24/12V dual??

[macca81]

my MQ curently runs the 24V twin bat system, but as most aftermarket lights, winches, compressors etc are 12V i was thinkin that i would run an aditional bat rather than overload my 24-12 convertor. can i still hook this bat upto the others in a dual bat system or would i be best to keep it totaly seperate and get an additional alternator to charge the lone bat??


Edit: just had a brainwave... being a diesel, and not needing to send spark to spark plugs, do i even have an alt??

[-Scott-]

If you don't have an alternator, how are your batteries being charged?

I don't agree with your logic. Yes, many accessories are 12V - but lights, winches, compessors etc are all available in 24V versions (think trucks ) and are generally much better - same power comes from less current, so less is lost to resistance in the wires.

Take the extra time to source 24V versions of the high power stuff, and use your converter for the low power stuff.

[macca81]

not so much time, more the $$...

[drivesafe]

Hi macca81, fitting a second alternator is fairly common on 24 volt motor homes and as long as you keep the 12v and 24v positives away from one another, usually the hardest job is actually mounting the 12 volt alternator.

Cheers

[MART]

Is the current battery a 24 volt battery or two 12 volt bateries in series If it is a 24 volt battery,you can run 2 12v european style batteries in series to give you 24 volt. then split your charge wire through an isolater.Run one wire to original 24volt battery to charge as normal. Run the other one to the two series batteries, hooking to the out going positive terminal,then run the negative of the other bat to chassis or motor or both. European battreries are smaller in size and you should be able to fit themm under bonnet. On the other hand if you currently run 2 12 volt batteries,add a third battery and parallel it of one of the originals. It will still charge like that, but i would use an isolater to stop main batteries from draining,hope this makes sense and helps,Cheers Paul.

[-Scott-]

On the other hand if you currently run 2 12 volt batteries,add a third battery and parallel it of one of the originals. It will still charge like that,

No.

Batteries are all about charge. Current is literally the flow of charge - two batteries in series charge and discharge the same current, so they charge and discharge at the same rate.

Parallel two batteries, then throw another in series, and you're looking at a world of trouble. The current through the single battery will be split between the parallel batteries, depending on the individual state of charge of each. If you start with ALL batteries in top condition, and 100% charge, in theory it could work OK - but using all three batteries to their full potential will be difficult.

For example, the single battery carries the same current as the other two combined - so it would need about twice the capacity. But, balancing state of charge with current will depend on battery construction and the magnitude of the current. Get it wrong, and you'll either over-discharge or under-utilise battery capacity. What's the point?

[drivesafe]

Mart, just continuing on from Scott’s post, quite a few truckies have tried your suggestion over the years and all have had disastrous results where they have shortened their battery’s life span dramatically. Even just tapping in between the batteries to run a CB will cause serious problems.

Cheers.

[MART]

I think i said use a Isolater,and yes you can parallel one battery off another and have it charge correctly,we do this at work all the time of 24 volt dc gear,to adapt for 12 volt equipment which has to be battery backed by individual battery.

I also charge my second battery of my first with a duty solenoid,the voltages read exactly the same when charging. I run a UNI power alternater which puts out 220 volt dc,so my batteries charge fairly quickly.Recently before engine blow up,I cranked engfine for 5 hours trying to start it,also running lights and then again the next day for 3 hours and the batteries where fine.


My original question was or is the battery a 24 volt bat or 2 12volt in series. Most of the trucks i have seen ru 2 in series,Cheers Paul.

[ausoops]

does any company even make a 24v battery?

ive never seen one before

ive got a 24v safari with a 30A dc/dc converter and have yet to run it at full capacity. as for a winch i am still thinking of going a third battery charged with a redarc 24/12 volt charger for a 12v winch, or just spend the dollars and get a 24v winch.

or get a ox hydraulic and change the relays to 24v (but ive been told by a few people that the ox couldn't pull the skin of a custard)

[Dooley]

I think i said use a Isolater,and yes you can parallel one battery off another and have it charge correctly

You sure ?

I thought paralleling caused an imbalance as the cells aren't perfectly matched so cells receive different charge and fail prematurely.

[-Scott-]

I think i said use a Isolater,and yes you can parallel one battery off another and have it charge correctly

You sure ?

I thought paralleling caused an imbalance as the cells aren't perfectly matched so cells receive different charge and fail prematurely.

I would agree if we're talking NiCad or NiMH cells.

Parallel lead-acid batteries are (within limits) fine. If you apply the correct voltage each battery will self-regulate it's charge current, and accept only the current it wants.

Series batteries is where you need to be careful. If the batteries are not very carefully matched (size, characteristics, age, state of charge) you can end up with one battery being overcharged while the other is still undercharged. As soon as you pull charge from one battery and not the other, you've thrown out the balance and it CANNOT be restored by series charging.

Buy two identical 12V batteries, FULLY charge them in parallel and then connect them in series; then you should be OK. But you MUST treat them as a single 24V battery, and not tap 12V from the middle.

The above applies to Lead Acid batteries (SLAs, gel cells, AGM, calcium batteries etc.) NiCads/MiMH are different; they require a more complicated charging system. The new wave of Lithium cells, I have NFI.

Cheers,

Scott

[Dooley]

Cheers for that, yeah well I heard it happened to nickel batteries so thought it would be the same for lead, guess not.

Lithium are fussy as hell, tend to asplode when you don't do it right as well.

I had a bit of a look into them, you can get ICs for it specifically, they need voltage and temp monitoring though, theres more to it than that but the IC takes care of it from what the voltage and temp tell it. Can charge a few in series with them. Don't have a clue about paralleling them though.

Nickel are easy enough to charge in series and if you're happy with slow/trickle charging. I prefer that anway as really fast charging tends to send them to the grave a little early.

[macca81]

can you get 24v bats?? its just 2 12v bats.

i figure get a 3rd bat and hook up another alt/gen to charge it totaly seperate from the other 2. yes?

[-Scott-]

I think this is a great setup if you have the space, and the skill to do it.

[macca81]

space, shiteloads. skill, we shall see...