Dual battery setup

Submitted: Sunday, Jan 12, 2003 at 18:58
ThreadID: 2925 Views:6424 Replies:8 FollowUps:13
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G'day everyone,
I've got the The Piranha DBE 150S MKII Electronic Isolator fitted to my 80 series, went to Fraser for a week expecting to drive at least a half to an hour each day (which I did)Third day for 2 hrs but next morning aux battery almost flat.
Got batteries checked out before leaving by auto-electrian and he said they were in excellent working order. Great!!!!
Ok me thinking 80 amp alternator would charge the aux battery up fairly quickly after topping up the main after initial start up but Oh no!!!!! come on banter me up and tell me WHY the aux batteryalmost went flat.

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Reply By: OziExplorer - Sunday, Jan 12, 2003 at 19:24

Sunday, Jan 12, 2003 at 19:24
Steve what are you running from your auxilliary battery?
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Follow Up By: Stevea - Sunday, Jan 12, 2003 at 21:04

Sunday, Jan 12, 2003 at 21:04
56 litre explorer fridge freezer thats all Ozi
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Follow Up By: Oziexplorer - Sunday, Jan 12, 2003 at 21:29

Sunday, Jan 12, 2003 at 21:29
Steve what I have posted then is reasonably accurate. I am presuming you have approximately 85amp hour deep cycle battery.

None of these dual battery systems explain how they operate, and have never found a 4WD outlet that knows how they work - they just sell them. To get the second battery to charge at full alternator capacity requires a whole different system to what you have fitted.
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Follow Up By: Robroy - Monday, Jan 13, 2003 at 16:57

Monday, Jan 13, 2003 at 16:57
I am thinking off buying the same system that Stevea has does that mean I will have the same problem running an 52lt waeco.
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Follow Up By: Rodeoowner - Monday, Jan 13, 2003 at 18:56

Monday, Jan 13, 2003 at 18:56
Ozi, that's the exact problem that I had when I was buying my dual battery system. I had a DBS in my Kombi (Piranha 150) and an Exide battery. A couple of years later and the Piranha price had gone from $150 to $250. A got in contact with GSL in Sydney and they referred me to a dealer in Tas, but it was the same price as Piranha. After asking numerous salespeople how their DB isolators work, I got the standard response, ie what is written in the ads. Rotronics were the only place I could get any answers from, so I bought one of their units (though not the independant charge system).
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Follow Up By: Rodeoowner - Monday, Jan 13, 2003 at 19:05

Monday, Jan 13, 2003 at 19:05
And........ I have a comaro in an old Overlander Magazine. If an Explorer 56 litre fridge is run with the temperature at 35deg C for 12 hours and 24deg C for 12 hours, over the 24 hour period it will draw 37 amps. This is not including openeing and closing of course, so in fact it could be drawing up to 50 amps per day. Cheers.
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Follow Up By: Oziexplorer - Monday, Jan 13, 2003 at 19:13

Monday, Jan 13, 2003 at 19:13
Rodeoowner, they sure had some markup then in that GSL unit. I know what the GSL units are worth wholesale, and they should not be anymore than $129. I use a Redarc unit as my base unit, with some of my own home made system. However, there is not much to choose from between the GSL and Redarc, they both do the same job. I just prefer the Redarc unit for some of the features it has. From what I can see, the Piranha is just horribly overpriced dressed up GSL stuff. Flash colour, flash name, exhorbitent price as much of the other stuff is.
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Follow Up By: Oziexplorer - Monday, Jan 13, 2003 at 19:18

Monday, Jan 13, 2003 at 19:18
Rodeoowner 50amps is closer to the mark than the 37 amps in summer.
My evaKool was running at 43amps as I had a data logger attached over the holidays just for interest sake. With evaKool being one of the better insulated fridges, you can imagine what some of the others are with thinner insulation. I run mine at as close to 4°C as I can keep it.
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Reply By: OziExplorer - Sunday, Jan 12, 2003 at 19:58

Sunday, Jan 12, 2003 at 19:58
Steve, just as a matter of interest, for 30 minutes running for two days, and two hours the third day, you would have at best put back 20 amp hours. With the battery being close to flat by the third day, I would estimage the figure of 20 amp hours to be reasonably accurate. At most it would probably be 26 amp hours.

Your alternator does not charge 80 amps into the auxillary battery. On the first day of driving around for 30 mins as the battery was not to flat you probably got in the 30 minutes driving 8 amp hours, on the second day, 4 amp hours and on the third day due to the battery now being close to flat 8 amp hours, and at best 14 amp hours.

To charge a second battery at full alternator capability requires a totally different system.
AnswerID: 11137

Follow Up By: Stevea - Sunday, Jan 12, 2003 at 21:14

Sunday, Jan 12, 2003 at 21:14
Ozi can you describe the other system because after paying reasonably big bucks for the dual battery system I'm interested in this other system you have written about or can I add some thing to my system to achieve a better result than what I'm getting now. Don't wan to get into the solar debate thanks
Steve
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Follow Up By: Oziexplorer - Sunday, Jan 12, 2003 at 22:11

Sunday, Jan 12, 2003 at 22:11
Steve what brand of vehicle, model, year and engine type do you have?

