Hybrid system using new Sterling Power B2B chargers

[Deividas]

I have a feeling that my old house battery bank (2 x 125 AGM) is sinking little by little. It is time to think about an upgrade. I would like to save as much as possible from the old system and have a possibility to upgrade/grow in the future.
I'm not an engineer so would like to hear your opinion on my project.

Batteries (cells) - Winston WB-LYP200
BMS - BMS123 Smart
Charger - Sterling Power Pro Charge Ultra 1250
B2B Charger - Sterling Power BBS1230

More detailed specifications with links to all products, prices could be found on this Google sheet - https://docs.google.com/spreadsheets...it?usp=sharing

Maybe someone already using the BBS1230 B2B charger would be happy to hear some opinion.

[Pete7]

Are you on a budget? If you are quick there are some cheap BB1230 available in Sterling's Clearance range:

https://sterling-power.com/collectio...nt=44923987541

What other BMS's have you considered? That is also an expensive item, could you make do with a large Daly?

Pete

[Deividas]

Originally Posted by Pete7

Are you on a budget? If you are quick there are some cheap BB1230 available in Sterling's Clearance range:

Pete

I'm thinking about BBS1230 - with a solar charging option. That makes the price much more reasonable. And a 5-year warranty sounds good too.

Originally Posted by Pete7

What other BMS's have you considered? That is also an expensive item, could you make do with a large Daly?

Pete

Yes, BMS is an open question. And not because of the budget. I have heard some bad comments regarding Smart123. One more option I'm considering is REC Active BMS - https://www.off-grid-systems.de/REC-...ePo4-Bausatz_1 . It is even more expensive But considering that I'm planning to add more cells in parallel REC will be able to manage them. In long term it will be more reasonable investment.

[Pete7]

A question first, what engine have you got? and are there any bigger alternators even up to 100A?

https://www.startermotor-alternator-store.co.uk/

I saw the YT video of the BB1230 Solar, shame its only 31v or I might have chosen it, but I did ask them on the comments to come up with a 60A version and a higher spec for solar which I am sure they have in hand.

However, on the diagram, if the BB1230 from alternator fails at sea your only charging is then a bit weak. Perhaps a battery switch to remove the LFP and another to connect in the engine start bank, so that VHF, CP and AP still work all be it needing the engine to run every few hours to keep the charge up.

Instead, how about paralleling the two BB1230s from the engine battery to the LFP. Since they can be controlled with the ignition lead, one could be turned off if not needed, or if the LFP is deeply discharged, switch on both BB1230s and give the engine a few revs (assuming a slightly bigger alternator, say 100a). You then put the solar and wind into the engine start battery enabling both BB1230s if you need or revert to one. Should one BB1230 fail, you have a spare already wired and tested ready to go whilst still at sea.

I am also thinking about a very similar set up to yours. Just working on the alternator upgrade with external regulator and was looking at BB1230s, until yesterday afternoon when my Sterling Pure Sine wave inverter went "puff" in a cloud of smoke" So that is another item I need to replace.

Pete

[Pete7]

Picked this link up from somewhere and a strong recommendation for the Junior BMS. I think the "big" ones are really expensive. Don't know much else about them so its a possibility but just that at the moment.

https://www.orionbms.com/

[Deividas]

Originally Posted by Pete7

A question first, what engine have you got? and are there any bigger alternators even up to 100A?

However, on the diagram, if the BB1230 from alternator fails at sea your only charging is then a bit weak. Perhaps a battery switch to remove the LFP and another to connect in the engine start bank, so that VHF, CP and AP still work all be it needing the engine to run every few hours to keep the charge up.

Pete

My engine is Volvo Penta MD 2030.
I'm considering the next upgrade - a bigger alternator and an additional BBS1230. Then I would have some duplication in case of failure.

You can find in my scheme that I have added a direct connection between two banks. In the case of B2B failure there theoretically would be possible to charge the house bank directly from the alternator. This connection would help in case of starter battery failure too. I would be able to start the engine using the house battery.

[Pete7]

Originally Posted by Deividas

My engine is Volvo Penta MD 2030.
I'm considering the next upgrade - a bigger alternator and an additional BBS1230. Then I would have some duplication in case of failure.

You can find in my scheme that I have added a direct connection between two banks. In the case of B2B failure there theoretically would be possible to charge the house bank directly from the alternator. This connection would help in case of starter battery failure too. I would be able to start the engine using the house battery.

