DIY Battery Is Alive !!

[johnb2713]

Hi John where did you purchase your BMS from and which setup have you used model wise cheers

I contacted Seplos directly, I gave them the spec of the batteries and inverter, they suggested the right model of BMS and put me in direct contact with one their engineers for setup / wiring advice (none was needed).

The sales guy I dealt with: [email protected]

Great company, product works out of the box, I left all settings at default, it seems to be emulating Pylontech protocol.

 

[johnb2713]

This is different to Island mode, which is where I am getting confused, if I may ask what I am trying to achieve is cheaper electric bills from charging the batteries on my cheap overnight electric I get 4 hours at a greatly reduced rate over night, what is the best type of system if there is such a thing?

This is exactly what I do with this system. Octopus GO tariff, 00:30 to 04:30 off peak rate, fully charge the battery 14kWh and then it runs the house for the rest of the day. If it's a good day and the Solar PV is working, any excess energy from that is also fed into this battery rather than being exported to the grid.

 

[Ronski]

Nice system and nicely installed.

I really should put a build thread on here for my system which although taking a very long time is progressing well.

 

[johnb2713]

Nice system and nicely installed.

I really should put a build thread on here for my system which although taking a very long time is progressing well.

Mine took months for various reasons.

 

[Ronski]

Its all the learning, waiting for parts, then ordering suitable parts because the parts I got weren't suitable, it's all the smaller bits that take the time.

 

[johnb2713]

Its all the learning, waiting for parts, then ordering suitable parts because the parts I got weren't suitable, it's all the smaller bits that take the time.

Yup, thats a decent assessment.

 

[johnb2713]

I've had a slight niggle with my battery, it's been working fine but the batteries have very slowly gone out of balance by 150 mV between the highest and the lowest. The net result of this is apparent loss of capacity, during discharge the lowest voltage battery trips the BMS which switches the battery off from the inverter, during charging the highest voltage battery stops the charge when it hits maximum voltage.

The solution is this:-


This is a smart active balancer by NEEY. It can handle up to 24 cells and is easily configured by it's APP. It monitors all of cells and will balance them within preset voltages. It discharges the highest voltage cell and charges the lowest voltage cell until all of the cells are within 'x' mV of each other. My cells were 154mV between highest and lowest 90 minutes ago (charging from Solar ATM), I enabled the active balancer with a 4 amp balance current the cells are now 30mV between highest and lowest.

Installation was easy, setup straight forward and it seems to work very efficiently. Unlike many balancers, this unit will still do the full 4 amps with just the smallest of variations eg 5mV.

Available from Aliexpress circa £80 - bargain in my book.

 

[binky]

I've had a slight niggle with my battery, it's been working fine but the batteries have very slowly gone out of balance by 150 mV between the highest and the lowest. The net result of this is apparent loss of capacity, during discharge the lowest voltage battery trips the BMS which switches the battery off from the inverter, during charging the highest voltage battery stops the charge when it hits maximum voltage.

The solution is this:-
View attachment 15014

This is a smart active balancer by NEEY. It can handle up to 24 cells and is easily configured by it's APP. It monitors all of cells and will balance them within preset voltages. It discharges the highest voltage cell and charges the lowest voltage cell until all of the cells are within 'x' mV of each other. My cells were 154mV between highest and lowest 90 minutes ago (charging from Solar ATM), I enabled the active balancer with a 4 amp balance current the cells are now 30mV between highest and lowest.

Installation was easy, setup straight forward and it seems to work very efficiently. Unlike many balancers, this unit will still do the full 4 amps with just the smallest of variations eg 5mV.

Available from Aliexpress circa £80 - bargain in my book.

You wouldn't think 150mV would be enough to cause a problem .

So, your current BMS is possibly not up to the job? I have to say, I'm impressed how many gadgets you can buy for your self build battery.

 

[johnb2713]

You wouldn't think 150mV would be enough to cause a problem .

It wouldnt cause a problem because the BMS stops the charge / discharge within the limits for LifeP04.

So, your current BMS is possibly not up to the job?

It depends on what youre looking for, I hadnt realised it's balancing capability was relatively low. It's only capable of a few hundred milliamps of balance current on a 280a/h cell. Maybe I should have chosen more wisely, it is the first pack I'd built. Who knows how the balance of commercial packs is done and to what level, at least with this I KNOW the cell voltages and it's all under my control. Maybe ignorance is bliss

I have to say, I'm impressed how many gadgets you can buy for your self build battery.

Tools to do a job, not unlike optimisers for panels.

 

[Badger]

question john if you dont mind if there arev16 batteries connected in series thats 4400 ah total how do you get 14kwh from the battery build many thanks

 

[Badger]

solis inverter rai 3k 48es 5g - ac coupled inverter is what im installing will seplos work with this inverter

 

[johnb2713]

question john if you dont mind if there arev16 batteries connected in series thats 4400 ah total how do you get 14kwh from the battery build many thanks

3.2v x 280 ah = 14.336 kWh. It's actually closer to 15kWh because the terminal voltage of the packs is always 3.35 to 3.42 v

 

[johnb2713]

solis inverter rai 3k 48es 5g - ac coupled inverter is what im installing will seplos work with this inverter

It has 10 different emulations programmed in so I'm told, my Victron sees it as a Pylontech battery, it can see all of the pack temperatures and individual cell voltages as well as cumulative and SOC etc.

 

[Oldman22]

solis inverter rai 3k 48es 5g - ac coupled inverter is what im installing will seplos work with this inverter

I have this inverter, from another forum
Part of the Pylontech CANBus protocol is that the 8 character string "PYLON " (i.e. PYLON and 3 spaces) should be sent as CANBus message 0x35E.

The Solis will fail with the battery name error if the Solis is set to PYLONLV battery type and it does not receive this packet of data periodically.
So all is well if the emulation includes the msg, if not then you may need to select "user defined" from the list of batteries in the Solis menu.
Do keep us informed how you get on with the Solis RAI-3.0KW 48ES 5G AC Coupled Inverter.

 

[Badger]

Thank you, it's been a lot of work but very worthwhile and I've learned a lot on the journey.

just a thought im installing mins in the garage in a ventilated area that will be frost free can anyone see any issues installing the battery bank in the garage

 

[johnb2713]

just a thought im installing mins in the garage in a ventilated area that will be frost free can anyone see any issues installing the battery bank in the garage

Only winter temperature. Mine is in a tiny shed on the side of my house, I installed heater mats under the batteries which maintain a minimum temperature of 10 deg C, manufacturer of the cells recommends not charging at 0 deg C or less.

 

[Badger]

we have the heating pipes running up the wall behind the bateries and tge boiler in there aswell the heating pipes go to porch radiator

 

[Badger]

Only winter temperature. Mine is in a tiny shed on the side of my house, I installed heater mats under the batteries which maintain a minimum temperature of 10 deg C, manufacturer of the cells recommends not charging at 0 deg C or less.

have you got a picture of the batteries all setup under your inverter in place please

 

[johnb2713]

have you got a picture of the batteries all setup under your inverter in place please

Here are the piccys, the sunlight is blasting through the fence making bright stripes on the photo's, sorry!

Here's the shed, only a small gap to fit in to.



In the bottom half is the batteries, the cable mounted connectors with the singles are for the new active balancer, I have some flexible conduit to fit now that it's proved to work ok. You can see the heatmat under the batteries, they're meant for fish tanks and vivarium's.



Top section the inverter and BMS etc. To the RH side temperature controllers looking after heating for the batteries and ventillation for the inverter. DC isolator switch, DC fuse. Small CU for local supplies for lighting, heating , fans and inverter.


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