More on Bush Power

[bicter]

Hi bicter,
Say you have a very large diameter copper wire carrying DC, the current density is uniform throughout the wire.
For AC however, the current is increased towards the outside of the wire due to increased "back EMF" towards the wire's centre. The current density decreases away from the surface. The "skin depth" is the depth at which the current density is ~37% (chosen as 1/E - the Naperian logarithm (2.718281828)) of that on the surface.-This skin depth decreases inversely to the square root of the frequency in non magnetic conductors. i.e.: at 4 times the frequency, the skin depth is roughly halved.
At very high frequencies, save money by making conductors out of tubes - the internal copper does nothing. At microwave frequencies, a thin silver plating on the outside of a stronger internal structure (even glass), is all that's required, although the silver should be protected in a pressurised Nitrogen environment (viz: as used in professional waveguides).
Sorry to diverge from the intent of this thread, but the question was asked.

Thanks Bigwave, used to know all that stuff but retirement has trashed my memory. If you dont use it, you lose it ?
My question was directed at the 9.3mm - how does that work on a 2.5mm sq building cable? Are you saying that any conductors less than 9.3mm aren't affected by skin effect at 50Hz. that'd explain it ?
Not used to working/thinking in such low frequencies.

 

[Tathradj]

Not meaning to divert meself but a lot of the high frequency stuff
I worked with had an aluminum core with copper layers.
I still have a 20 meter length of foam core here for a
1 ghz Yagi i own. O

 

[condor22]

Well I'm in the GT, no genny this trip. solar working great.

Re previous comments on duel solar alternator charging. As I've stated before the big difference charging alternator and solar is in the input/s and outputs/s. I use the / plural because;

Having alternator charging direct to the aux battery and at the same time a solar input from a separate controller at the same time is what confuses the charge rate.

Having the alternator wired to the input of a solar compatible DC-DC charger and at the same time a solar panel to the same charger (different wire) is sourcing an automatic demand driven multiple source within the charger, BUT only one output to the battery and is the best option.

The other method, as in my instance where my DC-DC controller is not solar compatible will work on solar but require a relay to switch the input. in other words still only one input at a time and one output.

 

[Guest]

I am not an electrician so please excuse my ignorance and perhaps a dumb question?

Is there a reason why I could not just use a pure sine wave inverter (say 600 watt) and a regular 240v battery charger to charge an aux battery whilst driving? Install a VSR between main battery and 240 volt inverter. I did try this with a 150 watt inverter but it did not cope and could not run the 240 v battery charger.

Seems inverters and regular 240 volt smart chargers are cheaper than DC - DC Chargers.

Am I missing something?

Cheers

RS

 

[Ded Driver]

RetirementStone, it can be done, & I know a bloke who has done it, BUT its not very efficient, not best for your Deep Cycle Battery, & it takes up more space with having 2 units to do the one job.
From your problem using a 150W inverter, a 10A battery charger @ 13.8V is outputing approx 138W. If your inverter runs at around 85% efficiency you would need about 160Watts, so you can see your 150W unit is under-powered, hence it didnt cope.
The next issue is that unless your battery charger is a multi-stage smart charger it will shorten the life of the deep cycle battery. Maybe not a lot, but it will a bit.
Recharging a deep cycle battery ideally has a minimum 3 stages of voltage/current control. A traditional single stage charger puts out a continuous (nominal) 13.8V at whatever amperage its rated at, & can overcharge a battery when it is full.
A DC-DC charger takes the input voltage (which could be between 12-14V, even wider on modern alternators) & converts to the appropriate output voltage for the battery type & recharge stage, plus most now include a separate solar input as well.

 

[Guest]

Thank you mate,

That makes sense. Glad to get the correct info especially about the 150 watt inverter!

I have purchased the below as a trial:

My Triton and battery is 5 years old and I m going to buy a new one for the car. I ll use the old one in the tub/canopy to run a 12volt fridge when required (About 10 times a year prospecting for a 4 or 5 day stint)

Base camp is generally in a caravan mostly with 240v but the van does have a Projecta DC DC charger and a Projector 240v charger under the seats.

