Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley...

[CatNewBee]

So Hurricane season is approaching and we are in Amazon vincinity - some fancy projects pop up ahead. I built my manual balancing interface with switches and resistors to get my cells back close, as we rarerly charge full and the poor REC ABMS with his 1.5A active balacer simply cannot keep up with our big battery.

This should help him out, it is a 5A 4 channel active balancer, that can be controlled remotely (on/off switch) and a ESP32 microcontroller with built-in WiFi, BT, BTLE. It will do a lot more jobs (metering voltages and currents), but will also remote control the balancer module from the CERBO (RaspberryPi with VenusOS) via WiFi. I have integrated all the cell measurements and current readings from the REC into the Cerbo, so I will add some logic to force balancing if a cell difference exceeds a threshold and there is a charge current (so active only on the way up approaching the shoulders when necessary). This should do the trick and produces less heat than the resistors.

Looked up a lot of revies and they seem to be quite efficient when used properly.

Backup plan is to use a 4 relay module and my resistors to balance the cells by a program (measuring the Ah difference when 2 cells pass the same voltage at the knee area at similar current, them program a timer to discharge half of the Ah estimated on the higher cells) So I would monitor the difference on charging and then run the discharge algorithm once on discharge, halving the difference on each cycle (to not overshoot). As this is an exponential approach, It should get really close after 4 to 5 cycles at any imbalance registered.

[more]

Originally Posted by CatNewBee

So Hurricane season is approaching and we are in Amazon vincinity - some fancy projects pop up ahead. I built my manual balancing interface with switches and resistors to get my cells back close, as we rarerly charge full and the poor REC ABMS with his 1.5A active balacer simply cannot keep up with our big battery.

This should help him out, it is a 5A 4 channel active balancer, that can be controlled remotely (on/off switch) and a ESP32 microcontroller with built-in WiFi, BT, BTLE. It will do a lot more jobs (metering voltages and currents), but will also remote control the balancer module from the CERBO (RaspberryPi with VenusOS) via WiFi. I have integrated all the cell measurements and current readings from the REC into the Cerbo, so I will add some logic to force balancing if a cell difference exceeds a threshold and there is a charge current (so active only on the way up approaching the shoulders when necessary). This should do the trick and produces less heat than the resistors.

Looked up a lot of revies and they seem to be quite efficient when used properly.

Backup plan is to use a 4 relay module and my resistors to balance the cells by a program (measuring the Ah difference when 2 cells pass the same voltage at the knee area at similar current, them program a timer to discharge half of the Ah estimated on the higher cells) So I would monitor the difference on charging and then run the discharge algorithm once on discharge, halving the difference on each cycle (to not overshoot). As this is an exponential approach, It should get really close after 4 to 5 cycles at any imbalance registered.


Attachment 259554Attachment 259555

this is 3A
https://www.aliexpress.com/item/1005...089680880%21sh

https://www.aliexpress.com/item/1005...952408539%21sh

before 5-6 year i use this but 5A only no BMS but my alternator is 14.05v

[CatNewBee]

Originally Posted by more

this is 3A

https://www.aliexpress.com/item/1005...089680880%21sh



https://www.aliexpress.com/item/1005...952408539%21sh



before 5-6 year i use this but 5A only no BMS but my alternator is 14.05v

It is "up to" 5A, when one cell is empty and the other full, I expect not more than 1-2A of balance currents, as the cells are not too much off, maybe 100-150 mV in the worst case.

[CaptainRivet]

Fancy. Wish I would have your coding know how. A pity you have some parts of the cerbo integration hardcoded so it cannot be used by others.

[Catapault]

Anyone here running a Hybrid setup that can comment on how it performs and how you have it setup ?

That is, a Lead Battery (AGM), and a Lithium together ? (Refering to House batteries here, not just starter. )

[aybabtme]

Not a good idea unless you maintain two entirely separate circuits with battery-to-battery chargers to charge from one to the other. The lithium charging range is above the upper limits for lead and AGM and you'll either fry your AGM/lead, or never charge your lithium enough for cell-balancing to kick in, which will degrade your lithium's usable capacity over time.

