Epoch Made All What We Want

[rgleason]

Thank you again Capt Rivet. Interesting about the balancers. I expect that Epoch is #2 type.

It does look to me like the 100 watts of solar during spring, summer, fall, would over 3-5 days, fully balance the LFP if they were charged up to say 95%SOC.

(300ah x .95) -300ah = -15ah needed to get to 100% SOC - at 5 hrs/day solar (3-4ah) it will take 3ah x 5 = 15ah or about one day.

(300ah x.98) - 300ah = -6ah needed to get to 100% SOC

The cell voltage deviation also needs to be corrected.
Assume cell deviation is 40mV and we have a 2a Heltec active balancer.
How many hours would it take to fully balance the 300ah pack?

One other question.

I am considering using (3)100ah Epoch batteries wired carefully in parallel (same length cables), with canbus communications between batteries, to create a robust and resilient house battery while protecting the alternator from dumps (as secondary and tertiary protection, will also use a Victron 200a Argofet with the starter battery, and a Balmar APD), however inherent safety of (3)100 LFP batteries whne one shuts off is quite simple.

What concerns would you have with this type of system, insofar as installation, balancing and use?

[CaptainRivet]

Originally Posted by rgleason

Thank you again Capt Rivet. Interesting about the balancers. I expect that Epoch is #2 type.

It does look to me like the 100 watts of solar during spring, summer, fall, would over 3-5 days, fully balance the LFP if they were charged up to say 95%SOC.

(300ah x .95) -300ah = -15ah needed to get to 100% SOC - at 5 hrs/day solar (3-4ah) it will take 3ah x 5 = 15ah or about one day.

(300ah x.98) - 300ah = -6ah needed to get to 100% SOC

The cell voltage deviation also needs to be corrected.
Assume cell deviation is 40mV and we have a 2a Heltec active balancer.
How many hours would it take to fully balance the 300ah pack?

One other question.

I am considering using (3)100ah Epoch batteries wired carefully in parallel (same length cables), with canbus communications between batteries, to create a robust and resilient house battery while protecting the alternator from dumps (as secondary and tertiary protection, will also use a Victron 200a Argofet with the starter battery, and a Balmar APD), however inherent safety of (3)100 LFP batteries whne one shuts off is quite simple.

What concerns would you have with this type of system, insofar as installation, balancing and use?

40mV deviation would be very high for drop in of that quality. Assume you have max 20mV and that would be around 5h if its 2A from one cell to the others balancing maybe even faster. I would ask epoch this question.

Regarding 3x100AH is fake security and redudancy as
1) 100AH is too small for the surge load of starter or windlass as well as bigger inverters.
2)High quality dropins like epoch are far more reliable then any lead battery. If you really have a problem with them then the batteries are your smallest problem as this is caused by an external desaster event and not by the battery itself.
3)if the batteries disconnect then all 3 will do as its 99.999% an external disaster event or a faulty install where all 3 will disconnect simulationsly and not just 1.
4) you pay for 3 BMS, 3 casings, 3 fuses, 3 disconnect switches better invest that in one big top notch one. Having victron to monitor you will already see it very early if something is not right and can act.
5) you have 6 points of failure more, 2x fuse, 2x disconnection switches, 2 battery terminals
6)having argofet and lead starter is already enough backup for the unlikely event you have a faulty epoch or the epoch disconnects.

My experience the smallest cells (except winston) i would use is 230AH as they have the size and surge capacity to drive all loads on the boat in case your lead fails which is 100% the case one day as they are far less relaible. 100A BMS are mostly a joke and their specs are far less then you need to be able to operate the big loads with one.
If you want more security use a bigger yellow optima as starter that can also work as house battery. The only lead i would trust, expensive but very good plus not prone to get a runaway like AGMs.

I would get one 300AH, create a simple robust system as they don't have a 2x200/2×230Ah as far as i know. Don't take version with paralleled cells inside.
If you want more capacity add Li-time.
I don't want dropins as i want access to cells all the time, thats curcial for me. Who don't want to DIY can buy sun fun kits batteries (you get kits or they do it for you) or SOX marine already as they allow to access cells anytime you need. But thats me. I understand if you wanna have good dropins with communication and for a lot the insurance doesn't allow DIY batteries.
I can get for 800Euro in DIY the same quality, capacity and BMS capabilities with acess to cells then the 2000Euro 300AH epoch.

