Low Budget Lifepo4 Experiences anyone?

[Franziska]

Thanks.

While 840Ah is a beast, we have this to run smallish loads nonstop (especially my power hungry CGI work computer & monitor, and no, a standart laptop does not suffice) occasionally over extended periods, not to run high Amp stuff at once.

We plan to use a 1000w or at most a 1500w inverter.

We have no intentions to cook electric, neither to run an AC, washing machine or similar.

I agree that big inverters may need a different BMS, but we do not intend to use big inverters.

Apart from that I try to cancel the 3 BMS. If we succeed we'll get a different one. If not we'll probably stick to what we have.
I know of at least one other boat who uses the same one without problems with one of those cell blocks we have on order.

[wholybee]

Originally Posted by CaptainRivet

...No idea why you chosen this one. A good,tested and reliable budget BMS are Daly.At ebayKleinanzeigen you can find a guy selling them from German stock, I would get the 250A one, it’s 250Euro. Running electronics on its limit shortens life and the 250A has enough room/safety margin.
...

It is actually a great BMS.

The JBD BMS (sold under various brand names) is very well regarded and considered to be underrated. They will work with several hundred amps of current-well over the rating, and will successfully disconnect and survive direct shorts.

One US distributor of the JBD BMS (Overkill Solar) has a "Whatever you did to break it, I will replace it" warranty. They claim that in testing they did manage to break one, but only repeatedly subjecting it to direct shorts.

[wholybee]

Originally Posted by CaptainRivet

I tested this config with 8x 272AH Lishen cells configured in 4 series packs and 2 Cheap BMS, the higher the load the more the 2 BMS interfered and cell voltages drifted apart. Also during charge and even drifted further apart then with no BMS and just a Victron BMV712 to cut for LV/ HV cutoff connected. Also you couldn‘t charge it to 100%Soc as 2 cells were too high and BMS cut charging, guess which cell = yes the last cell which sees the most load.Cells were properly top balanced before. There is also a video on YouTube where a guy tested his 8 cells 280AH eve and got exactly the problems described here, he just didn‘t now the origin of his issues...
Maybe I find it and will post.

I can show you dozen of similar looking BMS on Alixxxx but they have nothing in common with the overkill one, so does this one

A reliable, tested budget BMS are Daly which you can get up to 500A.
Will Prose tested the 272AH Lishen with a 250A Daly BMS and this pulled even 292A without an issue when he run it with a 3500W inverter and bat was near cutoff, so voltage down Amps raised.
If you are not an expert and especially if you want to do a budget build, I suggest get proven combos of equipment and don‘t play the genipig. Crap doesn‘t get better when you parallel it...
840AH lifepo4 is a beast, see posting above...

BMS's will not "interfere" with each other. Until a parameter is exceeded, they are completely passive and have no effect that will cause cells to go out of balance.

And if you have 4 cells in series, the cell "closer" does not get more charge.

What DOES happen, is that cells will charge at a rate determined in part by their internal resistance. This is why they need to be "matched" cells (all having the same IR), and one of the risks buying cells from Alixxx. If you have active balancers, this shouldn't be an issue.

Also, if you setup as 3p4s, then the IR of the 3p cells will "average" (1/IR1 + 1/IR2 + 1/IR3) and bring the IR closer together. So if the cells are not matched, a 3p4s setup will help that. That is most likely what you experienced. You have badly unmatched cells, and 3p4s keeps them in balance.

And, if using a 4s3p setup with 3 BMS's, you still need to wire them properly to keep the 3 batteries balanced to each other, just like if you were wiring 3 AGM batteries. If they did eventually go out of balance, simply charging them until all 3 BMS's cut out at full charge would bring them in balance again.

Franziska's plan is fine, even if it isn't what everyone else would do.

Overkills BMS is made by JBD in China. Just as there are lots of similar and inferior clones of it, there are also identical BMS's made by JBD sold under different brands.

[CaptainRivet]

Originally Posted by wholybee

It is actually a great BMS.

The JBD BMS (sold under various brand names) is very well regarded and considered to be underrated. They will work with several hundred amps of current-well over the rating, and will successfully disconnect and survive direct shorts.

One US distributor of the JBD BMS (Overkill Solar) has a "Whatever you did to break it, I will replace it" warranty. They claim that in testing they did manage to break one, but only repeatedly subjecting it to direct shorts.

The overkill is a great one, true. That’s why it’s sold out...
But how do you know the posted one is the same...look is definitely not enough.

