Thread: Alternator Capacity

Just to put myself in perspective......

I have posted many questions on this forum and have received invaluable replies, for which I am eternally grateful. I don't often get myself greasy, so on mechanics I don't have a lot to contribute.

Having spent all my life as an electronic engineer, with a particular and personal interest in automotive electronics, I can contribute on this subject, and will do so whenever I can, but I don't do so unless I am confident of my knowledge.

And yes Blknight, I do check my posts before sending, that is why they seldom have typos or spelling mistakes, thesaurus or no thesaurus.

Cheers,

Paul

just for poops and giggles...

now call me a fully qualified diesel/plant/heavy vehicle certified mechanic But I reckon that this thread nicely points out that you can actually do with just a dumb as a post dual battery charging system like what I setup what you're claiming cant be done unless you use an expensive DC/DC charger..


Drive safes system does it even better because it allows you access to some of the RC in the main battery as well and includes some pretty good protection that my (and presumably the one in the above thread) doesnt offer, it relies on you being smart enough to look after the batteries yourself.

This thread is much more suited for talk regarding the use of 12v DC-DC inverters to charge multiple 12v automotive style (be they deep, start, hybrid, SLAB, GEL, marine, DIN, ISO, JIC, spiral wound AGM, AGM, vented or non vented flooded cell) batteries.

Originally Posted by Blknight.aus

just for poops and giggles...

This thread is much more suited for talk regarding the use of 12v DC-DC inverters to charge multiple 12v automotive style (be they deep, start, hybrid, SLAB, GEL, marine, DIN, ISO, JIC, spiral wound AGM, AGM, vented or non vented flooded cell) batteries.

I could get personal right back, but that serves no-one.

If anyone needs an answer to what is being discussed in this topic, show this thread to a competent electronic engineer and ask them for an opinion.

funny, since this has been done to death before and since I happen to work in an environment that's lousy with electronics we happen to have access to some pretty good electrical engineers, I assume that an aviation electrical engineer is sufficiently qualified to work out how to best charge a battery...

the 3 areosprarkwranglers with camping setups I know run the same ignition controlled solenoid to charge their batteries.

the 2 of the 4 battery techs, as in guys whose sole purpose in life is looking after batteries, that go camping and have dual batteries run the redarc which when broken down is just a solenoid thats controlled by a VSR as opposed to the ignition directly.

ok my bad, you didnt have enough of a sense of humor when I poked a bit of fun your way, fair enough but you still haven't even attempted to answer my serious questions ..

I'll even cut it down to one for you.

explain to me how a dedicated alternator will not charge a set of batteries to the correct nominal full charge value.

and then when you've nailed that one down... I have another absolute pearler for you that relates to both that ^ question and the use of a computer controlled alternator to charge multiple batteries.

oh, just by the by as a while were at it kind of deal, what happens to a DC/DC inverter charger if you accidentally hook it up to an incorrect voltage battery, a completely discharged battery or inadvertently reverse polarity the battery its supposed to be charging on hook up and how do they go when they're required to not only supply the charging current to charge the batteries but also drive the nominal load that's normally drawn off of those batteries?

and please, if your going to quote me in a serious manner have the decency to address the whole post, not just the bits that suit you.

Hi Dave, and I just love that link. You truly have a warped sense of humour.

Wilbur, my apologies, I just re-read my first reply and while it sounds like I was calling your post as being crap, I meant your source of this information is crap.

I’m not sure where you are getting your info from but it is completely wrong.

For a starter, all automotive batteries are lead acid batteries and while some will have the ability to charge faster and/or be discharged to lower levels and so on, they are still lead acid batteries.

Next, mixing battery types in an automotive set up will have no effect on anything in that set up and using an alternator as the primary charge source is not only the most efficient means of charging batteries, even when the batteries are of different type and have different levels of charge when the starting the days drive.

Furthermore, an alternator will individually charge each battery in a set up at that battery’s optimum charge rate. None of these DC-DC devices or battery chargers can do that.

Wilbur, you need to look beyond the garbage the sellers of this crap use as adverting.

No, Drivesafe, my source of information is NOT crap, but it does come from the 21st century.

Blknight, there is no point in my putting lot of effort in answering your questions because your mind is already made up.

IF you are interested, read this book (Motorhome Electrics). It is not my source of information and I have not read it myself, but it is highly respected, and written by Colin Rivers, a highly qualified automotive and electronic engineer.

Must have books - CMCA (Campervan & Motorhome Club of Australia)

I strongly advise any members of this forum who are using multiple batteries to pay whatever it costs to buy this, or a similar book. You will save it ten times over in longer battery life and better performance. We all know that info gained on the net and on forums is seldom peer-reviewed, and mistakes can happen. Proper textbooks are usually correct and can be relied upon.

now that sounds a little defeatist of you...

or do you mean that you cant actually answer the simple question of how a dedicated alternator wont correctly charge a set of batteries?


Im quite willing to proove(and have the gear to do so) that the simple dumb as a post hook em together with decent wire and a suitable relay/solenoid is the fastest and easiest way to fully charge batteries.

not only that.

I'll tip that I have a 15amp alternator running on a small diesel engine that would charge 100AH of aux batteries faster than what your 25A DC/DC inverter could do it.

Well, I'm only an electrician not an engineer but I'm going on practical experience. For over 3 yrs on the D3 I had a 100ah battrey as a second in the car and 220ah house batteries in the van charged thru a Traxide and never had an under charging problem (BEP meter readings going to 100%)

Now for 17mths with same Traxide system, in D4 run a 55ah Optima ( in the spot where it was going too be hot ) and house batteries of 315ah (BEP meter in van still goes to 100% SOC) with out any problems, I do have solar panels on the roof connected all the time,

And after 2mths when I did hook up to 240v, thru Projector 50a, 7 stage charger, it went into float stage after 15 mins (during that time it does a battery check).

I took particular notice of what was going on with battery charge because Kimberley Karavan were pushing DC-DC units (they like techy stuff)

So from that I can only assume that the alternator and charge system is up to the job all by it's self. It has been noted by a LR tech on this site that the D4 charge system is not your normal run of the mill .

Just what is actually happening with mine.

Cheers Ken