diy solar

diy solar

Battery Charge Speed

You have VRM. On the advanced tab, what are the BMS Charge and Discharge limits (512)?

1718469345351.png

Example: Mine are 100A charge/discharge and 54.8V max voltage. They are set this way for a specific reason. Your batteries should feed the same information to the GX.
 
Shouldn't be hard to find using a clamp amp meter (make sure its a DC clamp meter and not an ac only one).

Clamp it on at different spots in the wiring and you find where things are "missing". Also as mentioned it could be your arrays are not putting out what they should or is being claimed by the controllers. The clamp meter will give you actually real world instant readings to know whats really going on. Plus they don't cost but $30 or so. I consider it a must have item with solar.
 
Like @sunshine_eggo said, if you have DVCC enabled, check what the maximum charge current is set to. That will limit the charging power used regardless of what the individual components are technically capable of.

Second, I am pretty confident that the cables going from the charge controllers to the batteries cannot handle 60A.

A screenshot of your VRM dashboard during a sunny period would help a lot (with "show details" enabled).
 
Jalle19 said:
Like @sunshine_eggo said, if you have DVCC enabled, check what the maximum charge current is set to. That will limit the charging power used regardless of what the individual components are technically capable of.

Second, I am pretty confident that the cables going from the charge controllers to the batteries cannot handle 60A.
Click to expand...

And I'm not at all confident the wires to the Lynx/quattros are 2/0.
 
Its hard to tell sizes from a distant picture but the network cable and the wire going between the batteries looks almost the same size.
 
Dooug said:
If DVCC is active in the cerbo it can control the overall current limit into the batteries. It won't stop the panels from running your AC loads, when the AC loads stop it would tell the MPPTs to throttle back to the set limit. It's possible that this is currently set to 124 amps.

11. DVCC - Distributed Voltage and Current Control

www.victronenergy.com www.victronenergy.com
Click to expand...
Hello, I don't think the DVCC is active because the maximum charge voltage is set to 54, but right now the batteries are charging up to 56, which is what the installer currently has set. I don't recall where he has the 56v limit set. At one point we had 58v set as the limit, that is when we got up to a 7,192w charge rate

dvcc.jpg
 
Crowz said:
Its hard to tell sizes from a distant picture but the network cable and the wire going between the batteries looks almost the same size.
Click to expand...
The cables are probably undersized. Would that limit the amps to 124 or cause the voltage at the terminals to reach the set limit (56v right now)?
 
Jalle19 said:
Like @sunshine_eggo said, if you have DVCC enabled, check what the maximum charge current is set to. That will limit the charging power used regardless of what the individual components are technically capable of.

Second, I am pretty confident that the cables going from the charge controllers to the batteries cannot handle 60A.

A screenshot of your VRM dashboard during a sunny period would help a lot (with "show details" enabled).
Click to expand...
The max current in the DVCC is set to 160amp. I don't think it is enabled, but I'm not sure. I agree that the cables may be undersized, but do you think that is what is causing the charge voltage to reach the set limit (56v right now) and also keep the current at 124amps in total?

It has been cloudy for a week, but the next time I get full sun, I will upload a screen shot of the dashboard.
 
Crowz said:
Shouldn't be hard to find using a clamp amp meter (make sure its a DC clamp meter and not an ac only one).

Clamp it on at different spots in the wiring and you find where things are "missing". Also as mentioned it could be your arrays are not putting out what they should or is being claimed by the controllers. The clamp meter will give you actually real world instant readings to know whats really going on. Plus they don't cost but $30 or so. I consider it a must have item with solar.
Click to expand...
I'm in Guatemala where the installation is located, but I can get one of these on the next trip back to the states in July. I think the arrays are putting out what victron is reporting as the PV Chargers have put out up to 13,500w.
 
sunshine_eggo said:
You have VRM. On the advanced tab, what are the BMS Charge and Discharge limits (512)?

View attachment 222256

Example: Mine are 100A charge/discharge and 54.8V max voltage. They are set this way for a specific reason. Your batteries should feed the same information to the GX.
Click to expand...
I don't see BMS info on the dashboard. Maybe that is because victron doesn't support Huawei batteries, but I'm not sure.
 
sunshine_eggo said:
Absolutely not. A 6V difference is massive. Even 1-2V is a concern.

V = I * R

6 = 124 * R

R = 6/124 = 48mΩ resistance.

For perspective, this is the same resistance provided by 979 feet of 4/0 cable.

See why I'm focused very intensely on the installation?

You have on the order of a maximum of 400A of charging capability assuming all sources can provide max output. Yet you're only getting 124A when you hit peak voltage.

There's a problem with your installation.
Click to expand...
I'm a bit confused. If you have a 48v system with a maximum battery charge rate of 58v, but currently set to a limit of 56v, and the battery cells are at a state of charge of say 50v, for example, and you are charging at maximum voltage and amperage, what would you expect the voltage to read at the battery terminals?
 
What a magnificent system. And a good looking install.

I’d be surprised if clamp meters are not easily available in Guatemala. No? Seems like the quickest route to resolution.
 
