Sterling Alternator to Battery

[pvb]

Their current brochure uses exactly the same description as to how the unit works.....

"We put a "load" on the alternator to pull the alternator voltage down. This fools the alternator into thinking that there is a major drain on the system and as such, the standard regulator works at full current. However, the voltage is pulled down to a totally useless voltage for charging batteries. So the new system takes in this high current, but low voltage, and amplifies the voltage to charge the auxiliary battery bank at a much higher voltage than the base system voltage."

Aditionally it now has a new 'FEATURE":
2) Alternator temperature sensing: This disengages the unit in the event of the alternator temperature getting too high, it then re-engages the unit when the alternator cools down.

So nothing has changed except that it maybe 'turns off' the alternate for much longer to let it cool down for more than 3 minutes. This not only makes the charging much less efficient but also means it will take much longer.

Not a new feature at all. Exactly the same feature was included in the 2007 brochure which you got the graph from in post 14. Here's what the 2007 brochure said...

 

[Frankklose]

You are correct with the spike, for this reason there is still the start battery on B+. Without it would kill my equipment. I'm even considering a power zener Diode. Sterling calls it alternator protector.

 

[Poey50]

You are correct with the spike, for this reason there is still the start battery on B+. Without it would kill my equipment. I'm even considering a power zener Diode. Sterling calls it alternator protector.

I'm not going to say more about the problems with your choice of A2B (instead of B2B or direct charging by alternator and external regulator) but I do need to point out that your choice of Overkill BMS is also not suitable for a boat. The reason is that you cannot separate your load bus from charge bus with that BMS so when you get a high voltage disconnect (if you use the A2B) the whole LFP pack will shut down and disconnect all your loads. Similarly if a low voltage disconnect occurs you will not be able to charge the pack. Those things would be merely annoying when trying to cook supper in the back of an RV but safety critical in a boat negotiating a busy waterway at night since everything will go dead and be unreachable. It's exactly the same problem as with so called 'drop-ins'. DIY builds have the great advantage of it being fairly straightforward to separate load circuits from charge and the Overkill gives up that advantage.

I strongly advise that you read the Rod Collins paper and the Nordkyn series of papers before going further with your project. On the positive side you got those 280ah of cells for a great price. Don't spoil them!

Lithium battery systems | Nordkyn Design

LiFePO4 Batteries On Boats - Marine How To

 

[Frankklose]

I agree with the overkill it shuts off the charge fet but the the discharge fet stays connected
. A separate port BMS like the Daly would have been a better choice. The most common BMS with the RV ls the JBD and has lots of software support. Since the monitor meter is always connected the discharge stays. I was very worrid about the spikes and the disconnect. Was rather surprised that the spike was caught by the starter battery (had a scope connected and recorded with the computer the voltage. Was also very worried about the disconnect. I did some reading and know the writeup from Nordkyn and the how to. There is a publication f
of a Dutch sailor to use lead acid and lfp in parallel. That could be dangerous. I studied Electrical engineering and main course was RF design...
Most of the publications are for RV and not for boats. The commercial companies concentrate in the RV market.

 

[Poey50]

I agree with the overkill it shuts off the charge fet but the the discharge fet stays connected
. A separate port BMS like the Daly would have been a better choice. The most common BMS with the RV ls the JBD and has lots of software support. Since the monitor meter is always connected the discharge stays. I was very worrid about the spikes and the disconnect. Was rather surprised that the spike was caught by the starter battery (had a scope connected and recorded with the computer the voltage. Was also very worried about the disconnect. I did some reading and know the writeup from Nordkyn and the how to. There is a publication f
of a Dutch sailor to use lead acid and lfp in parallel. That could be dangerous. I studied Electrical engineering and main course was RF design...
Most of the publications are for RV and not for boats. The commercial companies concentrate in the RV market.

Signing off with this post as this part of the thread has drifted. I recommend you join the Lithium Batteries on a Boat Facebook Group - currently the best resource on the web for marine use of LFP. Instead of the Overkill or Daly look at the 123SmartBMS (this is what I have and is the lowest level of sophistication you should use on a boat IMHO) or Electrodacus, REC Active, or Orion Jnr.

 

[Dilemma]

I'm in a process to exchange the house batteries to lithium batteries. Will use the Sterling A2B to limit the charge current. As you might Know these Lifepo4 take as much current as they can get, which means they will damage the alternator. I got the 60A version and it supplies from a 50 A Sterling power supply 43 A to the lithium batteries. I have only been able to do bench testing because of Covic1p can't get to the boat. Order the blue 280ah from China and JBD BMS (Overkill BMS). The footprint of the 280ah is the same as the 120A Lead Acid. It gives me 250ah usable energy this compares to a lead acid 500ah.
Also with charging it takes the available 50A out of the charger which is also an older Sterling Charger. Was very afrthat the charger or A2B would be killed, but survived already a few 280Ah charging cycles. Just for info paid 403 Euro for the batteries and 70 Euro for the smart BMS with Bluetooth. Looking forward to install it on the boat.

Hi Frankklose, I have AGM house and Bowthruster batteries with a LA engine starter battery and a Sterling A2B. I would like to replace the house AGM with LiFePo4 and123BMS but retain the A2B , bow thruster AGM and LA starter battery. This fits the model proposed by Zwerfcat: Lithium-Hybrid.

