270ah DIY LiFePO4 build

[Kelpie]

If you can avoid any high current loads then you can get a cheap FET based BMS and have a simple system. Lots of people use Daly or JBD successfully. I went for a 120A JBD myself.
If you are feeling a bit braver Electrodacus is interesting, not expensive but not an out of the box solution.

If you decide to go with induction cooking then that kind of changes everything. Normal domestic loads are <50A but an induction hob will be 200A+ and IMHO at that point a cheap FET based BMS no longer makes sense (and is no longer cheap, if you want to have a bit of margin).

My answer is to use an inverter which has a remote low current on/off switch, and use the BMS to trigger that using a £5 relay.

As I've said too many times now, it's still a work in progress, will report back when it's all assembled!

 

[sailaboutvic]

Yes I have 8 x EVE 280ah in a 2p 4s 560ah house bank using a REC ABMS which has been in and operational since March need to finish off the video series. It's so much quicker to just do stuff than trying to film as well.

I have also just installed 2 Wakespeed WS500 regulators which are connected to the victron VE CAN bus as well as the BMS so a lot to film and update every one on.

This new battery is a bit of a science project to see is I can get rid of our 2 110ah lead acid start batteries with this one nicer lighter package and if it performs well I might get the smaller 60ah version for the bow thruster too.

Neil you may be interested to know a few days back my LA engine die , so as a temporary measure I wired a isolation switch to my Lithium leaving the LA in place , it worked fine till I could replace the LA battery

 

[gregcope]

If you can avoid any high current loads then you can get a cheap FET based BMS and have a simple system. Lots of people use Daly or JBD successfully. I went for a 120A JBD myself.
If you are feeling a bit braver Electrodacus is interesting, not expensive but not an out of the box solution.

If you decide to go with induction cooking then that kind of changes everything. Normal domestic loads are <50A but an induction hob will be 200A+ and IMHO at that point a cheap FET based BMS no longer makes sense (and is no longer cheap, if you want to have a bit of margin).

My answer is to use an inverter which has a remote low current on/off switch, and use the BMS to trigger that using a £5 relay.

As I've said too many times now, it's still a work in progress, will report back when it's all assembled!

Can you expand on you design?

I am assuming you have two battery outputs. One from a FET based BMS that does all the cell management as well.

Another output tied to the above that connected to a relay (which one) for big loads. I assume the relay is powered/switched from the output of the other BMS so that when the FET BMS switches off the relay goes off too?

Would love to see a circuit diagram and a parts list if you could!

 

[vas]

dont have to be v.complicated (if I got Kelpie's concept right)
say a decent inverter (mine is a Victron Multiplus 24/3000VA) can be turned on and off from a simple relay (bearing no load, just closing a circuit to trigger the thing on).
So your BMS can run the small/largish DC loads directly, and if SOC/etc are fine, a simple circuit triggers the Inverter ON to run say cooker/watermaker/whatnot. If things turn sour (over/under charge or whatever else) BMS turns off the inveter so batteries are safe.

Things only get complicated if that inverter is also a charger which will be (occasionally with enough solar) used to charge the bank. Then we have a problem that also has to be addressed in a slightly different matter I guess using VSR on the 230V input side
I'll have to design this for my installation at some point during the winter.

cheers

V.

 

[vas]

along the same lines, anywhere I can get a quick comparison or comments on the BMSs below:

• LLT Power BMS
• Jiabaida JDB BMS
• Overkill Solar BMS
• Smart Daly BMS

they are all supported by the work done by Louis van der Walt on a VenusOS (Victron open source) driver enabling serial comms with the above. More here:
Home · Louisvdw/dbus-serialbattery Wiki

cheers

 

[Kelpie]

The system design (as yet not assembled!) had everything going through the 120A LLT BMS, except for the inverter, which runs directly off the battery. However the inverter has a simple on/off switch which sees very little current, and in series with this a small SSR will turn off the inverter off the BMS goes offline for any reason.

It's not particularly clever, and it will probably need manual intervention to reset. I don't think it would work with an inverter-charger, and might not be suitable if I wanted to have the inverter running all the time. But I think it will work well for my needs and should be very cost effective.

 

[Poey50]

Just a note on start batteries. Horses for courses but I can't think of anything more suitable for my system (and 29hp engine) than my Red Flash 1100 AGM. The high CCA in a small sealed package is perfect for me and should be long-lasting as it has an easy life. I keep it permanently on float via a Victron Orion B2B. The great thing about lead acid is the ability to take some abuse. I think, for example, it might have more chance of surviving a lightning strike. But I do have the wiring and switching in place to be able to start the engine with my LFP pack.

 

[gregcope]

@Poey50 i was thinking of going for something similar and having the alternator charge that whilst a victron b2b charges the Lifepo4 pack.

 

[Poey50]

@Poey50 i was thinking of going for something similar and having the alternator charge that whilst a victron b2b charges the Lifepo4 pack.

