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Killed my Batteries?

Ceefiveceefive

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Sep 28, 2019
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Greetings.

I made a mistake in wiring my LiFePo batteries to my system and am wondering if my batteries are salvageable.

I have two 48V, 289Ah LiFePo batteries in my system. I had been using only one battery at a time, switching between them. Both worked well for my needs.

I am installing a minisplit to my Homestead & wanted to up the amps of my system by putting both batteries in parallel.

The batteries use Anderson connectors. The way the individual cables were orientated, they were opposite one another.

I accidentally wired them to my MPP 6048 Hybrid inverter in series instead of parallel. The system turned on, then clicked off not turning on again.

I suspect I fried the BMS or some cells in my batteries, but I'm not sure as I have not taken them apart yet.

We measure close to 50V on both batteries, but they will not turn on my inverter (or a new substitute inverter we tried troubleshooting with).

Dies anyone have advice on what to look for that could be causing my battery troubles?
 
Greetings.

I made a mistake in wiring my LiFePo batteries to my system and am wondering if my batteries are salvageable.

I have two 48V, 289Ah LiFePo batteries in my system. I had been using only one battery at a time, switching between them. Both worked well for my needs.

I can't imagine a typical scenario where this is a good idea. I hope you stop doing it and never do it again.

I am installing a minisplit to my Homestead & wanted to up the amps of my system by putting both batteries in parallel.

The batteries use Anderson connectors. The way the individual cables were orientated, they were opposite one another.

I accidentally wired them to my MPP 6048 Hybrid inverter in series instead of parallel. The system turned on, then clicked off not turning on again.

If you're saying you applied ~100V to your inverter, I suspect you killed your inverter.

I suspect I fried the BMS or some cells in my batteries, but I'm not sure as I have not taken them apart yet.

It's possible, but it's far less likely than inverter death.

We measure close to 50V on both batteries,

Specific values are useful. Assuming you actually mean 50V, 50V is at an extremely low state of charge - about 14%.

but they will not turn on my inverter

Because it's probably dead.

(or a new substitute inverter we tried troubleshooting with).

Because your batteries are at too low of a state of charge, or you are not using a precharge resistor?

Dies anyone have advice on what to look for that could be causing my battery troubles?
 
Would you mind explaining using a pre-charged resistor? I have heard of this but do not know much about it.
I can't imagine a typical scenario where this is a good idea. I hope you stop doing it and never do it again.



If you're saying you applied ~100V to your inverter, I suspect you killed your inverter.



It's possible, but it's far less likely than inverter death.



Specific values are useful. Assuming you actually mean 50V, 50V is at an extremely low state of charge - about 14%.



Because it's probably dead.



Because your batteries are at too low of a state of charge, or you are not using a precharge resistor?
 
Are you using a transfer switch or circuit breaker? Sometimes it's a good measure to have "something to switch on" as it makes you psychologically wanting to re-check your connections one last time before actually switching it on. And yes measure everything up with a meter before actually switching it on.
 
The fact that you cannot start another inverter suggests the fault is with the BMS. As pointed out, 50V is the low end so try and see if you can charge the batteries?
 
General question: Do BMSes have both voltage and amperage ratings, such that you can't use a 12v BMS (example) in a 24v system?
 
Are you using a transfer switch or circuit breaker? Sometimes it's a good measure to have "something to switch on" as it makes you psychologically wanting to re-check your connections one last time before actually switching it on. And yes measure everything up with a meter before actually switching it on.
Yes, I used circuit breakers.

It is all my fault. I did check to see that I was putting them in parallel, but did not check good enough. My cables coming from the batteries are Anderson connectors. Pos and neg are color coded at the plug, not by wire color. I thought I had looked correctly at the polarity, but I did not.

A good lesson for all to double check & make certain.
 
General question: Do BMSes have both voltage and amperage ratings, such that you can't use a 12v BMS (example) in a 24v system?

Some 12V batteries have a BMS that can work with 4 in series for 48V, some do not.
When one opens, it experiences the full pack voltage.

We're not sure if OP's inverter blew something open, if the BMS shut down, or what.
If one (48V) BMS disconnected due to excessive current, it would experience 96V across it and likely fail shorted.
 
A sad situation. I would not do anything until you open the batteries and inspect the BMS boards in both of them.
If the BMS took a hit I think it will show visible damage. Are you saying that the fully charged battery is now reading 50V right after the event? If so then something is defintly been blown in the BMS. As for the Inverter, that is most certainly damaged. What model is it?
 
Both my batteries were at 50V before & after my mistake.

My inverter is MPP 6048 Hybrid.


A sad situation. I would not do anything until you open the batteries and inspect the BMS boards in both of them.
If the BMS took a hit I think it will show visible damage. Are you saying that the fully charged battery is now reading 50V right after the event? If so then something is defintly been blown in the BMS. As for the Inverter, that is most certainly damaged. What model is it?
 
The batteries use Anderson connectors. The way the individual cables were orientated, they were opposite one another.

I accidentally wired them to my MPP 6048 Hybrid inverter in series instead of parallel. The system turned on, then clicked off not turning on again.

Parallel requires a "Y" connection.
Two cables wired different from each other, opposite polarity? Is it possible you connected them in series so they delivered +48V + (-48V) = 0V when both turned on?

Both my batteries were at 50V before & after my mistake.

My inverter is MPP 6048 Hybrid.

In that case, hook a simple load to the battery. Could be 4x 12V automotive tail light in series. Could be 120V light bulb or space heater. (I've used a couple oil-filled radiator heaters in parallel to load a PV panel to approximately maximum power point. Switch and thermostat full on so it doesn't try to interrupt DC.) You can find out if the batteries do deliver power.

Try powering your inverter with 4x car batteries in series.

Assuming you did actually have batteries in series, 100V into inverter, best case would be capacitor charge inrush current tripped BMS over-current before voltage rose too high. If voltage did go to high, could pop capacitors (would be obvious by inspection, and you would have heard it), or killed transistors (either blow wirebonds open, or melt silicon shorted.)
 
It's possible the BMSs have gone to sleep after detecting the overload (your 50V reading could just be leakage).

Do you have a charger you can hook up, a small charge current could bring them back to life.
 
I try to operate with a level of certainty. No way would I be charge them without a visible inspection.
 
Can you show how you wired the anderson connectors on the inverter side? Just take a picture of the cable connecting to the inverter.
 
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