If you can give the the numbers off your alternator I will be able to give you better information.
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Follow Up By: Stevea - Monday, Jan 13, 2003 at 21:12

Monday, Jan 13, 2003 at 21:12
91 80 series turbo diesel I'll get the other info in the daylight tomorrow. Scared of the dark!!
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Reply By: Member - Nigel - Monday, Jan 13, 2003 at 01:24

Monday, Jan 13, 2003 at 01:24
An independant charge isolator (like the Rotronics RFC12 or better) would cope with your situation better, but even so, if you've nearly flattened a battery then the alternator won't do much to bring it back. If your only using an alternator to recharge then try to avoid going below 11.5 volts (measured with load off).

A flattened battery needs a mains charger and many hours to bring it back to full charge.

An alternator will only charge a battery to about 80% in any case.

A good investment is a decent charger (eg 8 amps DC - 12 amps RMS) that at least has an auto cutout - but don't leave it on for days.
AnswerID: 11162

Reply By: Topcat - Monday, Jan 13, 2003 at 01:31

Monday, Jan 13, 2003 at 01:31
Hi Steve, I can't fully answer your question without having more info as OzExplorer has explained, however here are some useful web sites on batteries, charging cycles & isolators you might find of interest to give a better insight to your problem.
www.batterytender.com
www.uuhome.de/william.darden
www.surepower.com/ebrochures.html
I myself run a 40amp Rotronics charge unit to my deepcycle battery bank & a 600amp rotary isolating switch between start & aux batteries. It is a fail safe method of making sure the start battery is isolated when engine is not running. (i.e provided you don't forget to switch it over!!!)
Cheers.
AnswerID: 11163

Follow Up By: Stevea - Monday, Jan 13, 2003 at 21:13

Monday, Jan 13, 2003 at 21:13
thanks Topcat, a bit of reading to do.
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Reply By: robroy - Monday, Jan 13, 2003 at 17:09

Monday, Jan 13, 2003 at 17:09
Hello steveA I am thinking of buying the same system as you but now I wonder will I have the same problem as you, I will be running a waeco 52lt have been quoted $810.00 fully installed in my 80 serries petrol.did you not go back to the people and complain they told me that it would be peace of mind fitting this system.
AnswerID: 11191

Follow Up By: Oziexplorer - Monday, Jan 13, 2003 at 17:25

Monday, Jan 13, 2003 at 17:25
Robroy what are you getting for $810 it is one hell of a lot of money for a battery system like that. The parts for that system including a battery, battery tray etc. etc. would be at best $400 - being generous to the extreme.

Robroy how do you want to use this system?

Will you be travelling on a daily basis and stopping overnight or perhaps for even up to two days?

Just using it on weekend or how?

What make and model of vehicle do you have?
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Follow Up By: Robroy - Tuesday, Jan 14, 2003 at 07:59

Tuesday, Jan 14, 2003 at 07:59
I would be getting DBE 150smk2 $297 battery tray and bottle bracket$121 Yuasa d/c powerglide $160 cable to acc,female socket and male plug and single fuse box $100 labour $132 total $810.00
I also could buy the kit for $437 plus battery and get our auto electrician to fit it could I use a cheaper battery and get the same result ?
I want to use the system to run a 52lt waeco fridge thats all at present.
I joined a 4wd club and on my first trip we drove during the day and camped at night.
I will also use it on sme w/ends.
I have a 92land cruiser 4.5 petrol waggon.
I also have an after market cruise control which I need to move so the washer bottle can fit in its place.

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FollowupID: 6194

Reply By: Raymond Charlton - Monday, Jan 13, 2003 at 19:54

Monday, Jan 13, 2003 at 19:54
Hi Stev
One of the problems is the type of battery you are using. From experience it takes 5-6 hours to totally recharge a deepcycle battery. The two solutions that I have come across are:
(1) I use a 32 watt solar panel (flexible type,easier to sore) to help keep the battery up.
(2) Seriously considering going over to a exide coil battery which only requires 2-3 hours of running. One problem they are only 55 amp hours and are about $350
So far the solar panel is working well
Ray
AnswerID: 11213

Reply By: Raymond Charlton - Monday, Jan 13, 2003 at 19:54

Monday, Jan 13, 2003 at 19:54
Hi Stev
One of the problems is the type of battery you are using. From experience it takes 5-6 hours to totally recharge a deepcycle battery. The two solutions that I have come across are:
(1) I use a 32 watt solar panel (flexible type,easier to sore) to help keep the battery up.
(2) Seriously considering going over to a exide coil battery which only requires 2-3 hours of running. One problem they are only 55 amp hours and are about $350
So far the solar panel is working well
Ray
AnswerID: 11214

Reply By: nissan4x4 - Monday, Jan 13, 2003 at 22:36

Monday, Jan 13, 2003 at 22:36
hi stevea,

I have the same one fitted to my GQ and I had the same problem, mine got replaced under warranty.
I pulled apart the second one to look inside, I was quite alarmed at what I found. The unit is just a box with wires sticking out and some smart electronics inside. There were two issues I saw. Firstly from the outside, the main power cables, as they enter, do not have any sort of weather protection. You have a gap around the cables thru which dust/water can pass thru. Secondly, they use open relays in the electronics. Coupled with the gap around the cables, dust/grime/moisture fowl the contacts. End result is your aux battery is not being charged.
Quick and simple fix, seal the gap with silicon sealant.
If your unit is out of warranty, try this. Pull the unit apart. You will notice several relays, use a sensitive brush and clean the contacts with metho (don't use turps or anything that leaves a residue) and alow to dry.
This may not be the cause of your problem, but its a start.

Good luck.
AnswerID: 11240

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