Battery charging (AGM)

Thanks Scuba, "nothing original here" I thought as much, more of a brain picking exercise I suppose after admitting to myself that I`m not as smart as i`d like to think I am. I have used audio wireing before, as you say, nice & flexiable, I think a 300W inverter would cover the charger??? But going a bit bigger won`t hurt. Jacar... Mate I hate going there, I don`t get out under an hour!!!! & the plastic cops a bit of a flogging as well... It`s a crule world. Cheers Ron.

300W should be enough. 16amps x say 15volts dangerous maximum on my calculator = 240watts.
PS I purchased an identical Jaycar 600w unit from your ebay equivalent here in NZ from www.trademe.co.nz for less than $140.
"I don`t get out under an hour!!!!" Only 1 hour? I know the feeling!

Neville

Thanks Nev, yeah 300W would cover it??? but sailing a bit close to the wind as you say, if I go down that road I`ll do the 600W jobby methinks. Keep your powder dry.
Cheers Ron.

Thanks notso, will check that 1 out. PS. Had a mate many moons ago with a surname of Bright. Another mate??? hung the nick name "noso" on him... He wasn`t impressed!!! Cheers Ron.

The nick name should read "notso" D`oh... I`m having junior moments all over the place this morning, might be due to the Townsville weather & I`m on the road again!!! Ron.

Yeah, Mate I went to school on a bus with 3 Smarts, 2 Wises and 2 other Brights??

Where did you meet the bloke called Bright? Not a great many of us around, could be a lation

Hell mate, a truckload of free kicks there. Was in the Army, last saw him at a reunion in 88 I think, first name Danny, came from Melbourne, that`s all I know apart from still being dirty on me for smashing his pride & joy, an EH Holden no less... Wasn`t my fault Danny... Honest!!! Drunk!!... Never???
Mate while I`ve got your attention, I`ve been all over bloody OZ trying to find info on the Arid twin... no joy, can you point me in a particular direction please.
Cheers Ron.

Arrid link:

www.arrid.net.au/index.html

Yep, I'm another devotee of the 20amp Arrid Twin Charge. I "inherited" mine when I bought the Chev last November. I've re-wired it to charge my Fullriver 120a/h AGM battery in the cargo box and have never had any trouble with it at all.

No, using an Arrid is the ideal solution, but very expensive and very complex, just like the Inverter+Charger solution.

The simplest (therefore most reliable) and least-costly solution is to use the Alternator specifically designed to charge wetcell LeadAcid batteries to 100%. You only have to install adequate wiring to the trailer (with no refigerator on the same cable) to also charge a battery in the Trailer. An AGM will charge even better than a wetcell.

G/day Mike, mate I`ve been told there is no such animal, would be interested in any info. Cheers Ron.

If you have a modern vehicle, the Alternator will charge the battery to 100%.

Those who are telling you that Alternators only charge to 70%, have to convince you of this so you will spend money on their "better" solution.

G/day Mike, modern veh... I wish!!! 1980 Effie 4X4, just might be a ring of truth in the "better" solution. An alternator up grade might be the go, I`ll put that one on the burner for the moment, see what else comes up here, interesting to say the least, I might add that I I`ve stuck me foot in me gob a couple of times, but I think that has been caused by information overload... Oh well, sei`la`vie Cheers Ron.

My 1971 Datsun Patrol had an Alternator, though I can't remember if it was compensated.

(btw that's "c'est la vie")

Oh bugger another fax`pass... they just never end, could never understand the practicalities of French being a required subject at high school... Have a guess as to what subject I flunked... No prizes!!! Cheers Ron.

(btw that's "fox paw")

. . . . LOL

BTW it's 'faux pas'

Norm

Have you ever measured the current charge using your method into a lets say a 50% charged AGM or Gel battery after say an hour ? I have. It is invariably less than a couple of amps. Is the battery anywhere near fully charged at this stage? No!!! Do the maths. The current entering the battery via your method at this stage will be less than perhaps 3 amps. Using my method it will still be at 25 amps until fully charged.

Neville

Hi Scubadoo, either it was a very small battery or there was something wrong with your charging set up, like low charge voltage because Norm is spot on the money.

Short of going to something like a Sterling 50 amp DC to DC inverter, an alternator will easily beat an inverter/battery charger set up on anything bigger that a 70 A/H battery and add the fact that it’s heaps cheaper to put an additional auxiliary battery in than the cost of an inverter/battery charger, is heap safer and at the end of the day you have far more stored capacity.

This set up has been kick around for a few years now an it still is not as efficient or cost effective as simply just adding another battery.

As for an alternator not being able to charge ANY automotive battery above 70% is a myth and as long as the vehicles electrics are in good condition, it's easy to get any battery charged to 95+% just off the alternator.

Cheers.

"The current entering the battery via your method at this stage will be less than perhaps 3 amps. Using my method it will still be at 25 amps until fully charged."

You can't charge ANY car-size Lead Acid battery at 25 amps until fully charged.

Norm, mate read my reply to sandman re limitations of the alternator, they just can`t do what what every one thinks they can... Ask a sparkie. Cheers Ron.

Ron, It is your decision. I (and others) can only offer the benefit of our knowledge and experience.

In my case, I have been running 210 AH of AGMs in my Hilux (330AH with CT connected) for over two years. We spend about 5 months per year on the road., rarely in CP with access to 240 V. Our principal means of charging is via alternator while driving.

