a battery way of life

Thought AGM's were the go til I got told today that they are NOT designed for our sort of uses. e.g running fridges and regularly discharging and charging.

All made sense when I heard they were designed for sitting around for long periods and holding their charge well, so they were always ready to crank something over . e.g army vehicles. They demand a reliable power supply and high rate discharge performance. Advised AGM's also need to be recharged asap to maintain life whereas GEL are more tolerant.

Have been advised GELs are the new 'black' in 4wd/camping deep cycle batteries. :) Designed for regular abuse and recover better than the AGM's.

I got the AGM 18 mths ago because it had to sit inside the vehicle and I was worried re gassing which isn't such a big problem with them. I'm not sure of the story with Gels on this ??

Got a price on a 130amp Gel today $250.00. Paid $320 for the AGM 18mths ago.

OK who's going to tell me all that's a load of rubbish.....

For your setup, I can recommend the "Thumper" Portable Dual Battery system made by Blue Apple.

Available in 3 sizes, but the 75Ah is the most practical.

List price on my brochure shows $849 and comes complete with a heavy duty (20 amp) charging kit. Included in the kit is a length of heavy duty twin core cable, Anderson Connector and "patch lead". Also has full instructions for installation.

Because the battery pack inside are of AGM design, it is completely safe inside the vehicle as no inflammable gases are produced like a wet cell battery.

No connection with the manufacturer, just a satisfied customer.
You may be able to haggle to get the price down a bit.

Blue Apple (Home of 12 Volt) are located in Strathalbyn, S.A. and from memory, the price includes dispatch by courier to anywhere in Australia.
Their contact number is 08 8536 2144.

thanks a heap thats the kind of s##t im after...im now one step closer to my ultimate adventure...cheers

Brom,

You've limited yourself by the location - In the back - I assume you're talking a wagon.

Sealed gel cells and AGMs are all you're able to use. And given the weight of these, it will have to be very well secured. For a decent size, you're looking at $250- $400. I take it you've already sorted out an isolator.

AGM - no question (except cost) but _DON'T_ put it in the engine compartment.

Mike Harding

$849 For that sort of money, I'd put an ordinary cranking battery inside a sealed case and vent it to the outside :-)

To do it right regarding 12V have a look here http://www.caravanandmotorhomebooks.com/
unbiased good information for us who have no idea who to believe what.

Reiner

Hi Brom

GEL batteries are great but need a slower charge to prevent damage. (Insert from windsun) "The advantage of these batteries is that it is impossible to spill acid even if they are broken. However, there are several disadvantages. One is that they must be charged at a slower rate (C/20) to prevent excess gas from damaging the cells. They cannot be fast charged on a conventional automotive charger or they may be permanently damaged."

AGM are better (Insert from windsun) "The charging voltages are the same as for any standard battery - no need for any special adjustments or problems with incompatible chargers or charge controls. And, since the internal resistance is extremely low, there is almost no heating of the battery even under heavy charge and discharge currents. The Concorde (and most AGM) batteries have no charge or discharge current limits.

AGM's have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries. The Concorde batteries can be almost fully recharged (95% or better) even after 30 days of being totally discharged."

I would go for the AGM.

No gases, no spill and they have a life of 10 years if looked after.

Regards Derek

Go for an AGM (similar characteristics to gel cell but later technology).

Am wary of Windsun's comment re charging voltages. These are at variance with many AGM makers specifications for float voltage (which most warn is very temperature dependent - and 13.0-13.3 volts max is typical in Oz).

Re under-bonnet mounting. There is anecdotal evidence that the life of some AGMs has been shortened by doing this through thermal runaway due to the high under-bonnet ambient temperature - and that a vehicle alternator will float them at over 14.0 volts once fully charged. The effect is like a nuclear melt-down but with a lesser bang - and more locally-limited after nasties.

To avoid this I have set up my new 4.2 TD Nissan as follows.

