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roamingyak

Any auto sparkies?

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Wondering if we have any resident qualified auto sparkies that have worked on expedition vehicles/ know about split charge systems etc that can sense check my wiring plans? 
I have dual Optima's fitted with a National Luna system (link) and am stripping that out and moving over to a Ctek system with all new fuse panels, battery cut off switch and so forth.
Thanks in advance if so...

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I am def. not qualified, def. not into keeping wiring original but have building looms for 30+ years.

I do not use the stuff you mention, sorry. We build everything ourselves and a bit different from what most people do.

There is not much about it, really, just follow the instructions.

There are several very good electricians here - and please have a look around to see some very, very nice write ups on electrics.

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Optimas have a poor reputation these days.

I've just read that National Luna thing you linked, god that's more awful than I realised.

What's the CTek system you're looking at?

Most importantly: What do you actually NEED?

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OK so that's about a million pounds of CTek gear, the important question is still WHAT DO YOU ACTUALLY NEED?

  • How many batteries do you have?
  • What power sources are you using? (Alternator, mains, solar?)
  • What things are you powering?
  • Are any of them critical?

 

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Posted (edited)

Thanks for the help, I understand what I need having lived in my Landy for many years, that wasn't really what I was asking for help with though.
What I was asking was do we have any "qualified auto sparkies that have worked on expedition vehicles/ know about split charge systems etc that can sense check my wiring plans" 

The plan overview is fairly standard - wire the ctec system with two batteries (red top/yellow top), a solar panel, battery cut off switch and a constant/ignition split fuse box that will run a fridge, battery charges, LED lights, air compressor and so forth.
The Ctec system is actually pretty good value, it includes a solar regulator for example, is 'field tested' on expeditions and maximises your battery capacity and minimises charge time (allegedly) so in my circumstances its money well spent.
http://www.simplysplitcharge.co.uk/store/index.php?route=product/category&path=257

This video has some opinions around this: https://www.youtube.com/watch?v=P6poRPUMKTI

 

Edited by roamingyak

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Hi, you have the full Ctek set-up with their paired units that will do almost anything; the D250SA and the Smartpass. This is all you need and a bit more besides and the wiring is a simple as it gets and is detailed in the booklet which you will have been sent with the units. You probably didn't need the Smartpass as you won't have a service battery capacity of >100Ah will you?Here is the wiring which is self explanatory and you just need to decide if you are going to define any "critical" items and if so, they go direct to the service battery as it says.

IMG_8058.thumb.jpg.e1cf2f11bc6ac8820ba1aaf90e1dc2bb.jpg

 

 

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1 hour ago, roamingyak said:

Thanks for the help, I understand what I need having lived in my Landy for many years, that wasn't really what I was asking for help with though.

You understand what you need but we have no idea, it's hard to give advice if we don't know what you're aiming to achieve. :rolleyes:

For what it's worth our Ambulance runs a similar setup to what you're proposing and the whole lot cost less than £100.

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I've done a few. 

You should get most of the info you need from the manuals, but chuck up a sketch of your intended scheme and I'll let you know if anything obvious is amiss. Your main consideration is going to getting cable lengths/guages appropriate for an efficient system. 

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Posted (edited)
On 8/22/2018 at 3:47 PM, Peaklander said:

Hi, you have the full Ctek set-up with their paired units that will do almost anything; the D250SA and the Smartpass. This is all you need and a bit more besides and the wiring is a simple as it gets and is detailed in the booklet which you will have been sent with the units. You probably didn't need the Smartpass as you won't have a service battery capacity of >100Ah will you?Here is the wiring which is self explanatory and you just need to decide if you are going to define any "critical" items and if so, they go direct to the service battery as it says.

IMG_8058.thumb.jpg.e1cf2f11bc6ac8820ba1aaf90e1dc2bb.jpg

 

 

Thanks mate, looking to add a removable large capacity deep cycle battery pack in the back, add it in for longer trips, remove it when in Europe was my thinking...
I also wanted the 'flat starter' option of the Smartpass etc

Edited by roamingyak

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Just checked out the price of that ctek kit - wow...:blink:

A Durite VSR and a regular solar charge controler will achieve the same for less than £100 including cables.. spend the change on diesel going somewhere nice?

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What Eightpot said...

I used one of these which gives smart split-charge (including topping the starter battery up once the leisure battery is full) and allows for a jump-start mode - although in a pinch it's so easy to just move the battery connection over to link the terminals, it's not like you need to be jump-starting the truck very often I'd hope! Cost £40 for the ~140A version.

Then used a cheap 10A MPPT solar controller from eBay for the solar panel (with plenty of fuses!), when we added the 2nd panel we added a 2nd controller. Cost about £20 delivered.

