DC/DC or ArgoFet

[CaptainRivet]

[QUOTE=Britishsea;3563368]

Originally Posted by CaptainRivet

. "Electrodacus BMS so the total current i don‘t care as it carries no current and switches the inverter off via the Remote on/off Switch if SOC is too low or an alarm disconnect event."

I am also using the Electrodacus. Seems a bit prone to corrosion in a marine environment, but hoping it will get through a couple of years until more BMS options are available or drop-in LFP becomes more sophisticated.

BritSea

Suggest to put Electrodacus in a sealed box.
I used a IP67 top mounted plastic cable diverted box and sealed all cable going in/out with hot glue and when all cables installed dipped the back of the Electrodacus in plastidip. Perfectly sealed now.

There is already a very good and even more sophisticated Taos BMS available, it’s around 800Euro with tax+shipping from Australia.
Electrodacus fits my needs as I have all Victron except the inverter, if no budget constrains i would have went with 4x1000AH Winston cells and the Taos BMS.
Lishen+Electrodacus is the budget route

[CaptainRivet]

Originally Posted by s/v Jedi

I have/had all the same gear you had… remember I had a 12V battery bank too. So let’s see:

Start engine when 12V battery breaks: I start with the 2nd start battery; surely you could see that in the diagram! Then there’s a shtf backup as well: a center tap on the 24V house battery: see the leftmost switch in the picture!

Backup when my house bank fails? I have a 2nd house bank as well as a 12 to 24V converter and a rather large 1875W solar array with 24V output.

I had a 12V windlass. I simply bought a 24V motor for it.

I have 12V alternators on engine and genset. They charge the 12V batteries. There are two 12-24V converters that charge the house bank from the alternator output.

You have a 12V winch? I have 4 massive 12V winches incl. the Lewmar 66 primaries. They simply run off the 12V.

Why you have 12 cells is beyond me because that would make a 36V battery. I did hear car manufacturers switching to that but I would keep it at 8 cells for 24V or 16 for 48V

You have a 12V shore power charger? Remember, I had 12V too. I still have a good as new Victron Quattro 3000 and a Xantrex 60A charger. I think I’ll keep the charger and sell the Quattro or use it at another project.

Clean install
And what’s the advantage? Did you have smaller diameter cabeling in and went to 24V to avoid relabeling or all of high power loads have very long cables (you have 64ft Mono)?
To me very complicated system design with 12/24V and expensive with all these converters.
The amp hungry high loads often used are still 12V and conversion losses are about 10%. Makes no sense to me.

As explained I decided to keep 12V due to all my high power loads are new or overhauled so no replacement in near future. To convert major invest and time with not much added value.
Except of the windlass (which already had an oversized cable installed by former owner) all other 12V high power loads are quite close to the house battery, optimized that too. And the windlass profits massively from the LifePo4 as no big voltage drop under load compared to LFA.
So voltage drop is small, invest in cables minimal as most was already there and appropriate.
Just used 5mmx25mm tinned Cooper busbars to connect the cells and massive T3 Fuses plus 750A and 300A shunts for the Electrodacus. Inverter with 2x120mm2 30cm cables directly to the main fuse T3 output (its rated for 1250A continuous/ 10000A light bow save so a short in the LifePo4 won‘t bypass the fuse with a light bow, a class T will). Would have done and build the battery the same if 24V.

12 cells because I wanted 5 days on anker without any recharge of the house and that resulted with 272AH cells in 3p4s 12V 840AH capacity, have 160AH/day in average. Ok went up to 220AH/day with some upgrades in the electric galley which is still 4 days now but my 1200W bifacials solar panels even put 25A charge in when it’s totally clouded.

Just a tip: measure resistance and therefor heat and voltage drop in your mega and class T fuses and compare this to T2 and T3 fuses, difference is huge had problems that main busbar got hot from heat transfer from these and replaced all mega from 100A on with T2 and class T from 250A with T3 and no problems anymore.
Additionally bought smart T2 and T3 are cheaper

[s/v Jedi]

Originally Posted by CaptainRivet

Clean install
And what’s the advantage? Did you have smaller diameter cabeling in and went to 24V to avoid relabeling or all of high power loads have very long cables (you have 64ft Mono)?
To me very complicated system design with 12/24V and expensive with all these converters.
The amp hungry high loads often used are still 12V and conversion losses are about 10%. Makes no sense to me.