It has a 60-litre Engel connected that is across a 100 Ah Lifeline AGM under the bonnet (via doubled up twin 8 sq mm cable). This is charged primarily by two Sharp 8-watt solar modules on the roof, via a Plasmatronic PL 20 regulator that I have programmed to boost charge at 14.6 volts, absorb at 14.2 volts, and float at only 12.8 volts.

There is also a feed to the battery via a Redarc relay, but I have the relay coil wired through an on/off switch on the dash. This is normally off (so that charging is normally via solar alone). It is only used exceptionally when the AGM is discharged through lack of sun, or excessive load (such as cooling a warm carton of ale).

The reason for using the Redarc is to protect the starter battery in the even of my forgetting that I have the alternator charge switched on. (Incidentally the Redarc is that company's new low-current draw device that Redarc sent me to trial. It works very well, and runs much cooler than the standard unit).

I also have their new three-stage 5 amp charger on trial. This has special AGM settings. As with many high quality three-stage chargers it totally outperforms two 10-amp conventional chargers that I have. Lovely unit.

Don't try to economise too much if buying a three-stage charger. Good ones are not cheap, but if you buy the typical chain store offerings you are doing yourself and anything you charge with it a disfavour.
Trust this is of interest
Collyn Rivers

my 2 bobs worth.
I located 3 * 110A Northstar gel batteries at the local recycling center.
Been playing with them for the past 2 months.
Using 12A charger and 1 or 2 * 50W headlight bulbs for load.
I find they charge faster than my current system. (2 * superstart M70ZH).
and they take longer to discharge than my current system.
Am about to swap the superstarts for the gels and see if it is better under actual load conditions.
So far They appear to be the way to go - so far.
Techie

Stephen F10

Thank you for raising this issue. As I responded on another current thread on this Forum (where a respondent strongly suggested newcomers shoud read earlier postings before asking questions) the problem with doing so is that technology constantly changes - and what may have been true some years back is no longer so now.

All my early books and articles that discuss parallel charging advised not to attempt this with AGM and non-AGM batteries. At that time virtually all AGM maker warned very strongly against it.This was emphasised so strongly in their data sheets that it was not possible for a technical writer to suggest otherwise without incurring legal liability by doing so.

The main (and valid) reason was that, because AGM batteries have very high charge acceptance (ie they grab almost all of whatever current is available), they will inevitably starve (or even discharge) any non-AGM paralleled battery. There was also a suggestion that (in vehicle applications) so doing may damage the alternator.

Over time it became clear that what the battery makers were concerned about was direct parallel charging with no safeguard for the non-AGM battery. That concern still exists - and is well-founded.

In the meantime howver the widespread acceptance of Redarc and other voltage sensing relays removed the main concern. These relays only parallel batteries for charging when the non-AGM battery (typically the starter battery) has reached about 13.6 volts.

Further, if the AGM battery does discharge the non-AGM battery, that relay opens (at about 12.5 volts) to once again isolate and protect that battery.

Some people have got away with parallel charging with no such safeguard - but in every case that I have checked of this - this is only because that the connecting cable was very long and/or light. The resultant voltage drop was preventing the AGM charging at full rate.

I am still a bit concerned that an alternator could be damaged if attempting to charge a very large AGM battery bank in high ambient temps, but in practice I am not aware of any actual such happening.

To cope with changes such as the above, all of my books on this and related subjects are printed in very short runs - and updated every three/four months if necessary. On the subject of parallel charging - they now advise much as above, as have all my published articles for the past two or so years. There will however inevitably be a few references still around to the contrary and I am grateful to you for bring one of them to my attention.

On a similar topic I receive emails every now and again re solar and electric fridges. Very early copies of my 'The Campervan & Motorhome Book' advised that 110-litres was aboiut the largest fridge that can be comfortably run from solar. But since the original publication (in early 2001) fridges have become more efficient and some 120-watt solar modules are smaller than early 64-watt modules - so that 110-litres is no longer relevant. That change too has long since been made.

I do post these changes on my website from time to time - and will be adding a comprehensive update shortly.
Collyn Rivers