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basb avatar image
basb asked

Older 12.8/200 Victron LiFePo BMS midlife update ?

Hello all,

Does anyone know whether it is possible to upgrade the old in-battery non-smart (passive?) cell-balancing part of the bms by the latest edition Smart BMS ?

In theory it should be, but I'm not sure if it is an available service at Victron and whether cost would be a factor.

Just purchased a pair of seven year old batteries with 300 cycles and had them checked by a Victron dealer. They seemed healthy. Would like to keep them around for another decade or so, and think a more modern BMS with cell-monitoring capabilities would be helpful.

Kind regards, Bas.

Lithium BatteryBMS
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3 Answers
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @BasB,

300 cycles is like new.

Which "smart" BMS do you have in mind?

Except that the "non-smart" batteries lack of bluetooth, there is not much of a difference. The "smart" capabilities have nothing to do with cell balancing. Victron BMSs are downwards compatible with those older batteries. The only downside is that you have to live without Bluetooth and the settings coming with it (ATC limit, cell under voltage pre-alarm threshold and ATC minimum temperature).

I don't think the circuit boards (with the Bluetooth module) are sold separately.

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basb avatar image basb commented ·

Hello Stefanie,

Thank you kindly for your quick answer. That covers most of it I think.

I was under the impression that the Bluetooth enabled boards also used a different cell-balancing method. I know the BMS's are compatible, but isn't the external VE Bus BMS just a translator/actor for data coming from the battery ?

As the batteries will age, not just from cycling, I figured it would be helpful to have insight in any imbalances. But as you say, I could live without out.

One of the two batteries has a slightly lower voltage, 0.4v, when charged to 28.4 in series. (14.4v vs. 14.0) So I was looking to see if I could gain insight into any imbalance and/or the balancing progress, as I am trying to re-balance. Time is not a factor.

I only have a Multiplus 24v at hand, so I charged them both all the way in series, and have now disconnected the Multiplus and connected them in parallel, in order to batt-2-batt charge them. A SBP between them (from HV batt to LV batt), connected to the VE Bus BMS ATC.

I'm about to order a 12V charger, but I'm not entirely sure which amperage. Elsewhere it is suggested to go as low as possible, but the manual of the newer Smart LiFePo states in 6.1.2 that balancing takes place when the charge current is > 1.8A in absorption stage. Does that mean a 12V/4A charger will do the balancing trick best (when charged in parallel, i.e. 2A per battery) by allowing the longest absorption stage and therefor the longest balancing stage ? The 13A IP67 charger can also be put in a 4A low power mode.

The Multiplus (latest Compact, latest firmware) allows me to go that low and lower in current, however, the voltage imbalance between the two batteries appears to stay. I would like to try to get them balanced. If that won't work, I'll set the 24v MP to 28.2v to not exceed the 14.2v for the higher voltage battery.

Kind regards, Bas.

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ basb commented ·

@BasB

There are some differences between Victron Lithium Smart batteries and those that you have. To give you an impression of how they look like, please go to professional.victronenergy.com, create an account (free), then scroll down to the firmware section and see the Lithium Smart batteries folder for the file Smart Lithium - changeling.docx.

0.4V I would consider significantly lower, which could be caused by cell imbalance or even a weak cell on that battery.

VE.Bus BMS and other Victron BMSs: balancing takes place automatically and independent of the BMS. The BMS cares about all loads and chargers in case a low/high cell voltage event or high temperature event occurs (signal from battery to BMS) and in this way safeguard your batteries.

Not recommended (unless you're experienced enough), but the easiest way to measure each cell is to open the battery and measure each cell separately with a multimeter.

Charging your unbalanced batteries in series connection is also not recommended. This will not balance your cells properly as long as they are in such an unbalanced state. See our new manual troubleshooting guide for cell imbalance and how to recover. It's for the newer type lithiums but can be easily adapted to the old LFPs.

Any 12V charger with a lithium specific algorithm will do. The less amperage, the longer it will take (which can be a good thing, but once balanced, you want more juice ;-)

As far as I remember, the balancing current is 250mA per cell. I can't tell when exactly balancing takes place on the old style lithiums. I think it was 3.40V per cell or 13.60V battery voltage. But it shouldn't matter if you follow the rough guide that once cells are properly in balance (after recovery), leave them at 14.20V for 2 hours at least once in a month or even on a daily basis, if there are full discharges going on frequently.


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basb avatar image basb Stefanie (Victron Energy Staff) ♦♦ commented ·
Hello Stefanie,


Thanks again, looks like I have some homework to do.


Kind regards, Bas

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klim8skeptic avatar image
klim8skeptic answered ·

Once upon a time, long long ago (2015??) Victron produced 2 variants of their lithium battery.

The basic version only had cell balancing. The flasher version had cell balancing, and connectors to enable a more thorough BMS.

lithium-1.png

lithuim-2015.png

I would not imagine that there would be any upgrade path for those original Li batteries.

Some ppl collect stamps. I prefer to collect data sheets :).


lithium-1.png (289.9 KiB)
lithuim-2015.png (131.0 KiB)
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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·
Doh! I forgot those w/o connectors...count me in collecting data sheets ;-)
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basb avatar image
basb answered ·

Hey Cli-mate, hello Stefanie,

The once-upon-a-time hit it just right. It reminds me of photosynthesis....(o; I'm all about evolution, and would like to honour inventions of the past. A midlife update would be perfect. It's easier to recycle a BMS board compared to a complete battery cell. One out of eight likely slightly misbehaving (the battery delivered 208Ah to 11.4V on a 25Ah discharge) and I'm trying to understand it's origin in order to prolong the life of this invention. Without having to recycle the hard way in the future.

Can lithium plating, or any other applicable chemical reaction, be reversed if tended to gently ? On an atomic and chemical scale, what ages lifepo that cannot be reversed with patience ? If the theoretical cycle life is 3000+, then these batteries could celebrate their 70th birthday sometime.

As far as measuring cells and data sheets, does anyone have a construction drawing of this specific battery ? So I can drill a tiny hole precisely onto each cell terminal to measure and prevent me from having to tear the beautiful case apart.

Cheers, Bas


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klim8skeptic avatar image klim8skeptic ♦ commented ·

People have de-lidded their batteries, and found this construction.

Apparently Winston cells.


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basb avatar image basb commented ·
Saw that yes, thank you though. That's why I asked the questions I asked. The pair is currently sitting in parallel at 13.6V. Fingers crossed.
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klim8skeptic avatar image klim8skeptic ♦ basb commented ·
Fully charge then to 14-14.2v for an extended period (24 hours) to properly balance the cells.


Maybe limit the charge current to 1-2 amp once in absorb, and keep a close eye on them.
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basb avatar image basb klim8skeptic ♦ commented ·

I set the absorb to a longer timeframe at 2A indeed and a daily repeat for balancing. I was hoping that would happen, even in a series connection. They're slowly coming together, now within 0.2V of each other. A 12V charger is underway. Needed it anyway for a camping trip...;o)

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