Help, Lithium’s not turning on. BMS crashed?

[UnNamedBeneteau]

Lithium Battery Crashed! Please help me find a way to troubleshoot and get it back up.

I’ve had a 700 ah 12 volt lifepo4 system in my boat running without issues for about 4 years. The Battery Management System has decided to shut down and I can’t get it back running. The cells each have a healthy and balanced charge and sit at about 13.5 volts collectively. I think I saw 3.4, 3.4, 3.4, 3.3 individually. No temperature change so not hot.

We were motoring along for a few hours when I noticed my two lead acid batteries (bow thruster and starter - on same alternator as lithium, but connected via isolators) were charging too high at about 15v. I then checked the lithiums and saw they were at about 14v at terminals, but 17v at the alternator side of fuse. So I shut down the engine.

When I shut down the engine, the lithium (ie house bank) also shut down. I pushed a reset button on them, they populated for about 70 seconds, then shut down again. I tried this repeatedly with the same result until the reset button no longer activated the system at all.

Some additional info:
- prior to the trip, I swapped out the two original lead acid starter type batteries for a couple of newer deep cycle lead acids. My originals were getting old, and these healthier batteries were available. I like having lead acids in case the lithium suddenly was to shut down during full alternator charging, the extra power would be spilled into the lead acids - which is what I think happened here - saving my alternator. I swapped them out without any changes to the configuration and no contact with the the lithium cells. So nothing else changed.

I have now swapped back to my original lead acid batteries for the starter and bow thruster. Reverting to the original configuration brought no change. (I’m now using those newer deep cycles as my house bank in place of the lithiums as a temporary solution until I solve the issue. All these batteries are behaving normally.

- one of the mini BMS circuit boards which monitors the individual cells was brittle at the ring connection on the cell post (and had been since the original installation). Now that I’ve been touching everything toward solving the issue, it broke off completely. I soldered it to a wire lead as a repair.

- the company I purchased from is no longer in business. Companies with similar BMSs will only sell replacement parts if you bought the whole battery system from them.

I don’t know where the failure is,
- an individual cell monitor
- The BMS controller
- The fuse or shunt
- The reset button

I don’t want to spend $2,000for a new monitoring system. Ideally I would like to rule out any small part failures or obvious issues. I’m hoping someone can put me onto a good solution. I am just an end user, not an electronics DIYer by any means.




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[CharlieJ]

What kind of boat do you have? How old is the system? Is the BMS a HousePower?

[Username25]

Why don't you post more tech details about your system with exact vendors? Maybe this could help to identify yours http://liionbms.com/php/bms_options.php

Can you measure every cell voltage at BMS end? We had continuity failure at one voltage sensor. As a result BMS was triggering safety alarm and shunting down all loads via latching relay.

BMS replacement. e.g. REC or EMUS would cost you about 500-600 euro.

[UnNamedBeneteau]

My system was boaught in 2014 from “Balqon” which is no longer in business but still helpful. They referred me to Clean Power Auto, because they had the same BMS as my original equipment.
Following the trail I see that company is now Lithionics! Which can’t sell under their UL restrictions. Housepower as another poster mentioned is also Clean Power.
Thank you for providing the supplier reference link.
I also suspected one of the mini bms pieces had failed as I described on to be fragile. They all however continue to blink at what looks to be the same cadence as always. I was afraid perhaps having one disconnected briefly could have damaged the controller. I don’t know how to check for that. I checked voltage of each individual cell and found them to be reletively consistent.
I’m in aBeneteau Sailboat with a high out put alternator and Balmar regulator. No parameters there were changed. No solar. Currently at anchor on Lake Ontario, Canada, on vacation with family, visitors, and neighbouring boats wondering why I suddenly need to charge twice a day!

[john61ct]

Two suggestions. And first, discharge a bit, that's too high to just sit like that!

A. strip off the BMS go bareback for now, get a decent ammeter and AH-counting monitor and regulate the system yourself manually, at least for a while.

Lowest voltage 11.9V at high discharge currents, 12.1V for a low rate.

Highest voltage charge at 13.8 for low rates, maybe 14 for high, but only when loads are active not for sitting.

B. Contact Bruce @ OceanPlanet, see if he can help. Participated in Lithionics newer system design.

[Username25]

Originally Posted by UnNamedBeneteau

I also suspected one of the mini bms pieces had failed as I described on to be fragile. They all however continue to blink at what looks to be the same cadence as always. I was afraid perhaps having one disconnected briefly could have damaged the controller. I don’t know how to check for that. I checked voltage of each individual cell and found them to be reletively consistent.

Your MiniBMS Control Board should get voltage data from each cell voltage module. "Single wire Normally Closed (NC) communication loop - OptoLoop. All modules connect in a single series string using automotive style Quick D is connect crimp terminals. NC loop is extra reliable since it senses loose wiring connections a s well as low and high cell conditions." You should figure out how to check voltage of each module or all modules to rule out voltage module failure. Setup looks quite primitive https://914electric.wordpress.com/20...attery-brains/

"MiniBMS relies on constant power supplied from your 12V aux battery. Please make sure your 12V battery is properly charged at all times to ensure correct BMS operation". I would check MiniBMS Control Board power supply voltage at B+ and GND http://cleanpowerauto.com/files/Mini...istributed.pdf

[mbartosch]

Originally Posted by UnNamedBeneteau

I also suspected one of the mini bms pieces had failed as I described on to be fragile. They all however continue to blink at what looks to be the same cadence as always. I was afraid perhaps having one disconnected briefly could have damaged the controller. I don’t know how to check for that.