I have one of these on the way and a Sterling alternator regulator ready to fit to it

https://www.startermotor-alternator-...73-15372-p.asp

This is my second step in the improvements, having upped the solar to 300w last winter.

Pete

[Deividas]

Originally Posted by Pete7

I have one of these on the way and a Sterling alternator regulator ready to fit to it

https://www.startermotor-alternator-...73-15372-p.asp

This is my second step in the improvements, having upped the solar to 300w last winter.

Pete

Reasonably priced alternator.
I Will bookmark this for the future. Thanks

[smac999]

The sterling b to b are junk. They are like 80% efficient. They create a lot of heat and the outgoing current was way less in incoming. I put 2 on a boat and took them off 2 weeks later replaced with mastervolt mac. Which were awesome.

Get a solar controller and run own Wires. Don’t share stuff. When it breaks you lose everything.

[rgleason]

I've been seriously considering DC to DC charging to protect the Alternator and LFP.
I do not know the answers here and have not pushed real numbers here, but I think using DC/DC or B2B is headed for some issues: Heat output and reduced efficiency.

For example the best B2B efficiency I've seen is 90% efficiency, now that is probably not at high output, but at some low output rate. Getting up to higher outputs the efficiency will probably drop to 70%, with the equivalent of 30% efficiency loss in heat.

I have been using Alternator output reductions through Balmar belt manager as follows:
- 10% for longevity
- 20% for reduction in output capacity due to hot continuous use.
- 30% total reduction.
which is 70% of the alternator rated output, inverting that is 142%.

So if I assume
200ah LFP x .35C (max) = 70ah + 10ah DC Loads + 20ah start battery= 100ah actual hot continuous output needed. To get the necessary alternator output 100ah x 1.42 = 142ah cold output rating is needed.

Now include the effect of the DC/DC B2B 70% efficiency at high output.
142ah x 1.42= 201 ah. This is ridiculous to get continuous hot output at the LFP batteries of say 90-100 ah and only roughly 50% efficient.

I think would rather have a more efficient charge system that goes directly to the LFP or paralleled LFP/FLA (with disconnect relay) and have the proper regulation and controls so the charge does not go through a B2B Charger.

I am interested in what others have figured out or learned when using similar B2B systems.

[Pete7]

Originally Posted by rgleason

So if I assume:

200ah LFP x .35C (max) = 70ah + 10ah DC Loads + 20ah start battery= 100ah actual hot continuous output needed. To get the necessary alternator output 100ah x 1.42 = 142ah cold output rating is needed.

Now include the effect of the DC/DC B2B 70% efficiency at high output.
142ah x 1.42= 201 ah. This is ridiculous to get continuous hot output at the LFP batteries of say 90-100 ah and only roughly 50% efficient.

I am kind of hoping that you have over stated the case here, but happy to be proven wrong. So why does the LFP bank need to be charged at 0.35c? why not slower? I think Charles Sterling or his son, mentions A BB1260 is going to output about 50A. Which is 0.25c for the bank, plus 10A for the domestics, then drawing 60A from a 140A alternator ought to be possible, with some leeway for losses, heat and without running it flat out.

Why does the engine start battery need 20A? The amount of power the start battery uses to start an engine is tiny, this assumes it starts straight away.

Originally Posted by rgleason

I think would rather have a more efficient charge system that goes directly to the LFP or paralleled LFP/FLA (with disconnect relay) and have the proper regulation and controls so the charge does not go through a B2B Charger.

I am interested in what others have figured out or learned when using similar B2B systems.

Me to, I'm still pondering the simple cost effective solution. SMAC999 said the B2B are only 80% efficient, really? I must go and check that. He also said "outgoing current was way less in incoming". Probably is if you are going from a low voltage to a higher voltage, something must give and that is probably the current and the efficiency.

Be interested to hear what others have found.

Originally Posted by rgleason

I think would rather have a more efficient charge system that goes directly to the LFP or paralleled LFP/FLA (with disconnect relay)

That sounds like the Lithium-Hybrid system again.

https://www.zwerfcat.nl/en/lithium-hybrid.html

[Deividas]

Originally Posted by rgleason

So if I assume
200ah LFP x .35C (max) = 70ah + 10ah DC Loads + 20ah start battery= 100ah actual hot continuous output needed. To get the necessary alternator output 100ah x 1.42 = 142ah cold output rating is needed.

