Sterling AB1290 and Battery switch

[Dave_Rolfe]

I have recently purchased a Sterling Alternator to battery charger (AB1290) which I intend to fit on my boat this winter while it is out of the water. I currently have two 110 Ah batteries fitted which I will be wiring in parallel to use as domestic batteries. I will also be fitting a new, third battery to be used as a dedicated starter battery. I currently do not have this as one of the existing batteries is used for engine start.

I am hoping with this setup to maximise the charge into the domestic batteries while maintaining a fully charged starter battery at all times. The AB1290 includes a split charge diode with the circuitry apparently compensating for the voltage loss of the diode

On the Sterling site I have found a wiring diagram for a simple installation which mine is but it does not include a battery switch. I have a 1-2-both battery switch currently fitted that I want to include and retain. When queried with Sterling themselves the reply I received was ‘Your battery switch would have nothing to do with this , simply connect this
as per the instructions and leave you battery switch in if you wish’ which I did not find very useful



My question is (yes there is one finally) – where should the battery switch be included in the wiring to allow the AB1290 to work efficiently but to retain the battery switch so I can still isolate everything when leaving the boat.

I have hopefully attached a link to a copy of the wiring diagram from the Sterling site below.

http://www.marine-super-store.com/posit/shop/index.php?selectedpartno=99197766

Thanks for any advice you can give me again.

 

[AIDY]

email sterling back to ask through there webpage.....

i emailed a question to them last night and had a efficient technical reply by mid morning.

 

[Dave_Rolfe]

My reply from Sterling to my e-mailed query was copied into my main text. You must have had a more useful response

 

[halcyon]

You can use the following diagram as a basis, ignor the relay connected to terminal 1 and 2.

Connect the Sterling engine battery output to the output terminal on the 1,2,both switch, the service battery Sterling output to the output side of the new isolator switch.

You run the engine on the 1 position, and turn the new isolator switch on for service power. If you have a flat engine battery you can select 2 to run from the service battery, and isolate the flat engine battery.

Hope this makes sense.

Brian

 

[Dave_Rolfe]

Am I reading this correctly ? If I substituted the P2400 for my Sterling AB1290 wired as per the diagram (ignoring the orange cable) all would work correctly. It seems too easy.

 

[halcyon]

No.

Connect the Sterling engine battery terminal to the output of the rotory switch, and the service battery output to the output side of your new isolator switch.

This will allow you to isolate the batteries and the Sterling unit from them.

OK ?

Sorry it looks simple, but I have spent the last 30 years trying to make charging systems simple.

Brian

 

[Dave_Rolfe]

Sorry Brian I seem to have misled you. I intend to use the existing 1-2-both battery isolation switch which i take would be the circle with 1, 2 & output on you diagram. No new battery isolation switch will be fitted

What I want to do is to be able to incorporate the existing switch into the new system that will have the Sterling unit to charge the new engine battery (new No 1) that I am to add and the two existing 110Ah batteries that are currently Nos 1 & 2 on the battery switch but which will be wired in parallel to become 220Ah of domestic battery (No 2).

I hope this is clearer and helps in any answers to my query.

As you might have guessed, I am not an electrical wizard at all, wish i was. I just need to get my head round what i need to do. Thanks for your patience

 

[halcyon]

I do not think you can do what you want with the Sterling unit. It works as per the diagram with the relay because it is bi-directional, thus it does not matter what battery is connected to the engine, the relay will charge the other.

The Sterling unit assumes a dedicated engine and service battery, with only your 12both switch you do not have it. But by fitting only one new isolator switch and a new link cable cable you can make it work.

Brian

 

[alan]

On the Sterling web site they say that if you have a split charge diode, then you can just bolt this unit in place of it (15mins).

If you have a look at the Adverc web site they show you some typical wiring diagrams with split charge diodes, 1/2/both/off switch and their alternator regulator. If you take Diagram#1 and ignore all the bells and whistles (i.e. Adverc regulator, solar panels, wind gen e.t.c.) then you should be able to fit your Sterling unit in place of the split charge diodes and including the 1/2/both/off switch.

