Battery question

[Lewis]

Okay, this is probably the first in a long line of obvious (to everyone else) questions relating to vehicle prep for UK challenge type events, so here goes:

My driver (is the competion sense, not chaufer) has just bought this

And the first thing under scrutiny is the electrical system. I am fairly confident in my ability to do the general re-wire but i am unsure on the battery situation.

The previous owners ran twin Optimas charged by two 85amp alternators, but for the sale the batteries were replaced by a single lead acid battery to make it drive. I am preparing the truck for hard use and giving it a complete electrical overhaul and therefore my question is this:

We want the capactity to run two 6HP 8274's, the engine (3.9V8), three fans, numerous auxillary lights, ARB compressor etc etc. I have been thinking that one alternator can charge a single red top optima to run the vehicle (ignition, headlights, wipers etc) and the second alternator can charge two yellow top optimas through an X-eng split charge system to run the winches, fans, aux lights, etc. Is this overkill?

Many thanks

Lewis

[LR90]

Is that the 110 trayback?

If you're already set with twin alternators I'd be tempted to change one to 24v. Use the 12v to run a red optima (or stock lead acid) for the vehicle and use the 24v for two big batteries in series to give 24v to the winches.

There's stuff on here about using the 6HP motors with 24v

[Lewis]

Is that the 110 trayback?

Sure is, its currently languising in a muddy field taking up valuable 90 time

I didnt make it clear in my post that neither winch is 6HP yet, we just want to make it upgrade proof

[will_warne]

IMHO keep it simple. If you want 12V winches then either a single alternator (arround 100 amps) with a split charge (one battery for winches, one for everything else) or 2 alternators (make sure they're the same) each running to one battery.

If your going 24V then a 24V alternator and 2 x your battery of choice and a 12V alternator with single battery to run everything else. FYI setups an FFR 90amp 24V alternator (cheap, powerful and tough) running a pair of yellow top Optimas and an 85 amp 12V alternator (standard on my engine) running a red top Optima. That winching setups designed for a pair of overvolted XPs at the front. With an 85 amp alternator and a split charged red and yellow top running an XP motored 8274 I never had an issue.

[Lewis]

IMHO keep it simple. If you want 12V winches then either a single alternator (arround 100 amps) with a split charge (one battery for winches, one for everything else) or 2 alternators (make sure they're the same) each running to one battery.

I wanted to keep the twin alts as they are already fitted, dont mind upgrading though

I guess my original question should have been more like "Whats required to run a pair of 8274s and a truck all day long with no issues"

Cheers

Lewis

[bishbosh]

Why optimas?

Lots of money IMHO. There are plenty of threads on here discussing batteries and or course you get two conclusions - personally I would get down to Mole Valley Farmers or similar and get a couple of large FRAM batteries. You should get both for considerably less than the cost of one Optima.

My 2p.

[Lewis]

Why optimas?

Mainly concerns about having lead acid all over the cab when the truck falls over, but also due to the optimas ability to cope with deep cycle use, and their small size. I had consisdered using 7.5ton truck batteries as i can get them cheapish but discarded for the above reasons

Did the bolts arrive? - posted yesterday

Lewis

[Andy]

I wanted to keep the twin alts as they are already fitted, dont mind upgrading though

I guess my original question should have been more like "Whats required to run a pair of 8274s and a truck all day long with no issues"

Cheers

Lewis

a hydrulic winch or not getting stuck? sorry someone was gonna say it wasnt they?

[Lewis]

a hydrulic winch or not getting stuck? sorry someone was gonna say it wasnt they?

I should probably get in their with "fit a diesel" too before anyone else does

[white90]

sealed lead acid batteries are just fine

optimas = mucho casho not requiredo

Odyssey are better batteries but again pricey.

I have

100amp alternator

x2 model 096 batteries from Mole Valley Farmers

[will_warne]

OK Lewis, a normal-ish 8274 will run fine with a 100 ish amp alternator, split charge and a good battery that hold plenty of charge. That all assumes good, crimped, terminals and as few joints as possible. Mine didn't have issues running like that for 15 months or so. No doubt that if you were pulling near the limit for hours at a time you'll have issues but no one has a true, 100% duty cycle, electric winch.

Battery flavour could be argued until the cows come home; there's no clear right and wrong choice. I've always used opimas in the 90 and been happy with them.

P.S. Tony's setup is very simerlar to the way mine was except for the battery choice. IMHO any more complex is OTT.

[white90]

No split charge on mine Will either.

I have fitted a battery cut off since the above pic was taken though

[Lewis]

Thanks for the info guys, especially the pic Tony, i had been working off the photo below (courtesy of gwynlewis4x4.co.uk)

So if i bought two normal batteries and wired them in parellel for the winches, but used one alternator for each batt would that work? Or am i about to get something very melty?

Lewis

[white90]

you would be wanting split charging to run twin Alternators

http://forums.lr4x4.com/index.php?showtopic=1521 for instructions on twin alternators

I would bin the twin alternators and fit just 1 either 100-120-140 amp version

connect the batteries in parallel they'll provide all the current you'll need for winching.

I've run both winches together and never been let down..

