Battery Charger Question
- Thread starter abraxus
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nigelmercier
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The new ones can be wired in parallel.
DaveS
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Well, that would be the case if the manufacturer's claims are accurate, but I'm becoming increasingly doubtful of that. The simplest explanation of what's going on is that they are in fact directly connected. I didn't pursue it at the time having found a work around, but when next on the boat I'll test between outputs with an ohmmeter which should give a conclusive answer.
I would expect to see a resistor divider chain between the output(s) and the microcontroller, but I can't see why anyone would use low values for this: it's for voltage measurement and the current flow will be negligible so I would have expected the resistors to be say 10kΩ and upwards.
nigelmercier
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The outputs will have a common source, but will have some form of switching / regulation on each output.
Back to the original question, why not wire the chargers direct to the batteries like you are meant to?
Maine Sail
Well-Known Member
It certainly can. I do this all winter long, while on the hard, with our Sterling PCU. Is it good for it? Probably not as good as having batteries connected but for non-motor loads eg: lights, stereo etc. the PCU works very well as a power pack. I don't run my Eberspacher with it however. When I run that I will bring a small lawn & garden battery on-line to buffer it.. Charles does prefer to see it connected to a bank but it will run fine without batteries in the loop, for certain loads..
ianj99
Well-Known Member
The3 outputs aren't directly paralleded and there are a lot of mosfets clamped to the heatsink.*
Don't forget the holding current of many relays is a fraction of the pull-in current and also, we don't whether the OP may have used a more sensitive relay than the typical auto types, so as little as 10ma may be all that was needed to keep the relay closed.
*On my Procharge D, before it expired, each bank showed a different voltage and the batteries were directly connected to the Procharge, bypassing the isolators. They'd have all read the same if connected to each other via the procharge outputs.
Sterling has stated the obvious in telling the OP to use the 3rd (unused) output, however, how is the fridge going to run when not on shore power?
abraxus
Well-Known Member
Ian, I'm not sure what you're saying here.
My understanding now is if I connect the third output to the common post on the battery switch then the fridge will be powered via the Pro charge power pack function, even if the battery switch is set to off. Hence the batteries are isolated and run no risk of discharge, but are being charged via direct connections to outputs 1 and 2.
Once away from shore power I put the switch to 1 or 2 and the fridge is powered by the batteries.
Obviously if the boat is at the marina and I lose shore power due to an outage at the marina, or a mains breaker tripping on the boat, then I lose power to the Pro Charge and thus the fridge.
This latter scenario I don't mind and prefer to leaving the batteries on, as any such loss of 240v power whilst leaving the fridge running off batteries would eventually drain the batteries if the charger isn't getting powered. So the possibility of losing power to the "power pack" is just the lesser of two evils.
My only query/concern with doing this was that by connecting the third output directly to the house load (via the common post on the switch) and not via a battery then it might somehow muck up the chargers sensing capability of the starter and house battery banks. From what I understand of what you're saying then isn't a concern as it will still sense the other banks correctly?
VicS
Well-Known Member
If Mr sterling says what you want to do will work OK then do it.
However does he understand that you want the charger to be able to charge the batteries in the normal way using two outputs at the same time as running the fridge and other domestics directly from the third output without being connected to the batteries?
My preference would be to wire all outputs to the batteries and run the fridge, and maybe other domestics, from the domestic bank via a low voltage cut out device as has been suggested earlier in the thread.
However does he understand that you want the charger to be able to charge the batteries in the normal way using two outputs at the same time as running the fridge and other domestics directly from the third output without being connected to the batteries?
My preference would be to wire all outputs to the batteries and run the fridge, and maybe other domestics, from the domestic bank via a low voltage cut out device as has been suggested earlier in the thread.
ianj99
Well-Known Member
The battery voltage sensing would not be affected because connected up as you describe above, the batteries are still being sensed and charged as necessary.
I think you may be confused about power pack mode. It only comes into operation when the batteries are fully charged. Ie once the charger has been through it's stages and deemed them charged, it then switches to power pack mode - ie ~13.5v. This also trickle charges the batteries enough to compensate for any self discharge but not enough to cause water loss due to gassing.
The Voltcraft charger I now use, does exactly the same and sits at 13.5v with a .1amp trickle charge showing. If I reset it by switching it off, it goes through its mullti step charging regime, which of course only takes a few minutes since the batteries are fully charged and then power pack mode is restored.
The Procharge will function in the same way.