What's the desired outcome here?

[Catapault]

Couple interesting articles / vids on the subject describe some of the benefits.
i.e.

https://www.youtube.com/watch?v=tAuP...k%27sAdventure

An initial concern is saftey. If the BMS takes the Lithium out due to some fault, thats boat power dead. Where as a dual bank provides some backup.

A second is cost, going to a full large lithium bank is expensive, vs adding some to existing setup.

Just in the invetigation stage currently, no decisions made.

[goboatingnow]

In my BMS design , the ability to reconnect the disconnects is present , manually operated

Hence I can determine if the disconnect was warranted ( or float closer to the safety margins ) if I want in order to restore emergency power to the boat ( not withstanding I have other power sources such as the alternator and solar

[Simi 60]

Originally Posted by Catapault

An initial concern is saftey. If the BMS takes the Lithium out due to some fault, thats boat power dead. Where as a dual bank provides some backup. .

We have 3 batteries and 3 BMS (3x280wh@24v)
Boat can run happily on one and have done it as proof of concept

A second is cost, going to a full large lithium bank is expensive, vs adding some to existing setup.

Yes, no, maybe
Our 840ah usable @ 24v cost less than replacing 840ah of AGM with 420ah usable

[Q Xopa]

Originally Posted by Simi 60

We have 3 batteries and 3 BMS (3x280wh@24v)
Boat can run happily on one and have done it as proof of concept


Yes, no, maybe
Our 840ah usable @ 24v cost less than replacing 840ah of AGM with 420ah usable

I assume your Batts 280 Ah?

[hzcruiser]

Originally Posted by Catapault

Anyone here running a Hybrid setup that can comment on how it performs and how you have it setup ?

That is, a Lead Battery (AGM), and a Lithium together ? (Refering to House batteries here, not just starter. )

Yes, I have done that for years without a problem, using latching relays to automatically disconnect batteries as required. Nevertheless you should search here in the forum for that thread.

[aybabtme]

Originally Posted by Catapault

Couple interesting articles / vids on the subject describe some of the benefits.
i.e.

An initial concern is saftey. If the BMS takes the Lithium out due to some fault, thats boat power dead. Where as a dual bank provides some backup.

A second is cost, going to a full large lithium bank is expensive, vs adding some to existing setup.

Just in the invetigation stage currently, no decisions made.

Apologies for not watching the video, short on time. Couldn't glance exactly what his setup is from the comments, but it seems like they have some circuit to disconnect the lead from the LFP so that both banks get charged to their target voltage independently? If so then I wouldn't see a problem with that. Personally I used battery-to-battery charger to maintain a starter battery from my LFP pack, I didn't want the problem I described before to occur.

[Catapault]

Originally Posted by hzcruiser

Yes, I have done that for years without a problem, using latching relays to automatically disconnect batteries as required. Nevertheless you should search here in the forum for that thread.

Thanks. Any diagrams / rules / hardware you use to manage the connect / disconnect ?

I've been doing some searching, but coming up blank on good discussion / design of Hybrid systems. If you happen to remember details that might aid a search, would be awesome.

I see some advantages for sure, especially as a migration project where I can't afford to just jump to the amount of Lithium I'd like to have.

I'm looking at the BlueSystems ML-RBS 7700 for disconnects in the design I'm starting to put together.

[Catapault]

Originally Posted by Simi 60

We have 3 batteries and 3 BMS (3x280wh@24v)
Boat can run happily on one and have done it as proof of concept


Yes, no, maybe
Our 840ah usable @ 24v cost less than replacing 840ah of AGM with 420ah usable

Having just had sticker shock at replacing our 4 x 260 AH Tubular Gel's with equivelent AGM, I'm taking another serious look at Lithium !.

Comming out of winter this year, our (now 4 year old), LEOCH Tubular Gel's have had a massive drop in capacity. Not even lasting overnight with just house loads. (~ 160w) before they crater to 11.4v or so.

So time to give this all another serious look.

[CatNewBee]

Do a clean lithium install, not worth it to run zombies in parallel. They will be dead when you need them, you won't notice in advance, as you would use all the time the power from the LFP.