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Old 13-09-2018, 15:01   #1
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FLA LA (FLA,AGM,GEL) 100%SoC House System

LFP is expensive and needs a BMS with LVC and HVC and there is a concern about connecting the alternator to LFP due to the possibility of a HVC event which would also damage the Alternator.

Here's is a suggestion which accepts that the starter battery is sacrificial (3-5 years) and is used to charge the House bank to full. Eventually over several days the starter battery would be charged by some small solar panels over a number of days. There is no need for a Sterling Alternator Linearizer.

Alternator -> Starter Bank-> B2B Charger -> House Bank & Starter -> Loads

The House Bank will have to be charged via the ICE Engine/Alternator up to 90%SoC at which point the Sterling12v40a Battery to Battery charger would take over to top it off.

The sacrificial starter battery will be left at 50%SoC and will be recharged by a second Engine/Alt charge session up to 80%SoC or excess Solar PV over a number of days. SolarPV will be connected to the Starter Battery.

Both banks would be FLA. Perhaps the Start Battery will be AGM or GEL. (Suggestions which would be best would be appreciated)
Starter Bank
- 80ah Range 50-80%SoC=.3C=24ah

House Bank
- 225ah Range 50-80%SoC=.3C=66ah Alternator
- 225ah Range 80-90%SoC=.1C=22ah Alternator
- 225ah Range 90-100%SoC=22ah B2B Charger

I think the Sterling Pro Ultra Charger would be connected to the Start Battery.

Ideally would be a much simpler system which uses Lead Acid batteries only and accepts the fact that the starter battery may have a 3year life, but keeps the House Batteries charged.

Is there any need need for an ACR?
Many thanks to Qayag for his FLA LFP Hybrid Idea and all that are contributing
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Old 13-09-2018, 15:27   #2
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Does the added cost of this system, $250-$350 Sterling B2B Charger make it worth considering Firefly Batteries.
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Old 13-09-2018, 16:16   #3
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Maybe I'm not following correctly. These are all LA batteries, right? If so, why not just have the alternator charge the house bank, and use an ACR, or a B2B charger to top up the Starter battery. That's how my last boat was set up.


The reason is that I think you want the max power of the alternator available to charge the larger house bank, and to support the larger house loads. I sure did. With the B2B charging the house bank, you are limiting charging rate to the B2B where the alternator is probably much higher capacity.
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Old 13-09-2018, 17:05   #4
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Tanglewood, good point about using the alternator, but with the Sterling B2B the alternator output/acceptance would be the same whether it is used with the smaller battery or larger bank attached. Switching the Alt to the House Battery it would be this way and I think the ACR would be useful when the alternator is working. Then after the alternator stops, the ACR would be hard disconnected and the Sterling B2B Charger would take over to bring the House up to full.

Alternator -> House Bank & Starter-> ACR > Reserve Bank

After House is 90%Soc

Reserve Bank -> Sterling B2B Charger -> House Bank to charge to 100%SoC
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Old 13-09-2018, 17:44   #5
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

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Originally Posted by rgleason View Post
Tanglewood, good point about using the alternator, but with the Sterling B2B the alternator output/acceptance would be the same whether it is used with the smaller battery or larger bank attached. Switching the Alt to the House Battery it would be this way and I think the ACR would be useful when the alternator is working. Then after the alternator stops, the ACR would be hard disconnected and the Sterling B2B Charger would take over to bring the House up to full.

Alternator -> House Bank & Starter-> ACR > Reserve Bank

After House is 90%Soc

Reserve Bank -> Sterling B2B Charger -> House Bank to charge to 100%SoC

I'm envisioning an alternator with significantly higher output than the B2B. Say 150A vs 50 for the B2B. It would be nice to dump that all into the house bank as fast as possible.
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Old 13-09-2018, 17:57   #6
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Yes, that is true. I was considering 120a with belt program set down to 80a for FLA
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Old 13-09-2018, 21:54   #7
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Feedback, some nitpicky about terminology if that's OK

Quote:
Originally Posted by rgleason View Post
possibility of a HVC event which would also damage the Alternator.
HVC (/ HVD / OVD) is a device, shuts off in response to an overvoltage or too-high voltage event.

> Alternator -> Starter Bank-> B2B Charger -> House Bank & Starter -> Loads

B2B charges from Starter to House. Starter is not a target.

> The sacrificial starter battery

Starter is not sacrificial, the latter means throwaway, "has no other function, may be destroyed without affecting other functionality"

In this case either a lead Starter **or** a little $20 batt can act as a protective load dump. Not just for alternator diodes but sensitive load devices.

> The sacrificial starter battery will be left at 50% SoC and will be recharged by a second

No, Starter is always Full, B2B spoofs the alt into thinking it isn't so it feeds high current, but Starter does not get significantly depleted.

So no need to do anything special to take care of Starter. Much less if a sacrificial lead batt is used instead.

Solar can be left out completely, whole point of Hybrid idea.

> Both banks would be FLA. Perhaps the Start Battery will be AGM or GEL.

What "both banks" are you talking about?

