1,2 Both Switch - When on Both do the 2 batteries even out on charge?

PaulRainbow said:
Vic, i saw that you posted regarding the square cluster, i'd assumed the OP had the one with four in a row. If he does have four in a row the links don't need changing, just the wiring. If, on the other hand, he has the square cluster, your post would be the appropriate one.

Perhaps Colin can clarify which one he has.
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the square one
 
ColinR said:
the square one
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OK, still the same wiring ;

Fit the battery cables to terminals (B) and (D) in the connection diagram. Connect the loads to (A) and (C). The two wires from the VSR also go to terminals (B) and (D)

With the square cluster the VSR wires are both long enough to change over.

The advantage here is that you can still use the yellow switch for a quick jump start, but if the dodgy battery is causing a problem you can isolate it.
 
PaulRainbow said:
OK, still the same wiring ;

Fit the battery cables to terminals (B) and (D) in the connection diagram. Connect the loads to (A) and (C). The two wires from the VSR also go to terminals (B) and (D)

With the square cluster the VSR wires are both long enough to change over.

The advantage here is that you can still use the yellow switch for a quick jump start, but if the dodgy battery is causing a problem you can isolate it.
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thanks for the info but I'm not sure I quite get why this is preferable. If one of my house batteries died I'd still have to disconnect it, or if the start battery dies then I would disconnect that and using the yellow paralleling switch presumably would mean the house batteries would crank the engine. I appreciate the input, I'm still trying to get my head round this new installation, the instructions are a bit minimal on explanation.
 
ColinR said:
thanks for the info but I'm not sure I quite get why this is preferable. If one of my house batteries died I'd still have to disconnect it, or if the start battery dies then I would disconnect that and using the yellow paralleling switch presumably would mean the house batteries would crank the engine. I appreciate the input, I'm still trying to get my head round this new installation, the instructions are a bit minimal on explanation.
Click to expand...

The way i described links the systems after the switches, the BEP way links them before the switches, so you can't quickly isolate a dead battery.

Your engine battery is flat. You turn the yellow switch but it still wan't start because it's dragging the domestic bank down, or it's knackered. BEP wiring means you now have to disconnect the engine battery, re-connecting it after starting if it was just flat. The way i outlined means you just turn the engine isolator off, start the engine and turn it back on (or leave it off if the battery is knackered. Pretty significant difference if you need to get the engine started in a hurry. Will that super tanker bearing down on you wait until you disconnect batteries ? (OK, extreme example, but you get the point)

Similar differences if there is a problem with the domestic bank, but typically less pressing and as you say, if one battery was toast you'd have to disconnect it anyway. There are still some useful reason though. You could isolate the domestic systems from their batteries but still power the systems from the engine battery until you disconnected the dead battery. It could be dark, the lights would be handy. You could be in a situation where you need the VHF or the Nav systems, this will buy you time and allow you to disconnect the battery at a more convenient time.

The changes are very simple. Just involves swapping the two cables over on each switch and moving the two VSR wires, so they stay with the battery cables. Five minute job.
 
PaulRainbow said:
The way i described links the systems after the switches, the BEP way links them before the switches, so you can't quickly isolate a dead battery.

Your engine battery is flat. You turn the yellow switch but it still wan't start because it's dragging the domestic bank down, or it's knackered. BEP wiring means you now have to disconnect the engine battery, re-connecting it after starting if it was just flat. The way i outlined means you just turn the engine isolator off, start the engine and turn it back on (or leave it off if the battery is knackered. Pretty significant difference if you need to get the engine started in a hurry. Will that super tanker bearing down on you wait until you disconnect batteries ? (OK, extreme example, but you get the point)

Similar differences if there is a problem with the domestic bank, but typically less pressing and as you say, if one battery was toast you'd have to disconnect it anyway. There are still some useful reason though. You could isolate the domestic systems from their batteries but still power the systems from the engine battery until you disconnected the dead battery. It could be dark, the lights would be handy. You could be in a situation where you need the VHF or the Nav systems, this will buy you time and allow you to disconnect the battery at a more convenient time.

The changes are very simple. Just involves swapping the two cables over on each switch and moving the two VSR wires, so they stay with the battery cables. Five minute job.
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that makes sense, thanks a lot. C
 
PaulRainbow said:
Most battery callouts are for flat batteries, but in 2006 the RAC replaced 130,000 dead ones. Of those, you are correct that most would be time expired. There are a lot that fail unexpectedly though. I've seen people stop to answer a phone call, car won't start, stop to get a loaf of bread, car won't start, etc. I've seen them fail whilst driving along, the car has just cut out and ground to a halt.
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We had a Renault diesel a few years ago, swmbo went to her sis 200 miles away. Went to start it in the morning, the whole computerised pile of poo went in to melt down. They put a new starter on, still wouldnt have it, insisted that the battery voltage was fine. It wasnt on load though as we found out on the second call out. It was doing what I have experienced, resting voltage ok, under load,ie starter winding, it drops and then the lo voltage protection kicks in and switches all the electronics off!
Stu
 
PaulRainbow said:
The way i described links the systems after the switches, the BEP way links them before the switches, so you can't quickly isolate a dead battery.

