More on Bush Power

[BigWave]

Sorry RR.
No one that I know (until maybe now) has ever asked for a charger that puts out: "Amps per hour".
Just "Amps", which is the charging rate.
Amperes*hours (or A.h - often written as Ah, or less correctly AH) is a measure of total charge.
Anyway, I'll try not to be a units Nazi, as I've learned (with patience) not to be a spelling Nazi.

 

[ctxkid]

Amps Per Hour is used when referring to Chargers.

i'm with Bigwave , first time i've heard this

 

[Manpa]

Keep it nice everyone or the mods will have you kept in AH (after hours) for misbehaving. layful: layful: layful:

 

[Jaros]

I will say that this topic is going way over the heads of the average Joe out there.
Jaros

 

[BigWave]

Sorry Jaros, and RR just that as a professional Electrical Engineer for over 40 years (1977), using correct units of measurement was drummed into undergraduates.
All credibility with a client - particularly Defence - is lost if these are mashed.
No more being a :units Nazi" for me, however I still find this thread interesting, with good ideas and new products (viz: Lead Crystal batteries).

 

[Jaros]

I understand all the terminology being used here as well.
There is no need for anybody on the forum to call another an idiot.
This is a very interesting topic but it does go over the heads of a lot of some of our members.
Jaros.

 

[condor22]

8.(

 

[Nightjar]

I will say that this topic is going way over the heads of the average Joe out there.
Jaros

Never truer words spoke Jaros. Very confused which is home solar/battery and camping systems?
However am finding the thread very interesting and informative. Will be reading it through over and over again to try and keep up with the modern technology. No doubt down the road my present set up will eventually die and will be looking for an up grade.

 

[Ded Driver]

just for interest;
bit of good info here for those that are interested in dual 12V/24V systems in their 4WD/Truck/Van.
not many people run 24V tho' & a lot of trucks (light & heavy) are now running 12V systems
keep in mind
2 batteries in parallel doubles the current draw available, but stays at 12V
2 batteries in series doubles the voltage to 24V but stays at single current draw rate.
https://www.redarc.com.au/blog/12v-dual-battery-in-24v-vehicle
The biggest benefit of a 24V system is, for a given power draw, the current is half.
eg 200W = 12V x 16.66A
200W = 24V x 8.33A
This means you can use lighter guage wiring &/or get less voltage drop.
This benefit is mostly applicable to longer vehicles where you might be running cables of 6m or more.
It is possible to run 2x 12V batteries in series, & tap off 12V at one battery, & 24V across both. Care needs to be taken in wiring that the 2 systems of wiring dont get cross-wired.

 

[BigWave]

Two 12V batteries in series makes charging difficult though DD. The batteries must be closely matched.
This is worsened if tapping 12V off one battery, as the batteries then become effectively "unmatched".
During charging, a heavily used one may require bulk charging, whilst the other may only require absorption or float.
The batteries should then be charged individually, requiring switching connections and 24V downtime.
I reckon that, if you need both 12V and 24V then, it would be better (more expensive but more reliable and easier to use), if you have two separate systems.

 

[ctxkid]

It is possible to run 2x 12V batteries in series, & tap off 12V at one battery, & 24V across both. Care needs to be taken in wiring that the 2 systems of wiring dont get cross-wired.

the tapped battery will be the first to die and will take the other with it , making replacing 2 essential
buy a 24v to 12 volt converter for longer battery life

 

[BigWave]

Ctxkid - a damn good option, only dependent on 12V current requirements.

 

[ctxkid]

Ctxkid - a damn good option, only dependent on 12V current requirements.

the ones i see have the cb and the radio wired to one , listening to the radio all day in the stationary truck is a battery salesman's friend
heres a couple, i reckon 10amps cover most things , but they seem to cover a large range of requirements

https://www.jaycar.com.au/power-bat...dc-dc-converters/c/0IA?sort=popularity-desc&q

 

[BigWave]

Yep, for those sorts of current loads, that'd likely be the best option.

 

[Ded Driver]

yeah I agree. both batteries would need to have nearly matched loads. Charging would be easiest by putting 24V across both.
The 24V to 12V converter is a good thought.

 

[condor22]

I have a mate with an small old motor home, that runs on 24V. All of the DC gear in the back is 12V, incl the CB in the front.
He has a separate house battery that is 12V, charged by the Alternator/generator (not sure which ) through an old Redarc (again don't know which one).
But as they operate from 9 to 32V and the input is 24V it drops the output to charge 12V. Solar on the roof is also 12V. There's a wire run to the front for the CB.

Went to Bunnings and Jaycar today, got all the hardware, fuse, relay and controller for the 4x4 add on. All I need to now is order the panel About $90 so far. The panel is about $110. A cheapy, but hey it's not as critically used as the van

 

[Nightjar]

The last few threads brings back memories of my first 4WD 1980? Nissan Patrol shortie.
24V system and as already mentioned it was a PIA when I tapped the fridge and CB radio into one battery. :N:
This old girl didn't have power steering but the pump positioning tapped holes were there on the engine.
:idea: Fitted a 12V alternator (new lengthened belts) and a separate battery to run/charge the increasing amount of 12V accessories + the trailer plug. :100:
Traveled 200k with this set up, never let me down.

