Sterling Alternator to Battery charger, dead Domestic bank

[Bob666]

Hi!

We have the Sterling Alternator to Battery Charger 80 A. It has two outputs:
Domestic +
Starter +

When putting the multimeter symbol for detecting if connection between point A and B:
I get "0000", not "OL" as expected. This means there is a connection between Sterling outputs Domestic and Starter.




Doesn't make sense as those are to two separate battery banks. There is a common minus in the system. However when charging I get different voltages on the two outputs.


I have emailed Sterling in UK but they don't answer emails.
The Sterling has always been like this. Did I get a faulty unit?


The thing is, the Domestic battery bank has died. It could be of high age (from 2011) or because the Sterling has in effect parallel coupled it with the Starter battery (which is conventional lead-acid). That would be catastrophic. But, should I have noticed? We've been cruising for four months and everything has worked ok, until a few nights ago when the NASA BM-1 Battery Monitor showed 10,5 V in the morning, and 0% charge of Domestic bank, before sun came up and solar panel started charging. Had left a few things on in the night, but should have set us back more than 10-20% in the Domestic bank.



Then did a capacity test of the Domestic bank, separated the four batteries and measured them one by one and determined that one is faulty, and two are not so good. I parallel coupled the three best ones, which is what I got now. Need to purchase four new ones.



It could also be the case that I am measuring a connection between Domestic and Start + outputs, but there is no current flowing, perhaps the Sterling, internally, has some smart system with Schottky diodes etc?


I would REALLY like to know what is going on here.


Cheers

[CatNewBee]

Originally Posted by Bob666

Hi!

We have the Sterling Alternator to Battery Charger 80 A. It has two outputs:
Domestic +
Starter +

When putting the multimeter symbol for detecting if connection between point A and B:
I get "0000", not "OL" as expected. This means there is a connection between Sterling outputs Domestic and Starter.




Doesn't make sense as those are to two separate battery banks. There is a common minus in the system. However when charging I get different voltages on the two outputs.


I have emailed Sterling in UK but they don't answer emails.
The Sterling has always been like this. Did I get a faulty unit?


The thing is, the Domestic battery bank has died. It could be of high age (from 2011) or because the Sterling has in effect parallel coupled it with the Starter battery (which is conventional lead-acid). That would be catastrophic. But, should I have noticed? We've been cruising for four months and everything has worked ok, until a few nights ago when the NASA BM-1 Battery Monitor showed 10,5 V in the morning, and 0% charge of Domestic bank, before sun came up and solar panel started charging. Had left a few things on in the night, but should have set us back more than 10-20% in the Domestic bank.



Then did a capacity test of the Domestic bank, separated the four batteries and measured them one by one and determined that one is faulty, and two are not so good. I parallel coupled the three best ones, which is what I got now. Need to purchase four new ones.



It could also be the case that I am measuring a connection between Domestic and Start + outputs, but there is no current flowing, perhaps the Sterling, internally, has some smart system with Schottky diodes etc?


I would REALLY like to know what is going on here.


Cheers

Its the faulty battery that dragged the rest down, a common issue in parallel setups. I guess, the sterling is ok.

[Bob666]

Thanks! There is not connections, i.e. "multimeter" tool shows "OL" when the Sterling is charging. Once it has completed charging and enters float phase or whatever, it goes into "timer on" mode, and then I get a faint connection, such as "0.194" (perfect connection is "0000").


Just beats me.


I also got 00.24 V on bank B, power turned off, but with an alarm connected (internal battery as backup) and stuff. I have put at least two relays between Battery bank A and battery Bank B, because I want one of the alarm systems to trigger the other one.


I read, from multiple sources, that the manouvering current circuit in a relay does not have any connection with the high current circuit inside the same relay. I sincerely hope so.


I think I don't have any problems and can go ahead and purchase batteries now. It seems with all modern electronics in a boat these days, you never get 0.0 V and 0 A flowing in every possible scenario even if all is turned off. And I have a fat solar panel so they always get a little charge, except during the nights of course.



The nearest dealer can get either 4 cheap batteries, 75 Ah each, or something better, like Mastervolt Gel or AGM. What do you recommend for an Atlantic crossing (in two months)? Maybe spend at least 1000 EUR or USD 1192 for the four? Maybe more? I would be nice, if I treat them right, if they last +10 years from now.


Has there been any improvement in the size/weight vs Ah ratio for lead-acid batteries lately? Would like to get more than 300 Ah (current bank) but with limited space. Does this differ between technologies such as: lead-acid vs. Gel vs. AGM?