The A2B overcomes a couple of the issues of connecting the LiFePo4 into my boat

1. I will use the alternator on my Volvo 2-40, protected by the A2B. To quote the A2B manual “The system will then sense the alternator temperature and will disengage the voltage amplifier if the alternator temperature exceeds 100°C.”
2. It will preferentially charge the LA starter battery: To quote the A2B manual “Starter battery priority: The system ensures that the starter battery is always kept in operational condition.”

There is one sailor (Flod) on Cruisers Forum that has good experience of the system: Lithium with Sterling Alternator to Batteri Charger - Cruisers & Sailing Forums

How is your install? Is it running now? What is your experience with the A2B and the 123BMS?

 

[Poey50]

Hi Frankklose, I have AGM house and Bowthruster batteries with a LA engine starter battery and a Sterling A2B. I would like to replace the house AGM with LiFePo4 and123BMS but retain the A2B , bow thruster AGM and LA starter battery. This fits the model proposed by Zwerfcat: Lithium-Hybrid.

The A2B overcomes a couple of the issues of connecting the LiFePo4 into my boat

1. I will use the alternator on my Volvo 2-40, protected by the A2B. To quote the A2B manual “The system will then sense the alternator temperature and will disengage the voltage amplifier if the alternator temperature exceeds 100°C.”
2. It will preferentially charge the LA starter battery: To quote the A2B manual “Starter battery priority: The system ensures that the starter battery is always kept in operational condition.”

There is one sailor (Flod) on Cruisers Forum that has good experience of the system: Lithium with Sterling Alternator to Batteri Charger - Cruisers & Sailing Forums

How is your install? Is it running now? What is your experience with the A2B and the 123BMS?

Flod on the Cruisers Forum ignores the advice from Sterling that the A2B does not limit current. People get away with all kinds of installations for LFP. Whether they get a long life from their investment is another matter. If you can find anyone sensible who would be prepared to use the Sterling A2B lithium profile of 14.6 volts absorption and 14.4 volts float I would be mightily surprised.

 

[IanCC]

On the face of it is a very clever idea to save the cost of having to modify the alternator, or buy a new one, but it is very very inefficient in electrical terms. It just puts a heavy load on the alternator to lower the voltage and sucks as much current as it can and then amplifies the voltage to charge the batteries. This can cause premature failure of an old alternator, so it would be more cost-effective to buy a new one that can be controlled by a cheaper external regulator.

Yes, it works and boosts the voltage, but the in-efficiency must be close to 30%. In previous versions of the publicity material Mr Sterling describes how it turns the main charging off for 3 minutes every 20 - he says to give priority to charging the starter battery. After 20 mins any starter battery will be fully charged, so I suspect this is to allow the alternator to cool down, but Mr sterling has made this a "feature".

3 mins in every 20 means 15% lost, and the high current DC to DC conversion will probably lose another 10-15%, you have a unit that does a job but you have lost 25-30% of any power produced by the alternator.

This is the graph from the old brochure showing the charge voltage dropping every 20 mins. He doesn't use this anymore, I wonder why?

View attachment 110633

Very interesting.
Re: 3 mins in 20. Surely it depends on battery to battery bank sizing. If one has an alternator rated at 70amps and a 210ah SLAcid domestic bank aiming for 60Ah usable, then 20mins will see Boost long gone so unlikely to be a problem. I think you know more than me. What am i missing?

 

[sailinglegend420]

Very interesting.
Re: 3 mins in 20. Surely it depends on battery to battery bank sizing.... then 20mins will see Boost long gone so unlikely to be a problem. I think you know more than me. What am i missing?

The battery is not charged when the Boost voltage is reached! The charger needs to stay at Boost voltage maybe for several hours before it drops to Float. Even at Float the battery will still be charging for several more hours. All the time in Boost and Flot it will switch on and off to keep the alternator cool. Modifying the alternator to take an external regulator is very cheap at an auto garage and a much better and much more efficient solution.

 

[IanCC]

The battery is not charged when the Boost voltage is reached! The charger needs to stay at Boost voltage maybe for several hours before it drops to Float. Even at Float the battery will still be charging for several more hours. All the time in Boost and Flot it will switch on and off to keep the alternator cool. Modifying the alternator to take an external regulator is very cheap at an auto garage and a much better and much more efficient solution.

That wouldn't be the case if you bought a Balmar posh regulator. Factory settings boost is 18 minutes and then 18 minutes absorption before switching to float.

 

[sailinglegend420]

That wouldn't be the case if you bought a Balmar posh regulator. Factory settings boost is 18 minutes and then 18 minutes absorption before switching to float.

Many people misunderstand the manual. I have a Balmar and this 18 minutes is confusing as it is modified by another parameter which lengthens this time dependent on how long it takes to get to the Absorption voltage.
So it can take hours at Absorption or minutes.

 

[Poey50]

I'm not sure I understand the reference to 'factory settings' on the Balmar external regulator. On my Balmar MC614 it is true that there are some selectable profiles but it has a remarkable range of user-configurable settings. There are some good MarineHowTo videos (Rod Collins) on how to programme these. Very good kit.

 

[IanCC]

I'm not sure I understand the reference to 'factory settings' on the Balmar external regulator. On my Balmar MC614 it is true that there are some selectable profiles but it has a remarkable range of user-configurable settings. There are some good MarineHowTo videos (Rod Collins) on how to programme these. Very good kit.

Just what i read from balmars publicity, that when bought their regulators are set up as described.