 

[condor22]

Thought I'd explain the difference between wiring solar panels in Parallel v Series, the effects and the pros and cons. For those not conversant...
Although similar in context to household, this is with particular reference to mobile 12V installations.

Parallel connection is probably the most common used in a caravan or motor home. The current moves along multiple paths to the load (controller), so if one path is broken the remainder will continue to work whilst ignoring the broken one. The break might be the wiring, a connector or the panel itself. In a parallel circuit the voltage remains constant whilst the amperage is cumulative. If you had 4 panels rated at 12VDC @ 5 amps, then the output would be 12V @ 20A.

In a Series connection, the panels are connected with only one path i.e. the + of one panel is connected to the - of the next and the output comes from the - of the first panel and the + of the last. In this instance the amperage remains constant whilst the volts are cumulative. In the above example of 4 panels, the output would be 48V @ 5A. In both instances the output in W = 240W (VxA).

Note, I am aware that solar panels output anywhere between 18-21V, but am using 12V for illustration only. Remember: like batteries, solar panels have a - and +, the current flows from the - through a load (i.e. Solar Controller) to the +.

Pros and cons -

Parallel - Pro = Redundancy in the system in that if a panel or wiring etc fails, you still have some output from the remaining good part. Con = Requires heavier wiring than series connection to achieve the same voltage drop.

Series - Pro = Smaller wiring gauge needed. Con = if one item/area of the circuit fails, then the whole system goes down.

More.........

 

[condor22]

Which do you use - This depends on the system. If you have a larger array of panels with a large amperage or the distance between them and the controller is significant, then series.

If you have a smaller array and a shorter distance between them and the panel, then parallel. Consider the environment, if there is a risk of failure, a mix of both series and parallel or parallel only may be the option to chose.

Wiring gauge example - In the panel example, (previous post) we will assume a distance from the panel of 5 M to the controller, the wiring length is then 10M (this takes into account the length of the + added to the length of the -) Also assuming that a voltage drop of approx 0.13V is chosen. In parallel @ 20A total over 10M you would need 9AWG (6.6mm sq). In parallel using 12AWG (3.3mm sq) would give roughly the same result.

The other consideration with this in mind is the location of the cable run i.e. will the heavier cable fit or not. i.e. in a caravan, you need probably need to drill holes, squeeze in to tight spots if retro fitting.

My van installation is parallel, 100W panel x qty 2 for a total of 200W. The negative cables from each panel are joined above the roof and one negative cable goes through the roof. This could be done with the positive wire, however I chose to run a wire from each panel into the van, for a total 3 wires. There were 2 considerations - 1. The ability to isolate both panels individually and 2. Circuit protection on the panel input. I mounted a dual circuit breaker box inside the van, about 15cm under the roof where the wiring entered. The + wire from each panel goes to the input of one of the CCTBKRs and each output is linked with one wire going down to the controller along with the - wire.

Should one of the panels fail or get damaged, I can isolate it and still get half my normal output from the other. It also gives the ability to switch solar off when charging from 240VAC and prevent 2 smart chargers from confusing each other. A combination of Series and Parallel would reduce wiring requirements at the same time as giving some redundancy.

Were they series connected, a CCTBKR would still protect and isolate, however any failure would result in NO output.

 

[Ded Driver]

explained very well there Condor22
One thing to keep in mind but, is the maximum input voltage of the charge controller.
this extract from the Victron website
"Exceeding the input voltage range will (as it did with the PWM controllers) damage the controller permanently".
https://www.victronenergy.com/blog/...ar-modules-to-the-new-mppt-charge-regulators/
and this bit on max input power (total Watts), with the caveat of not exceeding max voltage
https://community.victronenergy.com...ns-if-you-add-more-solar-wattage-than-th.html
.
One thing I have been told, but I don't know how correct it is, some charge controllers will 'clip' the input voltage if it exceeds the maximum.
This would reduce the max power that could be drawn from a PV system
ie, If you had 2x 200W (400W total) panels in series running at a nominal 18V each, that would deliver 36V to your charge controller @11.1A
If your charge controller clipped the input voltage to 25V then you would likely only be getting around 25V x11.1A =278W, instead of the 400W possible.
Domestic systems are usually designed for higher voltages, but mobile (car/caravan) system are usually somewhere between 20-30V input.
For example, my Projecta IDC45 is rated at 28Vdc max solar input. I have seen others with a 23Vdc max solar input.
(The max alternator input voltage is higher)

Nightjar, where you have stated you have panels in series, but your system has never failed, I suspect that yours may be clipping the input voltage as above, hence not reaching best efficiency & losing input power.