Boat is seriously under-charged

We are about to do more on the hook cruising and I need to upgrade my charging capacity. I currently have

• (5) 105 AH AGM house batteries connected in parallel to form the house bank
• (1) 105 AH AGM start battery that is the start bank
• (2) 100 amp alternators, one on each engine
• (1) Battery switch that isolates or combines the house and start banks.
• (1) 30 amp Charles 3 bank battery charger
• (1) Westerbeke 7.6 KW generator. AC power is divided into (2) 30 amp circuits. One circuit power 2 air conditioning units, the other circuit powers all other AC powered items.

I've estimated my daily power usage while anchored at 300 amps. My older Norcold refrig is the primary power user. It still works fine and I won't replace it until it dies.



Some considerations:

• I don't want to use the engine alternators as a primary way to charge the batteries
• My current 30 amp charger would require I run the genny 10 hrs a day to replace the 300 amps used. Actually much longer when you consider the charger goes to a float charger at 80% charge. 10 hrs of run time per day is not reasonable.

So this is my plan:
Add a new battery charger. In my notes I came across the following formula to determine the required amp out put of a battery charger; 25% of the total amp hours of the largest battery bank. In my case; (5) 105 AH batteries = 525 amps. 525 * 25% = 130 amps.

So if I can find a 130 amp battery charger I will connect it to my house bank and leave my current 30 amp charger connected to the engine start bank and genny start battery.

This would require a genny run time of 3 hours per day to replace the 300 amps used each day. I would probably run an hour and a half twice a day.


Please comment on my plans.


Questions:
Do I need an ACR? I am pretty good about selecting the Battery switch to the house bank when we anchor. This of course keeps the engine start bank isolated and unused. After engine start I reselect Both on the battery switch which then allows the engine alternators to charge both the engine start bank and house bank.



Battery monitor/SOC meter. Is this necessary?



I don't need an inverter, so where can I get a 130 amp or something close battery charger. One bank is sufficient and does the battery charger need to have a selection to charge AGM batteries?

I think you're in the ball park. First, you mixed up Amps and Amp-Hours, but I know what you meant. If you're using 300AH a day, and your house bank is 525AH, and you really shouldn't let it get below 50%, then you'll want to recharge by the time you've used about 263 AH. Or, as you say, twice a day. If you have an electric stove and water heater, do this while cooking breakfast and dinner, and heat your water at the same time. You'll need that extra margin because you won't charge back up to 100% in just an hour or two. As you point out, that last bit of the charging takes the longest.

There are probably a hundred opinions on ways to solve this, but I think a 100A charger (or a little bigger if you want) will get you where YOU want to be.

Most batt chargers do not hold their rating , charge ability with small, under 10KW noisemakers.

So you may be running a very long time.at 70A not 130A.

I would install a big truck alt (135-150A) on the noisemaker , two if there is room and the units assembler will allow 3-5 hp taken off the front.

The AGM can absorb a good deal better than wet batts , so a smart V reg with a temp control would work best.

In the long run it will be far cheaper to toss the Norcold antique and cut your power draw in half.

As always the FIRST item installed should be a SOC meter to actually allow you to understand and keep track whats happening.

If you will spend weeks or months on the hook , plan on and size the batts to cycle between 50% and 85% , to reduce noisemaker ON time.

FF said:

I would install a big truck alt (135-150A) on the noisemaker , two if there is room and the units assembler will allow 3-5 hp taken off the front.

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I've given that some thought but came to the conclusion after reading several posts on TF that a higher amp alternator on the genny would require expensive retooling, ie two belt drives and associated pulleys and I'm not sure I've got the room for such a modification. Besides would my 7.6 KV genny be able to handle air conditioning too?

I probably should contact Westerbeke and find out.

Anybody know?

IOTA makes efficient but inexpensive chargers. Two 75 amp units in parallel with a common 3 step regulator would be your best bet. AGMs can charge at 50% of AH capacity.