Will see how long that lasts or whether its going to be effective.

I suspect that I will go DC DC Charger and AGM Battery in the future. But am always looking for a short cut (aka poor man pays twice) !!!!!!!!!!

Cheers

RS

 

[Nightjar]

A DC-DC charger takes the input voltage (which could be between 12-14V, even wider on modern alternators) & converts to the appropriate output voltage for the battery type & recharge stage, plus most now include a separate solar input as well.

Totally confused? Your vehicle battery + auxilliary charges from your vehicle alternator with out a DC-DC in the circuit.
Why is it when you fit an extra auxilliary battery you should fit a DC-DC?

 

[Guest]

Also my Mitsi shows 14.3 volt output through the electric brake controller screen so should be ok to charge two lead acid batteries for my minimal use.

 

[Manpa]

A DC-DC charger takes the input voltage (which could be between 12-14V, even wider on modern alternators) & converts to the appropriate output voltage for the battery type & recharge stage, plus most now include a separate solar input as well.

Totally confused? Your vehicle battery + auxilliary charges from your vehicle alternator with out a DC-DC in the circuit.
Why is it when you fit an extra auxilliary battery you should fit a DC-DC?

Dont quote me on this, my mitsi Challenger charges my car battery and my auxillary ( camper trailer battery) via an anderson plug with an ignition relay fitted to prevent draw when ignition is off. No Dc- Dc charger fitted and i think this is because the vehicle does not have the modern " smart charger alternators " that are fitted to late model vehicles. The dc-dc charger is req with a smart alternator as far as i can gather.

 

[Nightjar]

Dont quote me on this, my mitsi Challenger charges my car battery and my auxillary ( camper trailer battery) via an anderson plug with an ignition relay fitted to prevent draw when ignition is off. No Dc- Dc charger fitted and i think this is because the vehicle does not have the modern " smart charger alternators " that are fitted to late model vehicles. The dc-dc charger is req with a smart alternator as far as i can gather.

As already mentioned have been charging combined alternator + solar while on the road for past 11 years with no problems. (100,000km's)
The alternator also charges the two 110AH in tha caravan as well while travelling.
All up the vehicle alternator charges five (5) batteries while on the road with the caravan hooked up. Solar charging one (1)

Me thinks the only "smarts" here are the retailers promoting the DC-DC.
(ducking for cover the oop: is going to hit the fan.) :bomb:

 

[Ded Driver]

Nightjar, Manpa, the alternator can charge both batteries, but the alternator with its regulator are optimised for simplicity, cheap production, & for a regular wet lead-acid battery.
The output is not ideal for an AGM, Crystal, SLA, or Lithium battery. The Aux generally wont be fully charged to its capacity, & it wont reach its longest life. This is how it has been done traditionally but most people rarely get more than 4 years from an AGM (there are of course exceptions)
The DC-DC charger is effectively 3 units in 1.
1st it is a battery analyser, determining what state of charge a battery is at.
2nd it is a converter, taking a variable input voltage (alternator &/or solar), & converting & holding it to the appropriate output voltage.
3rd it is a smart charger, applying the correct voltage & current profile to suit the battery.
.
Manpa, from what I have read, a VSR (Voltage Sensitive Relay) may have problems with a modern variable alternator, although some VSR's are programmable & should be able to overcome this issue.

 

[Jaros]

460W Solar Panel
https://news.google.com/articles/CB...hdXN0cmFsaWEvYW1wLw?hl=en-AU&gl=AU&ceid=AU:en[/url

https://www.prnewswire.com/news-rel...y-at-all-energy-australia-2019-300943670.html

 

[condor22]

mmmm, 2M x 1M in round figures at 23kg and that's the 310-345W, couldn't find the specs on the link Jaros.

My 2 panels weigh < 3kg each so a big trade off re size to weight, particularly if on a van with limited space and load capacity.

Couldn't find a price.

 

[Jaros]

I couldn't find any either.

 

[condor22]

Bugger !