As explained I decided to keep 12V due to all my high power loads are new or overhauled so no replacement in near future. To convert major invest and time with not much added value.
Except of the windlass (which already had an oversized cable installed by former owner) all other 12V high power loads are quite close to the house battery, optimized that too. And the windlass profits massively from the LifePo4 as no big voltage drop under load compared to LFA.
So voltage drop is small, invest in cables minimal as most was already there and appropriate.
Just used 5mmx25mm tinned Cooper busbars to connect the cells and massive T3 Fuses plus 750A and 300A shunts for the Electrodacus. Inverter with 2x120mm2 30cm cables directly to the main fuse T3 output (its rated for 1250A continuous/ 10000A light bow save so a short in the LifePo4 won‘t bypass the fuse with a light bow, a class T will). Would have done and build the battery the same if 24V.

12 cells because I wanted 5 days on anker without any recharge of the house and that resulted with 272AH cells in 3p4s 12V 840AH capacity, have 160AH/day in average. Ok went up to 220AH/day with some upgrades in the electric galley which is still 4 days now but my 1200W bifacials solar panels even put 25A charge in when it’s totally clouded.

Just a tip: measure resistance and therefor heat and voltage drop in your mega and class T fuses and compare this to T2 and T3 fuses, difference is huge had problems that main busbar got hot from heat transfer from these and replaced all mega from 100A on with T2 and class T from 250A with T3 and no problems anymore.
Additionally bought smart T2 and T3 are cheaper

The biggest advantages of going for 24V or 48V house bank:

1. All cells in series. You can get Winston 1000Ah cells so this is possible for a 12V 1000Ah (= 12.8kWh) battery too, but if you look at more affordable cells like Eve 280Ah then you end up with only 3.6kWh unless you put cells in parallel. If you would go for all in series 24V then you get 7.2kWh and 48V even 14.4kWh while keeping all cells in series.

2. Run cool. See, the problems you had with fuses and busbars heating up are caused by the current. At 24V you only have half the current and at 48V only 25% of the current. Everything runs cool and easy.

3. Inverter performance. When you get into the 5-10kW inverter range, it is very difficult to get full performance out of them at 12V while at higher voltages it is a breeze. I needed 4 conductors of 4/0 gauge for 1 inverter on 12V to get ripple on DC under control, now I don’t even remember but think its 4x 1/0. See https://www.victronenergy.com/live/_...ery_system.pdf

4. Prevent rewiring. While changing a boat from propane to electric and adding more and more electric appliances, circuits need to be upgraded to bigger diameter unless you go for a higher voltage.

[Britishsea]

[QUOTE=CaptainRivet;3563655]

Originally Posted by Britishsea

Suggest to put Electrodacus in a sealed box.
I used a IP67 top mounted plastic cable diverted box and sealed all cable going in/out with hot glue and when all cables installed dipped the back of the Electrodacus in plastidip. Perfectly sealed now.

There is already a very good and even more sophisticated Taos BMS available, it’s around 800Euro with tax+shipping from Australia.
Electrodacus fits my needs as I have all Victron except the inverter, if no budget constrains i would have went with 4x1000AH Winston cells and the Taos BMS.
Lishen+Electrodacus is the budget route

CaptainRivet

That's a very impressive procedure for sealing the Electrodacus. You are clearly very skilled and meticulous in your instal. I'll re-examine what I might do to similarly help protect my unit.

Yours too, SVJedi. The craftsmanship and attention to detail extraordinary.

I could not find your Taos BMS by google search. Name of manufacture or link?

I considered the REC BMS, which does seem like a top notch unit for 4S configurations - but I cheaped-out. The work required to get the Elctrodacus to fit for this application on the margin for funds saved. Not knocking the Electrodadus. It's feature rich and a great piece of engineering.

REC BMS plus 400ah of CALB, Winston or even GBS would be great for my needs.

BritSea

[CaptainRivet]

https://www.taobms.com

Thanks….well metricolous install not really, wish I did that‘s why I am redoing it right now. Costs a lot time and patience. But good so you can quickly make chances, now I know that’s how it’s kinda final and make it neat and right.
I am sleeping on top of it, so it’s my butt that’s on the BBQ first if things go wrong

If you go the budget route you have to really check what you buy, where the manufacturer saved money and what you as DIY can do to overcome that and make it Marine safe. If you don‘t you will pay doubled in best case….