Yes, that's a common set-up for those who don't require direct alternator charging of the LFP.

 

[Pete7]

@Poey50 i was thinking of going for something similar and having the alternator charge that whilst a victron b2b charges the Lifepo4 pack.

Yes, but do watch the temperature the Victron DC>DC runs at, after all there are big cooling fins on the back for a reason. I have seen some installing them under bunks on YT, but when I measured mine under the chart table with a 4" hole behind it to increase circulation it still went to 59c. So they want lots of cool air flow. We don't use it much as solar does most of the charging. Nice to see 18A of solar out of a max of 20A going into the LFP even at 99% full. That is way better than we could achieve with FLAs.

Pete

 

[nfluester]

Victron Orion TR smart 30A DC - DC gets hotter than the surface of the sun in about 10 mins and then thermal throttles to about 20 amps for the rest of the charge cycle. to save cost and complexity i just run the mains shore charger through the inverter when under way to maintain the engine start and thruster battery the inefficiencies of going through the inverter seem minimal and it saves on extra chargers

 

[gregcope]

Good info, thanks.

Would a 12V computer fan help?

 

[Pete7]

Good info, thanks.

Would a 12V computer fan help?

Yes, that's on the cards and an easy fix with a switch alongside the DC>DC charger.

Scary to think what the temperature would be under a bunk and out of sight though.

Pete

 

[Kelpie]

Interesting discussion about heat output. I was originally going to put all my new gear- the battery, the inverter, and the MPPTs, into the same locker. Would certainly make wiring easier, and the locker I want to use is the perfect size.
But maybe I should move the MPPTs to a different location? I guess cooling is more important than length of wiring runs?

 

[gregcope]

Is Shenzhen Xuba Electronic Trading Co., Ltd still the place for 280Ah cells from alibaba?

Anyone got any contacts?

Was up and down in the night due to the low battery volts alarm… so now is the time…

Also, any known good Daly BMS models for a 4S 12V pack?

 

[Pete7]

Interesting discussion about heat output. I was originally going to put all my new gear- the battery, the inverter, and the MPPTs, into the same locker. Would certainly make wiring easier, and the locker I want to use is the perfect size.
But maybe I should move the MPPTs to a different location? I guess cooling is more important than length of wiring runs?

My Victron 100/20 with 300w of solar runs much cooler than the Victron DC>DC charger. If we have a nice sunny day so the MPPT is working hard I will see if I can get a temperature reading. Its currently mounted under the saloon seats so reasonably cool.

 

[gregcope]

along the same lines, anywhere I can get a quick comparison or comments on the BMSs below:

• LLT Power BMS
• Jiabaida JDB BMS
• Overkill Solar BMS
• Smart Daly BMS

they are all supported by the work done by Louis van der Walt on a VenusOS (Victron open source) driver enabling serial comms with the above. More here:
Home · Louisvdw/dbus-serialbattery Wiki

cheers

@vas did you get anywhere?

I am looking at similar 120a FET based BMSs'. Overkill is a preference as the others have confusing product selection (ie Lifepo4, USB UART and Bluetooth IOS app) as well as large cables.

I am not doing induction and/or anything else that requires large loads either draw or charge. Water pump, fridge, nav instruments and auto pilot; Which collectively come to around 15A if I run them all at once. Charge side is 20a of solar (as if in the UK!) and 30a from a planned Victron B2B. Peak I have seen go into the batteries is 45a which was probably output limited.

I am chatting to Wab Amy from Shenzhen Luyuan Technology Co which seem to have good feedback on DIYSolarForum. Am looking at 280Ah or 304Ah cells.

 

[vas]

not yet greg, I'm still at planning stage, had a day off and studied a bit more when I posted that originally, I'll start looking at them more carefully when back home next week. My main point is that I want to pass some of the protection from the BMS via the VictronOS raspberry to the MPPT and Multiplus. Hence searching for the most configurable BMS - the ones listed are supported by some opensource s/w written by a guy in the Victron board.
Mind, not in the UK, want to buy kit from an EU reseller (or someone that can convince me that I wont have to be more tax again!) so I don't get an unknown sting from our local customs (who are known to charge whatever they feel like...)

Also looking for 8X280Ah preferably cells, but don't want to pay a lot. Last time I checked seems that the best VFM is in 280cells ali clad not plastic.

cheers

V.

 

[gregcope]

@vas i would check the Diysolar forums as some suppliers are better than others…

i assume you mean the blue plastic covered ali cells made by companies like Eve as opposed to the yellow winston corrugated plastic cells.

i am probably goingto order from Amy / Luyan as although a bit more expensive than the cheapest the cells are matched. She can also supply a box.

 

[vas]

yep, blue plasticy covered ones that need careful isolation one another and making sure they dont live/float on a wet patch...
got a link for amy/luyan? No need for a box, will do my own for 24V

cheers

V