[rgleason]

I think my calculation, ignores the fact that there is increasing resistance at these high levels of SOC, so that the charge and balancing current is not as efficient as it is at lower SOC below the "knee". I guess it is hard to know exactly how long the balancing charge will take.


LATER: Oh Capt Rivet responded below...

[rgleason]

Originally Posted by CaptainRivet

Regarding 3x100AH is fake security and redudancy as

1. 100AH is too small for the surge load of starter or windlass as well as bigger inverters.
2. High quality dropins like epoch are far more reliable then any lead battery. If you really have a problem with them then the batteries are your smallest problem as this is caused by an external desaster event and not by the battery itself.
3. if the batteries disconnect then all 3 will do as its 99.999% an external disaster event or a faulty install where all 3 will disconnect simulationsly and not just 1.
4. You pay for 3 BMS, 3 casings, 3 fuses, 3 disconnect switches better invest that in one big top notch one. Having victron to monitor you will already see it very early if something is not right and can act.
5. You have 6 points of failure more, 2x fuse, 2x disconnection switches, 2 battery terminals
6. Having argofet and lead starter is already enough backup for the unlikely event you have a faulty epoch or the epoch disconnects.

My experience the smallest cells (except Winston) i would use is 230AH as they have the size and surge capacity to drive all loads on the boat in case your lead fails which is 100% the case one day as they are far less reliable.

100A BMS are mostly a joke and their specs are far less then you need to be able to operate the big loads with one.

If you want more security use a bigger yellow optima as starter that can also work as house battery. The only lead i would trust, expensive but very good plus not prone to get a runaway like AGMs.

I would get one 300AH, create a simple robust system as they don't have a 2x200/2×230Ah as far as i know. Don't take version with paralleled cells inside.

If you want more capacity add Li-time.

I don't want dropins as i want access to cells all the time, thats curcial for me. Who don't want to DIY can buy sun fun kits batteries (you get kits or they do it for you) or SOX marine already as they allow to access cells anytime you need. But thats me. I understand if you wanna have good dropins with communication and for a lot the insurance doesn't allow DIY batteries.

I can get for 800Euro in DIY the same quality, capacity and BMS capabilities with acess to cells then the 2000Euro 300AH epoch.

I accept your advice about getting one good 300ah battery, and we will get an Optima Yellow.

I kind of agree about having access to the cells, but the boat is small, and the battery is going right back into the same location as the FLA in the port cockpit locker, so I like the packaging of the Epoch and IP67. (The seat lid has deep gutters and never gets wet (yet), but I am going to add some seals too.

I don't see how I can build a 1p4s battery with same or better characteristics as Epoch. First of all, where would I get a waterproof housing? Also a DIY battery by me is probably not going to be as robust as I've never built one and I don't want it to be ad hoc.

However if thought there was a good path forward to build my own, I think I would do it. I would just need to have enough experience or examples and access to the right parts.

[CaptainRivet]

Originally Posted by rgleason

I accept your advice about getting one good 300ah battery, and we will get an Optima Yellow.

I kind of agree about having access to the cells, but the boat is small, and the battery is going right back into the same location as the FLA in the port cockpit locker, so I like the packaging of the Epoch and IP67. (The seat lid has deep gutters and never gets wet (yet), but I am going to add some seals too.

I don't see how I can build a 1p4s battery with same or better characteristics as Epoch. First of all, where would I get a waterproof housing? Also a DIY battery by me is probably not going to be as robust as I've never built one and I don't want it to be ad hoc.

However if thought there was a good path forward to build my own, I think I would do it. I would just need to have enough experience or examples and access to the right parts.

