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

vyv_cox said:
I have been using 1-2-both switches on all my boats since 1988. I never had the slightest problem with any of them and they provide the ultimate versatility. There is nothing wrong with these switches, it's the owners who need to be changed :)
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Indeed, the owners need to be convinced that 1-2-both switches belong on the seabed :)
 
geem said:
Have a look at ' problems with voltage sensitive relays' on the american forum. Lots of issues.
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Incorrectly specified or incorrectly wired VSRs can cause problems, as indeed can any incorrect equipment. But a simple installation of two on/off switches - one for the start battery, one for the domestic bank - together with a split-charge arrangement, leaves no room for doubt, no room for confusion, no room for mistakenly or forgetfully setting a switch in the wrong position. Just arrive at the boat, turn both switches on, use the boat, turn both switches off when you leave. Absolutely foolproof. In contrast, the antiquated 1-2-Both switch has lots of potential for confusion and error, which can lead to flattening the start battery or damaging the alternator. There's a good reason why modern boats aren't fitted with 1-2-Both switches.
 
pvb said:
Incorrectly specified or incorrectly wired VSRs can cause problems, as indeed can any incorrect equipment. But a simple installation of two on/off switches - one for the start battery, one for the domestic bank - together with a split-charge arrangement, leaves no room for doubt, no room for confusion, no room for mistakenly or forgetfully setting a switch in the wrong position. Just arrive at the boat, turn both switches on, use the boat, turn both switches off when you leave. Absolutely foolproof. In contrast, the antiquated 1-2-Both switch has lots of potential for confusion and error, which can lead to flattening the start battery or damaging the alternator. There's a good reason why modern boats aren't fitted with 1-2-Both switches.
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What about brass seacocks on modern boats are they better than the bronze of yesteryear
 
vyv_cox said:
I have been using 1-2-both switches on all my boats since 1988. I never had the slightest problem with any of them and they provide the ultimate versatility. There is nothing wrong with these switches, it's the owners who need to be changed :)
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Like many things, if you understand how they work and follow the correct procedure they are fine.

However from the constant stream of questions about these antiquated devices it is clear that many people don't and then get into potential trouble. Remember these things came in over 40 years ago and were a first attempt to have some control over dual battery banks. Times have moved on (it is now 2017!) and there are now far better, simpler trouble free systems available. Easy to install them and forget all about switching in the right sequence etc and always having a fully charged dedicated engine start battery.
 
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Having a 1-2-both switch and using it on both is just asking for trouble. Even in the event of emergency starting it isn't always a good idea. I see people question why you may need to disconnect the faulty battery before using the domestic bank to start the engine, not something i always thought of myself. Why should we, we don't take a car battery off before we jump start it ? Mostly a small jump start pack is all that is needed. But in some cases the jump pack won't do it, i've had to use a set of very heavy jump leads, wired directly to a Transit van fitted with two heavy duty batteries, can't do that on a boat. I have, just in the past few weeks, been out to three vehicles where i have been unable to start them, even using the jump leads with the van having been run for a while, only solution was to fit new batteries, try that one at sea.

Batteries will die without warning, whilst you are driving along and you won't even know until you stop the engine, only to find it won't start again. I see cars where the owners have stopped to answer the phone, popped into the shop, picked the kids up from school etc and then the car won't start. These batteries didn't go flat in the moments the engine was off, they were flat when they stopped, they didn't know because the car was running on the alternator.

Say you turn your switch to both to top all of the batteries up, you arrive at your anchorage and forget to change it back to 1 or 2. When you want to leave, the engine won't start.

There is no wind, so you decide to motor and put the switch to both to make sure all of the batteries are fully charged when you get to your destination. You decide to stop for a while and do a spot of fishing/make a cuppa/have a nap/whatever. You take the engine out of gear and switch the engine off. All of the electrics go off, everything, WTF ? Unknown to you, one of your batteries has catastrophically failed and has dragged the other down, your systems appeared to be fine because everything was running from the alternator. So, you're becalmed with no engine, no nav equipment and no VHF to summon help. You are out of range with your handheld VHF. What now skip ?

Of course, you can use a 1-2-both switch for 50 years without a problem, but why risk it ?

You carry flares for 50 years, renewing them regularly, how many have you used ? How about the liferaft, the grab bag, your life jackets, lifelines etc etc.

What could be more simple and bullet proof. even for the daftest of crew members to arrive at the boat and switch the domestic switch to the "ON" position ? The domestic circuits are now all on, the engine battery remains isolated. When you need the engine, switch it on.

