Lithium 304Ah Build

[gregcope]

Great write up - thanks for taking the time and the links.

Your welcome. Hope people find it useful.

 

[Poey50]

Hi All

I thought I would document my Lithium build and share. This thread is inspired by Poey50’s thread. Thank you @Poey50!

Our sailing is coastal and we like nothing more than staying at anchor for days, exploring and relaxing. We had 250Ah of cheap Flooded Lead Acid house batteries and 360W of Solar, a usable capacity of 125Ah. If it is sunny we are self sufficient, just. Our main consumers are the fridge, charging iDevices add instruments & ram autohelm when sailing. Even with everything on we seem to only draw about 30A, mostly it is around 10A when sailing and 4A ish when just the fridge. Usual draw is around 30Ah per day. I wanted to increase capacity to cover grey days as well as more laptop use (WFB; Work From Boat!). I was going to add another 125Ah FLA.

I have been looking at Lithium for nearly two years as it seems to offer many advantages;

• More usable capacity (80-90%) compared to FLA (50%).
• Much better charging efficiency compared to FLA; 99% compared to 85%. Ie if you put 20A in, that is what the battery can give back. Compared to FLA that will only give back 16A.
• Low internal resistance that allows LifePo4 to accept lots of amps (ie 0.5C, or around 152A for 304Ah cells)
• Not having the 80%+ SOC drop in charge rate that FLAs have. This and the ones above effectively means any charging (like Solar) becomes much more effective.
• Much higher energy density (smaller and lighter than FLA); 250Ah of FLA is 56Kg, 304Ah of LifePo4 is 16Kg and half the volume.
• Much longer life (with care well over 10years+) compared to 6 years (ish) with FLA.
• Prices appear to be comparable, or cheaper for capacity over lifetime now.

Some disadvantages;

• Often higher initial cost.
• If going DIY risks of purchasing from dubious sellers.
• DIY assembly mistakes.
• Most charging and monitoring sources need review and reconfiguring or changing.
• Issues with Alternator and BMS disconnect.
• Battery complexity & reliability could be an issue.
• Cells are fragile and affected by temperature. For example charging below 0c will severely damage them. Along with over / under charging.
• Cell life is affected by warmth, even 45c affects life.

Nordkyndesign has a good comparison of pros/cons on this page. I would encourage anyone to understand the tradeoffs with Lithium. I remain unconvinced about “Drop in replacements” due to the fundamental differences. This is specifically around charging regimes that are aimed to keep FLA going whereas LifePo4 requires significantly different settings.

Things came to a head this year when one of our house 125Ah FLA cooked itself. I decided to go to LifePo4. There are various different decisions to make. Drop in replacement vs DIY; Which cells; Which Battery Management System (BMS); How to deal with the Alternator ; Charge profiles and where to get it all from.

Well done, Greg. Will open some popcorn and get reading ...

 

[Kelpie]

Good writeup, thanks for sharing.
Lots of commonality with my own project- JBD 120A BMS, similar cells (although mine are 271Ah Lishen). Same CV/CC PSU. Most of your parameters are the same as mine too which is reassuring.

I haven't followed the steps you detailed in measuring the resistance of busbars etc. Maybe I should have. I did recently do a fresh top balance and reassemble the pack, using copious contact cleaner. It's now staying within about 0.005v whereas beforehand it was reaching 0.2v imbalance under heavy discharge loads. Hopefully I won't have to rebalance every six months...

Good to see more of these projects coming to fruition. Mine worked out considerably cheaper than the deep cycle batteries I was originally going to buy. I'd like to build a second pack but prices seem to have gone up again... hmmm decisions, decisions!

 

[gregcope]

Well done, Greg. Will open some popcorn and get reading ...

Thanks. Hope no pop corn was spat out at it!

 

[Poey50]

Thanks. Hope no pop corn was spat out at it!

None at all! I enjoyed the write-up. I totally agree about the poor documention on many BMSs especially trying to match to suitable relays. Your BMS choice has exceptionally good documentation but I really wanted to separate charge and load circuits so went with the 123Smart which is also well supported. This also solved the problem of external relays since I paired that with the neat 123Smart bistable relays which have excellent documentation when integrating with the BMS. The 123SmartBMS does have it's downside however which is that the outer boards do draw a little more residual current so the pack can go out of balance a little faster than I like. Not a problem if charging to 95% about once per month - more of a problem over winter storage at mid-range state of charge as at present.

