What Charger to buy?

[adamleah]

I am looking at buying some 235AH batteries to run my fridge and lights for about a week camping . but have been told by about half of the battery mobs that I should be running a 3 stage charger of which are very very expensive...

Have any of you had any experience with charging larger deep cycle batteries off these style or cheaper type battery chargers?

Would also be interested if any of you know anywhere cheap to buy 12v 36w flouro fittings?

Cheers
Adam

[NormC]

I think the advice you have received (get a good 3 Stage Charger) is spot on. I run 4 deep cycle batteries (1@105AH, 2@ 120AH and 1@ 60AH. I charge them all in parrallel, so it is the same as a 405AH battery.

I use a CTek 25 2500 (25Amp) 3 stage charger. Although it is an expensive charger, it is much cheaper than the total cost of the batteries. It charges them well and fully, and is likely to extend the life of the batteries considerably.

Think of it as an investment rather than a cost.

[NeilD]

The 12 v flouro lights can be easily converted from standard 240v ones. The 240 volt ones have a regulator that converts the 240 to something like 32 volts that actually run the lights. This is replaced by a different converter. A mate had a few done up at about $30.00 a pop

Neil

[Poseidon]

As Norm said, buy yourself a decent multi-stage charger. The cheap 4 amp chargers won't cut the mustard.

I have a 4 stage 16amp charger that has given me about twice the run time on my Motorguide battery since ditching the old 4 amp cheapie.

Regards Cameron.

[somervillebm]

Hi Adam and Norm ... I will be interested to hear how you are going to set the battries up... I work with a team of electrical Eng and I asked them about placing the battries in series or parallel or seperate... In my case suggested not to place the Duel batties together rather have seperate plugs for each on a A-B-C switch. If I had they in parallel I would need to use 6V units... If I of these die then not more power ... If I went the other way they said even if I had the same make and model of battery one would be stronger thus current flow and in the end kill the other unit.

[NormC]

Somervillebm, either you misunderstood the Electrical Engineers or they don't know 12 V systems as well as the bigger systems they normally use; perhaps both.

If you were to connect two 6V batteries in SERIES, that would give 12 V and it is almost essential to have identical batteries to do this. In fact you would never need to do it. The main time batteries are connected in series for mobile use is to run a 24V (typically truck) system from 12V batteries.

Connecting in parallel does not increase the voltage. Every 4WD with a dual battery system has at least two 12V batteries connected in parallel at times. Typically (and ideally) they are isolated by a solenoid or relay when the vehicle is not running, but when you start up and start charging, they are connected directly in parallel.

This is the system I use. On trips I have all 4 of my deep cycle batteries in either the 4B or the camper trailer. All 4 of the deep cycles can, and sometimes are connected in parallel (I have a series of plugs that let me change the set up). They are isolated from the starter battery until the vehicle is running, then they connect in parallel with the starter. This is to prevent the starter from being drained when at rest, running the fridge, lights etc.

The only difference between my system and many thousands of others in 4WDs, is the number of deep cycles I run, though it is very common to run two deep cycles, plus starter.

A fellow by the name of Collyn Rivers has written several books on this subject and is widely regarded as the Guru of 12V mobile systems in Australia. Although my first trade was Electronics Technician (did an apprenticeship in the Army) I took advice from Collyn (via e-mail and a 4WD forum we both participated in at the time) when I was designing my system. Google him and you should find enough info to spin your brain. During my design phase I got so much different and contradictory advice from 'experts' that I became very confused, despite my prior knowledge of the subject. I chose to rely on two, one was Collyn, the other a specialist marine electrical engineer who does work for many of the big boat builders on the Gold Coast.

My system has been in operation for 18 months (though I have added one more battery, the 60 AH AGM in that time), and has worked perfectly, including during a 16 week trip to the Kimberley, NT and Gulf this year.

The risk of connecting batteries in parallel is that if one dies by plates collapsing and shorting out, and it goes undetected for a while, you can stuff all the batteries. The risk is there, but I and thousand of others take it as there is no simple, convenient and cheap solution. I check my batteries regularly and in any case the incidence of the problem I mention occurring is very rare. I don't personally know anyone it has happened to. In any case, my starter is isolated so is protected, so I won't get stranded.

Sorry to post such a long tirade, but opinions on battery systems are like ars@holes. Everybody has one including me :)

In the end you will take advice from those you trust and you don't know me from a bar of soap. Can I suggest though, that you at least check out some of Collyn Rivers' writings and possibly even invest in one of his more recent books.

Good luck.

[Grey_Ghost]

Hi Adam
I Brought a 3 Stag 40 amp charger from solarforce
works really well It runs 2 120amp batties thourgh a I kva genny
Cheers chris

[adamleah]

Thanks guys for comments ...

As Norm C says - 2x6v 235A/h batteries in series = 12v with 235a/h
Whilst 2 x 6v 235 a/h in parrallel = 6v with 470a/h

I am still not bought on the 3 stage charger however as the batteries are worth about $350 whilst a charger is worth like $6-700.. I may as well have a cheaper charger and get 2 sets of extra batteries...??

re lights- I am actually a sparky and was too lazy too do a conversion on a standard 36w flouro as I thought it may have been cheaper and easier then buying one off the shelf...

NormC, you mention you have 4 batteries running off your one alternator for charging ... A standard alternator I believe wouldnt be able to charge this amount ? Did you find the batteries lasting less and less throughout your trip..
Interested on what charger you run to recharge batteries once at home also....

Adam

[NormC]

Hi Adam, I use a CTek 25 Amp charger. Used to have a Ctek 7Amp back when I ran only one Deep Cycle, but upgraded about a year ago. I think I paid about $350 for the 25 Amp, but that is from memory. It's a great charger.

On the recent trip I had 3 deep cycles (2 AGMs @ 120 AH and 1 vented @ 105AH). I've added a further 60AH AGM since (powers the Min Kota in the tinnie). We were away about 16 weeks or about 110 days. Had access to power in caravan parks on about 20 days. The rest of the time we were bush camping or in NPs, so no power. I carry a 1KVA Kipor generator and run it through the CTek when necessary to charge batteries. We ran the gennie no more than 10 times. I left home with a 20 litre gerry of ULP for the gennie and arrived home with a couple of litres left in it.

I think my alternator puts out around 70 Amps, but not certain. My advantage is that the 2 AGMs will accept pretty much whatever current is available and charge very quickly. A few hours driving every couple of days kept enough charge in the batteries. We ran the gennie for 3 or 4 hours when we stopped in the same place for more than 2 days.

Whenever I had access to 240 Volt power, I fully charged, which was possible overnight with the 25 Amp charger. We normally had a CP stop ever 10 to 14 days, except for a 25 or so day period on the Gibb River Road and Mitchell Plateau.

Power was not a problem on the trip. In fact, we became quite blase about it. We carry 4 x 12V flouro lights, plus have 3 built in lights in the camper trailer (kitchen ,plus 2 reading lights). We often had them all on. Other than going to bed, the main reason we turned them off was due to insects, or so we could better enjoy the stars.