dual battery AGAIN!

Hi Roger,
it is highly recommended the betteries are the same - but in reality its not going to happen when you have to mix starting and deep cycle batteries together for different purposes - camping.
I have a starting battery for the engine only and then run the fridge from my fully sealed deep cycle batteries (I use Hawker energy SBS60 batteries and depending how long we are away I will use 2 or 3 in parrellel to give me eaither 120 or 180Ah or capacity). 2 of these batteries in parrellel will run my 50L waeco for over 4 days without any recharging and Im still not at the low voltage cut over setting at 10.2v. When we are travelling I then let the alternator charge them. The batteries are protected by a battery box to protect them/us incase of any damage.
when at home I keep them connected to the smart charge which is fitted in our Camprite camper to ensure they are kept charged and in good condition.
I ran 8mm core cable from the front of the car to the batteries in the back of the Patrol and used cct breakers for short cct protection, and interconnect the batteries with 10mm core cable.
I think you will find everyone has slightly different setups to suit their needs. mine is certianly far from perfect.

hope this helps.
regards
Bryan

interesting read.
isolating batteries
note the references to external sources.

Roger, provided the recomended charging voltages are similar for both, then no problem.
Alternators Vs are often a bit low to get full charge into some battery types. The float setting on the solar controller might be a bit high for some batteries.
Since they are both wet cells, you are probably OK, but check the manufacturers recommendations and the actual voltages of your charger/controllers.

I am using a two way Redarc between my crank (calcium) and house (AGMs). The alternator is 14.3V and the solar PL controller is the same. This way, my solar also tops up the crank when the house is full. Not quite your question, but in the same paddock?

Cheers,
Peter
OKA196 Motorhome

to brian,
thanks for your input,sounds a good setup you have.I am being "tight"as times are tough and i will be bush camping almost 7 months.I dont want to spend excessive money and rely on the cranking battery when i will be stopped weeks at a time.
If i buy another 115ah battery i will have more than enough energy in store,need fish frozen an beer cold.
just had a squizz at greybeards article[thanks] and will study it further.confusion still reigns.
Peter i might give the two batts. a go and take seperate readings at intervals to see whats doing.
When the sun shines again that is ,overcast and wet the last 5 days here in the hunter valley.
May have to leave something else behind and throw the genny in after all.

thanks guys Roger P

My son has a set-up that is budget AND different.
He has NO isolators and uses both of his DC batteries for both house AND cranking (in parallel).
Risky you ask?
No problem. All of the accessories (incuding lights and fridge) are run via low voltage cut-outs. This lets him use about 50% of both batteries (double that available if they were isolated) before the fridge etc gets turned off automatically. At that point, there is still plenty of grunt left to start the engine.
He also has a couple of solar panels to poke power in when camped.
This is all on an FJ40 shorty. Works well.

Cheers,
Peter
OKA196 Motorhome

thanks you guys,
I have the low v cutouts sorted and as i aint using main cranking batt in system have that as reserve at all times anyway.
It cost me 50.00 last year for a jump start[from fellow nomads] for my xt falcon, towing a camper trailer at clem walton park 65km east of mt isa, after a few nights ,cd player and m/phone charging flattened the batt.so no start- till these others came along.
Any way i will be much wiser after this next 7 months,great to have MUCH sunshine up north in winter.See u all there!!!nd will let you know how it goes.
cheers Roger
P.S
checking out sidewinder site now.

hi kevanancy,
hope thats spelt write.nice of you to reply.
I think those people may have been doin it a bit tougher than me in their 4wds and vans and i was keen on a start. with a solar panel ,at least i would have had a free charge in a couple of hrs hey.
i am not like that either,to expect $ for a hand on the road.a beer or cold drink helps start a conversation that leads to information money doesnt buy.
take care roger p

Hi Roger p, the stories about not being able to have dissimilar batteries connected in parallel is nothing more than a myth.

If you were to have two identical batteries, one your cranker and the other your auxiliary, you are going to continually have a situation where the batteries are going to be at different states of charge when you connect them together in a parallel set up, how does this differ from have two dissimilar batteries being connected in parallel.

As stated, this is nothing more than a myth based on a misunderstanding. People continually mix up the requirements for connecting batteries in parallel with what is required when connecting batteries in series.

When connecting batteries in series, you MUST use the same type and size batteries otherwise one of them will never be fully charged and will have a shortened life span.

No such thing occurs when connecting dissimilar batteries in a parallel set up, tens of thousands of RV uses have been doing it for decades and don’t have any problems.

drivesafe,
thats what i wanted to hear and will set it up today and give it a trial for a bit before i leave.
takes a LOT of home work when one starts from scratch.
This site is a veritable encyclopedia of information.Working out what is best for ones own use is the head scratchin bit.
thanks for that info.
cheers Roger