12 volt dual battery charging systems

Submitted: Saturday, Nov 06, 2004 at 01:46

ThreadID: 17577 Views:6663 Replies:7 FollowUps:5

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stabacon

Greetings all! was wondering if someone may be able to assist with the dilemma of choosing between an electro-mechanical (ie. solenoids etc) or a solid state 12 volt dual battery charging system to install into our Subaru Forrester & camper trailer.
The Forrester does not have room under the bonnet to install a larger sized deep cycle auxillary battery so the option being considered is to locate the auxillary battery inside the toolbox mounted on the drawbar of the trailer. The auxillary battery will mainly be used to run low current apppliances such as a Waeco CF50 fridge and fluro lighting. However am confused somewhat as to the best option of a charging system to have installed into the Subaru. Has anyone with a Subaru Forrester had to face this problem? Would appreciate some advice from those more experienced in these matters. Will look forward to your responses!
Many thanks Stan

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Reply By: Wayne (NSW) - Saturday, Nov 06, 2004 at 05:24

Saturday, Nov 06, 2004 at 05:24

Stan,
I think that the solid state isolating system is the wat to go with any vehicle with on board computers that look after the engine management. Soleniods are cheaper but offer no protection to the vehicles electrical system.

Wayne

AnswerID: 83206

Reply By: Mike Harding - Saturday, Nov 06, 2004 at 07:15

Saturday, Nov 06, 2004 at 07:15

Cost or convenience?

A solid state system will do it all for you - it'll even top up the battery and make toast each morning - almost :) A good one will ensure your 2nd battery is always kept at an optimum state of charge - fit and forget, BUT it will cost you some money, these people seem to have a good range of battery thingies (no idea about their quality)
http://www.redarc.com.au/

also Jaycar do a kit (KA1782 in case the link won't work)
http://www1.jaycar.com.au/productView.asp?ID=KA1782&CATID=25&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=347

The solenoid (relay) solution is fine but you have to remember to switch the system on after your main battery has charged. If you search this forum back about three months you'll find a post I made giving details of how to make a simple solenoid system.

Mike Harding

mike_harding@fastmail.fm

AnswerID: 83210

Follow Up By: Mad Dog (Victoria) - Saturday, Nov 06, 2004 at 09:11

Saturday, Nov 06, 2004 at 09:11

Mike, the redarc is a mechanical relay but it does have some electronic smarts built into the unit. A brilliant device, cheap compared to the solid state devices, works well and the quality is second to none.

FollowupID: 342203

Follow Up By: Mike Harding - Saturday, Nov 06, 2004 at 10:48

Saturday, Nov 06, 2004 at 10:48

>Mike, the redarc is a mechanical relay but it does have some
>electronic smarts built into the unit. A brilliant device, cheap
>compared to the solid state devices, works well and the
>quality is second to none.

Thanks for that Ray, I didn’t know.

I had their site bookmarked because they had some good info. on the technicalities of dual battery systems and I was pinching ideas from them to design one of my own :) but haven’t gotten around to it yet.

There is nothing wrong with using a relay over a MOSFET for doing the switching of the second battery, each has certain advantages over the other, but the electronics really come into their own for the sensing circuitry and doing the whole thing automatically.

Glad to hear the Redarc products are good quality – they looked like they knew what they were doing in this area.

Mike Harding

FollowupID: 342206

Follow Up By: Mad Dog (Victoria) - Saturday, Nov 06, 2004 at 12:10

Saturday, Nov 06, 2004 at 12:10

Mike, the redarc unit has built voltage sensing circuitry to automatically operate the contacts. The relay closes at 13.6v and opens at 12.7v
Spike protection is included. For starting the batteries can be joined with a button push. It's great value at roughly $130

FollowupID: 342213

Reply By: Troopy Travellers (NSW) - Saturday, Nov 06, 2004 at 09:44

Saturday, Nov 06, 2004 at 09:44

I recently bought a Redarc unit & it cost me $132, seems the go though.
Sparky

AnswerID: 83217

Reply By: Penguin (NSW) - Saturday, Nov 06, 2004 at 10:57

Saturday, Nov 06, 2004 at 10:57

Hi Stan

You don't mention where you will be running the fridge when travelling. I assume it's in the trailer if you're considering putting the second battery there.

If that's the case, you could use an Arrid Twincharge mounted in the trailer. The advantage of this charger is that it's not so voltage sensitive and will accept 10-14V (I think) as an input. This means that you don't need to run big cables from the car to alleviate the voltage drop.

12 Volt Shopin Perth sells them as does About 12 Voltin Sydney.

They're expensive (around $300) but, by all accounts, a good 20A charger.

Mike

AnswerID: 83224

Follow Up By: Penguin (NSW) - Saturday, Nov 06, 2004 at 11:01

Saturday, Nov 06, 2004 at 11:01

Sorry, I'll try those links again.

12 volt shop

about 12 Volt

FollowupID: 342207

Follow Up By: Penguin (NSW) - Saturday, Nov 06, 2004 at 11:03

Saturday, Nov 06, 2004 at 11:03

Sorry, can't seem to get this working at the moment. Need more coffee!

http://www.12volt.com.au - Perth

http://www.allabout12volt.com.au - Sydney.

FollowupID: 342208

Reply By: stabacon - Saturday, Nov 06, 2004 at 12:41

Saturday, Nov 06, 2004 at 12:41

greetings all!

Many many thanks for your responses. Was great to hear from you all, have learnt something here today, will follow up on the suggestions made, thanks again.
Stan

AnswerID: 83228

Reply By: mr diamond - Saturday, Nov 06, 2004 at 16:27

Saturday, Nov 06, 2004 at 16:27

gday stabacon.
just come in side outa the rain from finishing off the same thing you plan on doing.
i have mounted the 90ltr weaco in a tool box on the camper with a deep cycle battery next to it.
i fitted a red arc to the jackaroo.exelent product ofers full spike protection and wont allow your main to run flat.so simple to install and quite cheap at around $130.they take up virtually no room.
easy simple reliable.
cheers

AnswerID: 83248

Reply By: Baz (NSW) - Saturday, Nov 06, 2004 at 16:40

Saturday, Nov 06, 2004 at 16:40

Go here Stan this is the Arrid twin charger and we use it as we have a camper too and this was recomened to us because of the distance from the car to the camper it is designed for when the second battery is in the camper.

CLICK HERE

Baz

AnswerID: 83249