Battery Charging voltage

[Mark1958]

Hi all, this my first post so be gentle.
Vehicle 2014 TDV6
I have installed a dual battery for my fridge and as the alternator generally charges at only 13v I have concerns that the battery will not fully charge.
In my previous vehicle, 150 Prado I installed a diode in the alternator fuse that uped the charge voltage.
Is this an option for the D4?
By the way love the car, kills the 150 series.


Thanks

Mark

[Tote]

Hi Mark,

Have a look at the FAQ for info, most of your questions will be answered there http://www.aulro.com/afvb/d3-d4-rrs/93220-aulro-discovery-3-4-rrs-faq.html

The Traxide kits are very good and I have had one installed in my D3 for the last 6 years. The alternator in a D3 is electronically controlled and simply wiring another battery in parallel is not recommended. A diode in the charge circuit might be a very expensive exercise for you and is also not recommended.

Home Page | TRAXIDE - RV | Traxide - RV (http://www.traxide.com.au) for the kits and they offer discounts to forum members as well.

Regards,
Tote

[JamesH]

Interesting to hear you say it charges at 13v, mine charges at around 14.3 to 14.7.

If it's dropped to 13 maybe it's because the batteries are fully charged? I better leave that for experts to comment on.

I got one of those cigarette lighter plugin voltage readers andI sometimes take a peak at the voltage before starting the car to see the state of charge.

The general belief here on this forum is the D4 is not great at keeping the charge up to the batteries and they can start to sit at around 12.4 volts (measured after a few hours rest) when they should be up around 12.7. So a lot of owners will chuck a ctek charger (smart charge) on the car once a month.

[PeterOZ]

My d3 charges at over 14v @ about 2500RPM

What voltage is on battery with connectors removed?

What voltage at idle & at say 2500 RPM

a diode will not increase your charge voltage, that is not how they work. Diode will conduct current in one direction only, dropping around 0.6V in the process for a Si or 0.2v for a Ga diode. In AC circuits they can be used as a rectifier.

All do is drop 0.6v and isolate a 2nd battery if you have it wired that way.

By the sound of it the way you had it you would have drecreased voltage by 0.6V, not increased.

:angel:

[PeterOZ]

I'd also suggest that if you are doing shortish trips like I do that your battery is not getting a full charge is is in fact running down, alternator is not able to bring it up hence why you see a lower than expected "charge" voltage.

I recently ran a battery very flat and it took 2 days on high charge to bring it back to 12 v then 2 days on a specialsied float charger to get it to full capacity.

As other have said the cirtek chargers maybe an optioon. I'm also considering one. Not sure on model yet.

these D3 and more so on a D4 draw a lot of current with all the systems they are running so on a short run you are actually draining the battery.

Ramble over. :wasntme::censored:

[Redback]

Hi all, this my first post so be gentle.
Vehicle 2014 TDV6
I have installed a dual battery for my fridge and as the alternator generally charges at only 13v I have concerns that the battery will not fully charge.
In my previous vehicle, 150 Prado I installed a diode in the alternator fuse that uped the charge voltage.
Is this an option for the D4?
By the way love the car, kills the 150 series.


Thanks

Mark

To answer your question, the TDV6 alternater charges at a constant rate of 14.6, then after about 1/2 an hour, settles to around 13.4 to 13.6 or there abouts and doesn't need the diode you had on your Prado, it will fully charge both batteries.

Some guys on here have 3 batteries in their D4s and have had no problems with charging all 3 via the alternater, me included, although I now only have the 2 batteries.

Baz.

[jonesfam]

I have Scan Gauge 2, 1 normal battery & run a small fridge.
The Scan Gauge usually tells me that I have around 13.5v.
Is that the amount of charge going to the battery?
Does that sound like it is correct?
I usually do long runs, 10k minimum & a 900k run to work & back every 3 or 4 weeks. The car just sits locked when at work for 3 or 4 weeks at a time.
Should I put it on a battery charger while it is sitting?
Thanks
Jonesfam

[Redback]

I have Scan Gauge 2, 1 normal battery & run a small fridge.
The Scan Gauge usually tells me that I have around 13.5v.
Is that the amount of charge going to the battery?
Does that sound like it is correct?
I usually do long runs, 10k minimum & a 900k run to work & back every 3 or 4 weeks. The car just sits locked when at work for 3 or 4 weeks at a time.
Should I put it on a battery charger while it is sitting?
Thanks
Jonesfam

Better for the battery if it has some charge while it's sitting there doing nothing, a good multi stage charger will do the job, keeps it in a float charge and prolongs the life of the battery.

Baz.

[Graeme]

a diode will not increase your charge voltage, that is not how they work. Diode will conduct current in one direction only, dropping around 0.6V in the process for a Si or 0.2v for a Ga diode.People fit them to the Prado's regulator sense circuit to lower the voltage a little which makes the regulator think the output voltage is a little lower than it really is so raises the o/p voltage.

[Nicky]

The electronic engineers tell me on modern vehicle batteries the charger is unnecessary, as the software does checksums at every start, and the alternator adjusts as necessary.