You could use the switched output from the solar controller to drive a shutoff relay (standard automotive relay) for the non-essential loads, or drive them directly if they're small and don't expect the chassis to be grounded (most solar controllers are common-positive), stuff like phone chargers etc. it's fine.

Just for comparison:

Our system currently is two 100W panels + two controllers + Smart VSR = ~£100 x2 + £20 x2 + £40 = About £300 with wiring bits.

CTEK D250SA + Smart Pass looks like the best part of £500 on their own. :blink:

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I bought one of these cheaper VSR units (can get them for less than £30 now on ebay/amazon) - very pleased with it, seems just as good if not identical to the Durite and has taken a damn good thrashing (soaked/baked/shaken) without ill effect.  And yeah my solar controllers are only cheap as well, can't fault the reliability though. One's been going for eight years now.

I can't jump-start with a VSR, but on the rare occasion the primary went flat I just bridged the solar controler to it and by time time I'd finished a brew there's been enough juice to start.  

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There is a problem with all the parallel charging systems out there, your batteries will never charge as fast as they can, and can never reach 'full' either, that is why DC-DC chargers have been invented, to make the most of your usable capacity.

They also look after your batteries as well, charging in cycles if they sense something is not quite right, and all sorts of other things :)

Cheap? No way, to rich for me, but where weight is really important and your life is dependent on you having power, they do have advantages.

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21 minutes ago, Bowie69 said:

There is a problem with all the parallel charging systems out there, your batteries will never charge as fast as they can, and can never reach 'full' either, that is why DC-DC chargers have been invented, to make the most of your usable capacity.

2 Batteries will charge slower than 1 as the current is split, but i dont see any reason why they will not reach 100% as the alternator voltage will still be the same at termination.

Of course you are correct that the intelligent chargers are kinder on the batteries.

But within a budget theres nothing wrong with the relay method.

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It charges faster because the DC-DC charger senses only the voltage of the battery it is charging, and ramps up the voltage (therefore current) to what the battery can accept in order to charge it, and pulls the power from the alternator. The alternator is blind to the second battery, just sees an additional load. The DC-DC charger can raise the voltage above what the alternator is kicking out if the battery can accept it.

Meanwhile the alternator is sensing the starter battery voltage and charging accordingly.

Many of the DC-DC chargers will allow you prioritise a certain battery in the chain as well, dependant on your needs.

As to not getting properly full, if the alternator senses that the combined battery voltage is pretty much there, current drops to a bare minimum, current to the flatter battery will be so small that it won't actually charge it, just maintain the charge level. Hence not absolutely full.

As I said, way to rich for me, and I am not travelling the Sahara, so no point, I use a relay, and it is fine. But for life-critical remote situations I'd go with a DC-Dc charger.

 

 

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When you're charging or reviving a flat battery, or keeping long term maintenance float charge , the intelligent chargers are great.

Otherwise for just keeping a good battery up to voltage, a relay is fine as long as the alternator can produce the current, which any charger will need anyway.

If you're using a second battery to run a fridge etc there are more demands whilst off alternator power, but that is usually taken care of by the solar charge controler, and just making sure you don't run the battery dangerously low in the first place. 

 

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14 minutes ago, Bowie69 said:

As to not getting properly full, if the alternator senses that the combined battery voltage is pretty much there, current drops to a bare minimum, current to the flatter battery will be so small that it won't actually charge it, just maintain the charge level. Hence not absolutely full.

Thats the part i disagree with. Alternators do not have an current sensing (except maybe the very new digital ones) the regulator provides a fixed output voltage, and that determines the battery termination. Both batteries will be taking the current they need based on internal resistance and the applied voltage.

But connection is important, see this https://www.impactbattery.com/blog/tutorials/how-to-charge-marine-and-rv-batteries-in-parallel/

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Posted (edited)
4 hours ago, Bowie69 said:

As to not getting properly full, if the alternator senses that the combined battery voltage is pretty much there, current drops to a bare minimum, current to the flatter battery will be so small that it won't actually charge it, just maintain the charge level. Hence not absolutely full.

 

4 hours ago, HoSS said:

Thats the part i disagree with. Alternators do not have an current sensing (except maybe the very new digital ones) the regulator provides a fixed output voltage, and that determines the battery termination. Both batteries will be taking the current they need based on internal resistance and the applied voltage.

But connection is important, see this https://www.impactbattery.com/blog/tutorials/how-to-charge-marine-and-rv-batteries-in-parallel/

I thought long and hard about this when my VSR split method almost killed one of my two batteries. Enersys examined it and said that it had not been charged fully and that the VSR regime was probably to blame. Fortunately they put it on a recovery program of discharge and charge and it was indeed restored to sufficient capacity.

