Generators or Alternators

Hmm, vewy interwesting....

What kinda $$$$ we lookin' at??

Regards, Ed. C.

With free trade from Jan 1st these things will be dirt cheap, right?

I'm intrigued; how does it produce "High frequency Direct Current"?
http://www.mobi-arc.com/application.htm
Product Highlights

From their website I had a lot of trouble working out what it actually was, it seems to be a switch mode supply which runs off 12V and produces the voltage and current required for welding, is that correct?

Mike Harding

That's true.

I have an AGM so my viewpoint is somewhat skewed.

I bought solar panels and would never stuff around again with car alternators or carrying petrol for generators
I no longer have to bother about flat or charging batteries
The battery does not charge from the car and is total solar
Bloody magic this power from the sun

Jimbo
The problem with what you suggest is that the charge rate is set by the most charged battery. In this case it will always be the starter battery as this has by far the higher acceptance rate.

The alternator takes its voltage reference (that tells it what to put outl) from the starter battery. This will literally recharge the starter battery (to a max of about 70%) within a minute or two. But even though the charging batteries are in parallel, the deep cycle battery will only receive a partial charge because the alternator regulator has cut it right back.

If practicable and affordable for you, solar is a better way - as it will charge a conventional lead-acid battery very close to 100%. It also gives you a really useful electrical backup in the event of vehicle alternator failure.

Am not totally convinced though of the belief re cylinder glazing - city-based cars used for commiting spend a large p[art of their lives idling in traffic - and do not appear to suffer accordingly.

If you really do need to charge via the engine it may help to know that the alternator generates about 60% of max output at little above idle, and virtually all of it by 2000 rpm.

I should perhaps add that our entire 10-acre house, workshop, swimming pool, and irrigation system in the Kimberley is 100% solar powered (has been for five years). The (mostly heavy steel framed) house is also believed to be unique in Oz in that it was also built using solar only. We used the system even for big angle grinders and arc welders.
Collyn Rivers

My OKA lights, fridge, satphone etc has also been running on solar for the past eight years - and has not run out power once in that length of time.
Collyn Rivers

In above 'commiting' should read 'commuting'.
Collyn

What needs to be done here Colin is to disconnect the main battery from the system so the aux bat can accept a higher charge. Have a look at ozi's website site where such a system is explained.

Can you see any problem with this, it's under "odds & sods" "battery & electrics"

http://users.bigpond.net.au/goldway/

Mad Dog

The system you mention is offered commercially by a couple of vendors. It helps but is only a partial solution (with deep cycle batteries) as one is still stuck with charging a battery with high internal resistance (and hence a low charge acceptance rate) with too low a charging voltage.

The inevitable result is a battery that cannot be charged beyond 70% and a charging rate from 55%-60% (of charge} onwards at only a very few amps. Upgrading the alternator does not help as the same charging regime as before is imposed by the regulator.

The only way to fully charge a deep cycle battery in realistic time is by charging to 15 volts during a boost stage, dropping back to about 14.1-14.2 for an absorbtion period, and then down again to float.

A UK company (Sterling) is looking at doing this via a dc-dc converter that (a) charges the starting battery (b) disconnects the starter battery from being charged and charge the deep cycle battery as I described.

For motorhomes and caravans I am increasingly recommending that the deep cycle battery be charged only by solar - not least because a good solar regulator charges as described above 9at up to 15 volts).

I switched my OKA over to this about six years ago and it works really well. Following my recommending this at a CMCA seminar in 1991, at least 200 CMCA members have done this themselves and found it works simply and well.

I believe the simplest, but costly, solution for 4WDs is to switch to AGM batteries. These charge fully and very fast from as little as 14.1 volts. They also withstand deep discharging very much better.

When considering cost bear in mind that their ability to be charged to (say) 95% and discharged to 20% (remaining) enables 75% of their nominal capacity to be used.

By comparison a conventional battery only charges to 70% (ie from a standard alternator/regulator) and cannot safely be taken much below 40% (remaining) without long term damage. Thus only 30% of nominal capacity is available. Even if you are prepared to kill it in infancy by discharging to 20% - there's still only 55% available.

As a matter of interest much of the above was set out by Peukert in 1897. It will not be of wide interest - but if you want to know about it it is on my website.
Collyn Rivers

I do use my engine to charge my batteries however I don't run the engine in the campsite as whether it would annoy anyone else I don't know but it would certainly annoy me LOL. I charge it by driving the car everyday as I would anyway. However I can go without charging for one day and still be ok.

My dual battery system consists of two cranking batteries, a relay and a switch. The batteries are isolated unless the key is in the ON position. However I can flick a switch and disconnect the main battery to charge the second battery faster.

I have looked into solar but as yet have not needed a second charging unit. The longest we go away for is nine days atm.

People running their engines or generators in campsites does annoy me. However if camping at the beach if they ran their engine while down on the beach it wouldn't be heard over the surf anyway.

Top Cat

I fear this is too big a topic to precis for a website answer!

Briefly: Peak Sun Hour maps show average irradiation and take into account typical cloud cover. From those one can reliably estimate what's likely to happen.

Charge rarely drops to zero but heavy cloud can cut it by 50-60%.

Cost depends totally on what you want to run - but it is not really practicable for fridges bigger than about 180 or so litres.

It is essential to get the sums right initially - but if that is done then the system will work very well indeed. If not, then not.

I am in the embarrasing situation here in that there are only four Australian-written books that cover this - and I wrote three of them.

So I'll honour the system by mentioning only that of my competitor Tasman Energy.

Collyn Rivers

Thanks for that..........Im a sparky so will look into it further.

Certainly have no plans to run anything more than a small esky sized fridge........I would be looking at using the solar panels to keep the 12v batteries charged and thats all.

Cheers.

Cost for solar panels is $650.00 each for 100w panels and then a regulator and battery. 2 x 100w panels is considered a minimum and will give you ample power to run up to a 60 litre fridge, lights and bit of other gear.
Type of battery you select and solar regulator is dependent if this system is going to be used full time or on a casual basis.
I will post a peak sun hour map on my website in the next day or two and post a link here.

Topcat

If you'd care to drop me an email I will be able to assist more (my background is research engineering, but that included both electrical engineeering and electronics - so we speak same language).

It is difficult for me to respond beyond what I have already without breaching the site's self-promotional obligations.
Collyn