[CatNewBee]

Originally Posted by Bob666

Thanks! There is not connections, i.e. "multimeter" tool shows "OL" when the Sterling is charging. Once it has completed charging and enters float phase or whatever, it goes into "timer on" mode, and then I get a faint connection, such as "0.194" (perfect connection is "0000").


Just beats me.


I also got 00.24 V on bank B, power turned off, but with an alarm connected (internal battery as backup) and stuff. I have put at least two relays between Battery bank A and battery Bank B, because I want one of the alarm systems to trigger the other one.


I read, from multiple sources, that the manouvering current circuit in a relay does not have any connection with the high current circuit inside the same relay. I sincerely hope so.


I think I don't have any problems and can go ahead and purchase batteries now. It seems with all modern electronics in a boat these days, you never get 0.0 V and 0 A flowing in every possible scenario even if all is turned off. And I have a fat solar panel so they always get a little charge, except during the nights of course.



The nearest dealer can get either 4 cheap batteries, 75 Ah each, or something better, like Mastervolt Gel or AGM. What do you recommend for an Atlantic crossing (in two months)? Maybe spend at least 1000 EUR or USD 1192 for the four? Maybe more? I would be nice, if I treat them right, if they last +10 years from now.


Has there been any improvement in the size/weight vs Ah ratio for lead-acid batteries lately? Would like to get more than 300 Ah (current bank) but with limited space. Does this differ between technologies such as: lead-acid vs. Gel vs. AGM?

Well, I do not like the lead acid stuff.

But a general rule of thumb for house batteries is:

The heavier they are and the less capacity they have, the longer they live.

Cheapest and sturdiest are plain lead acid golf cart patteries, which you can top up with water. Most lead, thick plates, little capacity per kg.

The more sophisticated a battery is, the more expensive it will be. Beware of using start batteries as house batteries. they are optimized for short high current use and not for deep cycling.

AGM spiral cells or GEL batteries are sealed maintenance free, deep cycle batteries, but they die too if not proper maintained. (drying out when overcharged, sulphation if left alone without keeping them at 100% SOC).

[john61ct]

Email Charles directly, he's usually pretty responsive.

Also UK and US each have different first-level tech support.

Phoning may be better than email sometimes.

[john61ct]

Also try pinging Maine Sail, he may find it interesting enough to address, or know the answer straight off.

[Bob666]

Thanks guys. We'll see where that leads. In the meantime. Will order batteries through a ship yard tomorrow. I think AGM will be ok? From a pretty good brand?

Not going to get GEL again. Fail to see any reason to. The alternator is rated to 50 A only. If it fails we'll get an 80 A alternator (the Sterling Alternator to Battery charger is rated to 80 A so I could get that but not more, right?).



Got 300 Ah Domestic power today and can only fit 4 x 75 Ah batteries without major rebuilding of boat. Could maybe add a fifth battery and get 375 Ah AGM. Would be a bit of a distance from the other four batteries though. Can be ok if I have thicker cables?



What about the parallel-coupling? I've done it with 35 mm2 cables in a cross-section wise fashion per recommendation. Is it ok to attach a fifth battery just to battery 3, for example, or will I mess up the bank then? My 35 mm2 are not exactly equal in length but all rather short so I think ok?


https://www.windynation.com/jzv/inf/...e-battery-bank
Here they have connected minus to the third battery. I connected it to the fourth to have all current going in and out go through all batteries. Better/worse?



Cheers

[john61ct]

Canonical starting point.

http://smartgauge.co.uk/batt_con.html


All the intra-string wires should be same gauge and length.

For parallel connections, same between pos/neg.

All loads and charging from same posts, and yes flow though the whole bank.

Post a drawing for feedback, showing distances.

[Bob666]

Originally Posted by john61ct

Canonical starting point.

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank


All the intra-string wires should be same gauge and length.

For parallel connections, same between pos/neg.

All loads and charging from same posts, and yes flow though the whole bank.

Post a drawing for feedback, showing distances.

Great, thanks.



SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank
(great link!)



I have method 2 currently. My little girl is sleeping on top of the batteries so cannot measure right now, but will post drawing shortly. If I may ask, in the meantime, what if I add cables to get method 4, but without remedying the situation with cables not being of the same length?