I have only had a quick look at this, so you should check it out properly before doing it ............. but it may give you a pointer.

EDIT: I just looked at the Diagrams on the Adverc site again and noticed that they have an additional isolator for the engine start ............. sorry for misleading you!!!! But good diagrams anyway.


Alan.

 

[Chris_d]

You can't use your 1-2-both switch, it will effectively short out the Sterling, the switch will no longer function as you want it too. The best solution will be to replace the combined switch with 2 new single switches in the load lines of your batteries, one for the domestics and one for the starter.

 

[VicS]

The Sterling AB1290 is an advanced alternator regulator, with outputs for two battery banks, the design of which overcomes the voltage drop problems associated with simple diode splitter circuits.

The use of a 1, 2, off, both switch with devices like this is not appropriate.
Separate isolator switches are appropriate with dedicated starting and domestic battery banks and any form of split charging.

You could however incorporate it so that the domestic circuits could be powered from either source (or both) or so that the engine starting could be selected to either (or both). That is basically what Brian's circuit does, except that the P2400 is some form of battery combining device which would be unnecessary once your Sterling charger is fitted.

HOWEVER I would have serious reservations about this because I do not know what implications selecting "both" would have on the AB1290 in view of the fact the two outputs are individually controlled. (Chris d says that but he thinks quicker than me)

Note Brian's circuit shows an isolator for the domestic circuits in addition to the 12offboth switch which then serves as the isolator for the engine electrics only.

My advice would be to ditch the 12off both switch if you are using the AB1290 and wire it as recommended OR ditch the AB1290 and its advanced charging features and use some form of VSR or battery combining relay as in Brian's diagram.

A better place than chandlers websites to read descriptions and view circuit diagrams is Sterling's website

 

[Chris_d]

Yes, basicaly the only place you can use the 1-2 switch is in the output lines of your 2 domestics, but with the new Sterling unit keeping the batteries efficently charged it would be a bit pointless. Best to keep it simple and only use a single switch.

 

[Dave_Rolfe]

Thanks for all your help. I am still confused as to how I need to wire the unit into the existing circuits on board but from all the replies I at least know that it will not be as straight forward as I thought it should.

Could I just leave the existing wiring in place and wire the Sterling unit direct to the batteries as shown on their diagram for a simple unit, then just use the 1-2 battery switch to switch for engine start or domestics?.

 

[AlanPound]

Well, having read this thread, I'm not too clear myself about what to think about this device.

But having now looked at the various web sites, and done a very quick assessment, I would say from...

[ QUOTE ]
This new product incorporates a split charger diode system to charge 2 battery banks. However, on the domestic battery bank only, there is a unique power amplifier on this channel

[/ QUOTE ]

... and from some other related information that:-

* This device is not intended to be used with a 1/2/both switch - it basically replaces both that, and a split-charge device.

* It contains a "split charge diode" (not usually regarded as the most efficient approach - but it should work ok - see below) to charge the starter battery.

* The "power amplifier" is a switch-mode boost regulator circuit, that in operating, loads up the alternator (even though, and such that it's output voltage is below that which would normally be able to charge a battery - especially via a split-charge diode), and produces at its output a voltage that *will* charge the domestic batteries at an efficient rate. It does this under control of the usual kind of smart-charge regimen.

* Every 15 mins, it has a 2.5 minute "rest", and during this time (and this time only), the alternator output is sufficient to charge the start battery via the split-charge diode. (That's probably enough for most normal situations - however, the situation isn't normal if you have problems starting, thus have to crank excessively, but then only have a short running time to recharge the start battery - you are probably *worse* off then with this device than with a more traditional approach).

So I would say, in terms of what it sets out to do (provide a much more efficient charging regimen for the domestic batteries) that it probably acheives it's aims, but not without some little "gotchas".

It would undoubtably be better if there was a second boost regulator to fast charge the start battery, but that would certainly increase the cost, and the benefit in normal use would be small.