Lishen and EVE are great quality cells for really small money and if grade A on the level of Calb BUT they saved money on case (caring positiv and need compression) and threads are too short and M6 or 8 which can only carry 8nm force. Like this they are not marine safe. You need and can address that well by making a case out of thick nylon boards with threaded rods to compress them, put a thin high temp Silicon baking mat between each cell to isolate them and busbars need to go to the case where you eg screw the shunt on and go directly with the busbar on the shunt. Other side of shunt goes the thick main cable. So shunt carries the load and forces of the vibrating main thick and heavy cable.
For around 200 Euro for the case and tinned copper busbars you can make a 840AH battery with 100% grade A cells for 2000Euro all in that would cost you easily 3500 Euro with Calb and won‘t be better and still need some measures to be marine safe too.

You don‘t need 12 good casings, one good around them addressing all the needs is enough and much cheaper.
That’s why they are so popular in DIY, saved on the right spot which you can fix easily and cheap.

[CaptainRivet]

Originally Posted by s/v Jedi

The biggest advantages of going for 24V or 48V house bank:

1. All cells in series. You can get Winston 1000Ah cells so this is possible for a 12V 1000Ah (= 12.8kWh) battery too, but if you look at more affordable cells like Eve 280Ah then you end up with only 3.6kWh unless you put cells in parallel. If you would go for all in series 24V then you get 7.2kWh and 48V even 14.4kWh while keeping all cells in series.

2. Run cool. See, the problems you had with fuses and busbars heating up are caused by the current. At 24V you only have half the current and at 48V only 25% of the current. Everything runs cool and easy.

3. Inverter performance. When you get into the 5-10kW inverter range, it is very difficult to get full performance out of them at 12V while at higher voltages it is a breeze. I needed 4 conductors of 4/0 gauge for 1 inverter on 12V to get ripple on DC under control, now I don’t even remember but think its 4x 1/0. See https://www.victronenergy.com/live/_...ery_system.pdf

4. Prevent rewiring. While changing a boat from propane to electric and adding more and more electric appliances, circuits need to be upgraded to bigger diameter unless you go for a higher voltage.

To 1: yes and no. Till 3 or 4p you can actually level out the best and worst cells (small deviations) as they are seen as one and on the other side they don‘t drift apart if you stay below 0.4C per cell and done a proper top balance before assembly. If one of 4 1000AH cell goes bust that’s expensive at least…if 3p cells go bust I can still reconfigure it to a 2p4S battery.
Pro‘s and cons…
To 2: well I ran hot because the Megafuse bs is rated for 300A but if you pull 200A it get melting hot because these thin connectors and the melting parts creates too much resistance. Wrong rating won’ use Megafuse over 100A now, that’s what it is good for. Take a T2 or 3 fuse and stay below 2/3 of the cables rating, crimp well and all is good even with 380A. 50A can run hot if you use wrong spec cable/fuses etc. but true above 250A you have to be quite metricoulous what you use. And above 250A it only makes sense if you can keep the high current loads close to battery. I could that’s why I stayed with 12V.
To 3) true, above 5kw 24V is a must. At or below 5kw if you can keep the cables short it’s ok. that’s why I add a 5kw to 1x5kw and 1x3,5kw will use them to around 3 and 2kw with 30cm cables next to the battery. 5kw is just for the 3,1kw induction cooktop. Nothing gets hot, inverter lives longer as use to 40-60% max and redundancy. No Victron as they are too expensive in inverter for what they deliver, the rest all Victron.
To 4) yes ripple is an issue. you need massive cables or if possible even massive busbars, if you can keep them below 70cm length and cable calculate 2/3 of its rating and use T3 fuses the ripple is ok. If you can‘t then 24V is a must. Semi-continuous 400A load is the limit from my experience.

Shorepower charger is only there so I can load the LifePo4 with a portable Honda gen as 3rd backup charge source. Cat is setup as 100%self sufficient and if I go to port I normally don‘t plug into shorepower….

[Britishsea]

Originally Posted by CaptainRivet

https://www.taobms.com

Thanks….well metricolous install not really, wish I did that‘s why I am redoing it right now. Costs a lot time and patience. But good so you can quickly make chances, now I know that’s how it’s kinda final and make it neat and right.
I am sleeping on top of it, so it’s my butt that’s on the BBQ first if things go wrong

If you go the budget route you have to really check what you buy, where the manufacturer saved money and what you as DIY can do to overcome that and make it Marine safe. If you don‘t you will pay doubled in best case….