The value of an ACR or equivalent depends on how good you are at remembering to turn the 1,2,all switch to protect the start battery.

David

timjet said:

We are about to do more on the hook cruising and I need to upgrade my charging capacity. I currently have

• (5) 105 AH AGM house batteries connected in parallel to form the house bank

Click to expand...

Sort of an OT/oblique comment... I think I've figured out that I can replace the 3x Group 31 AGMs in one of our banks with 4x 6v golf cart batteries... increasing available AH on that bank from 300-315 to approx. 450. I think I'll likely do that, whenever the 8-seasonold AGMs go south.

Perhaps you could eventually fit 6x GCs in the same space as your 5x G31... and that would increase your available AHs from 500-525 to approx. 675.

-Chris

ranger42c said:

Perhaps you could eventually fit 6x GCs in the same space as your 5x G31... and that would increase your available AHs from 500-525 to approx. 675.
-Chris

Click to expand...

I assume the golf cart batteries are wet cell. My battery compartment is extremely difficult to get to. I wouldn't/can't check fluid levels on a consistent basis, so I'll stick with AGM's.

Thanks though, good thought.

timjet said:

I assume the golf cart batteries are wet cell. My battery compartment is extremely difficult to get to. I wouldn't/can't check fluid levels on a consistent basis, so I'll stick with AGM's.

Thanks though, good thought.

Click to expand...

Lifeline makes some AGM gold cart batteries.

I'm in sorta the same boat in that I can't reach all our batteries easily; I know what you mean about the conveniences of AGMs.

-Chris

Installing a big alt on the Westerbeke will be difficult to engineer.

Getting a more efficient fridge is key in the whole matter. Consider a separate cooler/fridge for drinks and keep food in the fridge. Opening the door everytime someone wants a drink drains the cold air and unit has to run another half hour to catch up.

I have resorted to using a high dollar cooler to store ice and using it to feed ice to a smaller drink cooler. Ice lasts about 4days and is cheaper to replenish than all the diesel it would take to cool drinks otherwise. System is still imperfect, and evolving.

Solar panels? Looks like you may have a hardtop, the perfect place. I am about to install around 500 watts on our boat. The price has really dropped in the last few years, below $1.00 per watt. I am thinking 2 - 250w panels in series w/ a mppt controller. Around $1000 for parts. No moving parts.
Check emarine.com.

Rafe

Bear in mind that the rated output of a charger is its max, typically at 20C. It isn't smart to run these things at max output for hours and modern quality chargers often provide a de-rate feature. So getting 130A out may require a charger with a rating of more like 150-160A.

Not sure why you wouldn't want an inverter? Saves starting the genny for brief AC uses. If you are in the market for a new charger, why not consider a Victron or MasterVolt inverter/charger? Both make models that would give you your 130A.

I agree with your idea of keeping your current charger: it will help to properly load your genset as well as speeding up overall charging times/reducing genset run times.

The idea of putting really big alternators on a genset already properly sized for its AC end plus small (20A?) charging alternator has been discussed elsewhere: not a good idea.

SOC essential in my view. If you go Victron or MasterVolt, get one from them...there are models which give you remote control/monitoring of the charger (or charger/inverter) as well as SOC.

If you want to keep your Norcold but have concerns about its efficiency (and it will be your biggest pwr user when on the hook), consider putting a computer fan (small, brushless, quiet, negligible amp draw & literally only a few $) beside the Norcold's compressor to improve air circ/ventilation. You could get a 10-15% reduction in running amp draw from this alone.

Cat Daddy said:

Solar panels? Looks like you may have a hardtop, the perfect place. I am about to install around 500 watts on our boat. The price has really dropped in the last few years, below $1.00 per watt. I am thinking 2 - 250w panels in series w/ a mppt controller. Around $1000 for parts. No moving parts.
Check emarine.com.

