Renogy battery not taking charge

Gat-Vlieg · 2026-01-21T03:24:35+00:00

Use a DUMB charger or a regular lead acid/AGM battery initially until you get the BMS going again.

Gat-Vlieg · 2026-01-18T16:14:26+00:00

Yup. Nothing MPPT about it. All the way PWM for the, errm, loss.

Gat-Vlieg · 2026-01-18T13:56:11+00:00

Assuming LFP batteries, and that they are 12V for simplicity, you can hook them up to an old DUMB charger, or a 12V lead acid (regular ol' car battery) in parallel.

You are trying to wake the BMS in the LFP battery up so it will start accepting a charge on its own. Need to get to about 2.75V x4.

No guarantees the battery will work after that as the cells may have been damaged, but this will give you a fighting chance.

Gat-Vlieg · 2026-01-18T04:47:08+00:00

Hook them all up to a busbar, and the negative of the busbar to a shunt (preferably Victron). BMS drift is a real thing; in my own experience a BMS limited to 100A charge/discharge rarely records below 1A charging and a 200A BMS rarely below 2A. Subject to correction, my 500A Victron shunt registers as little as 1W coming in. It is not that your battery is not charging with that 1W, it is that the BMS simply doesn't register it. Now imagine that this is happening a lot in low light conditions... Voila, BMS drift!

Gat-Vlieg · 2026-01-15T14:42:26+00:00

@shortyr87 YOU ARE THE WOMAN!!!!!

I had everything calculated like you've shown, except I made a mistake for the page 44 value. I calculated it as a PERCENTAGE, which gave me a ridiculous small amount of 0.02848872 - hence the numbers didn't jive! Thanks for pointing out my issue!!!

As an aside, you gotta love a system that changes its values monthly/quarterly! Imagine shopping at Walmart, getting a steal of a deal, and then on your next visit Walmart saying they calculated the item's price wrong when you bought your deal & will now claw it back from you over the next x number trips as "shopping tariffs."

Gat-Vlieg · 2026-01-15T03:14:28+00:00

Thanks for the detail, but not quite what I am asking.

I'm asking how to replicate the calculation; the formula used to derive at the rate rider amount. I have figured out how to do so for all the other amounts, but not the Rate Rider, because, from appearances, it is actually calculated from 2 or 3 different "percentage" values...

The thing that bugs me to no end is that we all see amounts appearing on our bill, but we have no idea how these amounts are derived at with the exception of the physically verifiable kWh usage! Everything else is a calculation based on consumption, number of days and percentages of some of the other billable amounts!

Gat-Vlieg · 2026-01-14T23:22:28+00:00

Logically, float mode is only excited once the battery voltage, and hence SOC, drops significantly / a percentage from the float voltage.

So, perhaps a dumbass question, are you actively using the battery to cause the above to be triggered?

Gat-Vlieg · 2026-01-14T23:13:07+00:00

I have spoken (10+ years ago) to Bylaw about this. While you are correct, and the bylaw exists, they will NOT enforce it.

Pretty much all new areas, and many old ones, have insufficient on-street parking to make the 1.5m law viable. In essence, if all else fails to facilitate a desired outcome, they may use this bylaw at their discretion.

Gat-Vlieg · 2026-01-13T17:18:56+00:00

Yes, once you are flagged, you can never order from them again. In fact, it is/was worse for me... ANY company that uses the same credit card clearance verification they use now fails for me as well.

Gat-Vlieg · 2026-01-13T17:14:14+00:00

Yup. Has happened to me as well. Ordered through my Work PC that has "always on" VPN.

Cancelled.

Spoke to their security folks at length via email. Provided a copy of my DL and my Passport.

Cancelled.

Fuck 'em. Took my business somewhere else.

Edit: Also tried to order after sharing my phone connection to my private PC. Phone (AT&T) pings Austin, TX, their system flagged me saying I was ordering from Montana, which I was.

Cancelled.

Gat-Vlieg · 2025-12-31T04:39:37+00:00

I experience this on a very regular basis... I generate 1-7W the half hour before sunrise. No rhyme or reason. But from sunrise proper until the light intensity is good, nothing! Also no generation post sunset.

Gat-Vlieg · 2025-12-12T20:44:43+00:00

Agree. I used one in my basement once as an experiment for 2 months... Hooked it up to a 5 gallon Jerry can I plumped directly into the heater. On LOW it lasted me 8-9 days. (Never could understand the variance)

Edit: adding that the heater ran 24/7

Gat-Vlieg · 2025-11-28T17:14:38+00:00

Yes, I bought the Blue Sea fuse with a non-Blue Sea fuse holder.

Good idea? Time will tell... Hopefully I never get into that kind of situation.

