PX Ranger dual battery help

I am at a bit of a loss when it comes to hooking up my second battery cabling at the starter battery. Have researched and now i am a bit confused.

Ford state that you should not take the negative from the negative terminal if you are adding accessories, it should be taken from the body earth because of the current sensor.

Other opinions are when it comes to a second battery the positive and negative should be taken directly from the starter battery.

If someone with experience with these Rangers could set me straight it would be very appreciated.

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Reply By: Member - John and Val - Monday, Feb 04, 2013 at 08:58

Monday, Feb 04, 2013 at 08:58
Hi Rockape,

I have no experience with the Ranger and its electrics, but your post intrigued me. More and more technology, and smart technology that must be treated right. The obvious way of doing things isn't obvious any more because some computer will take offense or compensate in an unexpected way! Reckon we'll stick with our 25 year old Troopy!

On a more constructive note - the current sensing is likely to be in the negative line to the battery. To take it out of contention, I'd follow Ford's recommendation and make my connection at the earthy end, not at the negative terminal. I'd also go one step further if it's feasible, and connect to the engine block rather than just anywhere on the vehicle body. This will minimise losses, because the alternator negative is connected to the block.

I googled "ford ranger px dual battery" and got lots of hits. There's been a lot of discussion on this one and if you haven't already done so, there might be some useful reading there.


J and V
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Follow Up By: Rockape - Monday, Feb 04, 2013 at 09:06

Monday, Feb 04, 2013 at 09:06
thanks for your reply. The dedicated earth is adjacent the battery on the body so it is all good. Yes you are correct in saying the sensor is on the negative side.

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Follow Up By: Ross M - Monday, Feb 04, 2013 at 09:29

Monday, Feb 04, 2013 at 09:29
Apparently things weren't so hightech in the mines eh.

Have a look for the sensor you are talking about. From what you say it has to be somewhere along the negative battery cable between the neg terminal and the body.

When you vehicle is charging the "earthiest" ( as one person put it) point you can have is the case of the alternator.

The sensor will be there to read the amount of current returning to the battery from electrical gear and accessories connected to the body work.

If you have driving lights I would then imagine the earth wires of the lights would need to be also connected to that point.

I hope that sensor wire has a high rating because not only will it have to sense the normal current flows but also ALL extras if it is to sense and do what it is there for.

I presume the engine earth lead to the battery will be that particular earth wire and connect to both the engine and the battery so the sensing can happen.

I suspect your engine has an ECU controlled alternator output and it uses this info to reduce the alts output sometimes in order to save fuel. at present I'm not fully aware of when and what it does under various situations.

What I have said might help you make sense of other additional info you receive so your system can be connected trouble free and work correctly. PS don't always believe the dealer either sometimes it is spot on and other times erroneous.
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Follow Up By: Rockape - Monday, Feb 04, 2013 at 10:22

Monday, Feb 04, 2013 at 10:22
the sensor is at the battery terminal so no problem there and yes it is an ecu controlled alternator.

With the mining side boggers, trucks and drills they don't have ecu controlled alternators. Time is catching up with the introduction of Rangers on the surface and underground. They have a heap of Rangers operating on the surface and 3 operating underground for a couple of months now with no problems showing up yet.

Only problems have been from gear added aftermarket.

Early days yet so see what goes wrong at about the 12 month mark.

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Reply By: phasar - Monday, Feb 04, 2013 at 09:03

Monday, Feb 04, 2013 at 09:03
G'day RA

Have a look at the REDARC web page, has heaps of info on dual battery setup.
Whilst you may have a different brand of charger i'm sure you will find lots of info.
I have recently fitted dual battery to Mazda BT 50, nearly the same as your car
(only better......hehehehehe)

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Follow Up By: Rockape - Monday, Feb 04, 2013 at 09:09

Monday, Feb 04, 2013 at 09:09
I will have a look at the redarc site and check it out.

One of the problems is the BT50 and Ranger have a different charging setup. Ranger has a so called smart system. Guess we have to live with it.


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Reply By: tdv - Monday, Feb 04, 2013 at 09:12

Monday, Feb 04, 2013 at 09:12
Hi Rockape

I did a fair amount of research on this before fitting my second battery in my PX Ranger. Firstly, the charging rate is too low for a standard dual battery kit so I went with a Ctek DC-DC charger which steps up the voltage. I fitted the positive to the positive on the main battery (with fuse) and the negative to the body in the tray. This was just following the Ctek instructions on the box. It has been happily charging my 90 Amp Hour AGM for the past six months while running a fridge, boat winch, lights etc.

I hope this helps.

Cheers, Tez
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Follow Up By: Rockape - Monday, Feb 04, 2013 at 10:13

Monday, Feb 04, 2013 at 10:13
Yes I have a Ctek DC-DC charger for the system. One thing I have to ask is. Do you have to run with your lights on to get the voltage up high enough to get the dc-dc charger operating as the alternator charging voltage can be very low.

Have a good one,
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Follow Up By: tdv - Monday, Feb 04, 2013 at 10:31

Monday, Feb 04, 2013 at 10:31

I haven't had to but do drive with lights on for highway runs anyway. I'd have to dig out my ctek book but doesn't it work with anything above 12 volts?

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Follow Up By: Ross M - Monday, Feb 04, 2013 at 13:20

Monday, Feb 04, 2013 at 13:20
Isn't the load of having the lights on much the same as having a Ctek working off the same point?? I can't see any difference.
The ECU won't be programmed to make the battery go flat, so, it should sense the electrical loads and make the alternator run to provide the charge you require.

If it doesn't, all will go flat. Highly unlikely Fraud wants that to happen.