Now include the effect of the DC/DC B2B 70% efficiency at high output.
142ah x 1.42= 201 ah. This is ridiculous to get continuous hot output at the LFP batteries of say 90-100 ah and only roughly 50% efficient.

A little bit of difficult math to me But house batteries will not be 100% charged only by the alternator. Shore power, solar, and wind should do the biggest part in normal circumstances.

[cuffy]

Deividas
I have been running a system pretty close to your proposed for the last 2 years. We are full time lives boards spending the summer on anchor.
The Sterling B2B I have is the 60a and is 80% efficient. It quickly become evident that this was not good for solar charging My solar controller allows for end user custom settings ( Epever Tracer) so this is now connected directly to the lfp bank.
The 123 bms is OK, I love the app and the readings
that are available, but I to have a 0.2v difference between the boards, well 1 reading low. I believe that is in manufacturers tolerance but not good for top balancing on the go. I also have their relay, 120a, which does everything it says.
We have 400w of solar, with very little shading, which gives us majority of our needs throughout the summer, fridge, freezer and hot water, only using the Honda for about 8hrs this year.

[smac999]

The steerling b to b has big heat sinks and a fan that ran constantly. I can’t recall the exact numbers but I’d get something like 60a Input and 43a output. With similar voltages on both sides. After 15 mins the heat sinks were to hot to touch and it went into heat Protect mode. And would drop to like 20a output. Abd then cycle back and forth from 20a to 40a charging as it heated and cooled. From a 60a rated device.

The master volt mac plus is rated 97% peak eff. (95% worst) It has no heat sinks or fan. I had like 50a in and 49a out with simular voltages on both sides.

The steerling was the worst programming I’ve ever seen too. A nightmare of watching all the leds.

[rgleason]

Hi Pete, you bring up some good points.

Originally Posted by Pete7

.. hoping that you have over stated the case here, but happy to be proven wrong.
Why does the LFP bank need to be charged at 0.35c? why not slower?
Why does the engine start battery need 20A? The amount of power the start battery uses to start an engine is tiny, this assumes it starts straight away.
Still pondering the simple cost effective solution. SMAC999 said the B2B are only 80% efficient, really?
That sounds like the Lithium-Hybrid system again. https://www.zwerfcat.nl/en/lithium-hybrid.html

To answer why.

1. In my case we currently have no solar (30 watts) and I would ideally like to charge up batteries when going in and out of harbors for 30min-1 hour, so max C rate of .35C for lifepo is used. Earlier versions stated 1C or .5C, but the manufacturers have become more conservative. - Maybe I should not have waited so long to learn more? Yes, perhaps in time I would drop it down to .25C or .3C as I add solar and trying to forget the need to "top off" to prevent sulfation of FLA.
2. Perhaps you are right, depends on use. I was taking worst case, where we used the LFP and then had depleted the house bank somewhat, extending the time between recharges.
3. It appears there are more efficient DC/DC chargers, but we should really study and know for sure about performance before installing one. I think it needs to be at least 90% efficient and should not be installed in engine compartment or battery area or should have good airflow.
4. I think we need a new thread about DC/DC Converter efficiency and heat.

I keep going back to Franz Veldman's simple Lithium Hybrid System with one relay, a one port BMS, with common charge and discharge bus. Provided the charge devices:

• LFP Alternator regulator (Balmar ARS5 or 614 or Wakespeed LFP version or Al Tompson's VSR Alternator Regulator)
• 2 MPPT solar chargers for (2) 100w solar on adjust tilt posts
• LFP shore charger 15-20a clip-on

all shut off and work properly so the single relay never trips. I guess I don't care if when the single relay trips, the DC Loads then use the small "start" battery. If so, then a fancier dual port BMS with separate charge and discharge buses and relays aren't really that necessary. How often will the relay trip happen? In what conditions? What might be wrong that puts the LFP bank out of commission? Would I be able to operate with a single small AGM/FLA?

I think I prefer this setup to going through a DC/DC Converter because it is more efficient for charging and eliminates one device that adds inefficiency and heat. (Besides it is a small boat with no room for all this stuff.)

I do note that DC-DC Charger System is simple from a wiring point of view and safely allows use of LFP batteries with a built in BMS while protecting the LFP and the Alternator, which helps cruisers who don't want to mess with installing a BMS.


We need more information about DC-DC Chargers. Thanks smac999!