If the BMS is a House Power BMS then you can check for defective cell boards the following way:

First of all: Be very careful not to short anything or touch anything with the connections involved with this test.

Shut down your BMS main power. Bridge the contacts of the "cell loop" of one of the cell modules. Alligator clips work fine for this, or otherwise disconnect the automotive crimp connector of one module and directly attach the wire to the next module, leaving out the first. After you have done this the "cell loop" must be complete again, running from BMS to (and through) the remaining three cell modules in series and back to the BMS.

Power on the BMS. If the BMS engages the main contactor and you have power you have identified a defective cell module.
If your BMS remains dead the module you bridges was likely not the cause of the problem. Power off the BMS and bridge the second cell module as described above. Repeat until you have bypassed all cell modules.

If the BMS powers up boat power fine in all but one tests you have identified the defective cell module. If the BMS remains dead it's likely a problem with the main module. It could also be a problem with the cell loop wiring itself. Check all wires, crimp connectors thoroughly.

Hope this helps narrowing down the problem...

[YuvalOhali]

Try to disconnect the controlling wires to the engine controllers, and connect it again
It will reset them.

[Cpt Pat]

Originally Posted by UnNamedBeneteau

We were motoring along for a few hours when I noticed my two lead acid batteries (bow thruster and starter - on same alternator as lithium, but connected via isolators) were charging too high at about 15v. I then checked the lithiums and saw they were at about 14v at terminals, but 17v at the alternator side of fuse. So I shut down the engine.

All the posts here have good troubleshooting ideas. But...

Something is very wrong with your alternator regulator. Your BMS "pulled the ejection seat handle", took the battery off line, and probably saved your lithium battery. Bad things happen to lithiums when you dump 17 volts across a 12 volt battery.

BEWARE: if you get the lithium back on line, this problem will reoccur unless you fix the voltage regulator - with the potential for a catastrophic failure (smoke and fire) of your lithium battery. The cell BMS cards are probably shunt types (the most common) that dissipate a cell overvoltage above a threshold (usually anything over about 3.55 volts) through a shunt resistor. The cards are meant to shunt only hundredths of a volt of over voltage -- not several volts. The resistors or driver MOSFETS of one or more BMS cards have probably failed.

I suspect the failure of one or more BMS cards has cascaded to cause the lithium battery safety cut-off to stay active. It appears the designers used a failsafe tandem design for the cut-off sense circuit. Good. This is the best-case scenario. The alternative was an overcharged and destroyed lithium battery, and potential cell burst/smoke/fire.

You will have a safety hazard until you determine why the alternator is outputting 17 volts. At 20 degrees C ambient temp., the alternator output should never exceed 14.7 volts. Your lead-acid batteries will tolerate short periods (a few minutes) of overvoltage (eventually outgassing their electrolyte), but do not reconnect your lithium battery until you solve the alternator voltage regulation problem! And that problem will also destroy your lead-acid batteries -- it'll just take a little longer to boil them dry.


Also, carefully inspect each lithium cell looking for signs of physical bulging. If a cell is bulged, or a cell safety vent burst disk has blown out, I'd replace the entire battery. Overcharging a lithium cell promotes dendrite formation inside the cell, which can result in a ticking timebomb ending in a catastrophic internal short circuit. I never charge my cells above 3.5 volts per cell, though a maximum of 3.6 volts is usually acceptable - with diminished battery life.

[OceanSeaSpray]

Originally Posted by Cpt Pat

Something is very wrong with your alternator regulator. Your BMS "pulled the ejection seat handle", took the battery off line, and probably saved your lithium battery. Bad things happen to lithiums when you dump 17 volts across a 12 volt battery.

I would back this up. Furthermore, this BMS was never intended to be used on boats and with alternators by the way. It only controls a single contactor and dropping the battery with the engine running is asking for damage.

While a few people like mbartosch designed their way around its flaws, many of the installations using it have been either unsafe or exposed to serious electrical damage in case of HVC trip.

[hellosailor]

What john said. You'll need to go without a BMS if you want to get any quick fix.

"but 17v at the alternator side of fuse." And there's the problem. 17v from the regulator indicates a regulator or alternator failure. Anything over 14.4 (give or take a little for cable losses) indicates a gross failure. That should have blown out fuses or circuits, and in fact it is high enough to blow out every electronic device from your nav lights to the instruments and radio. Every electronic device on the boat is now suspect.

If the BMS did its job, it blew some fuses, and sometimes they blow components instead. In which case your batteries would still be OK, but you'll need information on the BMS and probably need to send it to an electronics tech to go over it. (Not easy to find, let alone to find competent ones.)

So for right now, as john said. Strip off the BMS, provide human adult supervision, and verify the regulator output, and whether there are any other damaged electronics. Your alternator/regulator probably need to be replaced/repaired immediately to prevent further damage.

[john61ct]

If you want to simply replace with a "packaged system" like Victron or Lithionics' current models, you will likely get a decent price for your bare cells with only four years of usage,

especially if you can document the results of a 20-hour load test demonstrating their residual capacity, aka SoH state of health.

Ballpark $200 per 100AH @12V / 4s ?

But careful about shipping, silly as it is classified Hazmat.