pvb
Well-Known Member
Why not just fit a VSR? No voltage drop, no need to put a diode in your alternator.
Split charge diodes versus split charge relays
- Thread starter catmandoo
- Start date
Why not just fit a VSR? No voltage drop, no need to put a diode in your alternator.
catmandoo
Well-Known Member
I would second that . Has two sealed batteries for about 2 years and last year found them as follows - one bulging considerably and the other very warm . Guess my reaction !!
I now have all vented lead acid batteries and as Jim says plenty of distilled water which is readily available Also a bit of trepidation when moving them
catmandoo
Well-Known Member
several reasons
1 existing system working very well for at least 20 years £2 for a diode . How much does your system cost to install
2 to change would involve a lot or rewiring in confined spaces and disposal of perfectly usable equipment
I have 2 alternators , 2 2 by 3 Sure Power isolators feeding 4 100 amphour batteries
3 boat is mainly a motor sailor and with reliablity of VSR i in question better the devil you know etc Dont like relays - mechanical devices moving parts etc . I assume the relays are not the plug in valve type but are permanently wired into their fancy box so if one fails its a dustbin job fro the whole gubbins
4 In existing system starter battery is always fully charged and cool - seems to go on for ever .
have manual switch down stream of isolators so can switch between no 2 and starter battery to engine instruments and starter and even off with out damaging alternators
5 No noisy relays
In all I think my system is tops and very easy to operate .
I can strum my Ukelele and drink beer watching the system take care of itself
pvb
Well-Known Member
But in post #20, you said "its possibly worth trying to do away with the loss by fitting a Mossfet unit which has low Delta V which I am currrently considering substituting for the Sure Power unit/s" which implied that you were looking at spending money. In this case, a VSR is probably a more economical solution.
Modern VSRs are not noisy, they are reliable, you only need one.
ghostlymoron
Well-Known Member
Agree with that! Also VSRs are cheap (£50) and easy to install. I replaced a diode system that had failed with a BEP VSR and have never regretted it. I too can sit strumming my guitar secure in the knowledge that the batteries are being topped up. A recent thread pointed to a cheaper VSR used on motorhomes - don't know if they are 'marine quality'
catmandoo
Well-Known Member
How many relays for 2 alternators and 3 battery banks ? What about required peripherals ?What is installed cost ?? When assessing every design option and vendors packages in my past life I took installed cost , running costs , reliability , ease of maintenance and availability of spares of the complete system into account before making any recommendation and selection.
When you say economical do you mean on a new unit or for an existing installation ? I cant do a direct substitution without completely ripping out the old system I see from the web site that the Merlin complete package comes in at around £300( Vat included ???) on top of that one would have to include for rewiring and it only seems to handle one input
. In fittting Mossfet its just a direct substitution . I might even get away with commoning all inputs to the one terminal with the Mossfet unit . Unbolt ,connect to same terminals Cost and B@$$eraton of rewiring minimal .
For 20 years never had problem with starter batteries over charging only domestic because of usage Any way what s problem with a little gassing if as Jim says we just have a lot of distilled water to hand and top up regularly
also found that in practice I can work on alternator without having to disconnect any thing from battery due to non return effect of diodes .
If you show me the cost figures and a wiring diagram for 2 inputs and 3 battery banks I might be less sceptical !!
halcyon
Well-Known Member
You could look at http://www.kddpowerstore.co.uk/page4.html.
All depends on what your layout is now, and the alternator / battery bank size.
Brian
pvb
Well-Known Member
What do the 3 battery banks do?
ghostlymoron
Well-Known Member
Basic wiring diagram here to modify an existing installation is simple - even I did it! The heavy duty cabling will between batteries and alternator/starter doesn't need to be altered, all the connections are made at the back of the isolator(s) be they 1-2-B-O or seperate switches. If paying someone to do it, 2hrs should be sufficient.
Without knowing details about your existing installation, I can't comment further. I've no particular axe to grind but, when I looked into it when my diode unit failed (as yours has) a couple of years ago, it was clear to me that the VSR was clearly the way to go.
Without knowing details about your existing installation, I can't comment further. I've no particular axe to grind but, when I looked into it when my diode unit failed (as yours has) a couple of years ago, it was clear to me that the VSR was clearly the way to go.
catmandoo
Well-Known Member
1 starter
2navigation lighting and instruments and no 2 for starter
3 power -fridge , bilge pumps shower pump , spot light biggest user
All prewired and sizes accordingly - remember minimum rehashing worked for 20 plus years so why change
pvb
Well-Known Member
If you want to keep 3 separate banks, easiest solution is 2 VSRs. Alternator outputs go to bank 1. One VSR connect bank 1 to bank 2. Second VSR connects bank 1 to bank 3.
But do you really need a separate bank for nav lights and instruments? Does this mean you're deep-discharging bank 3?
halcyon
Well-Known Member
Why both alternators to bank one ? bank 1 and 2 are stater batteries, so VSR between 1 and 3 and VSR between 2 and 3, saves alternator mods. If VSR's are bi-directional, they also allow for an alternator failure, with the remaining alternator charging all three battery banks.
