System has some issues

[Bribenn]

Hi friends,

It has become apparent that I need some actual real help on my solar electrical system and I'm wondering if anyone knows where I can find a consultant or something who will take a look at my system and tell me how to fix it, maybe a video chat showing what I have currently connected and diagnosing issues.

Current system (or system intentions): 300 watts solar, 400 ah battery bank, 2000 watt pure sine inverter charger, renogy dc-dc charge controller with MPPT, Victron BMV. I want my system to be able to charge via solar, alternator, and shore power.

Current issues: 1. undervoltage alarm. 2. Electrical shut off doesn't turn off all power to loads. 3. alternator is drawing energy, not feeding my batteries.

I modeled my system after @Will Prowse 400 watt system with alternator charging. I think the only things I did differently are add a victron shunt and a kill switch, but somehow, I've got problems.

I'm a complete newbie, so sometimes discussions on here can go over my head.
Any recommendations for actually speaking to someone who can help would be really appreciated!

Thanks so much!

 

[John Frum]

Don't forget those dodgy breakers.

 

[MichaelK]

The quick answer is that you don't have enough solar. Assuming that this is a lead-acid bank at 12V (is it two 6V L-16s?), you want to charge it at 1/10C, which is 400Ah. The math would be (Capacity) x (1/10) x (system voltage) x (fudge factor). That works out to be......
(400Ah) x (0.1) x (12V) x (1.25) =600W
So, basicly, you are only charging with about half as much solar as you actually need. You could go with as high as a 1/8 charge rate....
(400Ah) x (0.125) x (12V) x (1.25) =750W

Now, why do you think the alternator is drawing energy from your system? What evidence do you have to come to that conclusion?

One important issue before increasing your solar input is what is the amperage rating of your charge controller? You'd need at least a 40A controller to add panels up to 600W.
(Panels/Fudge factor)/system voltage=Amps, or (600W/1.25)/ 12V = 40A

 

[Bribenn]

I think it's drawing power because my bmv shows loss of power when the car is on.

 

[Hedges]

An "Alternator" has diodes, won't draw current unless they are bad.
But, output of alternator (which means this system is on a vehicle), goes to a number of electrical loads in the vehicle. Normally most of those are disconnected when ignition switch is off.

You haven't described your batteries beyond "400 ah". I will assume they are some type of lead-acid. (if Lithium, there are issues to avoid drawing too much current from alternator.)

Normally, "house batteries" would be isolated from vehicle electrical system by a "battery isolator", which allows charging but not discharging.
How are your 400 Ah batteries connected to the alternator?

A sketch of your system would help.

 

[Bribenn]

My batteries are 4 100 ah SLA batteries.

They are connected to the batteries through a renogy 50amp charge controller.

Does anyone know someone who consults in this via video chat?

 

[Hedges]

Does anyone know someone who consults in this via video chat?

Not off hand, but you can get free help here.
Post a schematic and maybe photo of what you've got.

So Renogy charge controller has alternator input? And you think battery is being drained by alternator?
Disconnect alternator cable from Renogy and see what system does.

There should never be a drain from battery into charge controller (except through charge controller to controlled loads, it it has a load output.)
Only loads should drain battery.

 

[Bribenn]

Not off hand, but you can get free help here.
Post a schematic and maybe photo of what you've got.

So Renogy charge controller has alternator input? And you think battery is being drained by alternator?
Disconnect alternator cable from Renogy and see what system does.

There should never be a drain from battery into charge controller (except through charge controller to controlled loads, it it has a load output.)
Only loads should drain battery.

When the starter battery is connected and I turn the car on, the used watts goes up to 400 from 40 on my victron bmv, showing that the output is more watts. Is that normal?

 

[Hedges]

Maybe that is showing 400W charging? As a load, that would be 35A at 12V, pretty excessive for a car's ignition system.
What is the 40W, is there such a load on the battery? Maybe an inverter, power consumption with no AC load?