Ian
abraxus
Well-Known Member
I'm assuming he understands because that's the question I asked.
That said, I guess I have three options.
a) Trust that it will work as intended and wire as Stirling say, therefore all batteries can be disconnected and isolated fom being discharged, but hopefully charged properly.
b) Wire to just the batteries and leave batteries on but fit a low voltage cut out to prevent complete battery discharge.
c) Wire as standard, to battery banks 1 & 2 and leave the battery switch on pos 1, which is the single, older start battery, therefore worst case scenario is that one old battery gets drained.
Given that the scenario I'm trying to protect against has happened only once in over ten years then I'm tempted to go with the easiest solution which is option c)
That said, I guess I have three options.
a) Trust that it will work as intended and wire as Stirling say, therefore all batteries can be disconnected and isolated fom being discharged, but hopefully charged properly.
b) Wire to just the batteries and leave batteries on but fit a low voltage cut out to prevent complete battery discharge.
c) Wire as standard, to battery banks 1 & 2 and leave the battery switch on pos 1, which is the single, older start battery, therefore worst case scenario is that one old battery gets drained.
Given that the scenario I'm trying to protect against has happened only once in over ten years then I'm tempted to go with the easiest solution which is option c)
abraxus
Well-Known Member
Oh ok Ian, thanks for that. You're right, maybe I am confused about power pack mode as it appears this function operates even when there are no batteries in place; either from the charger as a whole if the batteries are removed, or via output 3 if that's connected directly to the house load.
In which case I have another question if you don't mind.
I assume then that outputs 1, 2 and 3 on the Pro Charge sense each connected battery bank independently and deliver the appropriate charge as required. Is that a correct assumption?
If so, then what does it sense on output 3 if that's connected to the house load?
ianj99
Well-Known Member
I'd give A a try, I can't see why it won't work fine.
If you use C and leave the starter battery discharged for any length of time it will be useless. This might not matter if its due for replacement, but if the same thing happens to the new one...
VicS
Well-Known Member
Or option (d):
An additional battery charged from output no3 and supplying only the fridge. ( it could be the old starter battery if you fitted a new starter battery )
ianj99
Well-Known Member
As far as I know, all 3 outputs receive the same output. It will sense each output, but all the outputs are paralleled (but electrically isolated).
You'd be sure Sterling would shout about how it monitors and charges each battery separatley if did this and there is nothing in their blurb about this being the case. They'd claim it was "3 chargers in one".
So when all batteries are charged it will switch to trickle charge ie power pack mode. If there were no batteries connected then it would detect this and remain in power pack mode (presumably - I never tried mine without batteries).
Ian
Fr J Hackett
Well-Known Member
Go for a Balmar they offer ramped start up function so little load on the belts when putting charge into batteries that have been run down, they are well made and coupled with a Balmar high output alternator provide an excellent solution for the small boat charging problems. I had adverc which were OK but eventually ended up with a Balmar alternator and charge controller, expensive but the best that I have experienced.
pvb
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That's my understanding too.
nigelmercier
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While I totally agree, this thread is not about alternators.
abraxus
Well-Known Member
Thanks everyone for your help, very much appreciated.
I do have another question regarding the AC installation of the charger. In addition to the AC positive and neutral, the manual states to run a cable (green) from the bolt on the case to the boat's ground buss. This is easy enough to do but I've read conflicting views on whether one should ground AC to the common (DC) ground or not.
Is this a requierment? An American thing? What are the pros and cons?
I do have another question regarding the AC installation of the charger. In addition to the AC positive and neutral, the manual states to run a cable (green) from the bolt on the case to the boat's ground buss. This is easy enough to do but I've read conflicting views on whether one should ground AC to the common (DC) ground or not.
Is this a requierment? An American thing? What are the pros and cons?
pvb
Well-Known Member
It's a requirement, both here and in the US, for new boats. It's an important safety measure and you'd be recommended to do it. You'll find there are people here who say it's wrong, but they don't necessarily understand the potential danger. The only drawback is that if you leave shorepower connected for long periods, and if there are electrical faults on the marina supply or on neighbouring boats, your anodes could erode more rapidly - this can be avoided by fitting a galvanic isolator.
nigelmercier
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You should certainly earth the case to mains earth, this is mandatory.
Connecting to your battery negative is optional. I can see several reasons not to do so, but I'm also adamant that earthing straps directly under domestic sinks are pointless, so you may choose to ignore me.
