MPPT Controllers with Remote Voltage Sensing

[babock]

I see some of the expensive Morningstars have that feature. Is there anything available in the $200 range that has it?

[Lawrosa]

Originally Posted by babock

I see some of the expensive Morningstars have that feature. Is there anything available in the $200 range that has it?

V sense for knowing if 12v or 24v?

[babock]

12

[Lawrosa]

I read on voltage sense for undersized wiring if thats what you mean? Kind of like temp compensation?

If there is a 1 volt drop through wiring the mppt will increase to compensate.

Ive been reading on the victron products and if I had money to spen I would probably go in that direction of products.

But in the smart series versions. As they set time in absorption as how long its been in bulk.

Most others are time base with a set #. ie: 2 hrs etc.

I liked the renogy rover unit as its under 200 bucks. But I read the pv/batt terminal screws are flaky.. But its a 40 amper..

[Lawrosa]

Originally Posted by babock

12

If its auto sense for what voltage batts you have, I think they most all do it. Except my cheap 20 amp ecoworthy that I have to manually select 12/24 volt everytime I turn the unit on.

Im so cheap I may just get another ecoworthy and install next to my other one. And have two seperate systems ..

I run one 280 watt panel now through one ecoworthy. Just get another, and I have another panel and do it that way.

What are you trying to do?

[babock]

The Renogy Rovers don't have it. I just want the controller to adjust for line loss between controller and the battery.

[Lawrosa]

Victron thinks its not needed, and only thier multi chargers have such a thing. Price point I guess.. That features does not come cheap.

I have an MPPT 100/30 connect to two Panasonic HIT240 panels in parallel. VictronConnect reports a battery voltage (14.4) where the actual battery voltage is 13.9. This means that the MPPT thinks the battery is at its maximum charge voltage when it is actually 0.5v below, about a 3% voltage drop. I have very heavy gauge wires but there are a number of connections, including a shunt and a circuit breaker/switch, that could be causing the voltage drop. I can't "over-volt" the charge settings because the voltage drop is less when the amps drop as the battery approaches full charge.

My opinion is that this is a DESIGN FLAW -- all charging sources (MPPT, alternator regulators, shore power chargers) should have a direct battery sense wire to do a proper job.

Is 3% drop from the MPPT output to the battery acceptable?

Thanks

Jeff

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Jeff Stander Jeff Stander • 6 days ago
The voltage disparity kept getting worse and the only factor involved was the MPPT 100/30 itself. the latest readings showed the controller sensing 15.5v when the battery is at 13.2v. I am in the process of a warranty exchange.

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Johannes Boonstra Mod Jeff Stander • 6 days ago
Hello,
Yes please have it checked.
The other thing to consider is, IF the MPPT would be wrongly calibrated, the deviation remains exactly the same, it does certainly not get worse in a few months.
Please check wiring well before returning the unit.

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Johannes Boonstra Mod Jeff Stander • 2 months ago
Hello,
When having a 0,5Vdc loss on 30Amp charge power you should look at the wiring a bit more.
Is the wiring 10mm2 or more?
Not longer then 5mtr?

Eventually the voltage will go up as the battery becomes more charged and the current comes down (if the load is t not too high), but energy is wasted.

Design, well our powerful chargers/multi do have this, as at high current a voltage drop is hard to overcome with wiring alone.
But as always, there is a balance between features and buying price.

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Jeff Stander Johannes Boonstra • a month ago
I have gone through my wiring and have found two 350A rotary battery disconnect switches which were consuming amps. I've seen this before. It could be corrosion on the contacts but I just replaced them and the voltage drop is down to a reasonable level of < 3%. I believe I can improve this by a more direct run, as you mentioned.

I remain unconvinced that "a balance between features and buying price" should outweigh designing a product that works properly. If the solar controller cannot respond to true battery voltage because it is too expensive to incorporate a direct sensing wire; you could probably modify it with software, i.e. modify the charge profile so that it compensates for a set voltage drop (e.g. 3%) at higher amperages and then as the amperage falls it reduces that compensation to zero.

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Jeff Stander Johannes Boonstra • 2 months ago
I understand that more features can affect the price and marketability of the product, but the whole point of MPPT is to maximize the current from the PVA. But then we waste that energy because the MPPT is not sensing the true battery voltage.

[babock]

Not sure who all of that conversation is between but I agree with the points made.

[Lawrosa]

Originally Posted by babock

Not sure who all of that conversation is between but I agree with the points made.

victron tech and a customer.

[WolfWhistle]

I know the question is about MPPT, but My trimetric PWM does it. An excellent way to stretch (so to speak) the wire gauge. Mount it closer to the panels and it compensates the the VD from it to the battery.
WW