What battery for AUX

[KraftyPg]

It will cost you!

I need three people to agree with what I come up with so that it can be made internet fact and be immortalised forever.

 

[Old.Tony]

With a single railway spike you can turn any battery into the last one a person will ever need.

Place one ear on the battery. Place the railway spike in the other ear. Now hammer the spike into the battery.

They'll never need another battery once that circuit is complete.

 

[KraftyPg]

Like all items in the list they must be used properly and the only two ways such spikes can be used is to hold cables to panels or as in line fuses, in special cases one spike can do both.

 

[Rich64]

A dc-dc charger is a waste of money in my opinion but some people like that sort of thing.

Good to have an opinion, however the truth of the matter is : that with a conventional type of isolator there is NO WAY an alternator can deliver enough voltage to properly charge an auxiliary battery (especially an AGM), which in the short term will mean reduced reserve capacity and in the longer term, premature failure of the aux battery.

 

[Old.Tony]

+1. That's why I invert my incoming power in the tub and use a 240V charger. The added bonus is that the fridge automatically switches over to 240V and thus unloads the battery, allowing the charger to fully and accurately manage the battery.

 

[FatBoy89]

+1. That's why I invert my incoming power in the tub and use a 240V charger. The added bonus is that the fridge automatically switches over to 240V and thus unloads the battery, allowing the charger to fully and accurately manage the battery.

What charger do you use Tony? CTek what?

 

[Old.Tony]

I use a C-Tek inside the caravan (exact same setup for power in there). I have one of those 6A/16A Jaycar chargers in the tub - they don't sell them any more - I am thinking of changing that to one of the C-Tek clones just to see how the clone performs, but I've no qualms with this one. At startup, it delivers 2A of refresh current for a short time then takes a look at the battery and decides what to do with it. Not a bad unit, although the C-Tek in the caravan is 10 times better.

I just can't justify throwing away the $160 I paid for this Jaycar unit when it's still doing the job I bought it for.

 

[FatBoy89]

Which ctek though? Model?

 

[Old.Tony]

It's an MXS-7000 which has now been replaced by the MXS 7.0 charger - same thing in a new package.

I didn't want the smaller one because I wanted something that could also be a 12V supply and I also wanted something that had the "recycle" function, which delivers a constant load to rejuvenate batteries that have sulphated.

I've successfully used that function on the battery in my tub (normal deep cycle) and can't use it on the battery in the caravan (gel).

 

[terryc]

Anyway pay no attention to me I disagree with about 50% of the hydrogen in tyres theories on the internet

Umm, I though it was NITROGEN in tyres?
Which is a really pisser as tyres inflated with normal air are 80% nitrogen already.

Thank you Huey<tis raining today>

 

[Geoff3DMN]

Good to have an opinion, however the truth of the matter is : that with a conventional type of isolator there is NO WAY an alternator can deliver enough voltage to properly charge an auxiliary battery

That's not true, one can run twin alternators (1 for each battery) with isolated circuits and some of our work vehicles do just that.

 

[terryc]

A dc-dc charger is a waste of money in my opinion but some people like that sort of thing.

It is a horses for courses situation.
AFAIK, the problem with the "second/aux" battery just being tagged off the main battery is that the alternator never really charges the main battery to full charge. I was told/taught that as the main battery approaches full charge, the alternator field is reduced so that the charge rate decreases, i.e. is exponential. this is a design feature to stop the alternator boiling car batteries dry, which is what happens if you just keep pushing the full alternator capacity into the battery.

Meanwhile the auxillary(sp?) battery is usually metres away on the end of a thin and very warm cable which has an additional voltage drop.

In work vehicles(daily driving), this really means SFA as the fridge in the back doesn't draw (both(if no isolator) batteries down that much overnight and it is put back the next day. Problems usually start appearing, as the battery ages on Monday morning after a quiet weekend(no movement) with either a warm fridge or hard to start vehicle.

A dc-dc charger will cause the alternator to give more power for longer and it will push it into the second/auxillary battery till it is fully charged. Caveat, this can take hours to do. so if your work driving is only an hour to work and an hour home, then the dc-dc charger is probably a waste of time.

OTOH, if you are off touring, then it will be getting a good proper charge up.

About Fast chargers; the fundamental inescapable physical fact is that faster you charge/discharge any battery, the less the number of uses you get out of them. This is another reason for a dc-dc charger. Wisely chosen, it will restrict the charging rate to one that gives you long battery life.

One of the current claims doing the rounds that you can charge any modern AGM battery fully in two hours, which is true, BUT you are severely shortening the number of charge cycles if you are doing a very fast charge rate. It is something like 1,500 cycles(6 years?) to 500 cycles(2 years).

Anyway.

 

[KraftyPg]

Good to have an opinion, however the truth of the matter is : that with a conventional type of isolator there is NO WAY an alternator can deliver enough voltage to properly charge an auxiliary battery (especially an AGM), which in the short term will mean reduced reserve capacity and in the longer term, premature failure of the aux battery.

Opinions, no matter who has them don't automatically make them truth. I don't care what people believe and what websites people subscribe too at the end of the day if someone wants to waste money believing internet theory and not electrical facts then they are free to do as they like.

Umm, I though it was NITROGEN in tyres?
Which is a really pisser as tyres inflated with normal air are 80% nitrogen already.

I'm going for Hydrogen terry, and if 3 people agree I'm calling internet fact and dedicating an entire website too it.

 

[FatBoy89]

I'm
With sir krafty

 

[KraftyPg]

I'm with Krafty too

(that's two votes )

 

[ONLOCK]

krafty for pm

 

[FatBoy89]

That makes 3

 

[BravoBrad]

Where's the Website Krafty?

 

[RustyNav09]

ok well this is quite a large thread on aux batteries. so here i go. im still truggling ot find a spot for my redarc isolator under my already completely packed bonnet. having a 09 str which came standard with parrallel dual batteries so they are both cranking items. yes i have removed one battery and cranked off it and have had no problems with it. so my theory is. do i keep the 2 cranking batteries OR remove one of the batteries and install a AGM battery in the tub and integrate it into my draw system with a switch panel and fuse box to run easy wiring off for lights etc? by removing a battery from the bonnet gives me more room to add extra stuff. even though im pretty much done under the bonnet now with everything installed.

so do i keep 2 batteries and add another to the tub(AGM)? OR
remove 1 battery and add 1 to tub(AGM)

is it true thhat having 2 different batteries wont work properly when it comes to charging with just a redarc isolator in place? does this have to run 2 identical batteries for it to work properly?

Rusty

 

[ONLOCK]

i run 2 differnt batteries off my red arc and no dramas at all. with your setup id just put an isolator between the 2 batteries and run a supply cable down to the rear for outlets or whatever you need, thats what iv seen done a couple of late model d22's