Asking as I am a bit lazy yes, not saying I won't do the job to remedy this but in my case (as coming drawing will show) one of the four batteries have to be further away from the others, which means all the cables then would have to be long. Not ideal. I could however, but seems like complicated math, have a thicker cable to the off-center battery.


If I introduce a battery 5, which has to be maybe 2 meters away, I would rather have a thicker cable to that battery than having 2 m cables between ALL batteries. Again, seems like complicated math. What if cost wasn't an issue and I put different lenghts but 200 mm2 cables between all batteries? Surely the thickness cannot be important then?


It is not likely, but not impossible, that we'll buy a fifth battery.



When installing I figured 35 mm2 to be quite overkill, compared to previous owner's 16 mm2. I got cable lengths from 20 cm to 60 cm today.

[Bob666]

Originally Posted by john61ct

Canonical starting point.

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank


All the intra-string wires should be same gauge and length.

For parallel connections, same between pos/neg.

All loads and charging from same posts, and yes flow though the whole bank.

Post a drawing for feedback, showing distances.

Better answer:
See attached image. Not exact figures but roughly correct lenghts.



I got 350 mm - 950 mm, i.e. very varied. All 35 mm2 gauge. Battery 3 is slightly off-center due to bulkheads etc.


The battery pole terminals are high-end and have plenty of free terminals so I could also have 2 x 35 mm2 cables in some places, rather than swapping cables.

Is there a way to calculate what should be there?

Off work a year, so have to be cost-conscious, maybe better with slight resistance but same everywhere than virtually no resistance.


I also attached the measurement table when I did my capacity testing. Sorry for the Swedish but you'll see that battery four failed miserably.


Thanks!

[Bob666]

An additional question please:


In Method 4. Does it matter how long the cables are "to installation"? Or all ok if I just adhere to what's included in the drawing?


Theoretical question:
If I got 2 identical batteries and connect them in parallel. + cable between battery 1 + and battery 2 + is 1000 mm2 and 10 mm in length. - cable between battery 1 + and battery 2 + is 10000 mm2 and 20 mm in length.

...what I am getting at is, does the length matter at all, besides it adding up to the resistance number? The speed of light is...fast!


I have this on stock in the boat:
35 mm2 x 670 mm
25 mm2 x 1100 mm
25 mm2 x 2050 mm
16 mm2 x 400 mm
10 mm2 x 1450 mm
10 mm2 x 800 mm

Would like to use to boost the battery installation. Buy as little new cable as possible.


Sorry for the extra post, will await answers. Thanks!

[senormechanico]

The diode check on the meter is not intended to be used on a live circuit.
In the reverse direction, it will read OL, and in the forward direction it reads a voltage drop which is powered by an internal battery in the meter.
Read the directions...

[john61ct]

My limited understanding is that the variability as voltage and currents rise and fall make equivalencies impossible.

Same length & gauge.

But, we're not talking catastrophe here, just shortened lifespan from the resulting imbalance issues. Of course assuming replacing the whole bank at once, weakest link determines bank lifetime.

Cost benefit calculations between the choices are complex.

My default is, do it right, wiring is a once off project, banks are consumables try to make them last.

But in the end your rig your choice.

[Bob666]

Originally Posted by john61ct

My limited understanding is that the variability as voltage and currents rise and fall make equivalencies impossible.

Same length & gauge.

But, we're not talking catastrophe here, just shortened lifespan from the resulting imbalance issues. Of course assuming replacing the whole bank at once, weakest link determines bank lifetime.

Cost benefit calculations between the choices are complex.

My default is, do it right, wiring is a once off project, banks are consumables try to make them last.

But in the end your rig your choice.

Thanks. If I don’t change current cabling, add cables to get method 4, and beef up some of the long runs by adding additional cables there (instead of replacing with thicker). And without much measuring or calculating, instead more on a “feeling” basis.

It will not adhere to principle “same cable length”.

Will it improve my situation?

Update: dealer currently checking batteries for me. Some language barrier exist (Spain). Should I go for deep cycle or dual purpose?

It is 4 x 75 Ah so shouldn’t deep cycle rather than dual purpose be ok even if the bank is used for cranking the engine? No other high ampere usage besides that.

Cheers

[smac999]

fisrt of all you can't use an ohm meter on a powered wire. so if both posts are connected to the batteries you can't use an ohm meter between them. you would have to disconnect both batteries from the steerling to ohm between the 2 outputs. I would probably even disconnect the alt too. but I don't think that should mater.

if the voltages on the 2 outputs are different as you said. then obviously they are separated. otherwise both voltages would be the same.