auto charging the second battery with the minimal changes.. VSR?

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wipe_out

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I have a standard setup with two batteries and a O-1-2-B switch.. No real need to change anything because it all works fine for my needs but I usually run on battery 1 as a habit and often forget to switch to both or 2 when the engine is running to top up battery 2.. Or if I do I forget to switch it back to 1 or 2 when anchored.. Fortunately no flat battery issues yet.. :)

Anyway.. I am looking to make minimal changes but auto charge the second battery.. So I am thinking of simply adding a VSR to the two batteries and that's it, everything else stays the same..

Are there any issues I should be aware of doing this?
Is there a better/simpler way to automatically charge both batteries that doesn't involve changing the system much?
 
wipe_out said:
I have a standard setup with two batteries and a O-1-2-B switch.. No real need to change anything because it all works fine for my needs but I usually run on battery 1 as a habit and often forget to switch to both or 2 when the engine is running to top up battery 2.. Or if I do I forget to switch it back to 1 or 2 when anchored.. Fortunately no flat battery issues yet.. :)

Anyway.. I am looking to make minimal changes but auto charge the second battery.. So I am thinking of simply adding a VSR to the two batteries and that's it, everything else stays the same..

Are there any issues I should be aware of doing this?
Is there a better/simpler way to automatically charge both batteries that doesn't involve changing the system much?
Click to expand...

The VSR is powered all the time, connected permanently live to batteries.

You need VSR that will monitor output from 1, 2, both switch, but switch battery inputs. Thus you can charge batt 2 if running batt 1, or charge batt 1 if running batt 2 and isolate VSR when the switch is set to off.

Brian
 
halcyon said:
The VSR is powered all the time, connected permanently live to batteries.

You need VSR that will monitor output from 1, 2, both switch, but switch battery inputs. Thus you can charge batt 2 if running batt 1, or charge batt 1 if running batt 2 and isolate VSR when the switch is set to off.

Brian
Click to expand...

Yes, I knew they were powered all the time but do they draw enough to be of any concern?

I suppose I could find a way to connect it to the ignition in some way that it would turn on when the ignition was on..
 
wipe_out said:
I suppose I could find a way to connect it to the ignition in some way that it would turn on when the ignition was on..
Click to expand...
I've done exactly that, but not because of the minimal current draw, it's to turn off the VSR when the shore power chargers are running. I just put a relay in the negative return from the VSR.
Just rip out the switch and wire in the VSR. Remember you can choose which battery to monitor, my domestic is permanently connected, starter via VSR.
 
Couldn't you just wire everything up to battery 2 except for the starter motor left on battery 1. Connect the two with a relay energised when engine is running to charge. This is how it is done with camper vans.
 
Barleycorn said:
Couldn't you just wire everything up to battery 2 except for the starter motor left on battery 1. Connect the two with a relay energised when engine is running to charge. This is how it is done with camper vans.
Click to expand...

The problem with this is how you define "engine is running". If you use the ignition switch, then it needs to be delayed until the engine has started, which is essentially what a VSR does. Also needs to be a BIG relay.
 
nigelmercier said:
I've done exactly that, but not because of the minimal current draw, it's to turn off the VSR when the shore power chargers are running. I just put a relay in the negative return from the VSR.
Just rip out the switch and wire in the VSR. Remember you can choose which battery to monitor, my domestic is permanently connected, starter via VSR.
Click to expand...

I don't really have a domestic/starter setup.. Both batteries are connected to the O-1-2-B switch and that connects to everything so whichever battery is selected is connected to both starter and domestics with the other as a backup..

A relay in the negative on the VSR seems simple enough, apart from feeding a wire to the ignition switch.. :) I would see if I can trace a wire in the engine bay that works on the ignition switch and wire to that..

What is the current draw from say a Durite 140A VSR? Is it really enough to worry about?

I get the point about shore power being connected and needing to disconnect the VSR..
 
My boat works on the KISS principle, though also on the principle that if the skipper can do something stupid, he will, so try and make it foolproof.

Battery 1 is a starter battery. Thats all it does. It's connected to terminal 1 of the 0-1-2-both switch

Battery 2 is the domestic battery. It does everything else, but is connected to the 2 terminal in case of emergencies.

The alternator output also goes to terminal 1, as do the starting & "ignition" circuits.

The foolproofing bit is a 40amp relay (Maplin or motor factor) that connects terminals 1 and 2, activated by a connection to the field coil of the alternator. When the engine is started and the alternator starts to do its stuff, the two batteries are put in parallel. and remain that way as long as the alternator is producing electricity

The purists will say, and they're probably right in theory, that I risk dragging a charged battery down by putting a discharged one in parallel, but my experience over the 10 or more years I've had the setup is that it's never been an issue. The fact that I use a 40 amp relay and have a 55amp alternator isn't an issue either, as the relay kicks in as voltage rises, so the current hasn't built up to anywhere near maximum.

The advantage of this system is that, apart from drawing no current when the engine isn't running, the relay is change from a fiver, compared with a minimum of £20-odd for a simple VSR and hundreds for "clever" systems.
 
Stemar said:
My boat works on the KISS principle, though also on the principle that if the skipper can do something stupid, he will, so try and make it foolproof.

Battery 1 is a starter battery. Thats all it does. It's connected to terminal 1 of the 0-1-2-both switch

Battery 2 is the domestic battery. It does everything else, but is connected to the 2 terminal in case of emergencies.

