Excellent post and I will add a bit to it..

[QUOTE=newguy;20748][B]Charging system sizing[/B]
For charging systems not using battery temperature monitoring, the best practice is capacity (in amp-hours) divided by 5. So an 84-amp charging system is the right size for a 420ah battery bank (420/5=84). [I]Fair to note that only fresh batteries will pull this, and even then just for part of an ideal charge curve.[/I][/quote]

Battery temp sensing is critical for temperature of charging more so on the hot end. At temps above 80F temp compensation should adjust down so as to protect the battery. That said the vast majority of boats have chargers that already protect most FLA batteries from this by charging in the vicinity of 14.4V... Trojan & US Battery for example prefer to be charged at much higher voltages and this will lead to longer life. So 14.4V on a bank of Trojan or US Battery product and you've already temp compensated for hot weather protection.

I would not advise anyone owning expensive AGM or GEL batteries and not using temp compensation, but flooded batts tolerate it a tad better.

[QUOTE=newguy;20748][B]Charging time[/B]
The amount of time it takes to restore a depleted battery is a function of how deeply depleted AND the restoration capabilities of the charging system, essentially watts and stages. Some charging systems only go between stages based on metrics and some charging systems just put out a fixed voltage forever. There's everything in between and the selection here can have impact on restoration time.[/quote]

Absolutely charger selection and adjustment parameters can have a huge impact on charging time. Many "smart" chargers are actually quite dumb, MANY..

Batteries charge first on current (constant current/bulk) where the source is at max current output and not yet attained the absorption voltage set or limiting point.

The next stage is constant voltage/CV/voltage limited charging. In BULK the limitation is with the source. How may amps 40A out of a 40A charger is bulk charging. In CV the limitation is the voltage or what current the battery can take at a specific SOC & voltage.

With an absorption voltage of say 14.2V the battery will charge significantly slower in absorption than it will at 14.7V - 14.8V... Even thought the source is not the limiting factor a higher voltage in absorption means faster absorption charging and hitting absorption later in the SOC range...

[B]Your charger and your original question[/B]
Your 850 watt specification sounds like the AC watts for the Charles 30-amp charger, which is the factory charger on our 36 MKII. If so, then yes a 1000-watt gasoline generator will work here, but it leaves little for any other simultaneous AC loads.[/quote]

Personally I would not buy the EU1000 but people do. If you are going to suffer noise, fumes, grounding issues then go with the largest output you can get away with reasonably.

[QUOTE=newguy;20748]The Charles 30 is a 2-stage charger, going from bulk to float after a fixed 4 hours, so at most it will restore 120ah of depleted energy before going into float. [/quote]

In my experience the Charles SP series is a three stage charger, but a really dumb one.. Bulk is not a voltage limited stage of charging despite companies like Balmar & Charles trying to blur the definition of what bulk really is. For marketing BULK sounds like a good fancy term to use but it is simply incorrect when referring to a CV stage of charging. Bulk ends at teh absorption set point voltage. Once the charger begins limiting VOLTAGE you are in absorption. Bulk charging is CC.

The Charles does; BULK/CC>ABSORPTION/CV @ 14.5V>FLOAT/CV..

From what I was told they do not start the 4 hour 14.5V clock until the bank hits or attains 14.5V/absorption. Once the bank attains 14.5V the charger runs the 4 hour clock at 14.5V before dropping to the next CV stage of float.
[B]
Charles SP Charging[/B]
[B][I]"When power is applied, the SP series C-Charger will enter a bulk or “constant current” mode, during which a higher rate of charge is achieved to fully replenish the batteries. When the batteries near a full charge, the output
current will decrease and the charger will enter a timed absorption mode. After four hours in absorption mode, the output will drop to a float rate to maintain the batteries at a temperature compensated finishing voltage (13.6
VDC @ 25C for lead acid)"[/I][/B]

[QUOTE=newguy;20748]While excellent for dockside usage for a 200ah battery, it's undersized for efficiently charging a deeply discharged 420ah bank, especially when powered by a gasoline generator. If you did use this combination, then your generator run time to restore 75% of a 75% discharged bank plus an additional 10% for efficiency (=260ah) would be over 8 hours. During that time you'd have to power cycle the Charles once to trick it back into bulk. Fair to note that the time to replace the remaining 25% of the charge (87ah) is quite variable because the battery bank will no longer be drawing the rated output of the charger. You can live either with an undercharged battery bank (not good), or run your generator longer, or use solar/wind to finish the charge (best choice).[/quote]

For most cruisers charging back to 80-85% (pretty much bulk charging and a tad bit of early absorption) with a gen set is the reality of the world we live in unless you want to let it run for hours. Solar, wind or dock usually make up the finishing charge..

