, to make sure you can always start the car.

This is great! For running a fridge/freezer, or lights etc, from the Aux Battery. But... what if you want to:

a) Start the car from the aux battery?

b) run a winch from both batteries?

Well, with a 100AMP relay - put simply, my experience is that you can't!

So, here's what I've done... 1st, we've gotta deal with the 100AMP relay. We need more beans!. I've tried a couple of solenoids (eBay £25). They we not up to it. My winch draws (at peak load) 600AMPs! So, what can make an electrical contact, that can handle a load of 600AMPs?

The answer my friends is a "contactor" - as used by your local milkman in his milkfloat!. Search google for "SW80B-5, Albright single acting solenoid contactor 12V continuous".

Before I continue, I should point out that I'm most definately not an electrician - and not qualified in anyway, other that with enthusiam. So excuses over with, here's what I did:

Step1:

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Make a box with removable lid, to house the new electrics. see "box_b.JPG", and "box_complete.jpg". I made mine from 1.2mm Sheet aluminium + rivets, and the lid is secured via a couple of rivnuts + m8 bolts

Step 2:

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Buy, 2 x "contactors" (one for the 2 x batteries, 1 for the winch), 2 x 30 Amp relays with blade connectors, some 8 amp wire, crimp connectors,

2 x inline fuse holders, 2 x 8amp blade fuses

Step 3:

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Bung that lot in your new box - see "Soleniod_box_version2_a.JPG" and "Soleniod_box_version2_c.jpg".

Step 4:

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You now have 600+ AMPS available from your split charge system!

Of course, there was a bit more to this than I have explained - so if anyone is interested in what I've done - be happy to provide further details...

My final solution is that the IBS system works exactly as before, except this time it is indirectly (via a 30 amp relay) controlling a 600+AMP connection between the 2 x batteries. In addition, I have installed a new on/off switch on the dashboard, that controls the 2nd "Contactor". The job of the 2nd is to join the 2 x batteries to the winch - thereby enabling me to disable the winch from inside the car...

[Adam001]

Good work, I have always said that the 100amp relays used in these kits are absolute pants, including the x-eng offering

I like your solution, I just have a bigger relay in mine 200amp continuous which I use happily for low load/short duration winching (where the winch will draw 200amps from each battery). But I can just disable it for bigger winching jobs suits my 110 perfectly

[mahon257]

Forgot to include specs of the "contactors" - see attached pics. Should also mention, that there are beefier "contactors" available - but these were fit for my set-up.

[martifers]

Good work, I have always said that the 100amp relays used in these kits are absolute pants, including the x-eng offering

I like your solution, I just have a bigger relay in mine 200amp continuous which I use happily for low load/short duration winching (where the winch will draw 200amps from each battery). But I can just disable it for bigger winching jobs suits my 110 perfectly

X-Eng's is a 180amp continuous or 250amp for short durations. Have to say Adam, has done the job so far... But if I were to have problems then this does seem like a solution.

[outdoor_ian]

Hi

How much does one of those contactors cost approx ?

Cheers

[mahon257]

Hi

How much does one of those contactors cost approx ?

Cheers

I paid £68.49 for 2, inc. postage. See here

I should also mention, they ain't weatherproof - so you'll to make something to put then in (i.e. like the ali box I made).

[JohnnyB_300TDI]

Will the cables get "hot" if you subject them to serious load?

By serious load I mean aux battery is flat and the split chage shorts them together.

Has anyone tried a split charge like this with a flat battery?

[ricky tango]

hi mate can you do a wiring diagram of the whole system ? to show how they connect in to the relays and how the relays connect in to the vehicle

[mahon257]

hi mate can you do a wiring diagram of the whole system ? to show how they connect in to the relays and how the relays connect in to the vehicle

Here we go (apologies for the dodgy drawings - wiring ain't my thing)

I've attached the original IBS version, and a modified diagram showing 1 "contactor". As I mentioned, I have a 2nd Contactor that joins the winch to the 1st contactor (i.e. to 2 joined batteries) - but I've left that off this diagram - as it kinda over-complicates things!

[mahon257]

Here we go (apologies for the dodgy drawings - wiring ain't my thing)

I should also explain why the +'ve lead goes from the AUX battery to the relay "30" terminal.

Of course, once the engine (alternator) is running - it doesn't matter which battery you use to power the contactor. You could run this cable from either battery... but in my case I was planning to join to 2 batteries using the AUX battery to power the contactor - in case the Starter Battery ever goes flat (it does that on my car).

In addition, I have an 80w Solar panel on the roof that charges the AUX battery. So, in theory, as long as I have access to some sunlight - I should always be able to get the car started!.

I've also missed a fuse off the diagram! Doh... From the Starter Battery "+", to relay "85", (8 AMPS)

[mahon257]

One final note... have tested this system by intentionally running main (starter) battery flat - left the headlights on for a few hours!

By pressing the "link" button on the IBS unit, I was able to immediately start the car from the AUX battery - which is something I couldn't do before when was just the 100amp relay.

Awesome!