Split Charge System vs Diodes with Smart Charger?

[futureoptions]

I'm re-engineering my electrics for liveaboard on my 43' yacht from next summer. I have minimised power consumption, extra fridge insulation, LED lights, no A/C so I'm not a huge power user.
I'm plannining to fit about 150watt output solar panels with MPPT regulator, renew the battery banks (400ah+75ah) May also fit a wind genny at some point, but would rather avoid it if possible. Engine is volvo D255 with standard alternator.
Ive been looking at the Adverc smart alternator regulator and also the Smartbank/smartgauge split battery systems, however I can't come to any conclusion on which is best to maximise charge from the alternator, ie minimise engine running time whilst ovoiding overcharging of the start battery when I have to motor for extended periods.
Does anybody have any view on the best way to go?
Also- while I have your attention! I'm planning to set the voltage control for the solar controller slightly higher than the voltage of the alternator controller output, in the expectation that the solar will generally provide charge power in preference to the alternator when the battery charge requirement can be fully met by the solar panels, thus reducing belt wear, engine loading, and allow the solar controller to operate in three stage mode. I also expect both systems to supply charge when the battery demand is high, and the voltage is pulled down below the set level of both controllers.Am I correct in my thinking here?
thanks in advance!

[cal40john]

I'm not familiar with these products. If you mean that you are looking at using these three items together as a system to compare against other systems, ignore the following. If you are asking which of these three to use here's what I understand. After having a quick look at their web sites it looks like the Adverc is just a voltage regulator. If uses a high/low voltage cycling program that I haven't seen discussed anywhere. The diagrams show how to hook it up to multiple batteries using either switches or diodes. The Smart Gauge is only a battery monitor, tells you how full your battery is. The Smart Bank is only a relay battery combiner. When the voltage is correct (charge sources on) it combines the batteries so they all charge, charge sources off, batteries are disconnected from each other. So these products all have different functions, it isn't a which is better.


Voltage regulators to compare to the Adverc

Balmar 3 stage programmable regulators:
page14-Regulatorsmain

Xantrex:
http://www.xantrex.com/web/id/594/docserve.aspx


Battery combiners to compare to Smart Bank

Blue Seas battery combiners:
Automatic Charging Relays - Blue Sea Systems

Next step beyond combiners, DC to DC charger to not overcharge start battery when using a 3 stage regulator connected to the house bank:

Balmar duo charge:
http://www.balmar.net/PDF/Duo%20Charge%20Manual.pdf

Xantrex echo charge:
http://www.xantrex.com/web/id/421/docserve.aspx

Using the search button in the lower tool bar above between new posts and quick links, select the google custom search to search this site for combiners and regulators and you will get many hits where folks here will defend their favorite brand to the death.

John

[OceanPlanet]

Setting your solar controller higher than your alternator settings won't really matter very much, until the very end of the charge cycle, when the voltage gets high enough (depending on where you set the alternator regulator) to have the alt. reg. wind down the field current. At that point the amps will be so low that the wear/tear you're worried about won't exist. The biggest load/wear on the alternator/belts is earlier in the charge cycle when the batteries are low and the charging amps are high. However, one advantage of your approach is that you can probably get the solar controller to keep charging when the alternator is charging too...on many boats with PV the controller shuts out the panels when the alternator is charging. This is more likely in cold weather (when the batteries are cold) and you have temp-regulated charging (which you should!)...the alt. reg. will charge at higher voltage when the batteries are cold as they can take higher voltages then without trouble. In other words, you may have to set the solar controller higher in colder weather to "stay ahead" of the alternator.

On the other hand, what your panels put out is diddly compared to what the alternator does...so all this doesn't really matter much.

Regarding the combining/charging of the batteries, my favorite arrangement is to have the alternator output run to the house bank (where the temp sensor should be) and use an echo charger to the start battery with adjustable cut-in/cut-out voltages. If you are motoring a lot and are worried about gassing the start battery, you can turn down the cut-out. In any case, make sure your batteries are matched (same type and age) as closely as possible.

[bill good]

found a solid state relay to be useful. the mttp controller had an "aux" function which turned on the relay when the house batteries have received there daily input & tops up the starter battery. it had an "unexpected" function where it feed the house batteries when the engine was going!! (a protective diode built in to internal mosfet? in the relay) capable of 100A with a heat sink & 20A without. my system requirements is under 20A. but know & understand what you are doing! remember one flash & its ash.

regards Bill

[Albro359]

I have had battery combiners...failed...one was a giant solenoid from BEP - they don't make it any more

I have had diode blocks...they get hot...obviously wasting power with that 0.7v drop (0.7 x 110A = 77W !)

Now I have a Victron MOSFET battery isolator...just like a diode block but the voltage drop is <0.1V ...all solid state. nothing to break...wonderful

Regulator is an ample power NEXT STEP 2...great...only issue I have is trying to work out what the absorption time should be set at

All equation derived settings I've come across depend on the intial state of charge of the batteries..rather difficult to determione..and certainly not always the same

One marine electrician said "oh 60 mins should be good for boat batteries"...with no idea of the size of the alternator / battery bank / type of batteries....hmm

Anyone have a simple equation that would take into account bat type / size / voltage before charging ???

