Monitoring solar amps when using a DC to DC charger

Submitted: Friday, Oct 06, 2017 at 17:42
ThreadID: 135710 Views:5489 Replies:5 FollowUps:5
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If you're using a DC to DC charger how would one monitor what the solar is doing? besides installing an expensive shunt style amp meter.

I'm wanting to install a DC to DC such as the Ctek or Projecta, i currently use a cheap solar regulator and monitor it with a cheap watt meter.

if i install DC to DC i'm concerned about how i would monitor the solar amps etc.

Correct me if i'm wrong but there's no point putting a watt meter between the solar panel and the DC to DC as this would be unregulated and not the same amps as whats coming out o the DC to DC into the battery?

Thanks in advance
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Reply By: Member - Bigfish - Friday, Oct 06, 2017 at 19:00

Friday, Oct 06, 2017 at 19:00
I have a redarc dc/dc 20 amp charging 2 x 130 amp agm batteries in rear tub of car. I also have an 80 watt solar panel connected to a quality solar reg and this is connected to the batteries. The solar is on 100% of the time and naturally the dc/dc only when car engine is running. 3 years like this and no problems whatso ever. I have a digital readout near the batteries and they are always at near 100% soc if I don't use the car fridge. No need to monitor as the digital voltmeter shows the rise in voltage when panel is doing its job.
AnswerID: 614208

Follow Up By: duck - Saturday, Oct 07, 2017 at 13:10

Saturday, Oct 07, 2017 at 13:10
mine is set up about the same but more solar & the 40 amp 12v Redarc bcdc charger, plus 240 volt charger all hard wired in place & has the redarc monitor that shows what is going in from where e.g. Vehicle, Solar or 240 volt charger (it auto picks what is supplying the most power) & shows you on the monitor E.G. driving shows what the vehicle is putting in to the batteries, car stopped it shows how much solar is going in & if plugged in to 240v power the same, It will also show if any of the batteries are getting hot, normally a sign a battery is on its way out or the units regulator is faulty pumping too much power in
but I do run 2 systems & have more power than I should ever need 1 x 12v & 1 x 24v & have 360 amps in 12v batteries & 400amps in 24v & 240watts in 12v solar & 120 watts in 24v solar plus 3kva gen I must admit I hardly ever look at the monitors but I did notice once driving along that the 12v was getting solar pulled over to check & found I forgot to glug in the Anderson plug
FollowupID: 884787

Follow Up By: Member - Bigfish - Saturday, Oct 07, 2017 at 14:01

Saturday, Oct 07, 2017 at 14:01 have more power at your fingers than most of the Eastern states of Australia!

Any relation to Elon Musk?
FollowupID: 884788

Follow Up By: RMD - Saturday, Oct 07, 2017 at 19:20

Saturday, Oct 07, 2017 at 19:20
Perhaps you should talk to Jay the boss of SA. He thinks squillions of $ to Elon Musk is a way to cure his problems. Many little batteries called one big battery only makes SA RUN FOR 1 hour longer when required. Should be in Friday Funnies.
Your system is superior, get a job on the SA POWER advisory team.

FollowupID: 884789

Follow Up By: duck - Monday, Oct 09, 2017 at 12:21

Monday, Oct 09, 2017 at 12:21
Guys I had to laugh
Vehicle is a Isuzu NPS 300 dual cab tray back with warrior conversion with a slide on camper that I built all in foam sandwich construction (I’m a boat builder)
Truck 24v = The power is for 2nd Start + Fwd 24v 15000lbs warn winch, Aft 24v 17500lbs runva winch,the 24v can also be switched to run stainless steel 180ltr draw fridge & freezer that is 12/24v, 12v to run camper etc.
Last year I was in SA I should have had a wind generator as it blowed the main power lines down! I was to go to kangaroo island earlier this year but the misses had a heart opp so hopping to go in November this year so I’ll take the jumper leads & tap into the mains & help you out (LOL)
FollowupID: 884816

Reply By: Member - Phil G (SA) - Friday, Oct 06, 2017 at 23:38

Friday, Oct 06, 2017 at 23:38
I take spot current measurements using a digital clampmeter.
AnswerID: 614214

Reply By: The Bantam - Saturday, Oct 07, 2017 at 20:52

Saturday, Oct 07, 2017 at 20:52
The first question that needs to be asked is what you want to measure and why.

Are you trying to establish the effectivness of the solar panel/s, the state of charge of the batteries or what.

The most effective thing would be to have a voltmeter across the battery terminals and an ammeter in line with the positive lead connecting the battery.

the voltmeter will give a vague idea of hoe the battery is charging and it's state of charge.
The ammeter will give an idea of what is comming and going to and from the battery.

Drawing meaningful conclusions is a whole other story.

There is very little purpose having a volt meter across the solar panel, likewise very little use seeing how much current is running in the cables before the regulator

If you are considering a dc to dc charger ... and shunt ammeter will be a minor expense

A digital panel meter with a 100 amp shunt can be had for around $50

AnswerID: 614227

Reply By: HKB Electronics - Sunday, Oct 08, 2017 at 10:46

Sunday, Oct 08, 2017 at 10:46
Have a look at some of the latest DCDC chargers ie Enerdrive & Intervolt hey have display panels that tell you whats going on.

Another option though equally expensive is a BMS.

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AnswerID: 614237

Follow Up By: Gronk - Sunday, Oct 08, 2017 at 10:57

Sunday, Oct 08, 2017 at 10:57
Yep, that's the way I'd go. My "old" Steca solar controller has a readout of all things going on, so a new dc/dc charger with the same is an easy way rather than having separate meters adding to the "clutter"..
FollowupID: 884803

Reply By: Batt's - Sunday, Oct 08, 2017 at 17:09

Sunday, Oct 08, 2017 at 17:09
Don't know if this is the sort of thing your after but I have a volt meter monitor in my set up it doesn't tell me the direct volts from the solar panel which I don't need to know but it lets me know it is putting power into my batteries from the solar via the Redarc BCDC charger so you then know the system is working. Same thing when the car is running and the power supply is now coming from the alternator via the Redarc.
I also have all my output wires coming from the monitor so I get an instant readout of the current battery voltage and how many amps and watts are being used when the fridge etc is on. It's a handy little monitor easy to install I have it permanently set up or it can be fitted with Anderson plugs for easy removal.
Got mine from vic off-road don't think my first link worked correctly here's some eBay ones if your interested.
AnswerID: 614241

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