How to rapidly stuff a battery...... As I've mentioned before, I have my auxiliary battery in the rear of the 4by. It primarily powers the Engel, but also as needed a Travel Buddy oven. So a few days ago, I'm heating lunch, I get it out to eat and the timer on the oven still had 10 minutes to go, so I manually turn it off. However, I turned it a little too far, which turns it on all the time and did not notice.

Later that evening I went to check the Engel temperature to find it at near 10C. Not the fridge, so I check the voltage on the Aux at 5.8V and having noticed the oven on, the fridge contents were transferred to the van fridge and it was turned off. After using solar and going for a drive (next day) I finally got the battery back into float mode.

I then turned the fridge on using 240VAC mains and then ran it on 12V, overnight (empty) to see what it did to the battery voltage. It used 9AH overnight, but the voltage was 12.3 (should be nearer 12.6). I then turned the fridge off, recharged the battery and left it overnight, no load and the voltage was 12.4 next morning, no load should be nearer 12.8.

Conclusion - The battery is not holding voltage, but it will work enough to go shopping as I'd be driving. With the hot weather we are experiencing, it won't last long enough for my normal use.

Looks like a new battery - repeat - bugger !! 8.(

 

[Nightjar]

Condor,
Bought one of these years ago and usually once a year I pull the auxiliary 110AH out of the box under the tray of ute and hook the c-tek up to it in the shed and leave it ticking over for a day or so to let it go through the 8? stages.
This battery is hooked up to the "box of tricks" when prospecting season comes around and is set to cut out 11.5V. Some mornings if there has been cloud during previous day the fridges have shut down over night. This is not a problem because the overnight ambient temp is usually around fridge temperature, the freezer temp may have risen from -13C to -9C.
Have never, don't really know how to check AH usage so if the fridges are running all's well.
Did something similar to you with caravan (mentioned previously somewhere else) left the fridge running on 12V after returning from a trip. Few panic moments when 240V charger wouldn't kick in. Did the "jump start" method and batteries pumped up to normal and are in their 5th, maybe 6th year. After that episode, googled a manual for the regulator and set it to cut out at 11.5VC.
We set up our camp back in 1995 and use batteries stored there to run our 12V appliances and start diesel genny. These batteries probably dozens have cost us a whopping $5.00 ea from a battery recycle place near home. When we need a battery, usually a ZZ70, we drop in to the recycle yard, find one in good physical condition and showing a charge, hand over the $5.0, take it home and whack the C-Tek onto it and take it to the camp next trip. Several of these so called "dead" batteries started our onsite 3KVA diesel generator for many years. If we had been buying new batteries the bill would have been a few grand opposed to actual $100 or so.


https://www.sparesbox.com.au/part/ctek-mxs-5-0-12v-5a-battery-charger-mxs5-0

 

[condor22]

Thanks Nightjar, I have a 7 stage charger that might resurrect it. Thing is an AGM at 11.5V only has about 10% left and that too many times aint good

I personally don't want to go much below 12V, but I discharged it to less than 6V.

But that will have to wait a couple of weeks till I get home.

 

[bicter]

Shame the Travel Buddy doesn't have low voltage dropout fitted to it, could have saved your battery.
Can still get nice cheap 20A units for $10 from eBay.
This is the unit I've been using without a problem https://www.ebay.com.au/itm/Low-Vol...-Controller-/153595549606?hash=item23c30217a6

 

[ctxkid]

Have never, don't really know how to check AH usage so if the fridges are running all's well

may i recommend

https://www.ebay.com.au/itm/150A-Di...hash=item3d7d174947:m:mgRKbV9EPrel-ySJbaTBnvg

 

[bicter]

Have never, don't really know how to check AH usage so if the fridges are running all's well

may i recommend

https://www.ebay.com.au/itm/150A-Di...hash=item3d7d174947:m:mgRKbV9EPrel-ySJbaTBnvg

I'll second that recommendation. I've been using a couple for a few years now without any hassles, fitted my own Anderson plugs to it and have given trouble free performance.

Gives a good measure of the performance of your system.

One comment I'd make is they're not waterproof ..... don't ask me how I know :argh: