Battleborn batteries inverter startup issues

[vincei]

Hi,

I have 8 brand new Battleborn batteries that I bought from the company in March. Never been used. I currently have 4 of them connected in series to create nominal 48V for my 5KW inverters. The batteries are connected to the inverter with 4/0 wire ( https://www.amazon.com/gp/product/B00LIB5W4Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ) and go thru a pair of DC breakers rated at 100amps and 175amps(for 2 sets of 4 in parallel which will be the final configuration - the other 4 also have their own 100amp breaker).

I *had* a pair of mpp-solar inverters that would not startup properly with these batteries but those inverters had other problems and I marked the issue down to that. However, I just received a 6KW Growatt inverter and it also does not start up with these batteries even though I measure 53V at the terminals of the inverter before turning things on. Putting a multimeter across the +ve and -ve and turning the inverter on the output of the batteries drops to about 20V or less and nothing happens.

If I connect the inverter to 4 lead acid batteries the inverter starts just fine with no issue. Once it has started if I switch over to the battleborns the inverter is perfectly happy and indicates that it is charging them from the PV input and a battery charging voltage of about 53V. After a couple hours if I shut everything down and and wait a few minutes and try to start with the battleborns nothing happens. I have to get going by switching over to the lead acids.

It's as though the batteries have some sort of current limit and drop their output voltage when the inverter is turned on. I know the inverters have large capacitors in them but it is impractical to bootstrap the system every time with lead acid batteries.

Does anyone know what is going on here? For the amount of $$$$ i put into these batteries I was not expecting this kind of behavior.

Thanks,
Vince

 

[snoobler]

Did you use a resistor to pre-charge the capacitors, or did the cables spark like crazy when you connected them?

 

[vincei]

Did you use a resistor to pre-charge the capacitors, or did the cables spark like crazy when you connected them?

The breakers have spark arrestors in them. The inverters are connected to the batteries by flipping a breaker. What difference does it make? The 3 inverters I've tried start with the lead acid batteries. Seems impractical to me that whenever you need to turn on the inverter you have to disconnect the leads and charge things with a resistor? What am I missing?

 

[snoobler]

Surge from the pre-charge of the capacitors can blow out the BMS of LFP batteries. I think a call to Battleborn is in order.

 

[gnubie]

The breakers have spark arrestors in them. The inverters are connected to the batteries by flipping a breaker. What difference does it make? The 3 inverters I've tried start with the lead acid batteries. Seems impractical to me that whenever you need to turn on the inverter you have to disconnect the leads and charge things with a resistor? What am I missing?

The difference is that if you just dead drop the inverter onto batteries by turning on a breaker the input capacitors in the inverter will draw very large current for a brief time. That draw may be high enough to trip the BMS in one (or more of) the Battleborn batteries. It may be large enough to cause damage to the BMS too. If you had a multimeter that can handle the current (we could be talking > 300A, so that'd be a rare beast) with a fast enough response to capture the event that would lay it all out bare. A current shunt and DSO would let you capture it too.

You can get away with it with a lead acid battery because there is no BMS to step in and disconnect in the face of very high current draws.

Excessively high current in and out of those input capacitors will degrade them in time too, with cheapie capacitors failing faster than quality ones, so even if you have a lithium battery with a BMS that can take it, it's still a good idea to pre-charge. Reputable capacitor manufacturers spell this all out in black and white in their product datasheets.

*edit, as usual (sigh), to add more*

 

[vincei]

The batteries have short circuit protection. Why would large inrush current be any different?

Yes, I will be calling them on Monday.

Thanks!

 

[John Frum]

You can get away with it with a lead acid battery because there is no BMS to step in and disconnect in the face of very high current draws.

Can lead acid batteries deliver the same instantaneous current?

 

[gnubie]

The batteries have short circuit protection. Why would large inrush current be any different?

Yes, I will be calling them on Monday.

Thanks!

What happens when you short it? BMS disconnect.

What happens when you draw excessive current? BMS disconnect.

What happens to your inverter when the BMS disconnects? It doesn't turn on.

This isn't the first time we've seen the issue of people overloading BMSes by dead connecting inverters. No doubt it won't be the last.

 

[Steve_S]

Current Surge Limiter

Do you have Battle Born Batteries in your rig? Does your system have a 4kw or greater inverter? Then protect your system with our Current Surge Limiter!

battlebornbatteries.com

 

[gnubie]

Can lead acid batteries deliver the same instantaneous current?

Quite high enough to achieve the same damage, but obviously like for like an unprotected lithium cell will win.

 

[Steve_S]

FLA & LFP HERE.
Lead Acid handles the inrush as it has no BMS and Lead can deliver a huge burst demanded by big capacitors. A BMS on the other hand will cut off as safety, of course, this depends on the BMS Type and Configuration. Not applicable to BattleBorn, they require a precharge and I posted their solution above.

I've had this issue during my transition from FLA to LFP and luckily had the easy workaround of having the FLA online as well (that's tricky on its own) but now with decommissioning the FLA, the problem popped up too, but my BMS system has its solution for that coming in.

Description
If you have a Battle Born battery bank in your system and a 4kw or greater inverter, then you’ll need our Current Surge Limiter (CSL500).
This soft start avoids the high-current shutoff inherent to the BMS our batteries.

Features
The CSL500 Current Surge Limiter is a FET-based current limiting device that is to be used with Battle Born Batteries LiFePO4 battery packs when they are used in conjunction with large (greater than 4kW) inverter/chargers.

The device is mounted permanently in series between the negative pole of the battery bank and the negative DC input terminal of the inverter/charger. The device protects the battery management system (BMS) from damage caused by the initial current spike that is created when connecting directly to the large capacitors (> 5 milliFarads) that are typically on the DC input side of the inverter/chargers. The device allows the batteries to slowly charge the capacitors (within 1 ms). This soft start avoids the high-current shutoff inherent to the BMS of the batteries.

 

[snoobler]

Can lead acid batteries deliver the same instantaneous current?

Pretty much. The IR of a healthy 12V battery is only about 3-5mΩ or just under 1mΩ/cell - pretty comparable to LFP. The claim that LFP have substantially lower IR is unfounded unless comparing it to a 3-5 year old tired FLA/AGM

 

[vincei]

FLA & LFP HERE.
Lead Acid handles the inrush as it has no BMS and Lead can deliver a huge burst demanded by big capacitors. A BMS on the other hand will cut off as safety, of course, this depends on the BMS Type and Configuration. Not applicable to BattleBorn, they require a precharge and I posted their solution above.

I've had this issue during my transition from FLA to LFP and luckily had the easy workaround of having the FLA online as well (that's tricky on its own) but now with decommissioning the FLA, the problem popped up too, but my BMS system has its solution for that coming in.

Steve_S, thanks. already in quite a few grand what's another $280, eh ?

 

[evilroy]

Having same issue with my 12 volt inverters, what I found is 2 of 3 inverters had 15 volt overload protection default while number 3 has 15.5 volt....it works the others don't yet all my voltage reading on my single 100 amp BB show 14.4 volts yet it's still kicking a 15 volt switch, Battleborns response was " it's not suppose to do that" I kid you not!

 

[vincei]

Having same issue with my 12 volt inverters, what I found is 2 of 3 inverters had 15 volt overload protection default while number 3 has 15.5 volt....it works the others don't yet all my voltage reading on my single 100 amp BB show 14.4 volts yet it's still kicking a 15 volt switch, Battleborns response was " it's not suppose to do that" I kid you not!

Without going into too many gory details:

How have I worked around this problem? When the sun comes up the Solark starts up without drama and I can reconnect the batteries. Just never let the batteries run down low enough for the inverter to shutdown otherwise a restart with the batteries is a monumental pain in the ass which
involves disconnecting everything and doing the slow charge resistor thing even with their much vaunted surge suppressor.

I will *never* buy another BattleBorn product ever again. Lessons learned from here. Sell you a product that doesn't work and then blame you for it not working properly and before you've even broached the subject say "we don't accept returns on those" then ignore all your emails asking for an RMA, return and refund.

Pretty shitty.

 

[evilroy]

You must have been listening into my conversation with BB this morning, I requested a refund because the battery they insisted would out perform my two 7 year old 235 Ah 6 volt floodeds ( on life support) .... the BB clearly lacks capacity, as I told them it's like going to a gunfight with a knife, they referred me to their refund site that has me paying for return Hazardous Material rates, a restocking fee and if the battery was used they will test it and decide how much of the purchase price I will get, in other words S.O.L.!
Lesson here is yes I saved a hundred bucks buying direct from BB but had I bought from Amazon it would be a simple return, they pickup and I get a credit once picked up.....well worth not putting up with the BattleBorn B.S.!

The flip side, I like a challenge and living offgrid for last 9 years I have a motto, Less is More.....I will adjust to the batteries limitations and see where it takes me.

 

[cinergi]

How have I worked around this problem? When the sun comes up the Solark starts up without drama and I can reconnect the batteries. Just never let the batteries run down low enough for the inverter to shutdown otherwise a restart with the batteries is a monumental pain in the ass which
involves disconnecting everything and doing the slow charge resistor thing even with their much vaunted surge suppressor.

Can you help us understand this? Because once an inverter is physically connected, there'll never be inrush current again to trip the BMS. So I don't understand why it's difficult to restart the inverter after it shuts itself down.

 

[Bill Taylor]

A well made battery with a robust BMS will handle inverter inrush current without any trouble. But a lightweight BMS will trip out every time. I guess someone has to state the obvious, we continue to hear this same problem repeatedly with "certain brands"...

 

[Hedges]

The difference is that if you just dead drop the inverter onto batteries by turning on a breaker the input capacitors in the inverter will draw very large current for a brief time. That draw may be high enough to trip the BMS in one (or more of) the Battleborn batteries. It may be large enough to cause damage to the BMS too. If you had a multimeter that can handle the current (we could be talking > 300A, so that'd be a rare beast) with a fast enough response to capture the event that would lay it all out bare. A current shunt and DSO would let you capture it too.

You can get away with it with a lead acid battery because there is no BMS to step in and disconnect in the face of very high current draws.

And guess what I just happen to have???



I'm disappointed.
I wanted to see a surge of thousands of amps. All this showed was 382A peak.

This setup has 4x 12V 104Ah SunXtender AGM, and a couple meters of 2/0 cable (each of positive and negative.)
I've read of 4000A short circuit current from 100 Ah AGM, so was hoping for that. 12V/4000A = 0.003 ohm internal resistance or around 5x what I've seen quoted for 4x LiFePO4 cells.
2/0 is 0.26 milliohm/meter so about 0.001 ohm for 4m cable. Compared to 0.012 ohm for four batteries in series, insignificant.

My AC current probe is rated 100A, and probably meant for 60 Hz.
I figure the core is limited by Current X time. 60 Hz is 16 ms period, 8 ms phase. (or maybe just amps is the limit?)
The pulse I captured was something less than 400A and was over in 4 ms. Area occupied is about 0.8 Amp-Seconds.

Probe could also be bandwidth limited. Figure a 60 Hz sine wave was supposed to reach 100A in 4 ms (part of curve is steeper than 25A/ms).
The waveform I got shows 400A in 0.4ms, 1000A/ms.

The inverter I test, Sunny Island SI5048US, measured 3 uF with breaker off. Breaker on, was off scale of my meter. It contains 18, 2700 uF caps or 0.050 F. This is a 5kW inverter with 10x the 0.005 F which Battle Born says would be found in a 4kW or larger inverter, and would require their precharge circuit.

0.050 F x 50V = 2.4 amp-seconds or 2400 mA-seconds. That would be 600A for 4ms. Waveform I captured shows about 800 mA-seconds.

This would be better:

Fluke i3000s AC Current Clamp

The i3000s is a clamp-on AC Current Clamp for use with oscilloscopes and multimeters with banana input using the supplied Dual Banana to BNC Adapter.

www.fluke.com

3000A, 100 kHz.

"Maximum non-destructive current 4000 A"
I don't like the sound of that.

 

[orangeminnie]

Doesn't the inverter have an on/off switch? Why not leave it continuously connected to the battery bank, to keep the capacitor charged? My understanding is that the problem is only upon initial connection. The inverters I've seen have the monster capacitor across the DC input. Why repeatedly stress both the BMS and the inverter, by doing repeated full disconnections? Also, this issue is not unique to BB.