[matti4556]

PeterOz - you maybe aren't fully across the diode thing yourself - search the Pradopoint forums and you will see the modern Prado etc "diode swap in the fuse box trick" uses the forward bias voltage drop to fooling the alternator control circuit into thinking the battery is 0.4-0.7V lower than what it truly is. So it charges at a higher voltage to assist with charging a second battery (voltage drop blah blah) Cheers, Matti

Edit - just saw Graeme's post - yeah - what he said too! :-)

[Epic pooh]

I have Scan Gauge 2, 1 normal battery & run a small fridge.
The Scan Gauge usually tells me that I have around 13.5v.
Is that the amount of charge going to the battery?
Does that sound like it is correct?

I also run a scanguage, mine normally indicates a charge rate of around 13.9V in day to day use, if not used for a week or so it will up the charge to about 14.5V for a while and after a long run with a very full battery it will drop the charge rate as low as 12.9V.

[Mark1958]

Thanks all for your input. I checked the charge v again and is 13v whilst idling or accelerating and 14v whilst coasting. So it appears that it only charges when coasting. So the question is will it keep 2 batteries charged whilst towing a van?
Also running a Waco in the back seems to make no difference. I would rather charge my batteries fully than save 20c of fuel, if that's what is about!



Cheers

Mark

[drivesafe]

Hi Mark, it depends on the state of charge of your cranking battery and the type of battery isolator.

What isolator do you have?

[Mark1958]

I have installed a sidewinder isolator. IT seems to work ok.


Cheers

[drivesafe]

Hi Mark and like all standard type VSR isolators, that one will not work with 2013 and later D4's alternator variable voltage systems.

It will separate the cranking battery but when the motor is turned on, will not cause the BMS to charge the auxiliary and any house batteries, as the BMS will see the cranking battery is charged and lowers the operating voltage too soon to allow for any other batteries to be charged.

[Mark1958]

Hi Mark and like all standard type VSR isolators, that one will not work with 2013 and later D4's alternator variable voltage systems.

It will separate the cranking battery but when the motor is turned on, will not cause the BMS to charge the auxiliary and any house batteries, as the BMS will see the cranking battery is charged and lowers the operating voltage too soon to allow for any other batteries to be charged.
Thanks, how does the Bms know the difference between the batteries when they are connected as I would think the two batteries would equalize their voltages whilst connected.


Cheers

[drivesafe]

Hi Mark and because ordinary type VSR isolators turn off almost as soon as the ignition is turned off, or soon there after, the batteries will not equalise so you can have a fully or near fully charged cranking battery, but low auxiliary and/or house batteries.

With your Prado, where it does not have a BMS, a simple diode type fuse tricks the alternator into running at 0.6v higher than it normally runs at, but the Prado had no real idea of the state of charge of the cranking battery.

In that setup, a standard VSR type isolator works fine.

A D4 has a regenerative charging system, which monitors the cranking battery and adjusts the alternators operating voltage according to the state of charge of the cranking battery and whether the motor is under load or not.

As the standard type VSR does not allow the batteries to equalise, when you turn the motor on again, the BMS sees the cranking battery is fully charged and sets the alternator operation in accordance to that and lowers the operating voltage shortly after starting.

This means any other batteries in the system will not be charged, if they are in a low state, which is exactly what is happening in your D4, and why it runs at 13v.

So while you are running around town, a standard VSR is fine, but the first time you use any power from you auxiliary and/or house batteries, while the motor is off, using a standard VSR in a D4 stops the auxiliary/house batteries from being fully charged if they are in a low state at the start of a days drive.

[Mark1958]

Well explained, thanks, much appreciated.



Regards

Mark

[Mark1958]

I bypassed the BMS today then started the engine and sure enough went straight to 14.2 v.
You were dead right, thanks.


Cheers

[drivesafe]

Hi again Mark and just a tip.

Make sure nothing is connected to the NEGATIVE ( - ) terminal of your cranking battery, other than the D4's earth lead.

Doing so can cause all sorts of seemingly unrelated issues.

If you need to earth anything, there are two 6M studs in the inner guard, just in front of the cranking battery compartment.

Here is a picture of the studs, just ignore the EARTH PLATE info.

http://www.traxide.com.au/D4/Earth Nuts 2.jpg

[josh.huber]

My d3 charges at over 14v @ about 2500RPM

What voltage is on battery with connectors removed?

What voltage at idle & at say 2500 RPM

a diode will not increase your charge voltage, that is not how they work. Diode will conduct current in one direction only, dropping around 0.6V in the process for a Si or 0.2v for a Ga diode. In AC circuits they can be used as a rectifier.

All do is drop 0.6v and isolate a 2nd battery if you have it wired that way.

By the sound of it the way you had it you would have drecreased voltage by 0.6V, not increased.

:angel:


Peter, they use the diode for its voltage drop in a hilux prado circuit to confuse the ecm that the voltage is lower. so it compensates and charges the battery at 13.6 in stead of the 13.3 charge rate the factory has the ecm set at