Another dual battery system thread.

[Dan+Z]

Hay guys.

I was searching around to see what threads there wear about dual battery systems and I came across a few.

However I just wanted to know if anyone has thought of using an old PABX battery (dad works in telecommuniction). They are a decent size battery that is 12v 100AH. A family friend of mine has used one that we had on his D2a with a $149.00 dual unit from super cheap auto to charge his large fridge.

After charging the battery up he connected the fridge to test how long it would last and after 12 hours the battery had only lost 2v.

So technically that could run a fridge for up to 3 days correct?

Is this classed as good for the little price payed?? Or should some one pay the extra and get a known brand???

Thanks

Dan+Z

[Blknight.aus]

depends on what you want to call flat.

(assuming yout 10v is a no load 10v)

12v down to 10v in some circles is considered a battery thats been discharged as far as you can safely do so without shortening the battery life.

[beanie_205]

I think you might be struggling to run a fridge for 3 days with that battery, though it depends on a lot of things- how cold you run it, how many times you open it, how well insulated the fridge is etc etc. Ideally you would run a deep cycle battery- a bit more expensive initially but lasts a long time if not overheated. These are designed to work most efficiently with low draw appliances like portable fridges- they discharge very efficiently over a long time. They also take longer to charge initially (so called deep cycle). When you calculated 3 days based on losing 2v after 12 hours, you're assuming you can run it down to 0v, perhaps you can but I believe most fridges will stop working at around the 10-11volt mark. My Waeco cuts out at 11v, designed to prevent damage to the deep cycle battery which must not be discharged below 11v. I have a 105 amp hour deep cycle in the back of my d2, and have got 6 days out of it at 4 degrees C, temps were around the 25-30 degree mark each day. Works like a dream- hope that helps

[Paolo]

I think you might be struggling to run a fridge for 3 days with that battery, though it depends on a lot of things- how cold you run it, how many times you open it, how well insulated the fridge is etc etc. Ideally you would run a deep cycle battery- a bit more expensive initially but lasts a long time if not overheated. These are designed to work most efficiently with low draw appliances like portable fridges- they discharge very efficiently over a long time. They also take longer to charge initially (so called deep cycle). When you calculated 3 days based on losing 2v after 12 hours, you're assuming you can run it down to 0v, perhaps you can but I believe most fridges will stop working at around the 10-11volt mark. My Waeco cuts out at 11v, designed to prevent damage to the deep cycle battery which must not be discharged below 11v. I have a 105 amp hour deep cycle in the back of my d2, and have got 6 days out of it at 4 degrees C, temps were around the 25-30 degree mark each day. Works like a dream- hope that helps

hi beanie_205

I'm interested in installing a deep cycle battery in the back of my D2. Any chance of seeing pics of your install and getting some hints on best practice etc. Rather than interferring with this thread, could you please let me know by IM.

Thanks, Paolo.

[beanie_205]

Found this which explains a bit about deep cycle batteries and discharging them etc.

AGM Batteries

[beanie_205]

And this which runs through installing dual batt's and some do's and don'ts, interesting that they recommend running cable between the negative terminals of both batteries, not just earthing it to chassis, i did this on my last 4wd and it worked fine. Think I may have read somewhere that you can't just earth to chassis in a diesel or I may be dreaming.

[beanie_205]

and here's the missing link

Dual Battery Systems & Alternator charging

[Cairns Boy]

I have set up a Gel type, no maintenance battery... 55 Amp Hour. Its about the biggest i could fit under the bonnet of my D2 TD5. I got the battery tray from TJM (which was expensive $250). The thing i have different that no one has mentioned is the way it is charged... Have a look at the RED ARC website!

I've bought a Red Arc DC1220 charger... Basically my 2nd battery will be charged from this RATHER than the alternator! I have found in the past that once the alternator has charged the main battery it is really only a trickle charge that ends up charging the 2nd battery and if you are out camping for a week and not really driving around for long periods of time, they just don't charge up well enough!! The Red Arc DC1220 actually starts charging my 2nd battery from as little as 9v....So one must be careful not to leave the ignition on... So far, so good! TOTAL setup was near $1700 but it is the rolls royce of set ups... The Red Arc charger was fitted under the steering wheel INSIDE the fuse box! The electrician said, the cooler it is, the better it works!

He also suggested that this 2nd battery could be wired up as the main starter battery thereby leaving me with the possibility of running a new 110 amp hour battery for my fridge and lights!

[nathand]

hey mate thats pretty extreme ive used the same isolator in 5 diff trucks
red arc 100amp -$140 ebay
batt tray- $69 arb
ed4r 55amp hour- 160 any batt shop
then just use one of those big amp kits from super cheap for the wiring , or some 25mm 240v flex if ur on good terms with a sparkie shoulnt cost any more than 400 all up
oh yeah 3 bucks for the overide switch on the dash

[maggsie]

hi beanie_205

I'm interested in installing a deep cycle battery in the back of my D2. Any chance of seeing pics of your install and getting some hints on best practice etc. Rather than interferring with this thread, could you please let me know by IM.

Thanks, Paolo.

Hello Paolo,
if you haven't found any photos, just search the the thread D2 rear Battery Install, there is a couple of pictures of my set-up.

Regards
Maggsie
04 V8 Disco