Have a look at battery kits from
https://www.sunfunkits.com/product/1...kit-200amp-bms
Thats very close and even heated with 304AH EVE cells for 995$, includes all you need and for 40$ they just put it together for you.
For their 200A BMS there is a cerbo GX driver avaliable (you need the RS485 upgrade of BMS for that) that connects into to cerbo.
With garauntee...
There cells are a bit more expensive but 1000% grade A and they even put better terminals on the 304AH EVE. Worth the extra 150$ in my opinion but you can get them cheaper at 18650store or netherland.
If you wanna save you can get the REPT or the 280AH SFK cells from which are also eve but better terminals. And leave away the heating (on sale price its basically for free at the moment).

Another option
1p4S for 800Euro:
4x 304AH EVE V3 cells with the double pole,
Jk 4S BMS with 200A cont and 500A peak with 2A active balancing
Peter board for victron communication/alternativ dbus serialdriver from github, need the large venus OS version and root rights to install that.
Case from sunfunkits or just build your own from nylon boards...its a square box, i think every boater who does maintenance themself can build a square box.

[CaptainRivet]

For europe even below 600Euro possible:
https://www.nkon.nl/de/eve-lf304-prismatic-304ah-lifepo4-3-2v-a-grade.html
89Euro per cell makes 356Euro for the cells incl. busbars
Jk 200A/350A peak, 2A active balancing for 114Euro
https://www.nkon.nl/de/jk-bms-b2a8s20p-hc.html
Use dbus-serialdriver for victron communication
Build case yourself from nylon or pp boards. 50 Euro.
Cables, terminals are another 50Euro
There are plenty tutorials on youtube how to do that.
Total below 600Euro, means just build 2 for 1200Euro, then you have your redudancy.

[CaptainRivet]

For europe even below 600Euro possible:
https://www.nkon.nl/de/eve-lf304-pri...v-a-grade.html
89Euro per cell makes 356Euro for the cells incl. busbars. They are also true grade A, at least what my buddy and several youtuber received from them who published tests. They have also grade B but wouldn’t consider them when getting grade A for 89Euro. Well known reseller, i think Fuss also has his cells from them...for that price it actually makes sense to use them as starter and backup too...
I paid 180Euro for my 272AH grade A+ from Lishen in 2021...just ordered 8x304AH myself, for that price you cannot go wrong.
Jk 200A/350A peak, 2A active balancing for 114Euro
https://www.nkon.nl/de/jk-bms-b2a8s20p-hc.html
Use dbus-serialdriver for victron communication
Build case yourself from nylon or pp boards. 50 Euro.
Cables, terminals are another 50Euro
There are plenty tutorials on youtube how to do that.
Total below 600Euro, means just build 2 for 1200Euro, then you have your redudancy.

[rgleason]

Those are some great options. I feel like I took a big journey starting with Epoch.


200ah vs 300ah
I added up loads and with refrig, radar (limited) and autopilot (limited) use, I estimated 100ah cruising and 150ah at sea, ..this may be a little low but it is a small boat without that many systems.
We currently have FLA 200ah which is actually 100ah usable.
Should really get 300ah? Mostly charged by 160a regulated down to 100a alternator.


One thought is that the 300ah would be better at .3C x 300ah = 100ah which is closer to our alternator output.

[rslifkin]

If there's not a significant downside to having the bigger battery, I'd go for it. It's hard to truly have too much power on board.

[CaptainRivet]

Originally Posted by rslifkin

If there's not a significant downside to having the bigger battery, I'd go for it. It's hard to truly have too much power on board.

Fully agree on that. And 4x230AH Eve versus 4x304AH EVE is 60Euro...saving on the wrong end.
He had 2000Euro budget so when wanting redudancy he can get 8x230AH EVE and 2 JK BMS and for 1080 Euro have 2x230AH the redudancy he wanted plus each 230AH can fully support all tasks on board including starting the engine and windlass. In this case also a cheap FLA as starter and dumb load would do it instead optima yellow top saves another 200Euro.
Well i would invest the 120Euro more for the 304AH cells then, yes thats over the top but these are just the most proven cells. Means for half the budget he planed and willing to spend on epoch he get double capacity of epoch, his redudancy and is definitly never need to invest in anything on the battery side as this can drive everything he possibly can put on his vessel.
The 2x230AH will be totally fine too.
His vessel his choice, i think we gave him all the sensefull options and he can chose what he prefers.

