Can I Join multiple Batteries for 1 large Aux?

Bruosk
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Joined: January 20th, 2015, 6:41 pm

Can I Join multiple Batteries for 1 large Aux?

Unread post by Bruosk » February 14th, 2017, 4:50 pm

Some 4WD's like the Petrol Hilux look like they can fit 3 100ah sized deep cycles under the bonnet in various free spaces.
Can 2 or 3 100ah deep cycles be configured like this in a dual batt type setup to give a larger capacity for the role of the aux?
I read about charging issues when separate batteries are joined up, but I would just charge one battery at a time like connecting my charger to its terminals directly like I do with my standard red arc dual battery setup.

I have no interest in a solar panel for whatever reasons & just want a lot more capacity.

thanks

Peter Aawen
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Re: Can I Join multiple Batteries for 1 large Aux?

Unread post by Peter Aawen » February 14th, 2017, 7:48 pm

If you join a 'bank' of batteries in parallel (ie pos to pos & neg to neg) then the voltage remains the same but you get the capacity of all the batteries added together, & you can probably safely connect devices to any one of the bank of batteries & drain them equally thru use bar some voltage drop thru the cabling that will shorten the life of that battery eventually (altho if you can connect the load to pos on one end battery & earth via the other end battery you can 'evenly spread the voltage drop' & make 'em last longer) Just make sure the batteries are as 'identical' as they can be regarding type, construction, A/H's etc AND the connections & leads between them are as identical as they can be in cross section, length, capacity etc & you can usually even charge them ALL safely at the same time by leaving them linked & connecting your charger to any one of them.... :D

Any potential troubles really only start raising their ugly heads if one of the bank of batteries starts to fail, or gets charged by itself & then reconnected to the rest which are all still somewhat discharged (charge equalisation drags it down immediately it's connected again & can destroy one or more of them!) or if that previously mentioned voltage drop due to load wiring or you have a longer set of leads between any two of them than you have between any/all of the rest!! Keep them identical, connect them identically, charge them identically (while they are all identically linked), discharge them identically (while they are all identically linked) & any problems that occur should be minor - but they WILL take longer to charge once they get discharged!! If you discharge ONE Aux battery then if you are only using a basic charger, it will take just as long to re-charge properly as it took to discharge - if you have THREE batteries in a parallel bank & you discharge them that way, it generally takes THREE times as long to recharge them all properly as it took to discharge them!! Hence why solar panels are so handy for this sort of set-up, they can sit there charging a bit all day! Or hi-tech independent charge isolation systems that can drop any one battery out & recharge it at its optimum rate without the others noticing, then go on to the next in line without the others noticing - but they cost a lot!! ;)

Enjoy! :thumb:
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Bruosk
Here and there
Posts: 51
Joined: January 20th, 2015, 6:41 pm

Re: Can I Join multiple Batteries for 1 large Aux?

Unread post by Bruosk » February 15th, 2017, 5:19 pm

Thanks for the long detailed post Peter. appreciate it. :)

Gives me something to go & think about.

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