[B]Alternative designs[/B]
One choice would be an 80-amp charger @ 14.4 volts = 1152 DC watts. Assuming a "Charles-type" charger (2-stage and AC to DC conversion efficiency of 60%), you'll need a 2000-watt gasoline generator. In about 3 hours you'll replace the same 260ah as above. Same requirement as above for the last 25%. There are other possibilities, such as going with a 60-amp charger with higher AC/DC conversion efficiency to stay within a 1000-watt generator, etc. Using this combination, run time will just be be over 4 hours to replace the 260ah.[/quote]

Before sizing any charger I would first ascertain what your generator can run at under continuous duty conditions. I know my own Honda EU2000 can only run at about 1525W continuous despite the 1600W continuous rating. Honda considers this "within the range of acceptable"...:mad:

Purchasing a "PFC" or power factor corrected charger will yield good conversion efficiency and allow you to drive the most DC current with the least AC consumption. The range of efficiencies on chargers is vast... For example the Sterling ProCharge Ultra has an almost 90% efficiency as does the ProMariner ProNautic P (same charger different stickers).. The big problem is that many truly smart stand alone chargers tend to stop at 60A due to the price of switch mode power supplies jumping dramatically when you push beyond 60A...

[QUOTE=newguy;20748][B]Caveats[/B]
All these specifications are for new batteries. The figures get fudged for less-than-new batteries. Rule of thumb is 10% per year. A 5-year old battery bank can easily have 50% loss in capacity. Sometimes more, sometimes less. [B]Discharge depth, number of discharges, age, temperature, all have bearing here. [/B] Load testing a fully-charged battery is the only way to tell for sure. [I] A subject for another post.[/I] Also fair to note that there are different opinions on how deeply an AGM should be discharged and charge rates. I've used Trojan's specifications in this case.:p[/QUOTE]

I have a set of 8 year old Wal*Mart batteries that were installed on my own boat before converting to Li. They are still putting up 92-93% of the 20 hour rating using a 20 hour capacity test. I have GEL customers many of whom are well past ten years and one who is going into his 15th season this spring.. As you said use, charging, cycle depth and care matter more than anything.

It is my experience that solar for finishing, winter hibernation (very cold storage on the boat) and shallow cycles depths are what have lead to our banks longevity the most. For example if you need four batteries, add a fifth and your average cycle depth will be to 70% SOC vs. 50% SOC etc......

The only true way to test an off grid battery is with a capacity test and those testers just don't exist at a reasonable price point. The Midtronics testers can give an okay approximation but do not directly compare to a true discharge capacity test. I own both Midtronics and Argus capcitance testers as well as a 500A carbon pile load tester and none can replicate a 20 hour capacity test... I had to build my own capacity tester and am working with a company in California on a capacity testing machine for marine batteries. Course this tool will cost me about 4k and they are working out the software reporting glitches at this point........

I think the best one can do is to buy a truly smart charger, program it for the correct voltages, get back to full as often as possible and maximize your ability to restore the bulk charge quickly and you'll be doing well...

FWIW we have never used a generator just the alternator and solar when away from the mooring. Our boat sailed around the world doing the same and 95+% or the time was spent on the hook.. With some good energy management practices there is usually little to no need for a gen set on a 36' boat...

[QUOTE=Maine Sail;20757]...It is my experience that solar for finishing, winter hibernation (very cold storage on the boat) and shallow cycles depths are what have lead to our banks longevity the most....[/QUOTE]

We don't hibernate the boat, but our large solar panel array brings our battery bank (now 450Ah Trojan T-105s) back to full charge essentially every day, even when cruising for weeks and months at a time. I have to believe that, and hardly ever going below 80% state of charge, will surely lead to long battery life (keeping the flooded cells properly watered and using the correct charging parameters, too, of course).

It is nice to get professional affirmation of that.

[QUOTE=newguy;20758]Nice write up by Maine Sail. I think we could both write books on power management systems. Unfortunately, I used the specifications for a Charles 2000 SP charger (2-stage) instead of correctly using the 5000 SP (3-stage) specifications. I've deleted the need to power cycle the Charles after 4 hours to trick it back into bulk as stated in my earlier write-up.[/quote]

As far as I know the SP2000 use the same algorithm as the 5000 series (according to Charles all the SP chargers used the same algorithm).

