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split charge


moose
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Afternoon, after some input from any body who has set up a split charge system..

First iam not a sparky in fact being colour blind means i like to stay away from wiring jobs if i can :D

At the weekend i was winching through a bog and stalled out my which with a riding turn :ph34r:, which then drained the battery in few sec and stalled the engine. So there i was in the middle of a deep bog with no power thinking about the deep cycle battery that was sitting at home :huh:

so whats the best way to connect it all up with the one alternator...

I have thought about a split charge relay, but this means (if understand it) that power will be drawn from both batteries, the disadvantage being in that a heavily discharged auxiliary battery can drag down the engine battery voltage, due to imbalance.

other option seems to be a split charge diode, the diode block splits the alternator output whilst isolating the batteries from each other. This should prevent one battery discharging into the other, but i have head that there can be a 1v drop over the diode....

I have also seen battery management systems but they ££££ ....

So whats every one on here done?

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Depends really on what and how much you want to use it ?

Fit 2 x biggest batteries you can fit and parrallel them up 2 x the current and many use this on here with no problems

Fit a Diode based system and as you say it will under charge by 1-2 volts fupped battery and as it undercharged and hence poor performance

Fit a X-Eng split charge system which is dead easy to do and recomended, But if your running serious winching with a big alternator it can be a bit to much, but for normal use prob the second best way

But I just fitted a second alternator just for the winch battery ;)

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I have fitted a split charge in my disco, went to my local motor factors and got one that the boy racers use for their ice systems, extremely simple to fit.

Fitted a switch in the wiring so i can turn the split chatge on or off

I use my secound battery for my winch

Russ

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Have a read of this, might help explain the options a bit.

what size voltage sensitive relay (VSR) did you use? ... eg a 125A

So from your link am i right in saying that the (VSR) will open saving the engine battery if the aux battery is drained and takes the engine battery under 12.8V's ?

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Moose, for what you need an X-charge and a couple of HD batteries will be fine. Deep cycle is OK but your winch motor won't like operating on low voltage (much more heat but much less turning as the volts drop, very easy to kill a motor). As I understand it if the battery light comes on the X-charge will disconnect anyway so if you wire the winch from the "aux" battery and connect the alt to the main battery you shouldn't flatten it.

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I've not used a VSR for winching situations, but i suspect relay 'chatter' (hysteresis) may be a problem.

If the winch current exceeds the alternator output current, the voltage will drop, as the winch draws from the batteries. This will cause the VSR to open, which will recharge the engine battery quickly, but leave the aux battery on its own to cope with the winch. Then the VSR will close as the main battery is charged again, then it'll open again as the batteries are parallelled, the winch draws current etc etc.

In short, a VSR is more suited to 'engine off' situations.

A heavy duty relay such as X-eng's Durite relay is probably the better way to go.

Ultimately, unless your alternator outputs the same current as the winch draws, you are running on borrowed time as you flatten the batteries. The size of your battery bank determines how much borrowed time you have. The output of the alternator determines when you operate on this borrowed time, and how quickly you can earn it back, when you're not winching.

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I heard that the relay/diode systems can create spikes which can damage ECU's. OK for cars with carbs etc, but do you want to run the risk of damaging the ECU?

For this reason I have gone down the Piranah DB180 route. It's a dedicated dual battery management system.

The diode systems suck IMHO. I had a WARN one on my lightweight and fried it after only a few months.

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No offence streaky but I can't see that being true, the amount of nasty noise and interference that goes on in a car electrical system means that everything has to be very good at ignoring it. If spikes and back EMF killed ECU's then they would die as soon as you turned the starter or fired an injector.

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No offence streaky but I can't see that being true, the amount of nasty noise and interference that goes on in a car electrical system means that everything has to be very good at ignoring it. If spikes and back EMF killed ECU's then they would die as soon as you turned the starter or fired an injector.

None taken mate....tis a chat room after all!

I took the info from the Piranha 4x4 website though.....granted they'd probably want to sell more of the higher value units than the simple constantly rated 12v solenoids, but I didn't want to take any chances.

I've also heard this from a number of other sources outside of the chatrooms...but have yet to see actual evidence of it happening. I get paranoid about these things though....ECU's aint cheap out here!

I had a solenoid system on both of my trucks for a quite some time but as soon as I heard about the ECU issues I didn't want to chance it.

I've had to replace a few of them over the years (solenoids), the contacts probably got coked up with carbon? The Piranha has a five year warranty though....that shows the faith they have in their products.

Combine this and the type of cross country trips that I do, I wanted something abit more advanced. I still carry the solenoid as a spare though just in case. During my crossing of India I doubt if I'll be able to find a back up of either.

Regards.

S.

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