Brian
pvb
Well-Known Member
I thought that, as the OP explained it, bank 2 is for nav lights and instruments, and is a fall-back starter battery. But his posts aren't very clear, so you may be right.
catmandoo
Well-Known Member
Not sure what you are trying to prove - what have the alternate uses of my batteries got to do with it other than to justify a set up to suit VSRs
i think you chaps have equipment to sell and justify your systems with appropriate blinkers on .
I again reiterate that I have no wish to completely redesign and strip out my existing system which has worked for well over 20 years when for about £100 I can replace one Sure Power diode isolator with a Mossfet unit in half an hour and save some fuel costs in these days of increasing diesel prices with no other modifications or changes to hardware or wiring or alternatively just find a replacement diode for peanuts and live with the voltage drop and power loss .
Boat is a motor sailor cruises a lot in the Med and also sits at anchor in remote places at high ambient temperatures hence different modes of operation night and day as well as poor access to spares and the like
I have reviewed the Merlin bumph and am not overly impressed . Similarly with the Smart bank unit with its hint of manual adjustment tuning and fancy electronic add ons . At the end of the day it depends on a moving mechanical part with a limited life and some computer logic . My Sure Power diodes are still operating after at least 20 years and require no maintenance or pre-programmed chips and cope well in ambients of 40 degrees plus If it ever breaks down I have plenty of redundancy to get me out out trouble
halcyon
Well-Known Member
First you ask for comment, for that we need information, now on post what ever, we get near to your system and what your after. Second I'm not bothered if you buy anything, this forum is my time off work, thirdly over the last 40 years I've investigated more charging systems systems than you will ever see, fourthly, so it's worked for 20 years, I've VSR's out there 30 years old.
So you have blocking diodes, fitting MOSFET will be a simple change, and far more efficient.
So why not say that at the start
Brian
catmandoo
Well-Known Member
First you ask for comment, for that we need information, now on post what ever, we get near to your system and what your after. Second I'm not bothered if you buy anything, this forum is my time off work, thirdly over the last 40 years I've investigated more charging systems systems than you will ever see, fourthly, so it's worked for 20 years, I've VSR's out there 30 years old.
So you have blocking diodes, fitting MOSFET will be a simple change, and far more efficient.
So why not say that at the start
Brian
Because like all such installations its difficult to pass on information with out a wiring diagram and in my case there are a lot of cables and wires around 2 Split diode units , a three output Sterling shore powered battery charger , 4 large shunts , a Klockner 3 pole master switch a 3way supply switch to the starter and 4 batteries to say the least and not to mention 2 alternators off one engine
What I did gain from the posting was information that Mosfit units were available to replace Sure Power diode units and provide a significant improvement
Its a good example I suppose of being constrained by whatever kit was put in before hand
I got the impression that you were more interested in pushing VARs to a wider audience .
However if I had been starting from scratch to totally revamp the system then perhaps I would have followed your suggestions but it would be a lot of work as I would have ripped everything out rerouted and removed redundant cable etc
In my 45 years experience revamps never end up totally satisfactory
pvb
Well-Known Member
As I suspected, the information comes in dribs and drabs. It seems that there's only one engine, so only one starter battery is needed. The whole thing sounds impossibly complicated.
VicS
Well-Known Member
Why do you believe there are two starter batteries.
Battery No 1 is the starter battery
Battery no 2 is used for nav lights and instruments ... it can also be used as the back up battery for starting
Battery no 3 is for the fridge , bilge pump and spot light ( presumably there is no fixed provision to use it as a back up starter battery)
At least thats what I understood from the OP's earlier post.
Immaterial what they are used for surely. He has 3 battery banks to charge, full stop!
A diode system will do all three simultaneously.
A VSR system enables/requires them to be prioritized.
IMHO the simplest solution is to replace the compensating diode with another suitably rated diode.
Not the perfect solution maybe but the simplest and if it has performed satisfactorily for 20 years it will be good for another 20
I must admit though I am still unsure, despite the explanation I was given earlier, why the compensating diode is necessary instead of simply sensing one of the batteries,
The compensating diode system is not perfect as I understand it because the volts drop it is compensating for is not fixed.. it varies with current
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catmandoo
Well-Known Member
Compensating diode not necessary as Sterling regulator overrides alternator regulator and does the job taking signal direct from battery . However if Sterling regulator fails system goes back to machine sensed system hence desire for compensating diode
I dont' want to go back into battery argument because like you I dont see that it is relevant apart from the fact that I have 3 wires from each unit going some where .
Actually I have recently discovered Sterling's Pro Slip R and if you read the bumph he covers all the issues even a device to avoid gassing the starter battery
Intrigued as to what is in the little tin box though - magic Diodes? Mossfets ?FETs ?or little green Leprechauns playing ukeleles .?I wish he would refrain from using tiny self tapping screws though to keep the tin lid on his boxes I keep losing them
Getting late
slàinte mhath
VicS
Well-Known Member
With you now on the compensating diode and Sterling regulator .. I think
Pro Split R looks like it would suit your system but if you already have the diode splitter. Isn't the simplest thing to just replace the compensating diode with a suitably rated one from an electronics component suppliers .
