D4D charging voltage

[Violet Senior Member Find all posts View Profile Close Violet]

Leachy
I'm interested in your system - but I'm unsure of the connections. Can you describe please - what is connected to what and where?

I already have a 15amp Ctec charger and a 300W pure sine wave inverter - do you think the inverter is big enough to run the charger?

Also where do you mount the charger? I don't really want to have a permanent mounting since I want to use the charger out of the car as well (on a boat).

I'm running short on time and all of this is just getting too confusing. Perhaps I could come around and have a look at your setup?

Regards

Simon

[leachy_9 Advanced Member Find all posts View Profile Close leachy_9]

Simon,

If I was to recommed a size for use with a 15A charger it would be a 500W inverter. Though since you already have the 300W inverter, it should be adequate for the 15A Ctek charger, it will just be operating closer to it's max capacity. (Check that it has built-in output and thermal protection).
I have my inverter and charger mounted in the back of the Prado utilising one of the third row seat mounting points. This puts them up above the wheel arch in a space that wasn't used before. (I'm using an AGM battery mounted in a battery box in the rear). Removal of the whole system is just two bolts and an anderson plug.
I use a couple of 100Amp solid sate relays to isolate the inverter from the charging system and the battery from the charger when the vehicle is not running.
I'm pushed for time at the moment to put tegther pictures / circuit diagrams etc. But your more than welcome to come around and I'll go through the whole sytem with you. - send me a PM.

leachy

[waltec Senior Member Find all posts View Profile Close waltec]

Just wondering, has anyone checked the battery voltage other than at idle, say 1500rpm.

My understanding is that alternators work ok at idle but better at cruising speeds. Also if they are controlling the charge voltage to reduce engine load at idle (as suggested previously in this post), there would be no need to do this whilst driving.

End of the day the majority of the charging a battery will receive is whilst we're driving (1500rpm) not idling.

Matt

[clifton Advanced Member Find all posts View Profile Close clifton]

Hi All,
I could write pages on this issue but will not bore the hell out of our members, I left the interior lights on for two days and nights by leaving the rear door ajar, something I never do but was a bit crook with a bug so was in the sick bed.
Today when I went into Cairns the Batt voltage was up to 14.0V, for about 5 minutes then sat on 13.8 for the duration with +/- 1.0 volt variation depending on engine speed.
My Battery voltage normally sits on 13.6 to 13.7 when running, when I get the ping I might check this out with one of my dc Ammeters and see whats happening but at present I am not concerned, I will see what happens with the second Aux battery setup when I get time.
All the measurements were taken with an SG11.
Hope this helps a little

[Steve & Sandra Senior Member Find all posts View Profile Close Steve & Sandra]

Well i left the fridge on all night and this morning the battery voltage was 11.5. tried starting the engine and it was noticable that the battery was not fully charged. With the multimeter across the battery terminals i could only get a maximum of 13.58volts. This is on a D4D. I personally would have thought this would have been higher.
Oh well something to look into before i go and purchase/install a dual battery system. I purchased a 64 watt solar cell this week so hopefully this will make up for the shortfall in the alternator.

cheers

Steve

[wally Junior Member Find all posts View Profile Close wally]

FYI.

The Sure power seperator switches from 13 to 13.5 volts. They turn off at 12.4 to 12.9 volts.

[Hubble80 Member Find all posts View Profile Close Hubble80]

Has anyone made any headway with this issue?  Just seems to be something we have to live with...

[leachy_9 Advanced Member Find all posts View Profile Close leachy_9]

I've gone the inverter / three stage battery charger route.
The system can handle an input volatge as low as 10V and still fully charge the aux. battery. So the lower D4D alternator voltages are no issue.

leachy

[ploth Lurker Find all posts View Profile Close ploth]

Dual Battery setup

Gday guys - though you might like to try this link out. If you need any more info just email me...

http://www.bonzabuy.com.au/store/produc ... cts_id=313


As far as I am aware - if you go inverter & then 3 stage charge you will loose a lot of energy in the conversion and also produce excess heat.
A decent inverter (ie one that is 92% efficient or higher) is in excess of $700. Then the charger has to reduce the voltage again...

Of course this will also wear out your alternator faster as well.

The unit listed in the link above seems by far the best option - but willing to be corrected!

[leachy_9 Advanced Member Find all posts View Profile Close leachy_9]

With a 7 amp output the Redarc unit is going to take around 6hrs to recharge a 120AH battery that is at a 65% state of charge. I don't know about others other but that is too slow for me.
Also, with the Redarc unit you do not have the ability to recharge the battery from a 240Vac supply (ie caravan park or generator).