Ross M
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Follow Up By: Rockape - Monday, Feb 04, 2013 at 14:45

Monday, Feb 04, 2013 at 14:45
The Ctek does not start charging until it sees around 13 volts, it also stops charging if the voltage goes below 13 volts. It doesn't have a trigger like the redarcs which use and ignition source to start charging.

The Ranger alternator program is strange indeed. It is nothing to go for a 200k drive and come back to see your battery voltage sitting at 12.6 or 12.5 volts and sometimes down to 12.25 volts. This according to Ford is quite normal and many others have found this as well. So unless the ctek sees 13 + volts nothing happens because the alternator doesn't see any load from the charger.

I guess it was designed by engineers.

Maybe olcoolone could shed more light on this

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Follow Up By: Allan B (Member, SunCoast) - Monday, Feb 04, 2013 at 16:25

Monday, Feb 04, 2013 at 16:25

The Redarc BCDC1220 does not rely upon an ignition signal to start charging if being used on 12v. The "voltage sense" blue wire is normally connected directly to input +ve as per Redarc's instructions. Only when used in a 24v installation does this wire need to be connected to the ignition +ve.

The Redarc begins charging when the input rises above 13.2v but will then continue charging even if the input drops as low as 9 volt due to line loss. Every 20 seconds the charging is briefly interrupted to determine if the no-load supply is still above 13.2v, indicating that the alternator is still operating then continues to charge. Accordingly, when the motor is stopped and the crank battery falls below 13.2v the BCDC shuts down.
Even if the blue wire was connected via the ignition it would not change the above operating considerations. However an ignition trigger is necessary for a 24v application as the input will never fall below 13.2v

I am not familiar with the Ranger alternator charging characteristics but certainly if the Redarc is used it will not begin or maintain auxiliary charge unless the input reaches 13.2v. These new alternator/management systems can present concerns for after-market dual battery schemes.

It is quite possible that the Ctek operates in a similar manner to above as it has no "ignition" input however I can find only limited specifications or operating description online. The lack of technical data or backup is another reason why I prefer Redarc over Ctek.


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Follow Up By: Rockape - Monday, Feb 04, 2013 at 16:53

Monday, Feb 04, 2013 at 16:53
Thanks Alan,
The Ranger differently has very different charge characteristics from whet I am used to. It is setup to maximise the emissions to meet euro specs. Things like if you are freewheeling down a hill or slowing for a stop it will cut in and charge sometimes. You can actually feel it, very similar to retarder.

Ford also said it will smart charge at different times to stop sulphation.

I wish I had a plain old alternator but those times are gone.

Have a good one,
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Follow Up By: Millsy999 - Monday, Feb 04, 2013 at 18:43

Monday, Feb 04, 2013 at 18:43
There are actually 3 versions of Redarcs BCDC1220. The standard BCDC1220, the BCDC1220-IGN, which does use an ignition signal to start/stop charging, and the BCDC1220-LV, which has different cut-in voltage set points to the standard version. I would recommend spending a bit of time on the Redarc website to work out which is best for your Ranger, or even give them a call, they're generally pretty helpful. (the specs for each unti can be found in the product manual download)

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Follow Up By: olcoolone - Monday, Feb 04, 2013 at 20:55

Monday, Feb 04, 2013 at 20:55
Rockape your spot on with how the battery in the Ranger chargers, they will drop down to 12.5v whilst driving and the algorithm they use is very complicated....... they charge more when coasting or on light throttle, normal driving may not see them charge..... they work on the principle of "just enough is good enough".

They are not to only vehicles that do this but like most thing some people think they know more then others and these problems are often overlooked or not known.

Yes common earth point is correct and you do need a DC-DC charger that is switched by the ignition....... a voltage sensing one will not work.

Most modern vehicles will charge the starter battery between 60-70% SOC, the Ranger is more like 50-60% SOC........ end of the day the battery doesn't need to be fully charged as the vehicle will start with in 3-5 seconds.

Rangers have a big battery with a low SOC.

Many have been replaced under warranty and within 3-4 months of being new.

ECU or mapped charging has been around for a number of years..... gone are the days of checking voltage, now you also have the check ac ripple and frequency.
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Follow Up By: Rockape - Monday, Feb 04, 2013 at 22:13

Monday, Feb 04, 2013 at 22:13
cheers for the info, I think I will have to trick the alternator with headlights if I am going to use the ctek by switching the lights on. I will have to check the manual to see at what voltage the charger stops charging.

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Reply By: Member - Murray R (VIC) - Monday, Feb 04, 2013 at 21:23

Monday, Feb 04, 2013 at 21:23
The Redarc BCDC1220 is a better unit to use than the Ctec for the reasons stated above about voltage cut in & cut out settings. When the PX Ranger is first started the charging voltage goes up to 14.5-14.7 so on problems cutting in. The lowest voltage I've seen was 12.5 when it drops off which also suits the redarc unit. Re cable connections the negative lead must be connected to the engine block or at the earth point on the body next to the battery negative. The positive lead is connected to the battery positive terminal. If any doubts about the Redarc units get their phone number from their site and give their tech department a ring as they are very helpful.
As ford have said to you all accessories must be taken from the body earth no matter what they are because of the current sensor. Hope it makes sense.

PS Redarc make dcdc chargers up to 40 amp with solar regulators built in, check their site
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Follow Up By: Rockape - Monday, Feb 04, 2013 at 22:17

Monday, Feb 04, 2013 at 22:17
I know the redarc product is excellent and has good back up. I bought the ctek because we used them at work and they had given no trouble at all. Never mind, I will see if I can get it to constantly charge by using the lights.

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