Another 12v Upgrade thread...

CubicleDweller

autumnalcore wrote: »

You'd need a current limited supply otherwise your pwm will lightly go poof.

Solar controller metering in a system with alternator and mains charging reminds me of the life of the Life of Brian 'How many have gone through jailer'

:D
Nice one. Okay, I'll not try to mix a PWM controller with a non-current-limited DC supply. The things you learn on t'internet, eh?

Thanks!

rustynutz

Some great information here, I have been following with interest. I am on the verge of buying a 100w panel with controller ECO-WORTHY 100 Watt 12V Solar Panels Kit + 20A Charge Controller for Off-Grid 12 Volt Battery System https://www.amazon.co.uk/dp/B01N1H66G5/ref=cm_sw_r_cp_taa_i_z.36AbEVGZJCT I am just wondering about the couple of comments about isolating the solar panel before hooking up to 220v electricity, is something catastrophic likely to happen?

rustynutz

Just to add, I mostly use campsite (young kids) but would like the option of staying more than 1 night in an Aire on an upcoming trip to france, and a bit of wild camping around ireland, never more than 2-3 nights at a time. I have one recent 115a leisure battery at the moment that gives me about 24 hours of power during normal use, I'm hoping 100w setup is enough. I would add a second leisure battery but have done a bit of research on my charger and found this http://www.aandncaravanservices.co.uk/arsilicii.php , it doesn't recommended adding another leisure battery, as is can overload the charger, at least that's my understanding.

rustynutz

jace_da_face wrote: »

Just to be clear, but do you have existing solar panels(s) rustynuts? If not, you can absolutely add solar charging to compliment your charging system. And if you do already have solar charging, you can still add additional panels. I’m guessing that you have a charger that can accept solar input but you do not have solar panels? If so, I would add solar panel(s) with your existing charger and see how it goes. But you might find that to buy a solar setup, that you’re getting a good deal to include a new charge controller. In which case it would just compliment what you already have.

Just spotted your response now jace_da_face, your correct, I don't have existin solar panels, I am worried about installing a separate solar controller, and as mentioned by your self and Liamalot, would there be any problems if I forgot to turn off the solar panel before hooking up to 220v

autumnalcore

autumnalcore wrote: »

You'd need a current limited supply otherwise your pwm will lightly go poof.

MorningStar Corp Tech Notes wrote:

Description:

Can I use a power source other than a PV panel to charge my batteries?

We do not recommend using a DC power supply with any of our PWM controllers. While they appear to be similar to PV modules in function, DC power supplies have considerably more output capacitance. Connecting a DC power supply to our PWM controllers may cause excessive heating and premature failure. MPPT controllers can be used for this purpose without issue. In addition, AC powered battery chargers are often the best option for systems requiring AC battery charging.

Link

Recently I've asked MorningStar about this and they do not sanction doing this with their PWM controllers. Doing so is not covered by warranty.
They say it's fine to do with MPPT.

Under duress, they say if you do it then the most resilient way to do it is with a controller sized at least double the Power Supply's Capability.

Flyback diodes will help but the PSU capacitance can still harm the controller. I also add a series diode because I get changeover switching delatching issues.

I ran a 5A CC rectifier into a 45A Controller with success for 3 years. Having previously let the smoke outtov a battery charger feeding a solar controller and a constant voltage SMPS feeding a solar controller.

rustynutz wrote: »

I am just wondering about the couple of comments about isolating the solar panel before hooking up to 220v electricity, is something catastrophic likely to happen?

Mains chargers and solar charge controllers don't play nice together. They confuse each other and won't charge the battery fully because they think the voltage of the other is battery voltage and it reduces absorption duration.

You need to turn off solar between the panel and the charge controller to charge from mains or turn off your mains charger if you want to charge from solar.

rustynutz wrote: »

and found this .... , it doesn't recommend adding another leisure battery, as is can overload the charger, at least that's my understanding.

:rolleyes::rolleyes:
That site drives my BS detector wild.
If the charger can't handle it's environment then I'd fit a capable charger and not a feeble one that keeps an antiquated electronics repair operation centre thriving.

Modern onboard chargers with load supply capability don't get "overloaded".

CubicleDweller

CubicleDweller wrote: »

..do you mean upgrading the alternator?

Just the cable, routing and contactor. Depends on how much charge you want to gain and if what you are getting already is enough.

rustynutz

Ok, Thanks, I will fit a switch so and turn off the solar when charging. I was just worried that if I forgot to switch the solar off before mains charging that it might damage something

Isolating the battery from a solar controller with the PV input live kills solar controllers.
Isolating the solar panel input from the solar charge controller is the recommended safe way to disconnect solar charge for mains charger regulation.

Running both at the same time is safe but the battery won't see charge completion.

jace_da_face

CubicleDweller wrote: »

The whole PWM/MPPT debate has me confused. Some say the extra cost of MPPT is not worth it, others swear by it. One argument I've seen is that in poor lighting conditions - when the output of the panel falls below some threshold or other - the PWM will produce nothing whereas the MPPT will at least provide a small trickle of current. I take it you're not convinced about that? I'm skeptical myself...

I am not convinced about that argument. I can understand how MPPT would work better than PWM when there is enough light to keep both systems charging. But in low light at the threshold of the PWM charger cutting out, I don’t see how the MPPT charger keeps going. This is based on my tinkering with panels in different lighting conditions and measuring current. The panel voltage is ‘fairly’ constant over a range of lighting. It is possible to have a high enough voltage at the terminals when only a tiny amount of current is available.

But I would like to see the Duracell bunny test with two PVs and charger types side by side, and see if the MPPT lasts any longer into sunset.

You need to measure power (Pmax) for this not Voc and Isc.

PWM controllers only pass current the voltage is clamped by the battery and if you bought a 19Vmp solar panel instead of a 17Vmp because that's all that you can get then you have 4 cells that aren't producing useful voltage.

MPPT does produce more power if the array is overspec-ed for the battery which is impossible to avoid unless you make yer own Irish solar panels.
Small system MPPT gains are not financially competitive with other system upgrades.
If you point the panel at the sun instead of flat mount you get 20%- 60% more power and it costs much less.

Only at the point where MPPT is less expensive than more solar panels or you are outtov roof space and need more time to trawl boards for electrical advise or you get a good one cheep does it makes sense.

CubicleDweller

Thanks all, for keeping the useful information coming. I've been away for a bit, just catching up now.

It's good to know that solar and a mains charger shouldn't both be connected at once; it makes sense that the two chargers would confuse each other.

I'll probably want to wire in a switch then between the panels and controller. I'll need to find out what sort of cables and switches to order anyway. More research. Not to mention looking at ways to tilt panels towards the sun...

Thanks, again!

30A DC Fused Switch Disconnect

autumnalcore

autumnalcore wrote: »

'How many have gone through....

You need to train yer minions better!




185.4Ah in 7.88 days Guv'nor!

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