There are some extra losses with an inverter but these are minimal and the extra heat generated is negligible (I have a 1000W inverter running in the back of my Prado and there is no heat issue). As long as the load remains below the alternator rating the primary factors determining the life of an alternator are the number of revolutions and external environmental influences. The extra load with an inverter/charger setup shortening the life of an alternator is a furphy. This sounds like it came from a salesman. In fact the previous post smacks of a sales pitch disguised as free advice.

But each to their own, if you think the Redarc suits you better then great. I'd suggest that for someone wanting to go the boost converter / charger route that the RanOx is a better choice:
http://ranox.com.au/401.html

[ploth Lurker Find all posts View Profile Close ploth]

More choices...!

If 240v charging is required then I would recommend the CTEK battery chargers...
http://www.bonzabuy.com.au/store/produc ... cts_id=315

To have one of these and the Redarc units would cost less than the inverter setup - and last much longer.

No offense but I have had a lot of experience with cheap inverters and not only do they waste a lot of power, they don't last very long.

As for the alternator wearing issues - the wear factor is totally affected by the current drawn through it.
For instance an alternator with no load might spin for 10 years with no issues - but put close to it's rated charge and it would be strange if it lasted 2 years. Driving with your lights on continually can be a safe practise but it does put extra wear on the brushes, bushes and bearings on the alternator.

This is increased with power draw - ie a fridge & wasted power through an inverter to charge a battery is not a small load.

But yes each to his own

[leachy_9 Advanced Member Find all posts View Profile Close leachy_9]

Rather than deal with unsupported claims and antidotes lets have a look at some figures:

A 40 L Engel pulls 2.5 Amps at 12.8V.
As per Engle website:
http://www.engelaustralia.com.au/cgi-bin/faq.cgi?faq=8

For the purpose of this exercise I’ll make the following assumptions, all of which are generous towards the boost converter option:
Fridge duty cycle 50%
Charger efficiency 90%
Boost converter efficiency 95%
Inverter efficiency 75%

Boost converter system (average)

Average current to run fridge: 2.5 *0.5 = 1.25A
Average current into charger: 1.25/0.9 = 1.39A
Average current into boost converter (out of alternator): 1.39/0.95 = 1.46A

Inverter converter system (average)

Average current to run fridge: 2.5 *0.5 = 1.25A
Average current into charger: 1.25/0.9 = 1.39A
Average current into boost inverter (out of alternator): 1.39/0.75 = 1.85A

So even when being generous to boost converter the difference in average current draw between the systems is only:
1.85A – 1.46A = 0.39A
This will not have any significant effect on the life expectancy of an alternator.

If we where to look at peak current draw remembering that the max output of the Redarc is 7amps.

Boost converter system (peak)

Peak current out of charger: 7amps
Peak current into charger: 7/0.9 = 7.8amps
Peak current into boost converter (out of alternator): 7.8/0.95 = 8.2amps

Inverter converter system (peak)

Peak current out of charger: 7amps
Peak current into charger: 7/0.9 = 7.8amps
Peak current into inverter (out of alternator): 7.8/0.75 = 10.4amps

So at peak current draw the extra current draw in the inverter system is:
10.4 – 8.2 = 2.2amps

Again this amount of current will not significantly decrease the life expectancy of the alternator. This is easily demonstrated by the fact that most members of Pradopoint have accessories on their vehicles that would increase the alternator load. But when I searched, I could not find any reports of premature alternator failure.

Talk of an inverter system significantly decreasing alternator life expectancy is nothing more than an attempt to try and muddy the waters and justify an alternative product. As I have said before, I believe the 7Amp output of the Redarc is too low to provide an acceptable recharge rate that would be expected from someone looking to maximise the performance of their aux. battery(s).

If you are selling the products you are putting forward why not state that up front rather than disguise it in a post as “advise” which you try to support with completely unsupported claims like:

To have one of these and the Redarc units would cost less than the inverter setup - and last much longer.

Leachy

[Crammy Advanced Member Find all posts View Profile Close Crammy]

Another thing to consider when using the inverter method is the type of battery you're charging. If you're charging a wet cell and running your fridge off it at the same time, it will boil dry if you don't keep an eye on it.

[ploth Lurker Find all posts View Profile Close ploth]

Gday again - I am surprised at the tone of your reply... have I offended you?

And is your charger really 90% efficient? Let me know I'd be interested in the brand & model if this is the case.

Talk of alternator wear is not about muddy waters at all - but I have worked around the auto scene for years and know first hand that wear is an issue - to fail to mention it is (in my opinion) failing to give a needed warning about costs that will be incurred later. Unless your car has a PMA alternator you WILL be affected - the only thing is when. It is common sense - you have sneakers in the cupboard & use them once a week for a walk they last 10 years - run in them then they last 5 years, rock climb or play tennis then 2 years. The same with an alternator - the higher the energy draw the more it wears.