@franziska: it’s a beast and your install needs to be able to cope with the beast even if you only run low loads. If a short circuit happens it doesn‘t ask if you design it for low loads
And also a lessons learned for me..you will go up with the inverter size over time, why because you can 220V household stuff is much cheaper then 12V marine stuff and for gas usage too (eg tea cattle)...your bank can handle it easily and you can get a 3500W inverter for 350Euro so money saved at the end. And a 3500W one can handle 2700 with 40 degrees in Caribbean suggest to get a small high spec inverter like Victron (eg used one to save) for your computer stuff and a big cheap one for the rest.
Well that’s how I will do it too, I got a Victron 500W and 2 big cheap one with 6,5kw running on Max 4kw to do induction cooking (gas stove as backup and for bbq on the reeling)and washing machine

[Franziska]

He guys, horray, now we can discuss the BMS again :-)
Just received confirmation that the 3 BMS got canceled and that we get a full refund.
They had not left the factory.

So, while we stick to the rest of the equipment (MPPT, Auto balancer, Cells, ...), which specific BMS model (and how many) should we get at last for our system?
Recommendation?

http://www.electrodacus.com/?
Dale?

We are on a budget, and prefer a simple reliable system with little need for tregular adjustments.

[CaptainRivet]

Originally Posted by wholybee

BMS's will not "interfere" with each other. Until a parameter is exceeded, they are completely passive and have no effect that will cause cells to go out of balance.

And if you have 4 cells in series, the cell "closer" does not get more charge.

What DOES happen, is that cells will charge at a rate determined in part by their internal resistance. This is why they need to be "matched" cells (all having the same IR), and one of the risks buying cells from Alixxx. If you have active balancers, this shouldn't be an issue.

Also, if you setup as 3p4s, then the IR of the 3p cells will "average" (1/IR1 + 1/IR2 + 1/IR3) and bring the IR closer together. So if the cells are not matched, a 3p4s setup will help that. That is most likely what you experienced. You have badly unmatched cells, and 3p4s keeps them in balance.

And, if using a 4s3p setup with 3 BMS's, you still need to wire them properly to keep the 3 batteries balanced to each other, just like if you were wiring 3 AGM batteries. If they did eventually go out of balance, simply charging them until all 3 BMS's cut out at full charge would bring them in balance again.

Franziska's plan is fine, even if it isn't what everyone else would do.

Overkills BMS is made by JBD in China. Just as there are lots of similar and inferior clones of it, there are also identical BMS's made by JBD sold under different brands.

Hi Warren,

I have garunteed Grade A cells directly from the factory,matching IR and each 12 cell pack matched and already top balanced delivered. Ordered via a group buy from factory directly and paid 150Euro per cell... Buying cheap here is buying crap. Its still low budget for a lifepo...
All correct what you writing regarding unmatched grade b cells and what happen here.
So what you described doesn't match here, as mine are grade A and match and i get perfect balance and 100%Soc running 2 4cell packs without BMS, with 2 BMS on each one the described interference happens.
The test i have done with and without BMS and i can confirm the BMS interfere, how i cannot explain but they do.

If you have badly unmatched cell don't charge them like this with a balancer. Dismount them and put all in parallel for 24 or better 48h and let them sit. Them top balance them with a 3.6V charger till they all reach 3.6V, again wait 24h then dismantle and put them back like you had them before...

[CaptainRivet]

Originally Posted by Franziska

He guys, horray, now we can discuss the BMS again :-)
Just received confirmation that the 3 BMS got canceled and that we get a full refund.
They had not left the factory.

So, while we stick to the rest of the equipment (MPPT, Auto balancer, Cells, ...), which specific BMS model (and how many) should we get at last for our system?
Recommendation?

ElectroDacus
Dale?

We are on a budget, and prefer a simple reliable system with little need for tregular adjustments.

Electrodadacus looks good, what do they cost?

Proven, no nonsense and relaible are Daly.
If you need fast order via germany, if you have time cheaper aliexpress.
I would recommend to use a big BMS here min 250A and count with a 3000W inverter Savings are small and going small here will bite you in the ass later.

Simple without Bluetooth : chosse 4S 250A for 123Euro,the sweet spot.
€ 9,13 17%OFF | Daly bms 10S 36V 3S-24S Li-Ion LiFePO4 4S 7S 8S 12S 13S 14S 16S 20S 15A 20A 40A 60A 100A 200A 300A BMS For Lithium Battery Pack
https://a.aliexpress.com/_m0St9lf

With BT:choose 4s 12V BT and 250A is 168Euro
€ 33,75 17%OFF | Daly Smart BMS 3S-24S Li-Ion LiFePo4 With Bluetooth 4S 7S 8S 12S 13S 14S 15S 16S 17S 20S For Lithium Battery Pack
https://a.aliexpress.com/_m0DvYPJ

I have the 500A BT. why, simple its 323Euro so its just 180Euro more and this is the max load the 840AH pack can deliver long term, longlivety and i can start my 50Hp diesels while everything is running without the BMS cutting off if starter is dead. With outboards you don't need that, 250A is perfect fit.

