To Daly or Not, that is the Question!

Stepandwolf

Solar Addict
Joined
Nov 14, 2020
Messages
620
I am building my first system. I bought 8 Lishens to build a 24V system and paired it with a 250A Daly. Before having built that system, I have decided to buy another 8 cells and will need a second BMS. Since I haven't used the Daly software, does it work well with two BMS's? I have been encouraged to go with something smaller, like an Overkill 100A BMS. I want to do what makes the most sense since I have not ordered the second BMS yet.

Logic says get another Daly, but if isn't the best choice, especially since I can go with something that has lower amperage.

Thanks
 

JohnTHQ

New Member
Joined
Jul 27, 2021
Messages
15
I am about to build a 24v 280ah battery myself. Ive been on the fence not sure if i want to get a chargery unit or a Daly.
 

Stepandwolf

Solar Addict
Joined
Nov 14, 2020
Messages
620
I am about to build a 24v 280ah battery myself. Ive been on the fence not sure if i want to get a chargery unit or a Daly.
Since getting my Daly (not used yet) I have heard complaints about the Daly, in particular the models with fans. Since I have a Daly, it still might make sense for me to get a second one.
 

williamsk913

Solar Enthusiast
Joined
Sep 27, 2019
Messages
97
I am building my first system. I bought 8 Lishens to build a 24V system and paired it with a 250A Daly. Before having built that system, I have decided to buy another 8 cells and will need a second BMS. Since I haven't used the Daly software, does it work well with two BMS's? I have been encouraged to go with something smaller, like an Overkill 100A BMS. I want to do what makes the most sense since I have not ordered the second BMS yet.

Logic says get another Daly, but if isn't the best choice, especially since I can go with something that has lower amperage.

Thanks
I took a different approach. I used two JBD BMSes (same as overkill) on one battery. Seems to split current fairly evenly. YYMV.
 

Lt.Dan

Photon Sorcerer
Joined
Dec 25, 2020
Messages
1,376
Location
Visalia, Ca
I have no complaints with my 48v 200a Daly. It even overperforms when charging. I haven't been able to hit the discharge limit though, even with an 8KW draw!
 

Stepandwolf

Solar Addict
Joined
Nov 14, 2020
Messages
620
Thanks to both of you for your replies. Think I will stick with a Daly for the second one but it won't need to be 250A like my first one. Probably get a 150A.
 

curiouscarbon

Science Penguin
Joined
Jun 29, 2020
Messages
2,132
have been using JBD 4S with no problems so far, easy to program. soon to begin work on my 24V bank with 8S JBD.

i read too many horror stories of people with high amp rated daly bms suddenly having it malfunction that i swore off the brand to protect myself from potential disappointing frustrating diagnosis.

afaik they work fine most of the time but when they stop working good luck..

i read that daly just bought licensing for the design for all their high amp BMS. they don’t design the big ones with fans in house afaik. that does not give me the confidence to use them.

absolutely no judgement towards anyone for using daly bms. i just have steered clear personally.

good luck with your projects and may you get 3000 cycles ☮️
 

plaidcabin

Solar Enthusiast
Joined
May 3, 2021
Messages
28
Daly have worked well for me, you must be very careful when setting it up. If your connections are wrong, you may damage the equipment.

If all the cells you purchased are identical: you may top balance them, and connect them in parallel pairs. Then connect the single bms, each pair looks like a single 3.2v cell to the bms, and the cell balancing will still take place but take slightly longer.
 

Puiumeu

Solar Enthusiast
Joined
Aug 5, 2021
Messages
26
I took a different approach. I used two JBD BMSes (same as overkill) on one battery. Seems to split current fairly evenly. YYMV.
Hi, please forgive the newb but how do you do this? I would like to get 200A plus from my pack but don't want to go daly.
 

Stepandwolf

Solar Addict
Joined
Nov 14, 2020
Messages
620
Daly have worked well for me, you must be very careful when setting it up. If your connections are wrong, you may damage the equipment.

If all the cells you purchased are identical: you may top balance them, and connect them in parallel pairs. Then connect the single bms, each pair looks like a single 3.2v cell to the bms, and the cell balancing will still take place but take slightly longer.
Understand I can do that, but seems a second BMS and pack might give me some fallback if the BMS fails, or perhaps a bad cell in one pack.
 

williamsk913

Solar Enthusiast
Joined
Sep 27, 2019
Messages
97
Hi, please forgive the newb but how do you do this? I would like to get 200A plus from my pack but don't want to go daly.
Essentially install as normal, but you have two BMSes connecting the same way/locations. Only downside is columbmeter is not be accurate for battery overall, just for what passes through that BMS. But the BMSes split it roughly equal, so you can always roughly times by two instead of adding up readings from both BMSes. Or just use a battery monitor.

