• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

MPPT Controller - Over charge issue?

MattMan119

MattMan119

Solar Geek
Joined
Jun 12, 2024
Messages
1,384
Location
Merritt Island, FL
So, i though ok, let's build a cheap little solar system to keep the freezer running when the coffee truck is parked overnight at fairs. It was also used during the hurricane.

One of the "cheep" things I used in this test was


100A MPPT Solar Charge Controller 12V 24V 36V 48V LCD Display Battery Intelligent Regulator Max 100V Input Dual USB for Lead-Acid/Lithium (100A)​


Now that said, it appears to keep charging even after all it full forcing the battery to shut down or causing the inverter to have "High Voltage" warning or error.

Should I just give up on it, and install blue, or does someone have a good idea .. The charging other than not stopping works good (or it appears too anyhow)


1729721370469.png

BTW: Connect to 24v - 2 lithium batteries.
 
Stating the obvious: Clearly a fake MPPT.

Are you 100% certain your batteries are not triggering OVP due to cell imbalance? Most chargers, including blue ones, will spike the voltage when the BMS cuts the battery out of the circuit. This will trigger inverter over-voltage alarms/shutdowns.

Have you tried charging to something low like 27.2-27.6V?
 
sunshine_eggo said:
Stating the obvious: Clearly a fake MPPT.

Are you 100% certain your batteries are not triggering OVP due to cell imbalance? Most chargers, including blue ones, will spike the voltage when the BMS cuts the battery out of the circuit. This will trigger inverter over-voltage alarms/shutdowns.

Have you tried charging to something low like 27.2-27.6V?
Click to expand...
I watch the inverter cut off reset and turn back on 10 times in a row.. I have yet to see the CC stop charging OR go to absorption or float. As is states is part of how it works .. But NEVER did it..

Seemed to me it was sensing the battery voltage and just charging by adding X to the voltage and not using a charge voltage that is set for that type of battery .. Guess but what it looked like to me..
 
The times I have overcharged were when I connected the solar panels first, resulting with seeing 17v at the battery.

Double checking you connected battery first?
 
pollenface said:
The times I have overcharged were when I connected the solar panels first, resulting with seeing 17v at the battery.

Double checking you connected battery first?
Click to expand...
Based on everything I have seen here it was it appeared to do …

It would hit an undisclosed charge shut off as it charged .
The freezer would kick on and cause the voltage to drop from right at the edge of battery protection shutdown.
After running for a second or two the charge control would do some kind of calculation for charge voltage and spike in 15-20a charging power.
This new voltage it was using would then cause a fault with the inverter, over voltage … and shutdown inverter
And everything would jump back to top, with the exception the inverter would reset and turn back on and allow everything to start over again …

There does not appear to be a “charge” voltage that I can set … or a way I can tell it when to stop charging … it’s one of the super smart automatic catch your equipment on fire devices.
 
Interesting that you went from a 100 amp controller to a 20 amp model.
Anyway, I recently saw a similar problem with a system i changed out LA batteries for LFP. It appeared the BMS, was going into protection due to a low charging current setting. When it would go into protection, the controllers would go open circuit and the inverter did NOT like seeing that voltage and go into error mode. Once I set the charging current to an appropriate setting, problem solved.
 
MattMan119 said:
I got a CC 100/20 Victron I will replace it with … was a fun experiment, and I can confirm the cheap crap being sold has been the cause of every problem I have had with this system… cheap is cheap … only part not been a problem is the batteries.. they seem to be working …
Click to expand...
Some cheap crap is not bad. You just need to search for the gems. Overtime you learn to spot the more obvious things to avoid. Yes you can try to always go with the highest cost items to try and avoid issues but doing that has a price to it. It also may not be a guarantee of success.
 
Mattb4 said:
Some cheap crap is not bad. You just need to search for the gems. Overtime you learn to spot the more obvious things to avoid. Yes you can try to always go with the highest cost items to try and avoid issues but doing that has a price to it. It also may not be a guarantee of success.
Click to expand...
Right, I saw those buttons and said Oh No!
 
littleharbor2 said:
Interesting that you went from a 100 amp controller to a 20 amp model.
Anyway, I recently saw a similar problem with a system i changed out LA batteries for LFP. It appeared the BMS, was going into protection due to a low charging current setting. When it would go into protection, the controllers would go open circuit and the inverter did NOT like seeing that voltage and go into error mode. Once I set the charging current to an appropriate setting, problem solved.
Click to expand...
That unit is far from a 100a MPPT, probably more like 40a at best.
 
That company (MPPT) is running a very profitable scam.
You really have to give them credit for coming up with the idea.
 
littleharbor2 said:
Interesting that you went from a 100 amp controller to a 20 amp model.
Anyway, I recently saw a similar problem with a system i changed out LA batteries for LFP. It appeared the BMS, was going into protection due to a low charging current setting. When it would go into protection, the controllers would go open circuit and the inverter did NOT like seeing that voltage and go into error mode. Once I set the charging current to an appropriate setting, problem solved.
Click to expand...
It has no setting for charging voltage that I can find.. But I will look one more time prior to pulling ..

Would i like the 100amps sure, but is 24v on a trailer and all i have it two 370w panels for it, so it will work (~520 or so max and over panel will keep it running ) ... Other reason .. I own it already don't have to buy anything else to get it working.
 
littleharbor2 said:
I know it well. Question is, Did MattMan119 know that?
Click to expand...
Yeah , I never expected it to be 100A .. it's 24v system, and max would be 30a. I got the bigger version to hope it would not catch fire. LOL ... I have to say I was very nervous allowing it to run the first day with sun, it was the first time it moved over 20a ....
 
Ok so changed it today … here is my question not sure it matters …
IMG_4515.jpeg
I have to panels in parallel… is it worth my time to alter it to series ? It on 10gauge wire and only going 10 ft or less (12-15 round trip) it turned on like at 4w so power does not appear to be a problem … doubt any losses.. might at some point add a third so might have to be put back at some point cause charge controller can’t handle 3S .. but figured it’s worth asking
 
You must log in or register to reply here.

Similar threads

H
Renogy charge controller won’t charge?
2
Replies
26
Views
321
MTM98290
MTM98290
A
MPPT Controller Stuck in Boost Mode
Replies
17
Views
413
740GLE
7
Nef003
BougeRV MPPT 40Amp 120$ with coupon.
Replies
4
Views
494
BerndL
B
B
Victron mppt automatic system detection
Replies
2
Views
159
bolowo
B
W
Will Solar charge controller work.
Replies
6
Views
770
Rednecktek
Rednecktek

diy solar

diy solar
Back
Top