There is a faster method of top balancing with a modest capacity power supply which is to put the cells into a 4S pack, add the BMS and charge at 14 volts until the first cell reaches 3.65v high voltage disconnect and then put them in parallel to charge them all to 3.65v but that skips the ramping-up method that Rod Collins still seems to favour but many think unnecessary. It meant I could top balance in under 12 hours.

I very much liked the careful testing for resistance across the terminal connections and wish I had done the same.

Thanks for taking the trouble to present it so interestingly and look forward to hearing how it all works out longer term.

 

[vas]

This also solved the problem of external relays since I paired that with the neat 123Smart bistable relays which have excellent documentation when integrating with the BMS.

Poey, do you mean this:
123ELECTRIC BMS123 Smart - Dual Relay | shop.GWL.eu

are you aware of anything larger? like a 200A bistable relay @24V only found 1-2 and not got any info from anyone using them so reluctant to order yet

 

[Poey50]

Poey, do you mean this:
123ELECTRIC BMS123 Smart - Dual Relay | shop.GWL.eu

are you aware of anything larger? like a 200A bistable relay @24V only found 1-2 and not got any info from anyone using them so reluctant to order yet

That is the one, but sorry I haven't researched anything larger.

 

[gregcope]

Greg, how is one meant to measure the 300kgf clamping force?
I'm going to be using 4 M8 threaded rods, washers and nuts. I even have a torque wrench
now what?

Er I am not sure. I read around, watched lots of youtube and could really find an answer. That is why I clamped with my finest Lidl clamps (available this week in the UK btw) and use strong packing tape. I plan on redoing it as I need strong end plates. The 1.5mm Glass Fibre plates from ebay flex/bend a little when under tension.

I thought I shared the latest Datasheet I had which goes into how Eve clamp theirs. Let me know if you want it. Its a scanned PDF so quite large. My attempts to get the actual PDF version is proving futile...

 

[gregcope]

Good writeup, thanks for sharing.
Lots of commonality with my own project- JBD 120A BMS, similar cells (although mine are 271Ah Lishen). Same CV/CC PSU. Most of your parameters are the same as mine too which is reassuring.

I haven't followed the steps you detailed in measuring the resistance of busbars etc. Maybe I should have. I did recently do a fresh top balance and reassemble the pack, using copious contact cleaner. It's now staying within about 0.005v whereas beforehand it was reaching 0.2v imbalance under heavy discharge loads. Hopefully I won't have to rebalance every six months...

Good to see more of these projects coming to fruition. Mine worked out considerably cheaper than the deep cycle batteries I was originally going to buy. I'd like to build a second pack but prices seem to have gone up again... hmmm decisions, decisions!

@Kelpie your posts and others (again lots of youtube watching) suggested the JDB 120A as a good alternative so thank you for sharing. I have seen 0.2V of delta when at either end of the charge scale, aka at the "Knees".

Again you inspired me, as the astute will realise that this pack has not done a season yet. Its been cycle tested three times in the house

I went DIY as it was not much more than replacing my lead, well that is what I told myself. Also considerably cheaper than the cheapest packs. As I mention battle born and Victron look good, if more expensive. Most of the rest of my electrical kit is Victron.

 

[gregcope]

None at all! I enjoyed the write-up. I totally agree about the poor documention on many BMSs especially trying to match to suitable relays. Your BMS choice has exceptionally good documentation but I really wanted to separate charge and load circuits so went with the 123Smart which is also well supported. This also solved the problem of external relays since I paired that with the neat 123Smart bistable relays which have excellent documentation when integrating with the BMS. The 123SmartBMS does have it's downside however which is that the outer boards do draw a little more residual current so the pack can go out of balance a little faster than I like. Not a problem if charging to 95% about once per month - more of a problem over winter storage at mid-range state of charge as at present.

There is a faster method of top balancing with a modest capacity power supply which is to put the cells into a 4S pack, add the BMS and charge at 14 volts until the first cell reaches 3.65v high voltage disconnect and then put them in parallel to charge them all to 3.65v but that skips the ramping-up method that Rod Collins still seems to favour but many think unnecessary. It meant I could top balance in under 12 hours.

