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Old 23-02-2017, 19:32   #1
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VSR to use spare Starter Bank capacity.

I am using House Bank for all charging and consumption. Occassionally I will switch the 1,2, both,off switch to topup the starter. Been thinking that a Voltage Sensitive Relay (VSR) is the way to go.

However I have only small space, for House bank, and thinking it would be kind of nice to use some of the Ah from the starter bank, but keeping, more than enough for backup starting purposes.

So lets say VSR closes at 13.5 V and I use a adjustable opening setpoint around the 12.4 V.

Your thoughts are welcome, my intention is to maximising the use of all Ah available without pushing the SoC unnecessarally on starter bank or risking Engine start failure. Of course this could be done manually, but prefer the automated method.

PROJECTA VSR100 VOLTAGE SENSITIVE RELAY 12V VSR ISOLATOR 100A DUAL BATTERY SYST

This could be made useful, but pefer adjustable limits.
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Old 23-02-2017, 20:17   #2
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Re: VSR to use spare Starter Bank capacity.

They are not adjustable. Keep the start battery full.
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Old 23-02-2017, 23:00   #3
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Re: VSR to use spare Starter Bank capacity.

Yes, I think it is a good idea where space is limited to realize that although Starting is a critical function, it uses such a tiny proportion of a deep-cycle battery's energy, dedicating it to that function only is wasteful.

As long as you ensure the SoC never drops so low as to threaten its ability to crank, then it should help feed House loads.

Setting the charging issue aside for now - so many variables there -

Look at a Low Voltage Disconnect as protecting the Starter battery, isolating it from House loads at a particular voltage setpoint. A good one allows for user to program a custom cutoff (and combine) voltage, ideally also with custom delay periods. Obviously continuous current capacity must be larger than the loads carried. And IMO there should be an alarm or genset-startup relay triggered as well, separate from the protective cutoff.

There is also the issue of when does the starter carry these House loads, concurrently in parallel with the House bank, or only as a Reserve, perhaps after House has hit say 50% SoC.

Finally, there will likely be essential "always on" loads related to navigation, safety etc wired directly to the Starter battery before the LVD.

Since IMO the Charge buss should be separate from the Loads buss, these Load LVDs aren't really functioning as ACR/VSRs traditionally allowing for charging both banks in a combined circuit.

That function may be better performed by a one-way device like a DC-DC converter (batt2batt charger), especially if different battery chemistries dictate different voltage levels. Or if the same, simpler devices like modern efficient FET-based isolators or a Xantrex (ex-Heart) Echo Charger.

The primary sources should feed the larger, first-drawn down House bank, with the echo charger feeding a secondary charge to the smaller Starter/Reserve battery.
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Old 23-02-2017, 23:09   #4
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Re: VSR to use spare Starter Bank capacity.

http://www.intervolt.com/product/vol...ensing-relays/
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Old 24-02-2017, 09:26   #5
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Re: VSR to use spare Starter Bank capacity.

I agree with SMAC999. I have a VSR relay and its brilliant. I also have three banks. Start, domestic (2x110Ah) and AUX 110Ah. I have manual overide switches so I can switch start to domestic, aux to start and domestic. Any combination. But I usually use the start battery fully topped up and the VSR switches to the domestic as standard. That way I have the aux to bring in when I need some power for start or domestic. I also have an ADVERC to keep them maximum charge.

The reason is that I had Start and domestic with manual swicthes. I drained the Domestic and start overnight without knowing and had nowehere to go to start the engine. I had too use the portable genny for a few hours before I could start. Never again.
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Old 24-02-2017, 13:03   #6
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Re: VSR to use spare Starter Bank capacity.

Please, KISS . . . you know what that stands for, right? Go to Blue Seas and check out an ACR (automatic charging relay) . . . . will help to maintain your charging of the different banks and "opens" when the voltage gets down too low. Even better, you can wire up the two studs of the ACR to the two poles of your MBSS (master battery selector switch) and eliminate all that freakin' mess around the batteries themselves . . .
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Old 27-02-2017, 19:52   #7
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Re: VSR to use spare Starter Bank capacity.

Hi Oceanride007, I think I understand what you are trying to accomplish, but couple of questions
What is the AH capacity of each bank? As you noted you seem to have only a small amount of room for the House bank? If you parallel both batteries, the one with the higher terminal voltage will try to charge the lower voltage battery and the Terminal voltages will try to equalise. When you isolate each battery using the C/Over switch, will the SOC be sufficient to start the Engine? eg 50% SOC of a 100A/hr battery v 50% SOC of a 200A/hr battery
How do you currently charge the batteries? If this is from Solar, perhaps you could utilise the LV Disconnect in this? These are generally adjustable. Use this to turn on a Buzzer to remind you to change from Start to House battery?
Just a thought
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Old 27-02-2017, 22:02   #8
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Re: VSR to use spare Starter Bank capacity.

DD.
Think I'm up for new batteries, given that the space will allow 3 of 500mm x 180mm. Think that will be 3 batteries the same, 2 house 1 Start, about 200Ahrs each. So on the hook was trying to augment the House with some of the start, using the 80% to 50% rule for the house and say 80% to 65% for the starter. So upping my Available House yield by about 30Ah about 25%.
What got me thinking about this is that I found a VSR with a switchable contact.