One of the manuals, IIRC was misleading and incorrect, and I can't recall if it was the 2000 but I do remember calling them a few years ago to get clarification as to whether 14.5V triggered the 4 hours or if turning the charger on triggered the 4 hours....

Still any charger that uses a "timed" absorption in this day and age is not a charger I want to install..... There are much smarter chargers out there that calculate absorption time on the fly...

[QUOTE=deising;20759]We don't hibernate the boat, but our large solar panel array brings our battery bank (now 450Ah Trojan T-105s) back to full charge essentially every day, even when cruising for weeks and months at a time. I have to believe that, and hardly ever going below 80% state of charge, will surely lead to long battery life (keeping the flooded cells properly watered and using the correct charging parameters, too, of course).

It is nice to get professional affirmation of that.[/QUOTE]

Yes you should get good long life... Heat though is another killer of batts. Temps regularly above 80F will drastically shorten life. Our batts, due to Maine water temps, are lucky to ever break 65F. thus they do tend to last longer when you figure temps into overall life. There are soo many factors but shallow cycles, proper voltages and frequent top ups seem to be the biggest ones.. Just be sure to be pushing your T105's for at least an hour per charge cycles at 14.7V-14.8V..... This will greatly lessen the effects of sulfation...

Thanks, Maine Sail. Yeah, I know heat is the killer, but I live where I live.

Appreciate all your good input here, and elsewhere.

[QUOTE=KnotDoneYet;20773]There are two types of Honda 2000i generators. One has a 30 amp connector like for shore power so no adapter needed. The other has the standard outlet like in your house. For this one there is an adapter pigtail you can get at West Marine.

I am still confused on whether the 30 amp connector model puts out more amperage (whether burst or constant) than the standard outlet model.

My 2000i has trouble starting my A/C but charges the batteries just fine. I thought a 40 amp Pronautic was overkill but think I should have gone bigger now. BTW, I love the Pronautic charger it's taking great care of my lead acid batteries.[/QUOTE]

They have the same 1600W continuous rating. They also claim up to 30 minutes at 2000W but mine will go for about 10 minutes at 2k that's it...... They all vary very slightly as to output performance but the factory ratings are still 1600W continuous and 2000W peak. For the AC, depending upon size, you would likely need a soft start capacitor...

Guys,

I want to clarify some points I made that were in-fact not correct due to poor communications / data from the manufacturer..

[B]FACT: [/B]The Charles SP series of charger, the 2000 & 5000 series, start the 4 hour clock from the minute they are turned on.:mad: This applies to ALL Charles SP series chargers. (source Charles Application Engineering Department)

[B]FACT:[/B] They ALL do BULK>ABSORPTION>FLOAT (source Charles Application Engineering Department)

[B]WHAT WAS TRUE:[/B] Approx two years ago I called Charles to discuss the vagaries of their manuals and was told that ALL SP chargers used the SAME profile that is shown in the SP5000 series manual.. This part was TRUE. ALL SP Chargers use the identical charger profile and the description in the SP2000 series manual is misleading at best and completely incorrect at the worst..

[B]WHAT WAS INCORRECT:[/B] What was not true was that the chargers [I]start[/I] the time clock once they attain [I]14.5V[/I] or [I]the limiting voltage[/I]. They do not start the clock once limiting voltage has been attained. They [I]DO[/I] start the clock from the minute they power up!:eek::eek: DUMB charger! They had told me 2 years ago the clock starts at [I]14.5V[/I] or [I]limiting voltage[/I]. This is NOT TRUE.

Just for the heck of it I called Charles this morning and was told the SAME THING from first line tech support. When I pressed further with technical questions they sent me to the applications engineering department where they cleared up the confusion.

[B]All SP2000 & SP5000 chargers do BULK>ABSORPTION>FLOAT[/B]

[B]HOWEVER[/B] if the charger is not sized correctly they can literally bypass absorption all together if the 4 hour clock runs out!!!!!!!!!! They can literally go straight from BULK to FLOAT. This is just DUMB, DUMB, DUMB.........

When these chargers were designed, many moons ago, banks were much smaller than they are today. Today this 4 hour clock is grossly outdated for the way we use boats today. It can lead to chronic undercharging and an early demise of your bank.