[SteveG]

you would be wanting split charging to run twin Alternators

Not when it's two independent circuits. One alternator to run battery for car and ancillaries and one alternator for two winch batteries wired in parallel for winches.

Cheers

Steve

[simonr]

OK, I have a vested interest in split charging - so I'll avoid that.

I, personally, would keep the twin alternators simply for redundancy. Fit some anderson type connectors on them so you can swap them over easily should one circuit fail.

I run Yellow tops and have had very good life out of them (5 years). Previuosly I had a red top and an orange top as the main battery and thought they were rubbish.

I think if I were buying batteries now, I would probably go for the cheap sealed batteries Tony uses.

If you have more cash, an option is to use one Hawker PC680 for the main vehicle battery and one PC1200 for the winch battery - which saves 15kg compared to a pair of Yellow tops. The main battery does not need the capacity so a 17Ah PC680 will do.

The PC1200 has plenty of current delivery (1200A cranking) for running a pair of uprated winches. Some people go for the PC1700, but the only advantage this gives is slightly bigger capacity as I don't think anyone will be drawing 1700A (yet!).

Si

[Lewis]

Okay, maybe i'm not understanding some fundamentals here , apologies to those who are going over old ground on this one

Question 1) Can i charge two batteries off one alternator? I was under the impression that the batteries didnt like it and therefore a split charge of some description is required

Question 2) Is 60mm/sq cable suffiecient or overkill to wire up the winches? And is there a cheaper supplier than VWP?

Question 3) Is it sensible to have two completey separate batteries and associated wiring - one for the vehicle (ignition, lights wipers) and one for the winches/compressor/worklights? Or should i just run two batteries in parrellel and run all of the circuits from them?

Question 4) Are the Hawker batteries similar to the optimas - do they withstand deep-cycle use and are they sealed or are they conventional acid batteries? Does anyone have a link or prices?

Your help with this is greatly appreciated

Many Thanks

Lewis

[LandyManLuke]

Split charge circuits DO put the two batteries in parallel, and charge them off the one alternator.

IMHO, the only point of having split charging is when you want to use (and potentially flatten) the auxilary battery whilst the engine is off, a split charging circuit will protect the engine battery, allowing you to start the engine.

I don't see this situation arising with competition winching, expedition use maybe, but not a day's competition when the engine will be running all the time.

(in winching terms, with the engine on) The batteries are only there to make up the shortfallings in the alternator output. if the winch(es) are drawing the 200A and you've a 90A alternator, obviously the difference has to come from the batteries, which will only get charged when the draw from the motor(s) isn't there.

Hope that helps

[bishbosh]

I have run two identical (that's the improtant bit) batteries in parallel for a couple of years with no probs and I get stuck a lot!

[simonr]

True, split charges do in general put the bateries in parallel, but the reason for having one runs a bit deeper than you suggest.

Lead acid batteries do not like being trickle charged. It's one of the reasons you need to replace emergency lighting & UPS batteries every couple of years.

If you charge or discharge two bateries in parallel, unless they are very well matched, they will wind up with slightly different amounts of charge and different terminal voltages.

If you leave them connected, one battery will pump charge in to the other. That would be fine, except it overshoots and the other battery starts pumping charge back to the first. The amounts of charge are tiny - it would take years to flatten the batteries this way - but it is just like trickle charging the batteries!

The terminal voltage will stay the same, the peak current will stay more or less the same - what changes over time is the capacity. The reduction in capacity is much harder to measure than the voltage or current and because the change is slow, most people will not notice it. You will however be reducing the length of time you can run your winch for without letting the engine charge it up.

The split charge just isolates the batteries except when they are being charged or discharged and stops this cross-flow.

If you do decide to ignore this, then at least use two new, identical batteries. This will give you the best matching and reduce the need for a split charge.

You can actually buy batteries designed to connect in parallel. Hawker Cyclone is a good example. These are Laser trimmed to make them an exact match for one another.

Si

[Turbocharger]

Where does the electrical 'inertia' come from for this overshooting? If you connect two buckets of water together this doesn't happen, so obviously my mechy's analogy falls down here.

[LandyManLuke]

Ok, i stand corrected, i wasn't aware of that subtlety.

what sort of timescale and % loss would you be looking at?

[white90]

Mine have been connected for nearly 3 years direct to one another

no problems so far.

split charging before the X charge came along wasn't so simple or reasonably priced. so you pays your money etc etc

[Lewis]

I have just spoken to a supplier and they recommend a pair of Odyssey PC1500 batteries in parallel charging through one alternator with no split charge system. They seemed to know their stuff and i'm swaying towards this route.

One thing they did say though was that lead acid batteries will not last long under competion usage, which is at odds to what a lot of you are saying, probably because they sell odyssey though

Can anyone see a major downfall or issue with this or should i just order them? Do i really need the added capacity (and cost) of the PC1500 over the PC1200?

Cheers

Lewis

[bishbosh]

Lewis,

My two batteries are no name and cost me less than £100 for the pair. Never had a problem and if I do, well I can replace them a few times before I get close to the Optima prices.....

IMHO the FIAMM setup like Tony's is the way to go.