My own main concern would be that with Stirling's circuit as shown, there is no simple fall-back to utilise the domestic batteries in the event that the start battery got itself flat.

But if we take the words on the web-site at face value, then a simple switch to parallel the start battery with the domestic batteries would be sufficient (or indeed, a handy car jump-start cable would do the job). Once the engine started, the charger would reverse-bias the split charge diode, and see the start battery added to the domestic bank, but that should do no harm to the system (*if the words on the web-site can be taken literally*)

I'm sure a call to Stirling, with the simple question "in a flat start-battery situation, could I simply parallel the start and domestic batteries...", would get a simple answer (which I would expect to be "yes").

In that case, simply go with his circuit exactly as shown, except with a simple battery switch (reuse one position of your 1/2/both switch) to parallel your batteries in a flat start-battery emergency.

 

[VicS]

[ QUOTE ]
I am still confused

[/ QUOTE ] You have to start by accepting that the 1 2 off both switch has no real place in the system once you separate engine electrics from domestic electrics and use the AB1290! Many people would not use such a switch anyway, such is their reputation for unreliability.

Two suggestions for wiring the unit below. Both are based on the circuit from Sterling but include two isolating switches. In one the isolating switches isolate the domestic and engine circuits, in the other they isolate the batteries completely.

Comments are invited and maybe it would be good idea to run the ideas past Sterling.

There is, I realise, no provision for using the domestic bank for engine starting. A third switch to parallel the battery banks may not be accepatble due to the sepately controlled outputs from the AB1290. That is a question to put to Sterling.

 

[AlanPound]

Well yes, it does make absolutely good sense to be able to completely isloate the batteries (with the usual caveat not to do it whilst the alternator is running) - and for me, your lower circuit is the one to use (with an additional switch to parallel the two banks, as you have noted).

The only other thing to think of, is how you will re-arrange your wiring back to the original configuration when the clever charger dies a death and packs up (as inevitably, like every other piece of electronics on a boat, it will.)

 

[VicS]

[ QUOTE ]
with an additional switch to parallel the two banks, as you have noted

[/ QUOTE ] The point I was really trying to make is that a switch that parallels the battery banks may not be acceptable because it would also interconnect the two outputs from the AB1290. That may be OK or it may be a complete no no. One would have to check with Sterling to find out if that is acceptable or not.

 

[halcyon]

As I said at the start, he can keep his 12both switch, but with addition of a isolator switch, run the Sterling unit, and start from the service battery without linking the batteries.

Brian

 

[VicS]

[ QUOTE ]
As I said at the start

[/ QUOTE ] A diagram actually showing what you had in mind would have been helpful ... worth a thousand words.

However if I understand you correctly what you have in mind is below.

It was an option I had already considered BUT my fears about it are the consequences of switching to the "both" position which would not only interconnect the two batteries (no problem there) but would also connect the two outputs of the AB 1290 together. I would not want a system able to do that unless Sterling say it will cause no problems to the unit.

Now if the 1,2 off both switch could be replaced with a changeover switch with an off position that would be fine.

Added later:

I have now re-read AlanPound's post and the instructions for the AB 1290 on the website. I agree with what Alan says . If you take the descriptions on the website at face value interconnecting the two outputs of the unit should cause no problems . Not only therefore could a jump lead or an additional switch be used to connect both battery banks if required but the 1 2 off both switch could be unitised as suggested by Halcyon, and I hope shown in the above diagram, to switch the starting between batteries or to interconnect them. It also, when in the Off position, isolates the starter and engine circuits.

As AlanPound does say it would be advisable to check this with Sterling.

 

[AlanPound]

[ QUOTE ]
The point I was really trying to make is that a switch that parallels the battery banks may not be acceptable because it would also interconnect the two outputs from the AB1290. That may be OK or it may be a complete no no. One would have to check with Sterling to find out if that is acceptable or not.

[/ QUOTE ]

... agreed ... but as I said

[ QUOTE ]
But if we take the words on the web-site at face value, etc. etc. (*if the words on the web-site can be taken literally*)

[/ QUOTE ]