Regulator or DC charger

PeterD · Guru

Regulator or DC charger

Bryan · Guru

I'm about to have a 150 watt solar panel mounted on the motor home.s roof. I've been told that a DC charger is better than a regulator because the regulator wastes about 1/3 of the power.

My knowledge of solar is nil and I would much appreciate the views of the experts on here.

Happywanderer · The Master

Don't know a lot myself either Bryan. I think the regulator works better if closer to the battery than the solar panel.
I am sure there is someone on here who will correct me if I've got that wrong.

Bryan · Guru

I'm not technically minded but he pointed to a 20 amp C tek DC charger and said that a regulator wastes 33%.

The 150 watt is a Redarc unit costing $595.00

Regulator $125 versus $395 for the C Tek

Hardware, cabling etc giving a rough quote of $1,500.00

Haven't agreed to it yet. Looking for input.

Oops forgot to add that I was looking at solar to trickle charge currently one 105 amp/h AGM battery with another identical battery to be added soon.

-- Edited by Bryan on Saturday 21st of September 2013 07:28:02 PM

-- Edited by Bryan on Saturday 21st of September 2013 07:30:37 PM

oldtrack123 · Guru

Bryan wrote:
I'm about to have a 150 watt solar panel mounted on the motor home.s roof. I've been told that a DC charger is better than a regulator because the regulator wastes about 1/3 of the power.

My knowledge of solar is nil and I would much appreciate the views of the experts on here.

HI Byran

That is half ****ed information ,& not as simple as that!!!

It seems some one may be trying to sell you a DC to DC charger!!

Suggest you give some details of what your set up is & your concerns with it

Then just what do you want to achieve???

PeterQ

PeterInSa · Guru

I know of no one with a DC charger who has Sola fitted to their Van/campervan/mh, using a DC charger to charge 12v batteries, to me, its a Solar Controler that chargers the battery, regardless of the state you live in I would ring Springers in Brisbane for some industry advice.

Peter

Bryan · Guru

After a lot of googling I've come across a Redarc solar set up using a Redarc DC charger instead of a regulator. Lots of maths but it seems to be more efficient. In reality I'm totally confused.

Aaaaaargh, I've done my head in. I think I'll crack a bottle of red and watch a movie instead.

solo nomad · Veteran Member

in my limited knowledge on this subject.......this is what i understand

in my vehicle i have a redarc soleniod which charges my camper battery when i am driving and isolates it when stopped

if i had a dc-dc charger instead, the battery in my camper would be charged quicker and to a higher level than the redarc can do

in saying this i havent heard of them being used for solar panels.........my solars just have a solar regulator which works just fine

KFT · Guru

Redarc make a dc-dc charger in 25 and 40 amp versions that also include a solar panel input and MPPT regulator.

With these devices your aux battery is charged by the dc-dc charger while the engine is running and when the engine is off the charger automatically isolates your start battery.

These units also have a solar input and reg so when the engine is not running you have solar input to your aux battery.

designed and built in aus

www.redarc.com.au

hope that helps

frank

oldtrack123 · Guru

Bryan wrote:
I'm not technically minded but
[1] he pointed to a 20 amp C tek DC charger and said that a regulator wastes 33%.
[2]The 150 watt is a Redarc unit costing $595.00
Regulator $125 versus $395 for the C Tek
[3]Hardware, cabling etc giving a rough quote of $1,500.00
Haven't agreed to it yet. Looking for input.

[4]Oops forgot to add that I was looking at solar to trickle charge currently one 105 amp/h AGM battery with another identical battery to be added soon.

-- Edited by Bryan on Saturday 21st of September 2013 07:28:02 PM

-- Edited by Bryan on Saturday 21st of September 2013 07:30:37 PM

HI Bryan

first with regs

A pwm regulator cannot match the solar wattage output to the battery

It gives a constant charge current to the battery for a set condition of light intensity on the panel

'So its efficient use of the available panel energy varies with battery voltage

if we take a 100W panel its rated current is 5.88A @ the WATTS into the panthe rated light intensity & panel temp

With battery at 11.5 [FLAT] the INPUT INTO THE BATTERY will be 11.5Vx5.88A =67.62Watts that's where the so called loos of around 30% comes from

But if the Battery voltage is 14V we get 14vX5.88A= 82Wattsjust under 20% reduction in power into the battery Now that is not the panel's fault it is due to the type of regulator

IF you use a MPPT[MaX POWER POINT TRACKING} reg it converts that loss into useful energy

The charge current is increased by the reg to closely match the battery, so the above would be nearer 100W /11.5V =8.7 A charge current

AT 14V 100W /14V=7.14A

normally around 5to 7.5 & should be subtracted from the above due to conversion losses

now

[1] HE tells FIBS

A DC to dc charger is typically around 95% efficient

Be that the redarc or the Ctek]

To suggest 30% loss is outright stupid

BUT Cables losses can play big part in losses, no matter what brand DC<DC charger

[2] If you wish to charge the house battery from the car alternator we need more details of alternator voltage /car battery voltage when charged with engine running @ fast idle

Also what model fridge you may wish to run in the van while travelling?

Distance od cable required from vehicle battery to van battery

Ditto for fridge

[3] when you have made a final decision ,I would be looking for another quote!!

[4] is this the same set up, or a separate situation?

PeterQ

Plendo · Guru

Bryan,

the options on solar are now many and varied, and now that prices have more than halved it has become practical to fit good gear for not a huge amount of money.

When selecting your panel(s), they all work the same way, just some work better than others. The key factor is conversion efficiency (how much of the light energy is converted to electricity), in general panels made from monocrystaline solar cells generate more electricity than panels made from poly crystaline cells, this is only a factor if you are short of space to fit the number of panels you need.

If weight is a problem there is now the option of the light weight semi flexible panels, there are however about two to three times the price of normal mono panels, as an example my 100w semi flexibles are about $300 each.

Solar panels all generate DC electricity, at varying voltages and currents depending on the amount of sun and what the panel is connected to. Typically a panel designed for a 12V system will generate power at around 18V, and you need to charge your battery at around 14V

Cheaper early design charge controllers use a technique called PWM, which effectively throws away the extra volts, this is where the 30% loss comes from.

The newer more efficient design of controller is called a Maximum Power Point Tracking (MPPT) which loads the panel to it most efficient voltage, then converts the power to a voltage just above your battery voltage. There are many claims of MPPT units delivering significantly higher amounts of power into the battery, and there are also many tests documented online claiming to prove this.

I know some people do not believe the extra cost of MPPT is worth it, preferring to stay with PWM which they know. I personally do believe that MPPT makes perfect sense, and I am building my system around a good MPPT controller.

Sorry about the amount of techie knowledge knowledge in this post.

Bryan · Guru

Thanks for the information. I never realised how involved it is but I now understand it just enough to be able to get more information from the people doing the job.

-- Edited by Bryan on Sunday 22nd of September 2013 08:56:48 AM

Tiyul · Member

What Frank said!!

The Redarc 1225 and 1240 will put 25/40 amps charge into house battery maximising alternator output and minimising driving (ie petrol wasted!!) time.

Both come with an MPPT regulator, and if placed close to the house battery, will maximise current output from your solar panel; again, reducing charge time from appropriately scaled solar panel system.