X-Eng Dual charge, to buy or not to buy?

IamRobbie said:

DURITE Split Charge Voltage Sensitive Relay 12V 140A 0-727-33 | eBay

any good?

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Aye that'll do the job.

If you're going to connect batteries in parallel, use 50sq mm welding cable which is flexible and double-sheathed.

A simple contactor that is controlled by the alternator light or oil light switch is all you really need, Albright International do some nice kit, we use a lot of their contactoirs in our railway chargers, very good quality and reliable.

If you are running the control from the alternator light you need a small relay in between the alternator warning light connection and the contactor, the connection goes to 14V (approx) when the engine is running, the oil light switch goes open circuit from ground when the engine is running so different logic needed for the relay.

Parallelling batteries doesn't do any damage at all, but for the most effective setup, they should be of similar age and condition and similar capacity if possible.

There are other options, but for 90% of people, these will work fine.

We have a small 5000lb winch in the back of the trailer to load the Ruston engine, that winch has its own dedicated battery, charger and solar panels to keep it charged.

Peter

Quote:
Originally Posted by IamRobbie View Post
DURITE Split Charge Voltage Sensitive Relay 12V 140A 0-727-33 | eBay

any good?

Aye that'll do the job.

That's a good set up, if you use this type with the winch wired to the second battery this will keep charge in the starting battery. Nothing worse than an engine stall after winching and having a flat start battery.
As Pikey mentioned earlier you could also put a cut off switch between both batteries. This will allow a good link and you can jump start yourself from the comfort of the cab when not winching.
Also with the relay connected to the oil light or alternator light can cause problems if the second battery is very flat it will take charge from the starter battery and can flatten the starter battery. If you have an ECU on the lr (td5 etc.) Then you may get to a state where there is not enough voltage for the ECU to work.
Hope this helps.

So keep it basic and have that intelligent relay in between the batteries, do i bridge over the earths to each battery or is it just the positive?

Also what kind on amps will i need for this relay because they do 70 amp, 140 amp ect.. Would 70 be enough or is it best to go for 140?

IamRobbie said:

So keep it basic and have that intelligent relay in between the batteries, do i bridge over the earths to each battery or is it just the positive?

Just positive

Also what kind on amps will i need for this relay because they do 70 amp, 140 amp ect.. Would 70 be enough or is it best to go for 140?

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go for 140Amp, that way if you upgrade the Alt to an 100amp unit you won't need to change the relay.

Ok brill, ill order one, my last question, how does the alt keep up if the winch pulls say 2 300 amps? Does it just drain the battery and then when u stop for a while it puts the amps back in?

IamRobbie said:

Ok brill, ill order one, my last question, how does the alt keep up if the winch pulls say 2 300 amps? Does it just drain the battery and then when u stop for a while it puts the amps back in?

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Basically yes. Hence why the relays cuts the link between the batteries once the voltage drops below 12v or so. then when the load is off The batteries voltage goes up and the relay links them both together again. Thus preventing a flat main battery.

Awesome, I think i have some battery cable from a 200tdi disco i stripped. Ill get that 140amp relay and ill hook it up when it comes! I think i may need to upgrade my alt anyway because when i winch the belt starts squealing its tits off..

If its a std A127 alt you can also uprate that for under 20 quid to give slightly higher voltage

how? i have a disco 200tdi engine in with the alt that came with that.

IamRobbie said:

how? i have a disco 200tdi engine in with the alt that came with that.

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See here http://www.landyzone.co.uk/lz/f7/handy-tip-get-best-out-a127-alt-250306.html
I did think at the time the total lack of replies meant one of two things, either people didnt give a toss or much more likely they were frightened of doing something out of the normal.
I have since converted my 1959 tdi series 2 the same way and again its the exact same results, very pleased, ps its got a disco engine so same set up as yours.
Dead simple and very worthwhile mod.

Awesome ill take a read now.

OK seems simple enough, any chance you could get a pic of how you have fitted the resistor in line? is it a plug and play jobbie?

on mine I have two batteries directly linked on my TD5 , its a simple setup and seems to work well as both batteries are basicly the same , starts well,winches fine and has no problems

I once did winch so hard on the other 90 the winch killed the battery and cut the engine at the same time , could barely get ignition lights and defo not starting.....since using the twins in this setup I have had no problems

just get a T-max and fit and forget.

Press a button when you drain the main battery playing with your winch, and your golden.

Twin alternators and a switching system is the best way. True split charge as there independent and if you kill an alternator in the gloop you can use the other to get you started and home by linking the batteries together.

IamRobbie said:

OK seems simple enough, any chance you could get a pic of how you have fitted the resistor in line? is it a plug and play jobbie?

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Resistor is tiny bloody thing, bit of careful trimming and using two red heat shrink crimp fittings covered the resistor and allowed me to join the wire into each side, my aim was to make it waterproof for obvious reasons
I think the resistors were 99p for ten delivered
Vid of s2 one switching things on and off and very little voltage drop Battery sensed A127 alternator mod Land Rover Series 2 TDI - YouTube

Going by the switches its was in the order of
sidelights
headlights
heated screen
rear halogen worklamps x 2
the electric cooling fan
Remember thats all together so quite some current draw
Before mod battery voltage would be down to low twelves if I dared to switch the lot on together

I'm defiantly going to do this mod! Should help keep the battery topped up

`sorry to hijack the thread but wanting to put twin batteries on my p38 which bits do i need to buy any ideas please im a complete knob with electrickery

well this is the question mate

Do you go for a second battery and a fancy twin charge system or a basic one or a 2nd alt?

second battery basic split charge