LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[john61ct]

CAN bus protocol does not specify the message format, just the lower-level comms signaling.

Using inexpensive microcontrollers you can reverse-engineer any manufacturer codes, and send/receive whatever you like, even "translating" between different "dialects".

From my notes:

STM32 microcontroller, aka Blue Pill
The $2 32-Bit Arduino (with Debugging) https://hackaday.com/2017/03/30/the-...ith-debugging/

https://youtu.be/EaZuKRSvwdo


CAN bus controller hardware is part of several STM32 families, including the F103 and the F407. In the low-end F103 range, it shares memory with the USB hardware, which means that USB and CAN cannot be enabled at the same time. This is somewhat unfortunate, since one of the things I’d like to do is create a bridge between the two.

Luckily, the STM32F407 series µCs do support both. In fact, these chips tend to have*multiple*CAN bus controllers. With a single controller, at most 14 filters can be supported, with two this number increases to 28
https://jeelabs.org/2018/canbus-intro/

USB based viewer
https://github.com/Catethysis/CAN-vi...ster/README.md

[Q Xopa]

Originally Posted by ReneJK

the BMS inside is this one (it will download the user manual)

https://www.google.com/search?rlz=1C...dUDCAY&uact=5#

all disconnect electronics are build into the battery but I would much rather have outside disconnects and was wondering if these CANbus batteries will talk to a Victron BMS 12/200 and Venus GX , who will then operate the outside protections , display SOC /DOD , currents and voltages



Fuses is a good idea
I was thinking Blue Sea ML-7700's that are operated by the Victron or internal BMS (ie bring the connect / disconnect for the charge and load to the outside)

I think you missed CNBs point he was trying to make. What he is suggesting is that the physical internal cells in those batteries is not known. This can matter. As in if it is a lot of small cells all paralleled then there can be potential issues, which wont be mitigated with an external disconnect.
CAN bus is a monitoring protocol not internal disconnects, ie fuses or relays which maybe required depending on the unknown internal cell configuration.
This is one of the issues many have with sealed drop ins.

[rgleason]

Sunbang 100ah LiFePo
SHENZHEN SUNBANG TECHNOLOGY CO.,LTD

[sparrowhawk1]

Originally Posted by rgleason

Sunbang 100ah LiFePo
SHENZHEN SUNBANG TECHNOLOGY CO.,LTD

Price? Thanks.
PS. Link is for 110ah

[ReneJK]

Originally Posted by sparrowhawk1

Price? Thanks.
PS. Link is for 110ah

i will let you know as soon as i get info

[newhaul]

Originally Posted by sparrowhawk1

Price? Thanks.
PS. Link is for 110ah

what size bank are you actually wanting I will ask about them . 200ah battery.

Message sent . Should know within the next 2 hours

[ReneJK]

Originally Posted by newhaul

what size bank are you actually wanting I will ask about them . 200ah battery.

Message sent . Should know within the next 2 hours

I am looking to built a 600Ah bank
I have a quote from RJ Lithium for 12 cells @ $120 per cell excl shipping and I was wondering if it could be done easier by taking the internal BMS controls from packs (ie 3x 200Ah) and bring those to the outside to do separate High voltage cutoff and low voltage cutoff

so ideally 3x 200Ah packs with an accessible BMS that supports this or where the Mfg prepares this , and I was kinda hoping the CANbus could do this as well making it even easier

[newhaul]

Originally Posted by ReneJK

I am looking to built a 600Ah bank
I have a quote from RJ Lithium for 12 cells @ $120 per cell excl shipping and I was wondering if it could be done easier by taking the internal BMS controls from packs (ie 3x 200Ah) and bring those to the outside to do separate High voltage cutoff and low voltage cutoff

so ideally 3x 200Ah packs with an accessible BMS that supports this or where the Mfg prepares this , and I was kinda hoping the CANbus could do this as well making it even easier

waiting on the price but we already know they are compatible electronically

[newhaul]

Originally Posted by newhaul

what size bank are you actually wanting I will ask about them . 200ah battery.

Message sent . Should know within the next 2 hours

ok just heard back and 698 per 200ah battery. I would assume plus shipping .

[newhaul]

Originally Posted by newhaul

ok just heard back and 698 per 200ah battery. I would assume plus shipping .

shipping is 688 air freight for 3 200ah batteries to make a 600ah bank
Or 438 by ship and land shipment 28 day lead .

[sparrowhawk1]

Originally Posted by ReneJK

i will let you know as soon as i get info

Thank you

[sparrowhawk1]

Originally Posted by newhaul

what size bank are you actually wanting I will ask about them . 200ah battery.

Message sent . Should know within the next 2 hours

Well my budget right now is $4to5 hundred. But I was willing to pay more than$700 for 180ah Winstons. Shipped.
But it didn't go through.

[sparrowhawk1]

Originally Posted by sparrowhawk1

Well my budget right now is $4to5 hundred. But I was willing to pay more than$700 for 180ah Winstons. Shipped.
But it didn't go through.

Also what made the deal attractive is it was 90ah cells which would have allowed me to use one bank for house and possibly one bank for an electric dinghy. Possibly Swapping them as needed or put in parallel if I found I needed more for my house.

[Skip JayR]

Just like to share an article I just read about latest research of Lithium-Ion batteries and alternative materials, e.g. Sodium. Sounds promising for me.

https://oilprice.com/Energy/Energy-G...Batteries.html

[JmanC]

Originally Posted by CatNewBee

What you measure is the voltage drop along the connection wiring.

I first measured voltage drop by placing DMM probes on battery terminals direct & then on output + & - studs of charger. That difference is what I called the Voltage drop. And all volt drop calculators give that number.

But doing it across one + lead gives around half the value. So which value is correct? Does my system have 0.08V drop or 0.04V? as an example

Originally Posted by CatNewBee

The balancers usually kick in at 3.55 to 3.6V cell voltage, they work then all the time,

They work all the time when charging.

What if you start using lower charge voltages like 13.8V? Will they still balance or do they need the higher 14.2V+?