[CaptainRivet]

Originally Posted by rgleason

Those are some great options. I feel like I took a big journey starting with Epoch.


200ah vs 300ah
I added up loads and with refrig, radar (limited) and autopilot (limited) use, I estimated 100ah cruising and 150ah at sea, ..this may be a little low but it is a small boat without that many systems.
We currently have FLA 200ah which is actually 100ah usable.
Should really get 300ah? Mostly charged by 160a regulated down to 100a alternator.


One thought is that the 300ah would be better at .3C x 300ah = 100ah which is closer to our alternator output.

150AH so the 300AH gives you 2 days operation in case eg alternator or regulator dies...definitly makes sense to go 300, i personally have a 3 days rule so 450AH would be the capacity i would put.
Need 300-350AH a day and i have 1088AH, for the price of 8x89Euro=712Euro i will now add 8x304AH EVE to 1700AH or 5 days without any charge out of it. Means i will get the bank full in 8 month of the year and 4 month i won't but i most likely can avoid to run the engine or honda to charge as i go once a month to habour for one day to provison and clean the boat and can then recharge the house on shorepower in these 4 month.

[rgleason]

Thanks, it's a small boat, so unfortunately 305ah is what I can fit to start with. Maybe later I can figure out how to shoehorn some batteries into the other locker, but it is quite full right now.

[rgleason]

In thinking about the balancing charge, an alternator is overkill, this is more suitable for Solar panels I think, except they may not operate for a long enough period, but multiple days might work.

I'd like to get a feeling for how and when BMS shuts down, because top balancing is pushing the limits of voltage and current to get the deviation or differential between cells reduced.


I suppose the Solar Controller could push too much power into the cells, so the worst one goes more seriously out of balance and the BMS shuts down. When this happens I am guessing you wait a little, reset the BMS and continue balancing at a lower rate.

Do Solar Controllers know enough to do this kind of adjustment while balancing so the BMS is not constantly tripping off and the balancing takes place without much human intervention leaving the system operational?

[CaptainRivet]

Originally Posted by rgleason

In thinking about the balancing charge, an alternator is overkill, this is more suitable for Solar panels I think, except they may not operate for a long enough period, but multiple days might work.

I'd like to get a feeling for how and when BMS shuts down, because top balancing is pushing the limits of voltage and current to get the deviation or differential between cells reduced.


I suppose the Solar Controller could push too much power into the cells, so the worst one goes more seriously out of balance and the BMS shuts down. When this happens I am guessing you wait a little, reset the BMS and continue balancing at a lower rate.

Do Solar Controllers know enough to do this kind of adjustment while balancing so the BMS is not constantly tripping off and the balancing takes place without much human intervention leaving the system operational?

The balancing happening in normal operation by BMS in the upper knee and in case of an active balancer in charge and discharge. If you properly top balance each cell before putting together the balancer is fully capable of keeping them in balance during the time it has when the battery is in the >3,4V area. Which charge source is charging in this area the BMS don't care and yes the mppt is perfectly capable of doing that as very lttle current is needed here in the upper area. You shouldn't intervene at all.
Only once a year I suggest to use shorecharger when convinient, have BMS reengage charge at 3,45V and best over night just let it cycle in the area 3,45 to 3,55V (or which cutoff you will use) per cell so it basically top balance the bank. That is normally not a must but it also cannot hurt and in case the cell age differently it does a new top balance.

I do this all 3 month but I have 4P4S bank, so 4x272AH in parallel and the parallel cells also can only even them 100% internally out in the upper area and they need time for that. Additionally I am seldom in the top knee during normal usage as bank is really overspeced for my use. Like this I have 5mV deviation even when pulling 500A which is the actual deviation of the cells. That's not needed that frequent in 1p4S/8S battery at al, unless you have unmatched grade b cells.

[rgleason]

Thanks Capt. Rivet, Solar Support and rslifkin you've been superb instructors.