If your crew member isn't bright enough to remember he only has to switch the domestics on and switches the engine bank on too, so what ? Won't make any difference, the engine circuits are indeed live (same as they would be with a 1-2-both switch) but they are isolated from the domestic loads and the battery cannot be flattened.

Having the third switch for emergency starting means the faulty battery can be isolated and everything can be powered by the good bank. Can't do that with a 1-2-both.

Simple question, why use a system that has the potential for problems, operator error and confusion when a system exists that removes all of those factors ?
 
sailorman said:
What about brass seacocks on modern boats are they better than the bronze of yesteryear
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I'm not sure how long your memory is, but real bronze hasn't been used much on boats for a very long time, largely as a result of its cost. Way back in the 1800s, alternatives were being used, such as Naval Brass and Admiralty Bronze (which isn't bronze). The DZR seacocks fitted today are good for many years' life - that's why Blakes seacocks (greatly loved by traditionalists) are made from DZR.
 
lw395 said:
I think what matters on a boat wiring system is whether it works reliably and whether it meets the needs of the user.
I don't think having a 1-both-2 switch matters one way or the other.

To answer the OP, if one battery is at a higher state of charge, yes the two will equalise, but surprisingly slowly. If you have a fairly flat battery at say 12.1 volts and try charging it from 12.6 volts, the current will be very low and it will take a long time to equalise.
If one battery is past its best and has a self-discharge issue, it will drag the other down though.
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What is the story if the batteries are different sizes?

I have one 110ah and one 65ah, in practice I seldom switch them both in together but I might.
 
For 30 year I have had a 2 separate switches, one for the domestics which connects to the domestic batteries and one for the engine which connects to the engine batteries, the two circuits are quite separate. both battery banks .are charged from one alternator via an Adverc unit which ensures that the engine bank gets priority charging. So its very simple you just switch on both switches. I also have a third emergency switch wired in which can parallel the two banks if the engine batteries are down and hopefully the extra umph will get the engine to start. There is really nothing to go wrong. The KISS principle works for me.

regards
David H
 
ghostlymoron said:
The Blue Sea e-series dual circuit Plus seems to be the way to go these days. Two independent circuits which can be charged by VSR or other relay/diode and batteries can be combined if required. I know that sooner or later I'd leave a 1-2-B switch in the wrong position and be unable to start the engine.
https://www.bluesea.com/products/5511e/e-Series_Dual_Circuit_Plus_Battery_Switch
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We have seperate engine and domestic battery isolation switches. The 1,2, both switch is wired between the alternator and batteries. We use it to combine batteries in an emergency or send engine alternator output to the chosen battery bank. We dont use it to isolate the batteries. That is best done with a high quality isolator. We have never needed to move the switch from the domestic bank position because we have dual output solar charging and dual output from the wind generator.
 
doug748 said:
What is the story if the batteries are different sizes?

I have one 110ah and one 65ah, in practice I seldom switch them both in together but I might.
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Nothing wrong with that split. The requirements for domestic and starter batteries are best met by batteries/banks of different sizes and different design (principly plate thickness). I have one bank of 360Ah and a starter battery of 55Ah.

I guess you could manage such a system with a 1-2-Both switch but it would be a lot better with separate switches. The problem when charging through a 'both' switch would be to control how the two different batteries charge. You'd probably end up overcharging one or undercharging the other. Probably a good idea to check the water levels regularly just in case.
 
Thanks for that.

I do have two separate switches but I guess it only achieves the same as the combined switch. I will keep an eye on the electrolytes if I experiment with switching to both batteries.
 
pvb said:
You wouldn't. Batteries essentially only take as much charge as they need.
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Depends upon the charging voltage. I wouldn't want to put 14.8V for too long through a smaller battery from a charging system that is sensing a larger battery.
 
I too have used a 1 - both - 2 switch for many years on several boats and like the control it provides. Start on 1, switch to both, switch to to 2 on stopping engine to sail. It simply needs a bit of discipline .. and a decent quality switch.
David Morgan
 
morgandlm said:
I too have used a 1 - both - 2 switch for many years on several boats and like the control it provides. Start on 1, switch to both, switch to to 2 on stopping engine to sail. It simply needs a bit of discipline .. and a decent quality switch.
David Morgan
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Slight difference in operating regime for me. I almost never switch to 'both', as if the engine is charging the domestic battery bank the solar panels are charging the starter battery. I usually start on 1, run for 20 minutes or so, then switch to 2.
 
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