Your engine battery is flat. You turn the yellow switch but it still wan't start because it's dragging the domestic bank down, or it's knackered. BEP wiring means you now have to disconnect the engine battery, re-connecting it after starting if it was just flat. The way i outlined means you just turn the engine isolator off, start the engine and turn it back on (or leave it off if the battery is knackered. Pretty significant difference if you need to get the engine started in a hurry. Will that super tanker bearing down on you wait until you disconnect batteries ? (OK, extreme example, but you get the point)

Similar differences if there is a problem with the domestic bank, but typically less pressing and as you say, if one battery was toast you'd have to disconnect it anyway. There are still some useful reason though. You could isolate the domestic systems from their batteries but still power the systems from the engine battery until you disconnected the dead battery. It could be dark, the lights would be handy. You could be in a situation where you need the VHF or the Nav systems, this will buy you time and allow you to disconnect the battery at a more convenient time.

The changes are very simple. Just involves swapping the two cables over on each switch and moving the two VSR wires, so they stay with the battery cables. Five minute job.
Click to expand...

if I do this, will the house and start circuits still be separate when I start the engine, ie does the VSR detect charging and parallel the circuits only after the engine starts? Among other things I am trying to avoid spikes in the house side that is affecting my chartplotter when I start the engine. C
 
ColinR said:
if I do this, will the house and start circuits still be separate when I start the engine, ie does the VSR detect charging and parallel the circuits only after the engine starts? Among other things I am trying to avoid spikes in the house side that is affecting my chartplotter when I start the engine. C
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Yes, you have all of the feature that you currently have, but you can additionally isolate one battery and run everything from the other one. There is no downside to making the change.
 
ColinR said:
if I do this, will the house and start circuits still be separate when I start the engine, ie does the VSR detect charging and parallel the circuits only after the engine starts? Among other things I am trying to avoid spikes in the house side that is affecting my chartplotter when I start the engine. C
Click to expand...

If the VSR is 'made' due to e.g. solar power raising the voltage, then starting the engine will cause a dip on both batteries. Most VSRs seem to be designed not to drop out immediately in this situation.
The current will of course be shared between the two battery banks, so the dip will be smaller than if just starting from one battery. One could manually disable the VSR before turning the key.

Having your GPS reboot just when pilotage gets tricky is a pain. On one of my boats, I fitted a 12V alarm battery just to keep the GPS alive.
 
lw395 said:
If the VSR is 'made' due to e.g. solar power raising the voltage, then starting the engine will cause a dip on both batteries. Most VSRs seem to be designed not to drop out immediately in this situation.
The current will of course be shared between the two battery banks, so the dip will be smaller than if just starting from one battery. One could manually disable the VSR before turning the key.

Having your GPS reboot just when pilotage gets tricky is a pain. On one of my boats, I fitted a 12V alarm battery just to keep the GPS alive.
Click to expand...

But none of that is relevant to the question.
 
PaulRainbow said:
But none of that is relevant to the question.
Click to expand...

I thought the question was
1,2 Both Switch - When on Both do the 2 batteries even out on charge?
Click to expand...
which may have actually been answered somewhere in the irrelevant ramblings on diodes, VSRs, BEP switch clusters, etc. but buggered if I can see it.
I think the answer is "yes" but maybe not at the level you would like.
 
awol said:
I thought the question was
which may have actually been answered somewhere in the irrelevant ramblings on diodes, VSRs, BEP switch clusters, etc. but buggered if I can see it.
I think the answer is "yes" but maybe not at the level you would like.
Click to expand...


The latest question, and the one to which i was referring is contained within post #270
 
Yes but not instantly.
awol said:
I thought the question was
which may have actually been answered somewhere in the irrelevant ramblings on diodes, VSRs, BEP switch clusters, etc. but buggered if I can see it.
I think the answer is "yes" but maybe not at the level you would like.
Click to expand...
 
awol said:
I thought the question was
which may have actually been answered somewhere in the irrelevant ramblings on diodes, VSRs, BEP switch clusters, etc. but buggered if I can see it.
I think the answer is "yes" but maybe not at the level you would like.
Click to expand...

Couldn't agree more.

But to return to the original question, if different voltages are considered then potential difference will cause a current flow. But, cable size, length and thus resistance will have to be factored. This question only may be answered in a laboratory situation with sophisticated measuring equipment.
 
awol said:
I thought the question was
which may have actually been answered somewhere in the irrelevant ramblings on diodes, VSRs, BEP switch clusters, etc. but buggered if I can see it.
I think the answer is "yes" but maybe not at the level you would like.
Click to expand...

If it has not already been answered.

My setup has 2 domestic battery banks which are the same size being each 630 Ah, but the batteries are different ages.

Normally I use my 1,2,both domestic switch in the both position when on board but when I heave the boat for some time I switch this switch to the off position. I also each bank has a permanently connected 80 watt solar panel through a simple on off regulator to keep the batteries topped up when I am away.

Due to the different ages the resting voltage will and I can see are slightly as I have seperate volt meters and current meters for each bank.

So when I return to the boat and I switch my 1,2,both switch to both I can see a relatively current flow from one battery to the other as 1 battery ammeter will show a positive flow and the other a negative flow due to the small voltage difference and if you consider that a fully charges battery resting voltage will be about 12.7/12/8 volts and a battery of say 75% charge will be about 12.5/12.6 the volt difference is small so the current will be small depending on the internal and external resistance of the batteries and cables.
 
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