In my case I didn't have the solar panel fitted at the time and so the only charge source was the alternator. The Starter battery was not deep cycled but the Aux was (with the load of a cool box in high ambient temps). When the alternator was running, the Starter battery would reach a high voltage way before the Aux. I believe this being presented across the alternator, was then preventing current from flowing out and through the VSR into the Aux battery. So I don't think it's the alternator sensing as such but the effect is the same. You can't force the required current into the more discharged battery if the other one is closer to being fully charged as it acts as a block.

I do think that there is a lot of sense in re-configuring the arrangement as is the article referenced by HoSS. I either saw that or a similar one explaining the very same approach and it makes sense if it does indeed overcome this sort of problem. I wonder how many Aux (deep cycled) batteries fail prematurely due to under charging through VSR and what proportion of owners have actually discovered the failure mode?

When i eventually installed a solar panel I decided to use the Ctek unit (not the Smart pass). It is expensive but it is an extremely compact single solution for solar controller and DC-DC charger that can handle two AGM batteries.

Edited by Peaklander
Grammatical

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The other thing to remember is, if like on many overlanding vehicles, you end up with the starter battery up front near the engine, no matter how fat your cables to the battery in the back of the vehicles, there WILL be some voltage drop, HoSS's diagram peaked my memory on that one...

So yes, it would end up never fully charging for that reason too.

Not so much an issue when you have two batteries under  the seat in a Defender etc, but very relevant otherwise.

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1 hour ago, Peaklander said:

 

I thought long and hard about this when my VSR split method almost killed one of my two batteries. Enersys examined it and said that it had not been charged fully and that the VSR regime was probably to blame. Fortunately they put it on a recovery program of discharge and charge and it was indeed restored to sufficient capacity.

In my case I didn't have the solar panel fitted at the time and so the only charge source was the alternator. The Starter battery was not deep cycled but the Aux was (with the load of a cool box in high ambient temps). When the alternator was running, the Starter battery would reach a high voltage way before the Aux. I believe this being presented across the alternator, was then preventing current from flowing out and through the VSR into the Aux battery. So I don't think it's the alternator sensing as such but the effect is the same. You can't force the required current into the more discharged battery if the other one is closer to being fully charged as it acts as a block.

 

I think the battery guys gave you some fluff there - the VSR simply opens up a circuit between the main battery and the second battery (or alternator and battery depending how it's been wired).    The batteries are connected when the VSR opens the circuit, so the voltage should be pretty much equal unless there's a problem or the batteries are wildly different in size.  

Connecting the VSR to either battery with an undersize cable will slow down charging,  and the VSR needs to be rated sufficiently as well, the small caravan sized ones aren't much cop.

I would suggest a probably reason for your batteries failure may be down to using a coolbox (presuming you mean thermo-electric) - these have a high Ah rate and you may have been letting more out of the bucket than you've been pouring back in so to speak..  it's important to scale the batteries, cables, cable lengths, solar panels to the stuff you're running and work out the combined Ah or quite quickly you can have a dead battery.

As Bowie mentioned, cable length and diameter is very important - easy to loose 1v over two or three metres which can make your fridge low voltage protection cutout activate prematurely and prevent solar panels charging (always get the controler as close to the battery as possible as it doesn't matter if a little is lost between panel and controler)

 

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No that's not what happened. I know very well how it all connects up and the whole point is that the Aux battery deep cycles and the Starter doesn't. Yes it was a thermoelectric box and yes I know that it draws a hefty current and that's the whole point. If you stop for more than 24hrs in 30+C then it works very hard. Once you get on the road you have an alternator spinning like crazy and you can't get the Amps back into the Aux to replenish all that drain. The VSR was a 140A Durite and the batteries were close together with big thick solder lug cables. The problem comes when one battery close to fully charged is presented to the alternator with a second deeply discharged, plonked across it in parallel. I can't see how an alternator with fixed output can cope with two differing loads presented. The more highly charged battery will surely prevent much current flowing as it is holding the volts up in the common connections back to +/-

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The charged battery will charge the discharged one, its not all supplied from the alternator, and unless the VSR is switching in and out the load will not change.

You're thinking about it the wrong way round. A lead acid is charged constant voltage (not constant current like NiCad, Lipo etc) its charge current is self defined by the fixed input voltage and the internal resistance.

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Sorry Peaklander but you're talking bobbins there, as Hoss says you're thinking about it the wrong way round - connecting a flat battery to a charged one (plus an alternator or not) the charged one will pour current into the flat one to try and equalise the voltage. With the alternator going, it will be pouring current into the pair to try and drag them up to target voltage.

If your aux battery has been killed beyond its safe discharge limit then all bets are off on how much charge it will take & how much capacity it will retain - putting it on a smart charger to recover it may help but fundamentally it's on borrowed time. Our power guys would scrap all the UPS batteries in a building if they've cycled lower than their safe voltage during an outage, no question.

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Here's a video that came up recently and seems relevant to this discussion

 

 

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