[B]Why do they do it this way?[/B]

To justify this outdated charging technology Charles want to see you size your charger to [B]50% of bank capacity[/B]. HOLY COW!!!!

[quote=Charles Industries][B]What size charger do I need?[/B]
For standard and deep cycle batteries, we recommend sizing the charger to ([B][COLOR="Red"]50% of the total AHrs of the house/accessory battery bank[/COLOR][/B])[/quote]

When you do this it [I]can[/I] work, meaning BULK>ABSORPTION>FLOAT. In the real world however it is very, very rare that anyone sizes a battery charger to 50% of Ah capacity unless specifically sizing it for genset recharging on AGM or GEL.. Especially not the builders.. This means a 100A charger for a 200Ah bank and a 200A charger, which does not exist in that line, for a 400Ah bank. A 250A charger would be required for four 6V GC2 batteries....!!!

I also won't mention how 50A of charging on a 100Ah flooded battery (50% of "C") can actually SLOW charging, not speed it up, because the battery will simply hit absorption voltage sooner in the charge curve and accept LESS current once the plates have packed a massive surface charge and begun limiting current to what they can physically accept at that voltage.. When you slam flooded batts with that kind of current it makes it difficult for the plates to accept the charge deeply and they can actually charge slower than they might with 20%-30% of "C" because you start voltage limiting well before you really should... It kind of acts like sulfated plates driving the voltage up prematurely and current limiting earlier in the charge curve. Whoops...... I mentioned it..
[B]
How does it work in the real world??[/B]

Let's take a real world boat builder/Charles Charger instillation like the 20A version that came from the factory with our 2005 Catalina 310. Remember the builders are not doing you any favors nor are they sizing these chargers correctly. They are getting these boats out the door as cheaply as possible via the cheapest means possible.

I work on both power and sail and have NEVER, EVER, EVER seen any boat builder install a Charles charger sized at 50% of "C" for a house bank... Not a single builder...

When our C-310 left the dealer in 2005 it had a house bank of 320 Ah's and a group 27 starter all paired to the Catalina installed 20A Charles charger.....:confused:

[B]How about some math?[/B]

If we draw the 320Ah house bank to 50% SOC and then turn on the Charles charger it will replace 80Ah's of capacity or 20Ah per hour of run time. Before it even hits an absorption voltage it is hitting the 4 hour time limit and going straight into float!!!!!!!!!!!!!!!!!!!!!!!!!! No ABSORPTION!!!!

This means the battery bank NEVER EVEN HIT ABSORPTION VOLTAGE because in those 4 hours it only got back to 75% SOC! I am not even going to include for charge efficiencies here or the potential for voltage drop in the cabling which could really leave it at under 70% SOC when it enters float. So the 4 hours runs out, the charger drops to float voltage, and leaves you CHRONICALLY under charged and never reaching a gassing voltage which is CRITICAL to your banks longevity.

Now take that same installation and add a dockside load such as an icebox & some cabin lighting or a stereo or computer. Lets figure our dockside loads during those first four hours average 7A. Now we have a 13A charger and have only replaced 52Ah's and are stuck at 66% SOC not counting for inefficiencies etc. which could really leave you closer to 60% SOC when you enter float.

Voltage is your pressure, less voltage = less current flowing into the battery so it could take many DAYS to "recharge" but really you've not done a healthy recharge and are going to wind up with some sulfation and perhaps stratification because you never got the batteries to a gassing voltage....

Most every charger out there that uses a time based algorithm starts the clock once target absorption voltage has been attained. This means no matter how big the bank it it will ALWAYS hit absorption voltage FIRST before starting the timer. Not the Charles SP series. Doh'.....

I also asked what would reset the time clock. As has been mentioned you can manually reset the clock by cycling the charger on/off or by simply applying a DC load larger than the charger can handle, or about 110% of the charger capacity.

If you have an Espar heater, water pressure and a fridge and computers, some lights etc. and a 20A charger, you could literally be keeping that charger at 14.5V for long periods of time if the loads every exceed 21A on a 20A charger at least ever 4 hours. Not improbable with a small charger like ship with so many boats.. Start loads on items are significantly higher than running loads. Most truly smart chargers check the current flowing out of the power supply to help determine whether it is okay to pop out of float or remain in it. When the Charles SP series pops out it starts the 4 hour clock all over. Ideally a [I]smart charger[/I] would go back to bulk and then quickly revert back to float.