Hedges said:
If you see 13.5kW power coming in, it is going somewhere. Otherwise the 5kW loss would burn or boil something.

I think you have either unaccounted for loads or equipment giving erroneous readings.
Or Analyst Error.

Now as for round-trip power (not charging power), people with systems spec'd at 92% round-trip efficiency see 82%; I suspect power factor of loads caused greater losses in electronics.
Click to expand...
I may have miscommunicated, but the loads didn't go anywhere. When the PV charger is at 13.5k and the charge rate is at 7k, and the AC load is at 6k, and the loss/components are using about 500w, this all adds up. When the AC load drops down to 1k, for example, the charge rate stays at 7k, but the PV charger drops to about 8.5k. The point of this example is that the PV arrays are not limiting the charge rate, there is plenty of watts coming in when needed by the AC loads.
 
Bluedog225 said:
What a magnificent system. And a good looking install.

I’d be surprised if clamp meters are not easily available in Guatemala. No? Seems like the quickest route to resolution.
Click to expand...
Thank you. They are probably easily available in Guatemala city, we live on Lake Atitlan. I will get one ASAP. I'm sure my installer has one, but he has been here multiple times in the last few months, and he can't return for another month.
 
guybarth said:
and the battery cells are at a state of charge of say 50v, for example, and you are charging at maximum voltage and amperage, what would you expect the voltage to read at the battery terminals?
Click to expand...

50V. The battery will drag the charge controller voltage down because it's essentially an infinite load and would draw whatever it can, which means in reality the voltage must drop and the current goes to max. This is constant current charging.
 
Mattb4 said:
You do not want to set the voltage for charging at a higher than maximum battery voltage. You set amperage higher. Setting too high of a voltage can work against you if it causes a BMS trip to occur. Not to mention it is harmful for battery life to overcharge them.

Battery charging has 2 states CC (constant current) and CV (constant voltage). Initial charge is CC up to the maximum your supply can give it. During this time you should see DC bus voltage rise as the batteries voltage increases towards fully charge. When your charger reaches the voltage it is set to reach it switches to CV and the amperage tails downward as the charger attempts to maintain voltage. Once it does this it enters an absorption period of keeping at the charge voltage. The charge should be complete and the charger either allows voltage to drop to float or it shuts off.
Click to expand...
Roger that, I only did a short test with the maximum charge voltage set to 60v, and it only took about 30 seconds to get an alarm on the batteries. I quickly set it back. I just did it as a test.

The voltage of the battery cells does slowly increase as they are getting charged (I can check the voltage of the cells in the BMS device sitting below the right battery rack). However, when the batteries are charging, the voltage reported by Victron (same as what a meter shows at the battery terminals), is significantly higher the voltage (state of charge) of the cells.
 
guybarth said:
the voltage reported by Victron (same as what a meter shows at the battery terminals), is significantly higher the voltage (state of charge) of the cells.
Click to expand...

If the voltage at the charge controller is significantly higher than the voltage on the battery terminals, you have a high resistance connection - in other words, your cables would be undersized.
 
upnorthandpersonal said:
50V. The battery will drag the charge controller voltage down because it's essentially an infinite load and would draw whatever it can, which means in reality the voltage must drop and the current goes to max. This is constant current charging.
Click to expand...
Okay, so if the battery terminals are reading 56v while charging (which is the set maximum charge voltage), and the battery cells are at 50v (as reported by the BMS device), then you are telling me it shouldn't work that way. If it shouldn't work this way, then my guess is that the problem is how they are wired to the charge controllers/shunt, or wire sizing, or both. I'm thinking about having the installer modify the system to have all 8 batteries wired to bus bars.

I have two weird things going on. One is that the battery terminal voltage reaches the max set limit, 56v in this case, as soon as I get the charge current up to 124amps. The second is that the charge current doesn't go above 124 amps.
 
upnorthandpersonal said:
If the voltage at the charge controller is significantly higher than the voltage on the battery terminals, you have a high resistance connection - in other words, your cables would be undersized.
Click to expand...
I haven't tested the voltage at the charge controllers yet, but I will try in the next few days.
 
For an extreme example: here is a 10V supply (think charge controller) being connected to a single LFP cell (3.3V):


Notice the wire gauge. If I were to do this with long, thin wires, it would be similar to this:


Notice the voltage drop at the tester (load, on the screen) compared to at the cell (multimeter, skip to a minute in or so).
 
When testing the voltage at each connection, be sure you are placing the probes on the same surface that the cables make contact with. Do not put the probes on the stud or nut.
 
You must log in or register to reply here.

Similar threads

S
Single voltage charge
Replies
4
Views
243
Stircrazy
S
D
PowMr hvm 10.2 kw (seems axpert like clone) trouble to react the full battery charge
Replies
0
Views
188
deg87
D
Chris O
Victron SmartSolar Charge Controller MPPT 100 20 Share your configuration
Replies
9
Views
489
pollenface
pollenface
M
1,000 AH 12v battery bank help
Replies
18
Views
810
robbob2112
robbob2112
K
Speed Queen washer
Replies
15
Views
691
Browse
B

diy solar

diy solar
Back
Top