When you first turn on the car's ignition but have NOT cranked the engine over and started it, what does the victron show?
If there is a load draining the battery, that would be present even before engine is started.
Battery charging might begin as soon as car's system is connected (perhaps with a disconnect switch, or perhaps with a signal from ignition system to the victron).
For a simple battery isolator traditionally used to charge house batteries, there is no discharge back to the car, and charging only occurs with the higher voltage when alternator is operating.

 

[Bribenn]

Maybe that is showing 400W charging? As a load, that would be 35A at 12V, pretty excessive for a car's ignition system.
What is the 40W, is there such a load on the battery? Maybe an inverter, power consumption with no AC load?

When you first turn on the car's ignition but have NOT cranked the engine over and started it, what does the victron show?
If there is a load draining the battery, that would be present even before engine is started.
Battery charging might begin as soon as car's system is connected (perhaps with a disconnect switch, or perhaps with a signal from ignition system to the victron).
For a simple battery isolator traditionally used to charge house batteries, there is no discharge back to the car, and charging only occurs with the higher voltage when alternator is operating.

 

[Bribenn]

it keeps losing power even though nothing is on. The inverter is on, but nothing is drawing power from it.

 

[Hedges]

Disconnect cable from alternator; that will ensure no power flowing into car. Any difference?
Turn off inverter, which draws power with no AC load. What is drain then?

Are there any DC loads on the house battery?

"Starter battery 0.03V" indicates not connected.

 

[Bribenn]

This is with the wire not attached to alternator. The inverter is off. There are dc loads attached (fan, lights, usb charger), but none of them are running.

My victron is only attached with the shunt to the main house battery bank. Maybe that's why it says starter battery is .3v?


This is with it attached and car is on. There is no change when ignition in, but car not started.

 

[Hedges]

So it appears to draw 75W with nothing connected. PV panels connected?

411 Watts, "attached", car "on". But starter battery still 0.03V?
Does the unit have separate wires for alternator and for starter battery, like maybe it is supposed to trickle charge starter battery?

You added a shunt, you said. Any chance the two small wires to the shunt are backwards? 75W is charging from PV panels? 411W is charging from alternator? (rather than discharge)

 

[Bribenn]

I think you're right! I'm going to turn it around.

 

[Bribenn]

Turned it around and this is what I got. Turned the car on and nothing changed.

 

[Hedges]

What is voltage of battery, with battery disconnected?
Voltage of battery when controller says -411W?

(I still don't believe running engine draws power from house battery)

 

[Bribenn]

Turned it around and this is what I got. Turned the car on and nothing changed.

What is voltage of battery, with battery disconnected?
Voltage of battery when controller says -411W?

(I still don't believe running draws power from battery)

This is since I flipped the wires on the victron shunt.

 

[Hedges]

12.31V -74W
12.74V -411W
12.14V +23W

I had meant use a handheld DMM, battery completely disconnected from everything so no load (and victron wouldn't be able to display voltage)
But I observe the more negative the Watts figure is, the higher the voltage.
I'm pretty sure higher voltage means less load or more charging.
So I still think the readings are backwards of our/your interpretation is backwards.

"consumed Ah -24.8Ah" Doesn't negative consumed mean didn't draw from battery, rather recharged it?
After the system shows a change in the SoC, you can see if the change agrees with consumed or is backwards.

 

[Bribenn]

12.31V -74W
12.74V -411W
12.14V +23W

I had meant use a handheld DMM, battery completely disconnected from everything so no load (and victron wouldn't be able to display voltage)
But I observe the more negative the Watts figure is, the higher the voltage.
I'm pretty sure higher voltage means less load or more charging.
So I still think the readings are backwards of our/your interpretation is backwards.

"consumed Ah -24.8Ah" Doesn't negative consumed mean didn't draw from battery, rather recharged it?
After the system shows a change in the SoC, you can see if the change agrees with consumed or is backwards.

I need you to break it down more. So, you want me to disconnect the batteries from everything and then tell you the voltage of the batteries?