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Showing my ignorance about split charging


unclebill

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OK I admit it, that eletrickery stuff baffles me a bit, cant see it.

So thinking about an extra battery on board to boost up the system for winching, up to now I've been using a single heavy battery in the disco, v8 so problems to find the room and using a electric winch, never really had any problems but touch wood haven't had to use the winch a great deal.

Now thinking about being a bit more competitive and fitting a second battery.

Now why cant I just link the two batteries in parallel, still get 12 volts and presumably charging should be the same, just longer as the capacity is larger, so the question is why a split charging system and there lies my ignorance, so can anyone enlighten me.

Cheers fellas( and gals of course)

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You can if you get two batteries of exactly same spec, but over time you risk damaging the batteries. No two are or stay the same and so you get constant discharging and charging between the two batteries.

A split charge system solves this issue. Don't go spending silly money on one though. Just visit X-Eng for their split charge solution for around 30 quid

Cheers

Steve

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Guest diesel_jim

To add fuel to the fire.....

on all my rovers i've run twin alternators (especially easy on a V8 withought A/C as you can buy the brackets off the shelf).

that way, you have a totally separate system for running the winch, and say, for example, you have a 100A alternator as your main one, and a second 100A for the winch, then you'll have 100a charging your winch battery, as opposed to 1/2 that (approx, depending on the state of the main battery) when the one alternator is split to two batteries.

Not that i'm knocking the split charge, i'll have to go to that when i fit my york compressor to my Tdi, but if you have 2 alternators fitted, then you can link them (with both batteries) and get double the charge, and if one of them dies, then you can switch to the "other" one which is already fitted to your engine ready to play! B)

at the end of the day, it's really up to how you want to rig your truck. i'm sure there will be plenty of other posts to this thread.

jamie

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And another view: I voted for a twin matched batteries in parallel. Simple but also gives twice the power if you need it for winching than split charge with one bat for vehicle and one for winch.

If I do change it I'd like to fit a second alternator running 24v then I'd leave one bat on 12v for the vehicle and have a pair in series to give 24v for the winch.

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if Purely for winching, i'd say two batteries in parallel, simple as that.

that way you get twice the capacity for winching, but the downside is you have no protection of your cranking ability, which isn't really relevant for just winching.

for overlanding/cranking protection/running things with the engine off, i'd suggest a VSR (voltage sensitive relay) less wiring than an alternator fed relay, and more robust. (sorry Si)

Luke

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if Purely for winching, i'd say two batteries in parallel, simple as that.

that way you get twice the capacity for winching, but the downside is you have no protection of your cranking ability, which isn't really relevant for just winching.

for overlanding/cranking protection/running things with the engine off, i'd suggest a VSR (voltage sensitive relay) less wiring than an alternator fed relay, and more robust. (sorry Si)

Luke

No need to apologise - it is a better solution under some circumstances, but at a cost.

The single most improtant reason for a split charge is simply that if you connect two lead acid batteries in parallel, it will, over time damage them. Reason in a minute. There is talk of matched batteries. Two identical batteries, of the same type do not qualify as matched. Matched means that the plates have been trimmed to achieve exactly the same properties. You can buy Hawker Cyclone batteries in matched bundles, but generally not car batteries.

The reason for the damage is that lead acid does not like being trickle charged. It causes a build up of deposits on the plates and causes an effective reduction in max current delivery and capacity - although the terminal voltage will stay the same.

But, it's not being trickle charged? When you switch your vehicle off, it is likely that one battery will have a little more charge than the other. The one with the more charge, tries to charge the other one. Because the difference is very small, the charge current is very small - hence the trickle charging. In an ideal world, the batteries would even out pretty quickly. However, it over-shoots a bit and now charge is pushed the other way. This goes on until both are flat!

It may take months to flatten a battery this way - but the damage from the trickle charging is cumulative.

The oldest of my Optima yellow tops is now over 7 years - not bad for any battery, never mind one used for winching etc. The trick is just to look after them.

There are lots of solutions to the problem, many better than the X-Eng one - but few as cheap and simple!

Si

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Bill,

Putting a second battery on a disco is pretty straight forward, with minimal running of cables:

2ndbattery2.jpg

Cheers

Mark

Cheers guys, it makes sense now, OK rethink time for me, but I see a solution and cheers for the picture Mark, but mines a 300 and the snorkel plumbing goes through there as well.

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Check out the this auto split charge system from Antares. I have just put one in a Jeep TJ Wrangler they reatil at £100. It sorts out and charges as needed. Have a standard Batt plus an optima for the winch. All seems O.K and very simple to wire in. Used for commercial and marine applications, so should suit a winch set-up. Options for 2nd Alternator or 3rd batt can be introduced.

http://www.antares.co.uk/products/asc_133.htm

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Check out the this auto split charge system from Antares. I have just put one in a Jeep TJ Wrangler they reatil at £100. It sorts out and charges as needed. Have a standard Batt plus an optima for the winch. All seems O.K and very simple to wire in. Used for commercial and marine applications, so should suit a winch set-up. Options for 2nd Alternator or 3rd batt can be introduced.

http://www.antares.co.uk/products/asc_133.htm

that's a nice VSR! higher rated than the BEP VSRs, is the winch on the first battery? does the VSR cut out on high load winching(ie voltage drop)?

Luke

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that's a nice VSR! higher rated than the BEP VSRs, is the winch on the first battery? does the VSR cut out on high load winching(ie voltage drop)?

Luke

The winch is on the 2nd Batt, No tests have been done at present to see how it performs under high load. If the VSR does cut out charging the "2nd batt" on high load? Making the Winch batt the pimary Batt should sort it out. Keep ya posted on the outcome, going out to test the setup next Sunday.

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can see the trouble being, if the winch gets enough load on it to drop the voltage, the VSR will cut out, leaving you with only the one battery when you need it. be interested to hear what happens.

Luke

the answer to that is to wire a cut-out switch in parallel with your VSR, then you have manual control of your batteries aswell.... and for heavy winching you can flick the switch, link them all together and you're not drawing the winch amperage entirely through the VSR..

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Yup, but that kinda defeats the object of having an automated switch, if the VSR does drop out, (voltage drops to 12.65 - 12.8 Vdc) under heavy winching, an ignition fed relay is the better solution, as long as its rated to the current draw of the winch.

'course, i don't have any first hand experience of this, I've got a VSR but not a winch (nasty electric things, oil! oil! ), so i'm interested to see how it goes, for general use the VSR is great.

Luke

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Yup, but that kinda defeats the object of having an automated switch, if the VSR does drop out, (voltage drops to 12.65 - 12.8 Vdc) under heavy winching, an ignition fed relay is the better solution, as long as its rated to the current draw of the winch.

'course, i don't have any first hand experience of this, I've got a VSR but not a winch (nasty electric things, oil! oil! ), so i'm interested to see how it goes, for general use the VSR is great.

Luke

luke, the other good thing about wiring a key switch in parallel with your VSR, is that if your engine start battery goes flat, you can link them together and jump start yourself...

i followed the instructions supplied from merlin equipment, and the wiring diagram shows a key switch in parallel for this very reason..

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fair dinkum, if that's what merlin says.

if you parallel a flat battery with a full battery you end up with two half charged batteries. convenient yes, effecient no. on the two occasions when i've flattened my cranking battery i've just swapped over the battery leads.

Each to their own.

Luke

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