Will Prowse did a video showing two cheap BMSes used this way. I know of a couple other people that have ran batteries with two overkill solar BMSes, no issues so far that I know of. One did eventually buy another 4cells and just steal additional BMS for the new battery, but mainly just because he is thrifty and wanted more ahs.
 

smoothJoey

Ding Ding!
Joined
Nov 30, 2019
Messages
11,798
Essentially install as normal, but you have two BMSes connecting the same way/locations. Only downside is columbmeter is not be accurate for battery overall, just for what passes through that BMS. But the BMSes split it roughly equal, so you can always roughly times by two instead of adding up readings from both BMSes. Or just use a battery monitor.

Will Prowse did a video showing two cheap BMSes used this way. I know of a couple other people that have ran batteries with two overkill solar BMSes, no issues so far that I know of. One did eventually buy another 4cells and just steal additional BMS for the new battery, but mainly just because he is thrifty and wanted more ahs.

If you run multiple bms on a single pack I suggest you disable balancing on one.

There is an alternate strategy.
If your inverter can be controlled by an solid state relay
and your pure dc loads are light
and your charge current is does not exceed the capacity of a single bms
you can control the BMS by an SSR and have its high current bypass the bms fets.

I can explain in more detail if you are interested.
 

Stepandwolf

Solar Addict
Joined
Nov 14, 2020
Messages
620
Hoping to add some clarity or at least be sure we are all in the same understanding. Seems words like battery, pack, and bank are used interchangeably but I was told for these purposes they aren't all the same, i.e. pack vs. bank.

I started this string asking about second BMS for a second pack/bank in that my 8S 250A Daly is for the first one, but since I am adding an additional 8S pack/bank, it would need it's own BMS since I don't want to wire the first BMS such that one lead goes to two cells. It seems this conversation morphed into putting two BMS's on one bank or pack.

In a search for the most concise terms I could find, I did a search and ended up at Samsung. They don't use the word "bank" at all. They show cells being combined to make a module, and modules combined with a BMS to make a pack.

Samsung

They only thing that came up when using the word "bank" was for power banks, and in fact, a search for battery packs ended up at banks.

It seems then that an 8S grouping of cells with a BMS per Samsung is a pack. If I have two sets of 8S cells each with a BMS, they would be packs and when combined make a battery?!?!?

Regardless of the terms that are used, the topic of this thread is two "sets" of cells, each with their own BMS vs. trying to put two BMS on a single set of cells.
 

williamsk913

Solar Enthusiast
Joined
Sep 27, 2019
Messages
97
If you run multiple bms on a single pack I suggest you disable balancing on one.

There is an alternate strategy.
If your inverter can be controlled by an solid state relay
and your pure dc loads are light
and your charge current is does not exceed the capacity of a single bms
you can control the BMS by an SSR and have its high current bypass the bms fets.

I can explain in more detail if you are interested.
It hasn't really had an issue with balancing, but I think 280ah cells are perhaps a lot larger than the BMSes were designed for initially. Charge current is fairly low at this point (hoping that'll change soon though, lol).

I am happy as is, but open to learning.
 

smoothJoey

Ding Ding!
Joined
Nov 30, 2019
Messages
11,798
It hasn't really had an issue with balancing, but I think 280ah cells are perhaps a lot larger than the BMSes were designed for initially. Charge current is fairly low at this point (hoping that'll change soon though, lol).

I am happy as is, but open to learning.
Apologies there were two thoughts in my post.
One bit about balancing and the other about an alternative strategy to get mondo current from your battery.
 

plaidcabin

Solar Enthusiast
Joined
May 3, 2021
Messages
28
Understand I can do that, but seems a second BMS and pack might give me some fallback if the BMS fails, or perhaps a bad cell in one pack.
Not saying that it is for sure the cause, but I did see trailer burn down to the ground today, and the likely culprit is the large LiFePo4 parallel series battery (with no BMS) that was charging when the fire started.
 

curiouscarbon

Science Penguin
Joined
Jun 29, 2020
Messages
2,132
Not saying that it is for sure the cause, but I did see trailer burn down to the ground today, and the likely culprit is the large LiFePo4 parallel series battery (with no BMS) that was charging when the fire started.
Are you ok?? Be sure to keep away from the fumes.
 
Top