Before I get into a few more realistic figures, lease don't get me wrong. I am not saying that the difference between the two scenarios will burn out our alternator in a few months - but I am saying the more current you draw through the inverter the more the wear & heat increases.

If 7 amps is not big enough for you it is a different story altogether. If you flatten your battery so much & don't drive much in between I would be looking at a solar panel or petrol geny as going over 7 amps can damage some batteries depending on size / type etc. If the charge goes in too quickly and the battery is not designed for it...but this is opening a whole new can of worms!

Assuming your charger IS 90% (which I doubt is even close) and using the rest of the figures you quoted.
You stop somewhere for 12 hours & have your fridge running
1.25A / hour = 15AH

With the setup I would use: (Redarc $299)
15AH drawn out of the battery
15/7amp charging = 2.14 hours to recharge
drawing 7.37A off the alternator for 2.14 hours (15.77AH)

With your recommendation
15/0.75 = 20AH drawn out of the battery if using the inverter
20 / 10amp = 2 hours to charge.
drawing 14.8A off the alternator for 2 hours (29.6AH)

I am no boffin but correct me if I am wrong in just over 2 hours of driving you have used nearly DOUBLE the energy to recharge your batteries. This has to add up over the course of a number of kms. And 2.14 hours to recharge a battery after 12 hours of fridge use will suit most serious 'get awayers'... those who use more energy & drive less would be looking at generators / solar panels surely!

If you only use the inverter for charging it is better....

1) Redarc recharges in 2.14hrs drawing 7.37A (15.77AH)
2) Inverter recharges in 1.5hrs drawing 14.8A (22.2AH)

6.5AH for every 15AH drawn out of the battery directly! That's around 43% waste and extra wear & tear. Of course if you adjust the charger efficiency you will see this rise dramatically.

ie if the charger is 75% efficient (which would be more likely) the figures are -
inverter charges in 1.5 hrs drawing 17.7A (26.6AH)
This means the inverter / charger combo just wasted 11.97AH for 15AH used! This is 79.8% wasted energy, extra heat and wear !

This is still not taking into consideration the battery efficiency which reduces the lower the state of charge you take it to, making it harder to charge. Nor is it taking into consideration the heat from the inverter making it harder for the fridge to stay cool. Both of which favor option 1

Also with the cheaper inverters the efficiency goes down as the current goes up as well...and as mentioned the time that these units last will decrease the more it is used especially in the heat.

The effect of 2.2amps on fuel, alternator parts, fan belts etc does not sound much - but as seen this is actually not quite the case.
With just 12 hours fridge use you have got nearly 12AH difference!

This would not be noticed immediately (the heat inside the car might be a pain if you sleep near it - trust me I know from experience!) but over the course of 100,000kms? It would be interesting to see! Of course added heat means your fridge would need to work harder too...but in cold climates it can be nice!

The comment "To have one of these and the Redarc units would cost less than the inverter setup - and last much longer. " is not unsupported or some antidote...

First of all price - $299 for the redarc. IF you need the CTEK then $150 - $500 extra. How much did your setup cost?

Go to any reputable solar dealer & they will tell you the same thing - cheap inverters do not last. They are not saying that to get more money out of you - often they make less on good quality items...But they know over & over that cheap inverters are unreliable, inefficient and get way too hot. They also don't generally like bumps or vibration.

Compare this to world class items like Redarc and CTEK they are also world class leaders for a reason - because they outlast the 'competition' by many times over. If you want an inverter for a few years no problem get a cheapo but if you want it to last choose high quality. If you must waste energy at least get a Selectronic inverter that will last.

Don't take my word for it - ask Ferrari and major truck companies like Volvo etc who install some of the Redarc / CTEK products from the factory! As far as I am aware no manufacturers use Ranox? There's a reason the warranty on a Redarc is double that on a Ranox...

If you only get away for short trips every so often on the weekend, I would suggest you go for the cheapest / easiest option. (which may be the Redarc anyway!)...

But if you want to keep your car for a long period or get away more often or for longer my opinion is avoid stepping up, converting & stepping down of the current for any purpose as it is simply a waste and causes more wear (no matter how small) on all parts involved.

[leachy_9 Advanced Member Find all posts View Profile Close leachy_9]

Gday again - I am surprised at the tone of your reply... have I offended you?

Yes I find it offensive for someone to come on to a forum as first time poster and offer unsupported information in the guise of advise when they are trying to sell products.

As far as your assertions about significantly increased alternator wear or the appropriateness of certain products, I think I’ve made my position clear and I’ll leave it up to others to decide for themselves. But it’s only fair they know who is providing the information and any vested interest they may have.

Leachy