No reason to use anything but FLA for Starter, but if you want to spend more you can, no difference to the core idea.

If House is lead, no B2B is needed, just use an ACR. Now you've got me confused.

> 80ah Range 50-80%SoC=.3C=24ah

No idea what above is supposed to mean, please put in a sentence.

Same with this:
House Bank
- 225ah Range 50-80%SoC=.3C=66ah Alternator
- 225ah Range 80-90%SoC=.1C=22ah Alternator
- 225ah Range 90-100%SoC=22ah B2B Charger

Sorry but maybe best to just ask questions to clarify things in the main thread, I don't mind putting in time helping you learn but

correcting and getting confused by such "proposals" is time consuming,

it's clear you are missing some basic understandings, but here in fact I have no idea what the problem is you are trying to solve.
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Old 14-09-2018, 05:34   #8
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

John, the idea is to use the starter battery with the Sterling B2B to top off the house batteries to 100%SoC even if two sessions of ICE are needed to do that, leaving the start battery at a lower state of charge and ensuring the house bank is fully charged. The start battery will be charged over multiple days by PV. It would probably have to be replaced every 3 years, yet the house would last 6-8 years.
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Old 14-09-2018, 05:35   #9
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

John thanks for the training :-)
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Old 14-09-2018, 06:02   #10
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Quote:
Originally Posted by rgleason View Post
Here's is a suggestion which accepts that the starter battery is sacrificial (3-5 years) and is used to charge the House bank to full.

Alternator -> Starter Bank-> B2B Charger -> House Bank & Starter -> Loads

The House Bank will have to be charged via the ICE Engine/Alternator up to 90%SoC at which point the Sterling12v40a Battery to Battery charger would take over to top it off.

The sacrificial starter battery will be left at 50%SoC and will be recharged by a second Engine/Alt charge session up to 80%SoC or excess Solar PV over a number of days. SolarPV will be connected to the Starter Battery.

Both banks would be FLA. Perhaps the Start Battery will be AGM or GEL. (Suggestions which would be best would be appreciated)

I think the Sterling Pro Ultra Charger would be connected to the Start Battery.

Ideally would be a much simpler system which uses Lead Acid batteries only and accepts the fact that the starter battery may have a 3year life, but keeps the House Batteries charged.

I'm not able to follow all your ideas...

But FWIW, if you make the starter battery a good AGM, it won't self-discharge much, and it won't be sacrificial. Something like an Odyssey PC-2150 out to start your engine for 10-15 years or so... with no other charging except your engine alternator.

I think I'd connect the charger directly to the house bank and call it good... but I'm influenced by our own situation, with generator available on demand, etc. Presumably your engine alternator can be made to also charge your house bank while underway, though...

-Chris
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Old 14-09-2018, 06:53   #11
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Quote:
Originally Posted by rgleason View Post
John, the idea is to use the starter battery with the Sterling B2B to top off the house batteries to 100%SoC even if two sessions of ICE are needed to do that, leaving the start battery at a lower state of charge and ensuring the house bank is fully charged. The start battery will be charged over multiple days by PV. It would probably have to be replaced every 3 years, yet the house would last 6-8 years.
No.

Lead should be left Full AMAP, PSOC should never be intentional.

Batt to Batt charging with lead as source means with a primary charge source running.

The LFP as source is an out-there thought experiment, only sound as theory. Lead to lead with no primary charge source is worst of all worlds, no positive to justify the madness 8-)

All charge sources should go direct to House

Starter batt is dedicated to just one thing, otherwise use a different design model.

My Main/House vs Reserve maybe.
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Old 14-09-2018, 07:28   #12
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

I think I understand your idea -- so you mean to burn the starter battery, intentionally running it at PSOC in order to top off the house bank and keep it healthy, right?


If so, this is similar to the lithium/hybrid idea we've been discussing.


I think the problem with this will be the same one we just found in the lithium/hybrid idea -- charge efficiency.


Let's run the numbers -- 225 a/h (is that right? That's an awfully small bank). The 15% we don't get in when we terminate charging at 85% is 34 a/h. But charge efficiency at that stage is only about 50%. So we will have to use something like 68 amp/hours of power to put on the finishing charge. That's more than the starter battery will have to give, even it it's 100% full when you start. If you're cycling it at PSOC like the house ones, there will be even less. You will need quite a big battery to give you that much power even if you're happy to "burn" it by running it that way all the time.


And of course you will kill it quickly. I guess you will be ruining battery material faster, by concentrating this PSOC abuse in one battery, than you would be if you spread it over multiple batteries.


Of course you could use a single Firefly or lithium for this, and it would work much better.


But then we come back to the old question -- is it really worthwhile to sacrifice a good battery to keep a bunch of crappy ones inefficiently in the regime they need, instead of just using the power directly from the good batteries? 68 amp/hours of power is a significant percentage of the real usable power of a 225 amp/hour lead bank -- so you could make the one "good" battery a little bigger and just toss out the crappy house bank.


Anyway, that's how it looks to me.


Another important issue here -- do you really want to keep your STARTING battery at 50%? What do you do when you need to start the engine? Starting diesel engines was always for me a really high priority, something I did not want to risk, not being able to do.