In 2006, we spent 16 weeks on the road in one trip, with less than 3 weeks in CP with 240 V. We ran a generator on 5 days in the other 13 weeks. We regularly camped for 2 or 3 days at a time in one place. We carry 2 fridges and use plenty of lights, electric water pump etc. This would be quite impossible with the numbers and scenario you describe.

I can only state that by conventional theory and from my own experience, it is possible to 'fully' charge AGM batteries using alternator with the right set up.

If you don't accept that and seek another more expensive solution, that's fine. You may well have good a valid reasons for doing that.
I hope it works and achieves your objectives.

Good morning Norm, mate thanks for that, very timely & to the point, I can now see some light at the end of the tunnel, for a while I felt like a hunk of meat on a red ants nest, getting pulled hell west & crooked, thanks to you & the other contributes I can now put a system together that will work. Mate if I appeared to be a bit boof headed... I`ts the nature of the beast, it takes a good argument to sway me, the forum has triumphed again. Stay safe & cheers Ron.

An excellent summary of the issues.

Hi Sandman, misconception... Mmmm dunno!! I`m just going on what I`ve been told & experienced. I won`t argue the toss on the merits of an AGM that was the reason why I bought it, but as far as the alternator is concerned,"most effective & effective method of charging, I have some reservations there, the nature of an alternator ( I`ll stand corrected) is that they can`t deliver high amps & voltage simultaneiously: AGM batteries by their nature (I`m told) will absorb just about every amp you can throw at them right up to the point of being fully charged. The alternators efficiency is compromised by it`s lack of being able to provide the drive voltage resulting in a slower (maybe) charge time but definitely not fully charged 75% might be a tad on the low side but it`s a moot point, no alternator can deliver a 100% charge to a battery. Some one has suggested that specially built alternators specifically for AGM batts can be had, I`ve yet to check that out, Christies, the mob who make the Honda powered battery charges tweak their alternators for a fast charge so it can be done. "Smart" battery charges overcome the inefficiencies of the alternator, that was why I was proposing to go that way.
Cheers Ron.

Sorry to disappoint you Ron but your lecy is working on the misconception that ALL vehicles are used as shopping trollies and as such only get driven for a few minutes each time they are started.

Based on this type of operation, the battery in these vehicles will in all probability never get charged beyond 70 to 75% BUT this in no way means that an alternator can not fully charge any form of automotive battery.

I have been designing and manufacturing Dual Battery Controllers for nearly 20 years and our specific controller, unlike other controllers, are specifically designed to exploit the very fact that batteries are charged to at least 95% and I can assure you that it is a rare occasion that a battery, cranking or auxiliary battery in an RV type situation, is not regularly charged to at least 95% and this is without any additional assistance like inverter/battery chargers or the likes and this is also the case even when the battery is fitted at the end of a long run of cable, in a camper trailer, caravan or at the far end of a large motor home.

The only time there is a problem is when the installation is not carried out properly and/or someone has used incorrect cabling.

As our equipment is installed in thousands upon thousands of vehicles and doing exactly what they are designed to do based on the fact that batteries do have stored charges of around the 95% mark, your lecy obviously does not have too much experience with dual battery systems.

Cheers

Thanks D/S, yes possibly the victim of miss/to much information, my very reason for floating the idea on this forum... Pick the brains of the one`s that "know" & come up with the best possible solution to the problem, I think I`m on the right track now. Take care & cheers. Ron.

Ron, don’t forget to let us know how you get on.

Cheers and have fun setting it up, which ever way you go.

Roger that!!! did a quick prelim check this arvo alternator checks out ok about 14.2 V, not so at the battery, feed from alt goes through amp gauge then back to batt isolator, methinks resistance in there somewhere, keep you posted. Cheers Ron

Ron, what's the total voltage drop between Alternator and Battery ??

Measure at Alternator to 'in' at Amp gauge and from 'out' at Amp gauge to Battery.
Amp gauge should give no discernible voltage loss.

Hi Ron, 14.2 is a good average output voltage you would expect in most vehicles but just having thin wire can cause serious voltage drop problems, so check the size of your cable and another thing to consider is the is the state of charge of your battery at the time you measured the voltage.

If the battery is fairly low, this may pull the voltage down.

There’s lots more to it but this is a start.

Cheers.

Thanks DS, I wouldn`t say for sure but on inspection the wireing looks a bit dodgy size wise, I`m going to upgrade it anyway so we`ll see. Cheers Ron.

She’s all done, excellent result, doing what it should, thanks again fellas, enjoyed the experience, take care. Cheers Ron.

Ron,
now your happy please tell us what you actually did........

Hi Mainey, mate I did make a detailed reply but like my voltage... It disappeared, one to many XXXX Gold I think... One little ol wrong key... & poof she`s gone, I was cheesed off & not in the mood to do it all over again I am now so here`s the good oil.
Rewired from alt to Batt isolator with a heavier gauge wire... no rocket science there, one thing I like to do is solder the terminals over crimping, better performance/longevity, have seen the results of crimping only in a marine environment, not pretty!!! On inspecting the old wiring it was found to have a hot spot in it (cooked) I thought how the...??? then I recalled a little incident some years ago, can`t recall how it actually happened but remember nearly ripping the battery post out trying to get the terminal off. When I pealed the insulation away it was found to be sort of corroded a fine brownish green powder all over the wire plus I think it might have been a tad under size for the length of the run. The amp & volt gauges are telling a different story to the previous one so I`m thinking she`s all good, end of story. Take care & cheers. Ron.