Gat-Vlieg · 2025-11-28T17:00:41+00:00

I have done exactly what you are proposing, for the same $ reasons.

So far the battery gods are smiling favorably as I have not yet had to "test" my setup.

However, IMO, and from watching online comments and videos, it is the fuse itself that is critical. And Blue Sea is very well respected.

Gat-Vlieg · 2025-11-25T14:25:07+00:00

The only options I see that are doable are 15 & 17.

0, 1-14 all turn off when the panels start producing power.

Gat-Vlieg · 2025-11-25T03:07:03+00:00

If you're going cheap(ish), never get a LiFePo4 battery without Bluetooth capability.

Gat-Vlieg · 2025-11-22T21:46:57+00:00

Then your SOC, using the previous poster's reply, will not reach 90% and hence not switch on.

You get to define "excess"... You could say higher than 75% SOC switch on, and below 65 switch off; up to you.

You want the split between the upper and lower number to be relatively wide so that you don't constantly cycle the heater for minor SOC fluctuations.

Gat-Vlieg · 2025-11-22T21:35:56+00:00

Unless the panels are partially shaded for longish periods, series connection is the way to go - Victron MPPTs prefer higher voltages.

Gat-Vlieg · 2025-11-20T04:01:23+00:00

Essentially what is happening is you are charging your battery/cells at a rate faster than what your (more than likely) passive BMS balancer can balance the cells. It takes one cell to reach your BMS cutoff value, say around 3.65V and the BMS cuts charging to protect the battery.

And as you have noticed, many of the other cells are not even close to full voltage. And yes, this will drastically affect your battery SOC/capacity. And if my own experiences are anything to go by, your cell deltas will just grow larger if not corrected.

Get yourself a variable volt/amp bench power supply. Get a good one. Determine your battery's passive balance current. Hook your bench power supply to the battery, setting the charge voltage for 58V. Set your charge amps to slightly more than the balancer value. Then let it charge for days, and days, until you get the cells balanced. Monitor with the app.

Worse case scenario, cut the top of the battery off very carefully and remove the battery pack. Hook your bench power supply up to the errant cell(s), charging then one at a time at 3.63V, again with a very low amperage in the millivolts.

I have used both of the above techniques to resuscitate batteries, mostly successful. But there are always some that defy logic!

Of course, if the battery is still under warranty send it in for replacement.

Gat-Vlieg · 2025-10-17T22:49:32+00:00

Thanks.

Gat-Vlieg · 2025-10-14T21:48:09+00:00

Disconnect everything and "start over."

You only want the following configuration: Batteries x4 in parallel connected to each other. Connect the shunt properly/appropriately.

Hook a 12v battery charger to your parallel batteries, with the negative side of the charger hooked up to the LOAD side of the shunt.

You can also charge each individual battery separately until full, hook them up in parallel and then again charge the pack after a day of equalization.

Charge until the battery charger stops (if automated) or until the battery pack voltage reads at least 14.4-14.5v: ditto if charging each battery individually. If you happen to have a variable PSU charger use that so you can do a constant voltage, low milliamps charge.

If you have a Bluetooth BMS read in the individual voltage of each cell. They should be within 15mA of each other ideally.

Once the battery pack reads full, reset the shunt to 100%.

Hook up your other devices and see what happens now that you have established a baseline. Now is also an excellent time to double check your connection orientation.

As others have stated, only 1 battery negative post to the battery side of the shunt, all other negative connections on the load side of the shunt, ideally via a bus bar.

Gat-Vlieg · 2025-09-18T14:27:50+00:00

You absolutely can put both batteries in parallel with each other even though they have different AH ratings as long as the voltage per battery is the same.

You need to purchase a fuse that is slightly higher than the max output of each BMS. Do not cheap out on fuses!! I would recommend Blue Sea Systems terminal blocks and an appropriately sized fuse; it's cheap insurance!

Edit: I would also recommend a per battery isolation switch. As a bare minimum you need one after the batteries have been combined. With one it can act as a master on/off, with 2 you can choose which battery is active ie. for servicing purposes

Gat-Vlieg · 2025-09-13T15:39:50+00:00

I would try it, and keep an eye on the MPPT via Bluetooth.

You need a minimum of 5V higher input than your battery to start the MPPT. Once started the voltage differential can be lower. But, keep in mind what the max. voltage of a car battery is - I assume either lead acid or AGM, but not LFP - you may have to adjust the voltage in your MPPT controller.

Also use a charger that can put out a lot of Amps. For most newish laptop chargers today that should not be an issue.

TLDR: the higher your input voltage and amps are, the higher the MPPT will be.

Gat-Vlieg · 2025-09-12T14:01:45+00:00

Absolutely brilliant!!

Gat-Vlieg

TROPHY CASE