I very much liked the careful testing for resistance across the terminal connections and wish I had done the same.

Thanks for taking the trouble to present it so interestingly and look forward to hearing how it all works out longer term.

@Poey50 Thank you. You inspired it all!

I was aware of the faster method, but I was nervous about shorting something or breaking it so did it the slow way. It took ages.... like a week @10A as I switched it off during the day. I was also worried that the High Cell disconnect would work off the bat so timed it when I was around so that I could see it. I would recommend the way you suggest to say a long time.

The careful testing was inspired by Ray Builds Cool stuff - this video;

. I was luck to score a resistance meter on Amazon that was a return or something as it was "refurb" and nearly half price. A hole punch works well to create the holes btw.

 

[Poey50]

Poey, do you mean this:
123ELECTRIC BMS123 Smart - Dual Relay | shop.GWL.eu

are you aware of anything larger? like a 200A bistable relay @24V only found 1-2 and not got any info from anyone using them so reluctant to order yet

GWL offer these more powerful latching contactors in various sizes. They can handle up to 60 volts but it looks like the control voltage for latching is 12 volts.

AMETEK Magnetic Latching Contactor 12V, 600A (JEY4803AB00) | shop.GWL.eu

 

[Zing]

Poey, do you mean this:
123ELECTRIC BMS123 Smart - Dual Relay | shop.GWL.eu

are you aware of anything larger? like a 200A bistable relay @24V only found 1-2 and not got any info from anyone using them so reluctant to order yet

Check out this one:
https://www.bluesea.com/products/7702/ML-RBS_Remote_Battery_Switch_with_Manual_Control_-_24V_DC_500A

 

[Zing]

Which cells

I liked plastic encased Winston cells, however these are nearly double the cost of the Blue Ali-cased prismatic cells. I would go that route if slightly cheaper as the Winstons look robust and have a slightly different chemistry that allows charging at lower temperatures. I decided on Eve cells. I researched suppliers which is a bit of a minefield as there are lots of grey sellers on Aliexpress, Amazon, Ebay or Alibaba who are selling older, used or damaged cells repackaged, without any history. Lost of stories or videos about bloated cells or those that do not achieve capacity. Its a minefield!. After researching on Diysolarforum.com I decided to go with Amy from Luyuan on some new, balanced, matched cells with testing data.

During the ordering process I enquired about 300+Ah cells. These are the same size as 280Ah cells and only slightly more expensive. I decided to go with these 304Ah, the capacity report suggests they all have over 320Ah. Even if they do 304Ah, they should give 10% more capacity for the same physical size at less than 5% price difference.

How did you ship them. Air or sea? What did they cost to ship? Note that supplier in your link is quoting a price that will end up with nearly half the cost in shipping and clearance.

 

[vas]

How did you ship them. Air or sea? What did they cost to ship? Note that supplier in your link is quoting a price that will end up with nearly half the cost in shipping and clearance.

I think they don't ship them via air. Land/sea only. Mine took circa 40days from shipping in China to "appear" in dpd.com site as being in a European hub. Rest is less than a week. Note, no info on the first month which is slightly annoying.

I bought the exact same cells with greg (from the same person-he helped me ease the stress of buying from the unknown in the depths of China and I thank him for this!)
EVE 304Ah cells are 135usd each tax/shipping for 8 pieces to Greece was 270usd, so 1350USD total for 8cells and busbars.
I recon it's good VFM, the thing is the peripherals may add up to another that much depending on the approach. I'll post my Victron only full integration approach next week I recon when I have them all running

V.

 

[vas]

GWL offer these more powerful latching contactors in various sizes. They can handle up to 60 volts but it looks like the control voltage for latching is 12 volts.

AMETEK Magnetic Latching Contactor 12V, 600A (JEY4803AB00) | shop.GWL.eu

good find, thanks! looks substantial enough for my use.

also have this one bookmarked:
GVLH141CAX, 400A Latching DC Contactor

Check out this one:
https://www.bluesea.com/products/7702/ML-RBS_Remote_Battery_Switch_with_Manual_Control_-_24V_DC_500A

thanks I'm aware of that, wasn't particularly keen on the price tbh.