Lishen and EVE are great quality cells for really small money and if grade A on the level of Calb BUT they saved money on case (caring positiv and need compression) and threads are too short and M6 or 8 which can only carry 8nm force. Like this they are not marine safe. You need and can address that well by making a case out of thick nylon boards with threaded rods to compress them, put a thin high temp Silicon baking mat between each cell to isolate them and busbars need to go to the case where you eg screw the shunt on and go directly with the busbar on the shunt. Other side of shunt goes the thick main cable. So shunt carries the load and forces of the vibrating main thick and heavy cable.
For around 200 Euro for the case and tinned copper busbars you can make a 840AH battery with 100% grade A cells for 2000Euro all in that would cost you easily 3500 Euro with Calb and won‘t be better and still need some measures to be marine safe too.

You don‘t need 12 good casings, one good around them addressing all the needs is enough and much cheaper.
That’s why they are so popular in DIY, saved on the right spot which you can fix easily and cheap.

Well, meticulous is a relative term. Pic below - still a work in progress, especially on the charge bus side. Pardon the loose wires, not yet secured. This is under my nav seat.

Thxs for the link to the Toa BMS link. Interesting products. 6, 2 amp relays either NO or NC is a nice touch. It does remind me of many of the features of the REC BMS.

I have struggled with resistance in the bus bars giving erroneous readings. I used studs, not bolts on the terminals. I was using CALB flexible busbars and I think they did not like being matted to aluminum, notwithstanding I used dialectic grease. Switched to flexible, tinned"Webber" busbars. Best by far I have encountered.

I lightly compress my cells with 1/4 inch rod using 1/4inch aluminum end plates. I vinyl warped the ends plates for isolation. I also had a battery tray build from aluminium, so if any electrolyte were to every leak, it will stay contained. I have a plastic liner in the tray so the cells are not relying on their wrapping for electrical isolation.

I don't have my shunt attached by a busbar as you recommend. It's a great idea but i do not really have the space. I use 1 AWG wire that i tried to keep longish to allow for some flex btw the shunt and positive terminal. So far, so good. My max loads are lower than yours, so I think I can get away with lighter cable. I have an inverter, but its only 1000 watts.

You have mentioned a few times in this thread to maintain your loads under 0.4C to keep your cells in balance. Is that for continuous loads or does that include momentary loads? I don't have any continuous loads more than 70- 80 amps, but I do have some induction loads that likely spike momentarily to 200amps (windlass).

BritSea

[Britishsea]

[QUOTE=CaptainRivet;3564041]https://www.taobms.com

Interesting comparison chart attached (found on the Tao website) of it compared to the REC, and some other popular brands.

Tao looks good & the chart is interesting on its own as an exhaustive list of features you might want on your BMS.

BritSea

[johnmwalsh]

[QUOTE=CaptainRivet;3563655]

Originally Posted by Britishsea

Suggest to put Electrodacus in a sealed box.

I used a IP67 top mounted plastic cable diverted box and sealed all cable going in/out with hot glue and when all cables installed dipped the back of the Electrodacus in plastidip. Perfectly sealed now.



There is already a very good and even more sophisticated Taos BMS available, it’s around 800Euro with tax+shipping from Australia.

Electrodacus fits my needs as I have all Victron except the inverter, if no budget constrains i would have went with 4x1000AH Winston cells and the Taos BMS.

Lishen+Electrodacus is the budget route

How do you like the electrodacus? Does it do everything you need it to do? Are you using it with solar also? Thank you for your input

[Britishsea]

Not sure if this is to me or the Capt.

It's a great unit with lots of good features including SOC and 4 remote outputs that you can use to automate LVC and HVC events. I have solar but using a Victron MPPT not the DDR20. Amazing customer support and price point.

There are some downsides however:

Designed for a stationary environment (house/ cabin) not a boat

Fussy, shortish small gauge sense wires.

Very small inputs for the relays (need to use tiny ferrules)

Small max relay current (50ma)

Not protected from corrosion

Limited ability for implementing warning allarms before HVC shut down event

No current based LVC, HVC.

Small passive balancing capacity (200 ma)

There are work arounds for most of these issues, but it requires some effort.

BritSea


[QUOTE=johnmwalsh;3567931]

Originally Posted by CaptainRivet

How do you like the electrodacus? Does it do everything you need it to do? Are you using it with solar also? Thank you for your input

[CaptainRivet]

[QUOTE=Britishsea;3568168]Not sure if this is to me or the Capt.