When sizing ANY charger dock side loads need to be taken into account. The bottom line here is that a truly SMART charger such as the ProMariner ProNautic P or Sterling ProCharge Ultra will cost less money than a dumber Charles SP because you DO NOT need to size these chargers to 50% of "C" in order for them to work [I]properly[/I]...

I apologize for the confusion I created and hopefully this helps clear it up. Unfortunately this would not be the first time I have been given erroneous information by a manufactures tech support team. It gets very, very frustrating. Thanks to Nick's questions I reached out again the Charles to get some more clarification...

So if you want to use a Charles charger I would strongly advise you to size it large enough to at least hit at least 3 hours of absorption. While this is still far too short it is what it is. Otherwise buy a charger that is actually [B]smart[/B].

Just as a good data point I discharged a healthy but used 125Ah FLA deep cycle battery to exactly 50% SOC then recharged it at 20% of "C" using CC/CV charging. The voltage and current was recorded every two minutes. I wanted to see how long with 20% of "C" to full or less than .5% acceptance... This battery when truly full will accept about 0.09A at 14.4V. I stopped at 0.66A and 340 minutes...

2 Minutes - Current = 25A Voltage = 12.59V

20 Minutes - Current = 25A Voltage = 13.12V

40 Minutes - Current = 25A Voltage = 13.33V

60 Minutes - Current = 25A Voltage = 13.60V

80 Minutes - Current = 25A Voltage = 13.95V

100 Minutes - Current = 25A Voltage = 14.39V
[I](note: it took 102 minutes to hit 14.4V at 25A for a 125Ah battery from 50% SOC)[/I]

120 Minutes - Current = 15A Voltage = 14.40V

140 Minutes - Current = 9.5A Voltage = 14.40V

160 Minutes - Current = 6.3A Voltage = 14.40V

180 Minutes - Current = 4.1A Voltage = 14.40V

200 Minutes - Current = 3.1A Voltage = 14.40V

220 Minutes - Current = 2.3A Voltage = 14.40V

240 Minutes - Current = 1.8A Voltage = 14.40V

260 Minutes - Current = 1.5A Voltage = 14.40V

280 Minutes - Current = 1.25A Voltage = 14.40V

300 Minutes - Current = .96A Voltage = 14.40V

320 Minutes - Current = .72A Voltage = 14.40V

340 Minutes - Current = .66A Voltage = 14.40V

Rod,
Thank you, as usual, for your detailed explanation. It's great to have a knowledgeable former C36 owner looking over our shoulders!

For those who have not read this it may help put regulators, current, acceptance and voltage regulation into perspective:

[B][SIZE="4"][URL="http://forums.sbo.sailboatowners.com/showthread.php?p=775433#post775433"]Musings Regarding External Regulation[/URL][/SIZE][/B]

Thanks as always to Mainsail for sharing his expert knowledge with us.

Just a quick question. My boat has a ProMariner charger, which was a warranty replacement for the crappy flyback charger that came with the boat. I believe it's a ProTech-4 1220, 20 amp charger.

With all of the product re-branding that goes on these days, I'm just curious if these chargers are re-branded Charles products, or actually a different, hopefully superior, product actually manufactured by ProMariner? The charger has faithfully maintained my pair of 4D gel cells since about 2001.

[QUOTE=plaineolde;20790]Thanks as always to Mainsail for sharing his expert knowledge with us.

Just a quick question. My boat has a ProMariner charger, which was a warranty replacement for the crappy flyback charger that came with the boat. I believe it's a ProTech-4 1220, 20 amp charger.

With all of the product re-branding that goes on these days, I'm just curious if these chargers are re-branded Charles products, or actually a different, hopefully superior, product actually manufactured by ProMariner? The charger has faithfully maintained my pair of 4D gel cells since about 2001.[/QUOTE]

I believe those chargers were designed by ProMariner or Charlie Sterling (chicken / egg) but they also could have been a Charlie Sterling/ProMariner joint venture. ProMariner is relabeling a lot of Charlie's product these days and also co-designing with him... I think if you look at the history of that product you will see Charlie had that design marketed before PM so that means Charlie likely designed it.

[IMG]http://www.piplers.co.uk/media/catalog/product/cache/1/image/800x470/9df...

[IMG]http://promariner.com/wp-content/uploads/2013/06/ProTech-4a.jpg[/IMG]