Cheers

Alan

[CharlieJ]

Here is one equation that I have stumbled on but have not verified:

H = ((C x 0.25 x 1.15) / R) x 2

Where:
R= Available charge rate.
C = battery capacity in Amp Hours at 20 Hour rate.
H = Hours at absorption voltage to full charge.

Example: If R =110 amps, C= 820 Amp Hours

H= ((820x0.25x1.5)/110) x 2 H=4.29 hours

[futureoptions]

thanks everybody for your informative answers. From what youve all said, it seems that the best option is a split system, with a bettery sensed regulator, incorporating temperature sensing. Its interesting that the websites for these products appear to 'rubbish' the other option, when they are in fact serving a different purpose. However, it's interesting that Albro has had a poor experience with relays, I have heard of these failing elsewhere, seems to be a common problem, which I don't want to purchase! So, thinking this further through, the Victron duo charge looks like the solution to the diode problem, rather than a converntional split charge relay, as this configuration only needs to carry current to charge the start battery rather than the whole alternator output. I don't know what my alternator actually charges at, but as it's fairly recent, I would guess it's set at 14.5v. If it is 14.5v and if I use the Victron duo as above, my thinking is that as this set up will have no diodes etc causing voltage drop, to the house bank, I won't need a battery sensed charger, so I can stick with the existing machine based sensor in built to the alternator, which will fully charge the batteries at 14.5v output.
Sounds like win-win to me. Does anyone have a more informed opinion of my proposal?

[cal40john]

Originally Posted by futureoptions

thanks everybody for your informative answers. From what youve all said, it seems that the best option is a split system, with a bettery sensed regulator, incorporating temperature sensing. Its interesting that the websites for these products appear to 'rubbish' the other option, when they are in fact serving a different purpose. However, it's interesting that Albro has had a poor experience with relays, I have heard of these failing elsewhere, seems to be a common problem, which I don't want to purchase! So, thinking this further through, the Victron duo charge looks like the solution to the diode problem, rather than a converntional split charge relay, as this configuration only needs to carry current to charge the start battery rather than the whole alternator output. I don't know what my alternator actually charges at, but as it's fairly recent, I would guess it's set at 14.5v. If it is 14.5v and if I use the Victron duo as above, my thinking is that as this set up will have no diodes etc causing voltage drop, to the house bank, I won't need a battery sensed charger, so I can stick with the existing machine based sensor in built to the alternator, which will fully charge the batteries at 14.5v output.
Sounds like win-win to me. Does anyone have a more informed opinion of my proposal?

The combiner relay does not carry the entire alternator output. Think of it this way. Run the alternator output to one battery. Connect a wire to that battery that goes through a switch to the other battery. It will only carry the current going to the second battery to charge it when the switch is closed. If you run the alternator to the start battery the switch will usually be carrying a lot of current since the house bank is the one discharged and will take most of the alternator output. If you wire the alternator to the house bank instead then the switch carries less current since the only current it carries is that needed to charge the slightly discharged starter battery.

You mentioned in your first post that you want to minimize charging time. If you really want that then you want the external 3 stage regulator as that will leave the alternator on longer at a higher output than a conventional regulator. If you go to the 3 stage regulator then it might be a good idea to use one of the DC DC converters like Echo or Duo charge. The 3 stage charger charges at a higher voltage for a time. Fine for discharged house, excessive water consumption if not worse for the full start battery. The Echo and Duo are battery chargers in their own right and regulate what goes to the starter battery based on its need.

IMO if you stay with your internally regulated regulator a MOSFET option should work fine.

John

[Toys_with_time]

While we're on the subject of charging & regulators I would like to add a question (or 2)

Have ordered a FP Lipari 41. Comes standard with

• 2 x 115A/12V engine alternators
• 1 set port onboard/engine AGM batteries of 300Ah
• 1 starboard AGM engine battery of 100Ah
• 1 charging power relay

I plan to add myself:

• increase house batteries by 200Ah to 500Ah
• add +/- 240w of solar panels with peak powor regulator
• add duogen water/wind generator with regulator
• add temperature sensor(s?) to house bank only (?)

Questions:

• If all the regulaors are feeding into the same battery bank how do they read the underlying battery voltage and not each others output? Are there any tricks to watch out for with this?
• Assume the std FP fitted charging power relay controls output between house and startting batteries. Should I replace this with something more sophisticated?
• Any thoughts on the above set up, other extras I should add and things to consider / watch out for when designing and wiring it all up? Any sketches / wiring diagrams would be great!

All ideas and comments will be very gratefully received and a cold can of Ozzie amber nectar supplied if I meet you in a bay somewhere (assuming my charging system works so I can run the fridge)