It's a great unit with lots of good features including SOC and 4 remote outputs that you can use to automate LVC and HVC events. I have solar but using a Victron MPPT not the DDR20. Amazing customer support and price point.

There are some downsides however:

Designed for a stationary environment (house/ cabin) not a boat

Fussy, shortish small gauge sense wires.

Very small inputs for the relays (need to use tiny ferrules)

Small max relay current (50ma)

Not protected from corrosion

Limited ability for implementing warning allarms before HVC shut down event

No current based LVC, HVC.

Small passive balancing capacity (200 ma)

There are work arounds for most of these issues, but it requires some effort.

BritSea


quite a good overview and fully agree
Tao is 800Euro, Elctrodacus 150Euro, so you have to spend some extra effort to overcome downsides...you get what you pay for but here the best buck for the bang already.


one huge advantage is that it doesn't carry any current so if you plan to run windlass and starter from your house their 3 times+x surge and inrush current doesn't fry the BMS. A problem you can have with REC and TAO... have a cat so one hull is house+starter (as it was before with FLA), the other has 2 FLA as starter and can be joined to start the other engine too.


also if you add big loads nothing to change if your main busbars are speced properly...if too small you just keep and add new 2nd main busbar in parallel, maybe seperating must have and can easyly shut off loads. or you just wire the big load directly to the shunt of the Electrodacus and keep rest as is...What I am doing right now as adding a massive 4kw LF inverter.


regarding the relays, simple 718 optocoplers with already 4 switching connections are 5 Euro and then you can drive big relays...if you have all victron you don't need any of these.
I need 3 relays, one small for the non victron inverter on/off remote switch and on main load busbar two big in parallel to share the big load as absolute last resort to cut everything off. but maybe ditching them as Electrodacus shuts everything off and they create more issues then being a safety feature.

[Philtao]

Originally Posted by CaptainRivet

one huge advantage is that it doesn't carry any current so if you plan to run windlass and starter from your house their 3 times+x surge and inrush current doesn't fry the BMS. A problem you can have with REC and TAO...

Just a quick correction. TAO do not carry any current. It's outputs drive contactors or directly remote control chargers and loads / inverters

[PaulCrawhorn]

Just as true for Electrdacus and REC BMS right?

[Philtao]

Sorry I am late in the discussion, but to go back to the original question I would like to share a simple way it can be done using the TAO BMS.
This is for an installation with a FLA starter battery and a LiFePo4 house battery, using an alternator with external regulator set to charge the lithium battery (13.8 v for me). I like to keep it simple with minimum cables, connections and equipment between the chargers and the battery - so no DC/DC charger and no battery isolator (maybe that can help compensate for the price difference ).

My original assumption (which I have now validated over the last 3 years) is that trickle charging the starter FLA battery between 13.2 and 13.8 volt most of the time keeps it full and healthy... my starter battery is 5 years old now and when it is disconnected from the lithium battery, its rest voltage is 12.8 v. that keeps me happy and even if I have to replace it in a year or two it is a decent service life for less than USD150.

As suggested earlier in this thread the basic principle is to have the lithium and FLA batteries in parallel BUT:

• avoid draining the FLA battery when the lithium battery is low
• and use the FLA battery as a safety backup in case the BMS shuts down the lithium battery (quite important on a boat)

In summary:
The FLA battery is connected in parallel with the lithium battery when:

• the ignition is turned on (and no high voltage situation requiring to stop the charge)
• or the cell voltage or SOC are above set thresholds (example: 3.25 v / 50% SOC)
• or just before the lithium battery is disconnected by the BMS

The FLA battery is disconnected from the lithium battery when:

• the BMS detects a high voltage situation that requires to stop the charge
• or the cell voltage or SOC are below set thresholds

If you would like me to explain in details how it is done with the BMS, it might be better to open a new thread so that this one does not get side tracked.

[PaulCrawhorn]

^^ this ^^

but the key is the adjustable VR designed to limit current

not just any will do.

Implies most of your power comes from the alt?

If you choose a good DC-DC instead, upsides are, IMO simpler

and it will condition / regulate any source, goes with the LFP bank if you want that to provide power in other contexts, sticks with the bank not the boat.

Downside is just one may not deliver all the amps you want.

Neither is "cheap"