Split charge systems

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jai_landrover

jai_landrover

Well-Known Member
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Location
Luton
OK so I have my twin batteries linked together which is great for winching etc with a huge 300A cut off switch that cuts everything!

Now I may wish to run a fridge/freezer (Beers must be cold)! at some point in the future and maybe a light in roof tent MK2 and perhaps an inverter etc.

Now I Need the batteries to be linked together when engine is running with a decent current draw and must be able to handle some current i.e winching (abuse of winch). I was looking at just bolting in a relay from an old winch to perm connect the batteries together once the ignition is on which would work great aslong as the ignition wasn't left on over night.

But its not got the appeal that some switching relays have i.e charge up eng start battery to full capacity and then recharge second batt.

So Guys What do you reccomend? It must be cheap. I do not want fan dangles digi display my 90 has enough illuminated crap to have any more.

I think I have seen one on Ebay for around £40 which does what I want just wondering what everyone else runs really
 
Something like a metro remote solenoid and a feed from heated rear screen(only on when engine running)
should give capacity and switching you require
 
Hi fanatic,

I like your thinking nice and cheap however I'm worried that its not going to allow enough amps if I abuse my winch
 
jai_landrover said:
however I could build a transistor circuit
Click to expand...

Well if you can build a circuit you are half way there :D

Mine wasn't cheap, but for idea's this is what it does.

After starting it charges just main battery for two minutes to top it up, then charges both.

When there is negative charge the batteries are isolated unless:

You press the winch assist button, where both batteries are linked untill the main battery gets to an unsafe level, then they are separated again.
Only works with the engine on.

You press that start assist button, which links both batteries for starting, useful if you have left the ignition on, but still have aux battery. Only works when off.

All the aux bits, lights sound etc run off a relay which is also disabled when the aux battery gets too low.

Devon 4x4 have some new stuff (without bling) check it out, might give you some ideas Devon 4x4 Off Road - Management Systems - Off Road Equipment and 4x4 accessories from Devon 4x4
 
Last edited:
cheers Booger thats exactly what I'm after the HD solonoid/isolator £30 not bad. The HD solonoid combined with a little circuit would be perfect. I can always have a switch then that can overide the isolation and join both batts together on a timer say for 10 minutes for starting or winching. Coolio! Now I gotta dig out my old electronics stuff to get my head back into gear. Cheers Jai
 
ok have a circuit sort of worked out ish needs a mod so I can override the 6min wait for both batts to connect. 100k ohm x 33uF (1.1 Tsec x 100000 = 110000. 110000 x 0.0033 =363 sec 363/60= 6.05 minutes. Delay should work out to about 6 mins ish give or take.

Want the overide in case of winching straight away or if starting requires a boost from the second batt. So need to put a lower resistor in on a switch but i forgot the rule with paralell resistors bumf it will come back to me i'm sure Doh.

Need to go to maplins see if I can get there at lunch time
 
My idea for a circuit would be a nice simple voltage divider (1x micro pot for fine tuning) to disconnect the battery link at ~11.7V unless override is manually activated.

Simple but effective, timer would not always be optimal.
 
Yup! its amazing how your mind goes blank when you most need it..........Oh yea its me having a blonde moment. Have some components but as always maplins dont have stock la la la so cant finish it today! Doh!
 
agreed that a timer is not optimal but i'm after cheap and reliable my electronics knowledge is er very rusty and wasn't all that great way back when.
 
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