Conclusion - PostID: 20518 DB Isolator Mods

Submitted: Monday, Feb 21, 2005 at 18:14
ThreadID: 20642 Views:2306 Replies:3 FollowUps:4
This Thread has been Archived
Thanks everyone for their input and ideas, especially drivesafe for sparking the idea in the first place.

I had two batterys, both N70ZZ. The first was a 17 Plate 770CCA starter, the other an 85Amp/hr Wet Cell Deep Cycle.
I had an Arrid Smart Relay (just a glorified headlight relay but much bigger and with spike protection and a 1 min dely on the coil after activation) between the two bats. The Arrid was hooked up to the ignition so that when the motor was going they joined and when it switched off they seperated.

The aim was to extend my battery life while at camp without buying a bigger battery or leaving me stranded with no go in my bats.

What we did:
1. Build a "Low Battery Cut Off" kit from Altronics (cost us about $15).
2. Take the ignition plug off the arrid and replace with lead from cut off switch
3. Plug "input" side of cut off switch onto the Arrid "+" Terminal (from the main battery).
4. Run wire and mount L.E.D. on dash from cut off switch.

All done, mod took about 1/2 an hour to do (and that's only cos I had to pull the dash apart to put the LED in).

Not only did I get more run time out of my gear but it also seemed to make the batteries run more efficiantly. I'm not sure of the science but I think because the batteries are sharing the load 50/50 they are not working as hard and seem to last longer than when running by themselves. (if that makes any sense at all).

The system is fully automatic (the way I like it). When the car is switched off it now leaves the two batteries connected in parralel until the voltage of the starter battery drops below 11.9v (under load) then cut's the power to the coil on the Arrid Relay which seperates the batteries. The Waeco Cooler keeps running off the deep cycle and the starter has heaps left to crank the surf over in the morning. It worked REALLY well and was VERY EASY to do. I'd recommend it to anyone.
The LED on the dash is on 24/7 until the starter battery cut's out, it let's me know if both batteries are running or if one is running, just handy to keep an eye on things.
Previously after 12-14 hours of running my Waeco Cooler (drawing about 6-8amps) my deep cycle was getting pretty sad, like totally rooted basically. After running the cooler under the same conditions with the new setup the starter bat had'nt even cut out yet, it was just about too though as the battery was down to 11.9v under load (about 12.2 without load). I wanted to see how much it had left in it so I turn the high beams, spotties, fan on full, air con and all interior lights (2amps) on and turned the key. (first thing in the morn too). The Surf turned over twice and happily sprung to life.

VERY happy with it. So Thanks guys, Explore oz has saved me $$$ again!! :-)))

Back Expand Un-Read 0 Moderator

Reply By: muzzimbidgie - Monday, Feb 21, 2005 at 19:56

Monday, Feb 21, 2005 at 19:56
Good work, well done.

FYI, the redarc isolator runs on this very system. When the motor is running, it will not cut in until the starting battery has a good charge, 12.5 volts (I think). When the motor is not running, both batteries stay connected until the starting battery gets down to around 11.5 volts (I think).
AnswerID: 99366

Follow Up By: Member - Jeff M (WA) - Monday, Feb 21, 2005 at 20:00

Monday, Feb 21, 2005 at 20:00
Yes I was under the impression that's how the Redarc worked (from what I'd heard anyway). The advantage with the setup I have I guess is that I can trim the drop out cut in voltages to my liking.
FollowupID: 357687

Follow Up By: Tim HJ61 - Monday, Feb 21, 2005 at 23:48

Monday, Feb 21, 2005 at 23:48

My Redarc was preset to 13.6v and 12.6v, but if you want it set differently, they will do it for you. I asked for mine to be reset to 13.2v and 12.2v.

One disadvantage of the Redarc, and maybe all solenoid type isolators, is that it pulls about 0.5A when engaged. Not much, but it means the battery it is connected to is always pulled down slowly to the turn off voltage whether you have accessories on or not. Not sure how this affects battery life.

As per a previous post, I have the Altronics/Dick Smith kit but for a third battery - (I've got two starting batteries on a 24v HJ61). Like Jeff M, I like the adjustability of the home made kit. I often wonder if the high amp capacity solenoids are always necessary and what the disadvantages are of these kits costing $40 approx. if you are only charging an aux battery.

FollowupID: 357723

Reply By: drivesafe - Monday, Feb 21, 2005 at 20:31

Monday, Feb 21, 2005 at 20:31
Hi Jeff M, I’m glad you tried it out.

For more than 15 years we have lead the way with our gear doing just that and have been telling people that they could get longer operating times out of there auxiliary battery be simply tapping the extra charge available from there cranking battery.

Brother you would not believe some of the arguments put forward to say that it wont work.

Not only have we been supplying the trade with gear that works that way and had very little come back ( most of that usually related to their battery(s) having reached their use by date and not a problem with the DB gear but every Winnebago motor home for the last 10 years has similar equipment in it that we designed for them.

It’s finally good to hears that someone has finally showed, independently that our principal is sound, thanks very much Jeff M for trying it out and I’m sure you will not have any problems.
AnswerID: 99367

Reply By: Mainey (WA) - Tuesday, Feb 22, 2005 at 04:18

Tuesday, Feb 22, 2005 at 04:18
As I stated previously "This would be a great advantage to all battery isolator/charger manufacturers, and I bet it is taken up by some smart entrepreneur in the near future"
I did not expect your finished product so quickly!
Good on you for you for your optimism and the guts to give it a go.
AnswerID: 99430

Follow Up By: drivesafe - Tuesday, Feb 22, 2005 at 09:26

Tuesday, Feb 22, 2005 at 09:26
Mainey it was taken up, but it was over 15 years ago. Any manufactures taking it up now would just be playing catch up.

What's good about Jeff posting is that he experimented and found that he could improve on a system he found lacking, it makes no difference as to what brand it is.
This is the very same reason we developed a system that is basically the same only all in one device, because there was nothing back then that did what a customer was needing.

Here we are 15 years later and people like Jeff are still finding out the hard way that what's out there, is still not really meeting what customers need.
FollowupID: 357762

Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 22, 2005 at 12:16

Tuesday, Feb 22, 2005 at 12:16
Thanks Mainey and drivesafe, yeah when I get an idea in my head I go like a bull at a gate, it's kind of a flaw and a blessing at the same time! ;-)
Sometimes it works out good, sometimes I royally screw up because I didn't sit back and think about it for long enough... That's where this forum has served me so well, I think of a "crazy" idea and ask for people's opinions, they get improved and validated here and of I go towards the red flag! ;-)

Just one thing... :-)

When it's 37 degrees and your bare foot and sweating like a pig leaning over the car earthing yourself to the chasis and ground playing around with 4 guage cables, isolate them from the big ass batterys first, don't think she'll be right mate. 12v can still hurt. LOL
It reminds me of the time I was wipper snipping the front lawn, you know playing it safe... wearing ear muffs and saftey glasses...... and thongs! I stalled the 2 stroke snipper on my toes while I was shooing a bee away from my face! OUCH! LOL

Man I'm stoopid somtimes!
FollowupID: 357790

Sponsored Links