Dropin LFP: Pylontech RT12100G31

[rgleason]

Pylontech IP67 12V 100Ah Lithium Iron Battery LifePO4 RT12100G31

Question:
Does the CAN bus and BMS operate properly with the Wakespeed WS500 to provide an advance alarm before shutdown, and disconnection of the the alternator field current via the Wakespeed WS500 regulator?

https://shop.frankensolar.ca/pylontech-rt12100/
Datasheet
"Communication CAN, RS485, BlueTooth, Dry Contact enable data
transmission to meet the needs of different usage scenarios."
User Manual

It does have external communication via CANbus, but will it work with the Wakespeed WS500? They mention compatibility with "generators" but not alternators.

It does not have robust charging specs as I would would need, but it is IP67 so it could be put in the port cockpit locker, except it would probably be a little too warm from the engine. It is too expensive.

It might be a perfect solution for someone else.

[T1 Terry]

From what I've seen of their higher 48v installations, they use the 3.2v fully charged idea to avoid cell over voltage. This works fine to get the battery out of the warranty period, but the actual capacity is anywhere down to 40% of the advertised capacity .... this depends on how fast they are charged, I'm guessing this is why they limit the charging current so much, a slow recharge would get the cells up to some where near 70% SOC or even more before the 3.2v became 3.3v, but this is an unknown because they haven't been around for long enough for one to fail and refused warranty, that is when they bring them in here and I can see just what it actually inside the sealed box ....
I'm a great believer that you only seal stuff up in a box that can't be opened easily, if you don't want anyone to know just what is inside .....

T1 Terry

[rgleason]

Thanks Terry,
That is important consideration!

I wrote Outback Marine and this is there response to the question of Wakespeed WS500 working properly....contact Wakespeed.

However I am pretty sure Wakespeed would work, but what is the point, because it does not accept enough Amps.

Thank you for contacting us.


Pylontech batteries are not supported by Wakespeed WS500. I would recommend contacting Wakespeed.


Wakespeed WS500 can be connected to Victron GX device such as Cerbo GX. Cerbo GX can communicate with Pylontech.
https://www.victronenergy.com/media/...0-support.html


Victron Cerbo GX:
https://www.outbackmarine.com.au/victron-cerbo-gx


Victron Cerbo GX with a touchscreen:
https://www.outbackmarine.com.au/vic...ouch-50-displa


Regards,

[T1 Terry]

Yes, worth reading through the Victron PDF regarding the Pylontech to Victron working together. As far as I read it, Pylontech sort of over stated the Victron compatibility and seems to be using the Victron good name as a supporting endorsement, where Victron seem to be saying they have developed a way for their system to communicated some of the information from the Pylontech BMS.
I couldn't see where the Victron products actually took over the battery charging, balancing, disconnections etc, it really just seemed to show that it could read each one of these functions occurring, no matter if it was good or not for the battery itself .....

T1 Terry

[PaulCrawhorn]

When a battery has systems interconnects to the outside world

or even simply access to the per-cell/group voltages to monitor the balancing process

IMO for clarity in discussion here they should not be called Drop-Ins anymore; the Lithionics, Victron etc units certainly have never been included under that rubric.

These aspects are major failings of drop-ins (among others) and such improvements do materially change the advisability of using them for House banks

I suppose there could be a "dumb dropin" vs more intelligent dropins, but

"packaged system" batteries IMO is best

[hjohnson]

Doesn’t look like Wakespeed has a configuration file directly for pylontech. They’ve been recently acquired by firefly technology and the new website is annoying.

Anyhow, I’m running a WS500/REC-BMS/Victron setup. The important thing to know is that in this kind of a setup, the WS500 is being commanded directly by the BMS, rather than it being mediated by the victron setup. The WS500 then communicates its status to the victron via NMEA 2000 (over the same cable). The BMS protocol was not N2K.

[Harris Marine]

Yes Wakespeed support has gone down the gurgler since Battlebjorn bought them. Rick was much more helpful. Now they take ages to answer (if at all) and only give half assed answers.

I actually asked them the same thing regarding integration with Pylontech and they said it probably would work but they can’t guarantee it.

Worst case scenario you could always connect the dry contact to the feature in wire.

No idea about the pre-alarm function though, I guess your concerned about the upcoming ABYC and ISO regs.

[rgleason]

I just saw the battery and thought it was interesting because it supports Canbus.
I think these should be called drop-ins with external communication.


Thanks Terry and hjohnson good points.

[Harris Marine]

Well by definition a drop in battery is one without any external communication (apart from maybe blue tooth).

I think the RT12100G can safely be called non drop in.

[T1 Terry]

Originally Posted by Harris Marine

Well by definition a drop in battery is one without any external communication (apart from maybe blue tooth).

I think the RT12100G can safely be called non drop in.

Hmmm.... once you start adding bluetooth, all sorts of things are possible, especially if the signals are two way. Then individual batteries can be monitored and controlled via a central BMS that can also control both charging and load currents .... but then the whole simplicity appeal of the drop in battery is lost.
The fact that a battery has CANBUS communication doesn't sort the problems that we often deal with when sorting other companies conversion failures.