Main issue with both of these latching relays is that I have to rewrite the code for disconnect on the diyBMS I'm using (which is handy as it's opensource and you can do whatever you want!) and still not quite sure how I'm going to implement that and how states are sustained/monitored in real life use (or after a bms s/w crash or restart) will work on it

Whatever I buy must be (well preferably) from the EU so I avoid customs/delays/etc

cheers

V.

 

[gregcope]

How did you ship them. Air or sea? What did they cost to ship? Note that supplier in your link is quoting a price that will end up with nearly half the cost in shipping and clearance.

Similar to what @vas has said.

$135 per cell and $244 for shipping. Yes shipping is expensive. It is by sea or land. Like Vas I had few updates bar asking Amy and then got a text from DPD and delivery next day. Took around six weeks. I also ordered that Box from Amy.

 

[gregcope]

I bought the exact same cells with greg (from the same person-he helped me ease the stress of buying from the unknown in the depths of China and I thank him for this!)
EVE 304Ah cells are 135usd each tax/shipping for 8 pieces to Greece was 270usd, so 1350USD total for 8cells and busbars.
I recon it's good VFM, the thing is the peripherals may add up to another that much depending on the approach. I'll post my Victron only full integration approach next week I recon when I have them all running

It is quiet stress full ordering off Alibaba. I did quite a bit of research.

Ray has a good summary here:

His preferred supplier has a US distribution point which helps allot.

 

[gregcope]

I have a few updates ...

Flexible Bus bars

The supplied bus bar were copper, 2mm 1.5mm thick and 20mm wide. Which is reasonable, however as I wanted to push nearer 200A I wanted something thicker.

I thought about making my own out of copper bar or copper pipe. Bar was quite expensive and would need cutting as well as holes drilled, possibly oblong. Post / packing in the UK pushed the price even higher.

I then came across this video by LithiumSolar which recommended these flexible bus bars from Aliexpress. For my cells I needed the “L71.5mm + 300A” version. They arrived in a little over a week.

Fitting was seamless. They are remarkably flexible which I like as any movement in cells over time should mean no/little stress on the terminals. They are around 3mm thick so appreciably better and nicely overrated at 300A.

You will notice in my pictures that I kept one of the original bus bars that is chopped in two and each end has two M6 threaded holes tapped in for the BMS and Balancer leads.

 

[Poey50]

I have a few updates ...

Flexible Bus bars

The supplied bus bar were copper, 2mm 1.5mm thick and 20mm wide. Which is reasonable, however as I wanted to push nearer 200A I wanted something thicker.

I thought about making my own out of copper bar or copper pipe. Bar was quite expensive and would need cutting as well as holes drilled, possibly oblong. Post / packing in the UK pushed the price even higher.

I then came across this video by LithiumSolar which recommended these flexible bus bars from Aliexpress. For my cells I needed the “L71.5mm + 300A” version. They arrived in a little over a week.

Fitting was seamless. They are remarkably flexible which I like as any movement in cells over time should mean no/little stress on the terminals. They are around 3mm thick so appreciably better and nicely overrated at 300A.

You will notice in my pictures that I kept one of the original bus bars that is chopped in two and each end has two M6 threaded holes tapped in for the BMS and Balancer leads.

I bought a set after your previous post about them. They are perfect for the job and deserve to be the standard for DIY builds.

 

[vas]

interesting, btw Greg Amy's supplied busbars are 2.2mm thick (just measured them )

I agree that they are v.useful when you fit your cells in a box like you did and the only means of packing them is straps.
However, having checked how mine work with 20mm endplates clamped with 4 M8 bolts, I doubt they are really necessary on really secure setups.
Slightly worried on their temp under stress, saw on some video (don't think it was the one you mention above) some flex ones that were heating up, didn't like that. Have you checked them tempwise?
Further if you see how the battery is constructed (there are some videos of guys taking prismatic cells apart) it's obvious that there is a fair amount of give in both posts. I can see why there's a trend not to bother and not to clamp them.

What is indeed necessary is insulating the bus bars! got Φ14/7 thermoshrink tube to get them in.
Then also need to find rubber 10mm nut cups (for the M6 studs on the posts). I'll have a perspex cover on the whole thing, but would really like to make sure nothing is going to make a firework out of this battery bank!