I think if your needs are served with 225 amp/hours of lead, there ought to be a better solution. If not lithium, why not simply a larger bank of golf cart batts? How many cycles do you need to get?


I think that last question is a key one for the lead vs lithium decision. Lithium has a lot of advantages, but it is also CHEAPER, but only if you can actually use several thousand cycles within your lifetime.



We had one disruptive guy on this forum who sells cheap "leisure" batteries to his clients, and who was always insisting, arguing with anyone, about the virtues of these cheap batteries vs. lithium. But that's a wholly inappropriate comparison -- if you use your batteries so little that you can get more than a year out of leisure batteries, you shouldn't even start to think about lithium, which is a solution for the opposite end of the range of use cases. Lithium is a very expensive solution if you only cycle your batteries 40 or 50 times a year.


And if you only cycle your batteries 40 or 50 times a year, and if you're on shore power the rest of the time, then decent lead batteries will last a long time, with or without solar power.


So to the OP of this thread -- how about a larger bank, made of decent heavy duty batts like Trojan T-105's? Four of those will double the size of your bank, making it much easier for you to avoid deep discharges.



With the money you save not messing around with special connections with the starter bank, invest in a well regulated alternator, as heavy duty as you can fit on your engine (Mark Grasser makes semi-heavy duty small case alternators, for example).



If you really think you will be cycling a lot, then why not just straight lithium?


You can save money by making it quite a bit smaller. In combination with a decent sized alternator, it would not be so painful to charge twice a day if you need to. So how about 100 amp/hours or 140 amp/hours of lithium? That's really not expensive at all and might be cheaper than lead if you are spending much time off shore power.
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Old 14-09-2018, 08:59   #13
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

Dockhead wrote:
I think I understand your idea -- so you mean to burn the starter battery, intentionally running it at PSOC in order to top off the house bank and keep it healthy, right?

If so, this is similar to the lithium/hybrid idea we've been discussing.

Yes, correct.
Re 68ah finishing charge, I have no problem running ICE charging twice to get house fully charged.

Also there will be 100watts PV to charge both banks over multiple days. I don't expect too much Psoc abuse. Sailed from mooring, no or very little dock time. Out cruising 2 weeks average length, about 4x's per season, anchoring nightly, use 80ah per day, have ozifridge with big evaporator which holds temp 12hrs. Also expect/plan longer 1500 nm at sea using 140ah.

Current house batts are 2- Trojan T-105 new this summer. 225ah is more than we have had historically (2x70=140ah) but I would not mind having 300-450ah however space is limited. Small boat. When cruising we typically charge 2xs per day going in and out of harbor (45min-1.5 hr duration).
New alt will charge 40amps at 850 engine rpm and 80a at 1000 engine rpm, with a 2.2 belt ratio.




Planning a "Small Boat Electrical System" (thread) with new wiring, Balmar 120v alt + serpentine, Sterling charger, ACR, etc.

The current problem is finding a good location in the cabin under the seats rather than the more exposed cockpit locker. The choice is starboard side (height restriction requiring a change in batteries, about 9")
or port side (12" ht, accepts T105, problem is boat will list to port!).

I have been considering getting firefly house batteries and fitting them on the port side to solve the "listing" unbalenced problem. Then selling the Trojan perhaps.

The 2013 3YM30 Yanmar starts instantly with an old 70ah west marine AGM, 8 yrs old with no glow plug. It also starts easily off the house bank.

So what you are suggesting is just go with Firefly or LFP and forget using the start/reserve battery to top off the house bank and save the $300 cost of a Sterling battery to battery charger.

This would allow installation of the batteries under the cabin port seat, keeping boat port/starboard balence. Additionally it would save about 6' cabling in a 30' total run, which really helps voltage drop. I really do not want to go over 2/0 main wires.

If I could relocate the 3-way Switch to inside the battery box or closer to the battery box, I think I might save another 4'-5' in the main runs, but I don't know if this is a good idea from a practical standpoint.

So the real question if I am forced to get new batts again, is 2 Firefly G31 about $1000, or Lithium Winston with some BMS costing more like $1500 or $2k.

Thanks. Your thoughts are appreciated.
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Old 14-09-2018, 09:09   #14
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

I had this reversed:

cabin under the seats rather than the more exposed cockpit locker. The choice is PORT side (height restriction requiring a change in batteries, about 9")

or STARBOARD side (12" ht, accepts T105, problem is boat will list to STARBOARD.


I believe that Firefly still needs topping off with PV to regain capacity etc.
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Old 14-09-2018, 14:38   #15
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Re: FLA LA (FLA,AGM,GEL) 100%SoC House System

FF doesn't care the power source.

For control best to use shore, just like conditioning FLA.

My main point in using LFP for long-tail charging of a House bank,

is there is no harm for LFP to sit at PSOC, in fact healthier than if Full.

Using lead as the source when it will be quickly murdered makes this a non-starter. Pun intended.

By definition a Starter is / should be used only for cranking.

A Reserve bank likewise, not used for regular cycling.
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