A simple thing like an inverter being powered up can take out a BMS that is relying on Mosfets to do the load control, that first inrush current is way beyond any perceived load current because it has to charge the capacitors ... so then a precharge circuit needs to be added and that controlled and .... there goes the drop in simplicity and just because it has canbus communication won't sort those sort of problems. This is why Victron say they want to only work with the 48v Pylontech batteries, the inrush current is less that 1/4 of that seen in a 12v system.

In reality, a single drop in battery will work fine for a few lights, once you start to link additional batteries in parallel and/or add capacitive or inductive loads, or both, things get way beyond simple BMS control because the DC current suddenly becomes a rippled current requiring more capacitors to smooth it so it doesn't destroy the Mosfets and that adds more inrush current problems ......

T1 Terry

[rgleason]

Originally Posted by T1 Terry

The fact that a battery has CANBUS communication doesn't sort the problems that we often deal with when sorting other companies conversion failures.

A simple thing like an inverter being powered up can take out a BMS that is relying on Mosfets to do the load control, that first inrush current is way beyond any perceived load current because it has to charge the capacitors ... so then a precharge circuit needs to be added and that controlled and .... there goes the drop in simplicity and just because it has canbus communication won't sort those sort of problems.

T1 Terry

These kinds of good points get lost on most cruisers. Every system is somewhat different, but we need to have some good reference diagrams for various specific examples of use, to help people understand. This kind of big picture education is essential.

For Example

1. In our case, the boat is on a mooring, we generally anchor, and almost never are at dock with power, and we don't use 120vac equipment, so what is the use of a victron multipass inverter which we have little space for anyway?
2. That simplifies the system and we don't need a precharge circuit.
3. We could use a good permanent 120vac charger if I could find the space to mount it, but it wouldn't see much use.
4. What we need more is a good 120vac service setup with isolation. There is no, or totally minimal, 120vac panel in the boat. Goboatingnow has provided an inexpensive way of doing that and it is going to have to be in the port cockpit locker in a WP box.

It is a simple system, but actually not that simple, there are pitfalls and unknowns. That is the reason cruisers need to have some guides. Every case and boat is different.

So they think LFP is the answer and guickly identify LFP dropins as the answer, which is not necessarily a good idea and could lead to some bad failures if not properly done.

[T1 Terry]

I think part of the problem we are seeing is multiple inverters in parallel. This wasn't really a thing in the past, inverters were much smaller output and switch off as soon as they were no longer needed, the batteries back then just couldn't handle the constant load, not necessarily because of capacity, but more because of the slower recharging ability.
Once quality lithium systems hit the scene, the inverters got bigger, more solar and a lot more 240vac appliances where extra low voltage appliances (12v or 24v) were used in the past. A much bigger inverter household fridge and freezer, even pigeon pairs in the bigger rigs, full electric galley, hot water and air conditioning. Now the single inverter wasn't enough to run more than one high draw appliance at a time .... we now have systems with 3 inverters in parallel, 15kW continuous output and up to 30kW surge load that can be accessed for around 10 mins without any of the inverters tripping out.
Once the inverter/s are powered up and only the on/off of the inverters is used, there is no inrush current, but if the system has battery isolation contactors or the BMS uses Mosfets to isolate the load, then the inrush current is only limited by the size of the cabling and the ability of the battery to supply instant high current.
This is where lithium batteries add a problem that lead acid batteries did not. Lithium batteries can supply huge instant current, 20C or more, 800Ah x 20C = 16000 amps, so the cable or the fuse becomes the limiting factor .... A 300 amp maxi fuse can handle a 300% overload very short term, 900 amps really puts a strain across the faces of contactors and Mosfets just aren't in the hunt because they by nature limit current and this generates heat that just can't be moved quick enough ..... if it open circuits then things just don't turn on, but if the punch through, then there is no turning them off, just like a welded contactor.

Basically what i'm saying is, if a contactor that is rated for 350 amp continuous welds closed due to inrush current on a single 3,000w inverter, a BMS rated for 500 amps is not going to handle the inrush current if it is using a Mosfet to do the load switching ...... so be aware if you are using drop in batteries, the BMS inside the battery might fail open circuit and then you'll know straight away, but if it punches through, there is nothing protecting that battery from being dragged down to destructively low voltage ..... if the other batteries in parallel drop out due to low voltage, the ones with the punched through Mosfets will still be feeding power until they are destroyed ..... when the charging resumes and the batteries that drop out reconnect to the load, they are going to try to recharge the destroyed batteries that have had cells suffer reverse current flow ..... the end result is a full set of dead batteries in parallel.

The fix is to add a precharge circuit before the inverter, one for each if needed, this will stop the inrush current destroying the Mosfets in the drop in batteries.

T1 Terry

[rgleason]

What wonderful description! Kind of gruesome results, buyers of dropins beware if you have an inverter, same goes for anyone with a reasonable sized inverter and LFP