Difficulties are:
More Clutter around the batteries.
For safety need a LVD, hence the cost of the extra equipment is starting to compromise the return on the investment.
I have two methods of paralleling the batteries, 1 on charge side the 2nd on Discharge side. Placing the new devises needs a bit of thought.

I noticed that my vessel already has some of the consumer circuits coming off the Start bank. Perhaps, I could up that a bit, and monitor both banks for a while. Would need the VSR on the charge side. Leave the Consumer side of Starter Isolated (Consumer must be hard wired).

John that programable VSR is supercool but super expensive, I may be able to use a programmable auxillary contact on my Mppt to do it if req,d. (Not that I'm familiar with it.)
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Old 28-02-2017, 00:37   #9
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Re: VSR to use spare Starter Bank capacity.

This may help? I see you have already a MPPT Regulator, but this may give you an way of utilising that. All you would need is the External relay which generally aren't that expensive.
This is from the Plasmatronics Dingo 2020 Solar regulator. refer page 26 of the Reference manual.
http://www.plasmatronics.com.au/down...020Ref.1.5.pdf
The down side is that only 1 of the 2 panels charge the second battery. (i reckon you could get around this though) It's only a single stage controller so there's no equalisation, floats etc as you would for the primary battery. Perhaps you could talk to one of the tech guys as they are in Melbourne? I've got a old unit which has been obsoleted some time ago in my boat and still going strong
Hope this helps
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Old 28-02-2017, 08:10   #10
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Re: VSR to use spare Starter Bank capacity.

I might be misunderstanding the OP but I think that there is some confusion here with the purpose of a VSR.

The VSR cannot be used for the transfer of available amps or to utilize the spare Ah's. It can't be used to augment a house bank when it is running low. The VSR is used to allow both sets of batteries to be charged from one source and it is specifically designed to prevent one battery draining into the other. When there is no incoming charge and the battery voltage drops to say 12.4v, the VSR has already opened the circuit and prevents the flow of current across it. VSR's will open around 12.8v and will not allow current to pass until it see's 13.7v which will only happen in the event of an incoming charging source.
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Old 28-02-2017, 09:24   #11
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Re: VSR to use spare Starter Bank capacity.

Quote:
Originally Posted by Privilege View Post
I might be misunderstanding the OP but I think that there is some confusion here with the purpose of a VSR.

The VSR cannot be used for the transfer of available amps or to utilize the spare Ah's. It can't be used to augment a house bank when it is running low. The VSR is used to allow both sets of batteries to be charged from one source and it is specifically designed to prevent one battery draining into the other. When there is no incoming charge and the battery voltage drops to say 12.4v, the VSR has already opened the circuit and prevents the flow of current across it. VSR's will open around 12.8v and will not allow current to pass until it see's 13.7v which will only happen in the event of an incoming charging source.
That's correct. It's a "charge side" piece of equipment.

Only comment to add is that the voltages mentioned in Privilege's post are generic, and the actual voltages will be based on the specific unit installed.

For the OP: KISS, use the 1-2-B switch on B when using the banks, and carefully monitor them. Or buy another house battery and find a place for it. You're not the first skipper to think of this, so the choices are more house capacity or more charging from solar, wind of generator or engine. And/or reduce consumption.
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Old 28-02-2017, 10:50   #12
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Re: VSR to use spare Starter Bank capacity.

An adjustable setpoint LVD sensing bank voltage can be used to isolate non-essential loads from that battery, e.g. a starter, allowing it to share House loads but protecting it from too low depletion for cranking.

That load sharing could be as a backup reserve, switched to as needed only. Or routinely, helping to keep House from being discharged as deeply as when Starter is dedicated to cranking only.

That LVD will also usually act as an ACR/VSR (if there isn't a separate Load vs Charging buss) as charging current to that bank raises its voltage.

I completely understand that most people want to KISS, just putting the design option out there.
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Old 28-02-2017, 15:36   #13
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Re: VSR to use spare Starter Bank capacity.

Guys, I agree entirely with the concept of the VSR and only manages the Charge side of the equation.
I also understand what Ocean is trying to do , so I believe he has 2 issues here,
1. Managing the Load side demand
2. Managing the Charge side
Best to stay with the 1-2-B switch for Load side management, as this is pretty reliable. Just knowing when to change is the issue.
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Old 28-02-2017, 18:23   #14
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Re: VSR to use spare Starter Bank capacity.

Op here:
My thinking at this time. Is to leave the Start bank Load side isolated, except for some consistant load, say a fridge. But isolated from Battery Start.
On the charge side place my switchable VSR on charge side, it is free to operate as discussed.
2 choices.

Choice 1. When VSR looses its charge and opens, each battery will discharge depending on the load placed on each side of the switch.

Choice 2. Keep everything on the Housebank, and use the switchable function of the VSR until both batteries go down to say 12.5V, it then opens so that only the House bank supplies load the rest of the night.

Maybe my MPPT can do the swiching or a LVD or I could make something, sure would prefer not to reinvent wheels so if any body has been down this road, or not thoughts are welcome.
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Old 28-02-2017, 20:58   #15
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Re: VSR to use spare Starter Bank capacity.

Quote:
Originally Posted by Oceanride007 View Post
Op here:
.......thoughts are welcome.
The only load that should ever be connected to the start battery is the engine.

All other loads should be connected to the house bank.

All charging should go to the house bank.

The VSR will take care of the start battery automatically and you will never have a problem starting the engine.

Why try to change a system that works perfectly and is simple?
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