Which solar panels did you get? This is your main power source... Highly recommend LG or Candian Solar Bifacial panels as they will be high up on davits or roof i assume. The difference with bifacials LG or Candian solar in low light and shading conditions is enormous plus backside delivering a 3rd of the rated WP extra which is rhe difference still have full batteries in the eve during a cloudy week via running the gen every 2-3rd day waisting money and having noise... I speak from experience. Have LG now and on the cat it will be candian solar as panel size fits better.

[newhaul]

Originally Posted by Franziska

He guys, horray, now we can discuss the BMS again :-)
Just received confirmation that the 3 BMS got canceled and that we get a full refund.
They had not left the factory.

So, while we stick to the rest of the equipment (MPPT, Auto balancer, Cells, ...), which specific BMS model (and how many) should we get at last for our system?
Recommendation?

ElectroDacus
Dale?

We are on a budget, and prefer a simple reliable system with little need for tregular adjustments.

Well then we are back to needing a good bms. Get the 200amp or the 250amp Daly.
They will be able to handle any power draws you may want in the future.
Myself I am running the 200amp 1p4s unit and it feeds my trace 2500w inverter without any issues .

[Franziska]

Three or one of the 250A :-)?

Originally Posted by newhaul

Well then we are back to needing a good bms. Get the 200amp or the 250amp Daly.
They will be able to handle any power draws you may want in the future.
Myself I am running the 200amp 1p4s unit and it feeds my trace 2500w inverter without any issues .

[newhaul]

Originally Posted by Franziska

Three or one of the 250A :-)?

Personally I would go with a single bank and one 250amp Daly
In a 3p4s configuration.

[Franziska]

Thank you!

A 250A Daly BMS with Bluetooth it is then.
Cells will form one big block.

We have those three auto load balancers (thankfully not expensive). Guess we need one of those than instead of three.
Any thoughts how I wire that up with one big block then?

Before it was three balancers with connections for 4 cells on each....

[newhaul]

Originally Posted by Franziska

Thank you!

A 250A Daly BMS with Bluetooth it is then.
Cells will form one big block.

We have those three auto load balancers (thankfully not expensive). Guess we need one of those than instead of three.
Any thoughts how I wire that up with one big block then?

Before it was three balancers with connections for 4 cells on each....

Technically you still will only have 4 cells so wire up just the same as you would in a 1p4s

[CaptainRivet]

Originally Posted by Franziska

Thank you!

A 250A Daly BMS with Bluetooth it is then.
Cells will form one big block.

We have those three auto load balancers (thankfully not expensive). Guess we need one of those than instead of three.
Any thoughts how I wire that up with one big block then?

Before it was three balancers with connections for 4 cells on each....

One balancer and one cable per 3p block, similar to the BMS cell cables.
With Daly be super carefull that you connect the battery cables 1-4 in the right order. Check 3 times before connecting. If you mix this up and connect this wrongly you instantly kill the BMS. This is the pitfall of the budget Daly BMS. Other then this its super robust. Right choice

[more]

Originally Posted by Franziska

He guys, horray, now we can discuss the BMS again :-)
Just received confirmation that the 3 BMS got canceled and that we get a full refund.
They had not left the factory.

So, while we stick to the rest of the equipment (MPPT, Auto balancer, Cells, ...), which specific BMS model (and how many) should we get at last for our system?
Recommendation?

ElectroDacus
Dale?

We are on a budget, and prefer a simple reliable system with little need for tregular adjustments.

electrdacus is good but for more experienced user and you need protect with epoxy.


for you best simple BMS is Dally over 150A
don't look out Amperage look charging amp
Dally bms 150A charge 75A
Dally BMS 200A charge 100A
Dally BMS 250A charge 125A
Dally BMS 300A charge 150A

https://www.aliexpress.com/item/1005...639b412dWvYnrs

and I have JBD BMS this is totally **** and doesn't work anything,hi maybe protect battery 11 when a battery is on 0%

Dally don't have a temperature probe that works well. must be careful in winter

[more]

Originally Posted by Franziska

Thank you!

A 250A Daly BMS with Bluetooth it is then.
Cells will form one big block.

We have those three auto load balancers (thankfully not expensive). Guess we need one of those than instead of three.
Any thoughts how I wire that up with one big block then?

Before it was three balancers with connections for 4 cells on each....

250A Daly BMS with Bluetooth or all SMART line is not good, avoid for a couple of years.
install 250A Daly BMS vulgaris. plug and play