The alternator output also goes to terminal 1, as do the starting & "ignition" circuits.

The foolproofing bit is a 40amp relay (Maplin or motor factor) that connects terminals 1 and 2, activated by a connection to the field coil of the alternator. When the engine is started and the alternator starts to do its stuff, the two batteries are put in parallel. and remain that way as long as the alternator is producing electricity

The purists will say, and they're probably right in theory, that I risk dragging a charged battery down by putting a discharged one in parallel, but my experience over the 10 or more years I've had the setup is that it's never been an issue. The fact that I use a 40 amp relay and have a 55amp alternator isn't an issue either, as the relay kicks in as voltage rises, so the current hasn't built up to anywhere near maximum.

The advantage of this system is that, apart from drawing no current when the engine isn't running, the relay is change from a fiver, compared with a minimum of £20-odd for a simple VSR and hundreds for "clever" systems.
Click to expand...

Interesting setup but I am a bit confused..

So you have battery 1, the alternator and ignition on terminal 1 and you connect battery 2 to terminal 2..
Is the starter part of the "ignition" and also connected to terminal 1?
Where are the domestic circuits connected? Terminal 2 or common?

When you come on board where do you switch the isolator to because everything needed to start the engine is on terminal 1 so even in the OFF position the engine could still be started.. Or how do you isolate Battery 1 if there is a problem?

The part I don't get is if you switch to battery 2 as you "backup" to start the engine on the O-1-2-B switch then your "ignition" isn't powered because its all on terminal 1..

Or have I missed something?
Do you have a link to a diagram which might make it clearer?
 
wipe_out said:
Interesting setup but I am a bit confused..

So you have battery 1, the alternator and ignition on terminal 1 and you connect battery 2 to terminal 2..
Is the starter part of the "ignition" and also connected to terminal 1?
Where are the domestic circuits connected? Terminal 2 or common?

When you come on board where do you switch the isolator to because everything needed to start the engine is on terminal 1 so even in the OFF position the engine could still be started.. Or how do you isolate Battery 1 if there is a problem?

The part I don't get is if you switch to battery 2 as you "backup" to start the engine on the O-1-2-B switch then your "ignition" isn't powered because its all on terminal 1..

Or have I missed something?
Do you have a link to a diagram which might make it clearer?
Click to expand...

Sorry if I wasn't clear - it was a quick reply while waiting for a big file to load from a sloooowwww server!

Unfortunately, I haven't got a current wiring diagram - it's all in my head, but I need to do one to put in the boat file so, if you want one, that might persuade me that this weekend's a good time to do it! PM me if you do.

The starter & associated ignition stuff is connected to the common terminal on the 012B switch, so in the 0 position, the engine and related circuitry is completely isolated.

The entire domestic circuit is independent, with a master on the switch panel to control it, but the domestic battery has a starter-sized lead running to the no 2 terminal on 012B, so I can start the engine from the domestic battery if necessary by switching to position 2.

The relay connects 1 & 2 so, effectively, I'm automatically switched to both whenever there's power coming from the alternator. The only time I ever turned the switch to both was one evening when I needed lights on my mooring but the domestic battery had died completely, so I disconnected it and Both allowed me to run the domestics from the starter battery.
 
Stemar said:
Sorry if I wasn't clear - it was a quick reply while waiting for a big file to load from a sloooowwww server!

Unfortunately, I haven't got a current wiring diagram - it's all in my head, but I need to do one to put in the boat file so, if you want one, that might persuade me that this weekend's a good time to do it! PM me if you do.

The starter & associated ignition stuff is connected to the common terminal on the 012B switch, so in the 0 position, the engine and related circuitry is completely isolated.

The entire domestic circuit is independent, with a master on the switch panel to control it, but the domestic battery has a starter-sized lead running to the no 2 terminal on 012B, so I can start the engine from the domestic battery if necessary by switching to position 2.

The relay connects 1 & 2 so, effectively, I'm automatically switched to both whenever there's power coming from the alternator. The only time I ever turned the switch to both was one evening when I needed lights on my mooring but the domestic battery had died completely, so I disconnected it and Both allowed me to run the domestics from the starter battery.
Click to expand...

Ok, think I have got it.. It's essentially what I was thinking of doing without separating the "domestics" off the O-1-2-B switch because my "domestics" would just be the cabin lights, the fridge and the radio so didn't see a point of a separate circuit just for that.. Just having a second battery that can be used to start the engine if the first is flattened too much is fine.. So simply adding a VSR between terminals 1 and 2 is all I really need.. :)
 
wipe_out said:
Ok, think I have got it.. It's essentially what I was thinking of doing without separating the "domestics" off the O-1-2-B switch because my "domestics" would just be the cabin lights, the fridge and the radio so didn't see a point of a separate circuit just for that.. Just having a second battery that can be used to start the engine if the first is flattened too much is fine.. So simply adding a VSR between terminals 1 and 2 is all I really need.. :)
Click to expand...

A fridge is a hungry critter. You'd probably get away without separating your starting circuit if you only had a few lights, but a fridge will flatten your batteries while you aren't looking and then you'd better hope for the right breeze to get home!

Keep the two separate with the alternator output going to the starter battery and use a relay to join the circuits when it's charging. That way, if the relay fails, the starter battery gets the charge, which gets you home, but it doesn't need to be a VSR, a £5 car headlamp relay will do the job if the exciter coil is fed from the field terminal on the alternator, as that's only at +12v when the alternator's producing power.
 
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