Rafe

Click to expand...

I wish we had a hard top. A 500 watt install would go a long way to matching that 300 amp-hrs daily consumption rate. It would also prevent deep cycling the battery bank.

djmarchand said:

IOTA makes efficient but inexpensive chargers. Two 75 amp units in parallel with a common 3 step regulator would be your best bet. AGMs can charge at 50% of AH capacity.
David

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This looks like a cost effective plan. About $600 + installation costs. However please explain the 3 step regulator, I thought they were built into the charger.

Another thing, this was posted by Aquabelle on 7/1/2012:
Problem with 2 independent chargers both connected to same battery/bank is that their voltage sensors will confuse each other: each will 'see' the charge voltage being applied by the other charger and not the real charge of the battery and so will step back their charge delivery, wrongly sensing a charged battery. You can gang together chargers of the same type often, but then you only connect one voltage sensing wire (and one battery temp wire) not two.

I would need further explanation on how to wire two chargers to avoid the sensing problem.

Ski in NC said:

Installing a big alt on the Westerbeke will be difficult to engineer. Actually I've gone through and will no longer consider it.

Getting a more efficient fridge is key in the whole matter. Consider a separate cooler/fridge for drinks and keep food in the fridge. Opening the door everytime someone wants a drink drains the cold air and unit has to run another half hour to catch up.

When my current fridge craps out, I will replace it with a more efficient one. If I can get enough charge now with the current refrig, I'll be way ahead of the game when I replace it.

I have resorted to using a high dollar cooler to store ice and using it to feed ice to a smaller drink cooler. Ice lasts about 4days and is cheaper to replenish than all the diesel it would take to cool drinks otherwise. System is still imperfect, and evolving.

Click to expand...

Yes something to think about.

How about fold-down panels? Sailboats use 'em.

TONTOROSS said:

How about fold-down panels? Sailboats use 'em.

Click to expand...

Nah, for me it has to be pretty.

timjet:

It has been a while since I looked at IOTA chargers, but they used to sell a simple charger, presumably with just a preset float voltage, that you could hook up to their IQ three step controller that would make it a full 3 step charger. One controller could handle several chargers and the chargers were designed to be paralleled.

Almost all are sold now with an integral 3 step controller.

David

A 100 amp Charles will cost you $1400 plus cabling (I don't know your setup) plus the SOC unit.

One start battery for three engines doesn't work for me for redundancy so I would install 2 more, a standalone genset start plus another for the main engines. Don't forget cabling. Most marine stores will lend you a crimper, so make your own to fit.

Use your old Charles for the start banks to keep the floats correct. Start batteries are recharged in 5 minutes or so after being used so they are no problem, but they are the ones directly involved in safety issues, like anchor raising...

I would keep one alternator dedicated to charge the start bank and add a larger one for the house bank.

You need a new fridge system, so sell your old Notcold and get a more efficient method to keep things cool.

I agree that solar panels should be in your future.

If you wish to drop your fridge power load to ZERO, simply properly install a propane fridge.

WE have a full sized Dometic , that uses a 20# bottle a month.

Xsbank said:

A 100 amp Charles will cost you $1400 plus cabling (I don't know your setup) plus the SOC unit.

I agree that solar panels should be in your future.

Click to expand...

A IOTA 75 amp charger costs $225. I can't see why the Charles are so expensive. IOTA has a paralleling controller they sell with their chargers, seems to fit my need and well below some competitors.

I don't see solar panels as being a viable solution. A couple of rainy days and you're searching for a plug or worse, drinking warm beer.

FF said:

If you wish to drop your fridge power load to ZERO, simply properly install a propane fridge.

WE have a full sized Dometic , that uses a 20# bottle a month.

Click to expand...

That would solve the re-charging issue but create other problems. I really don't like propane plumbed throughout the boat and constantly pressurized. It's probably just me and probably why I choose diesel as a power plant.
Plus re-filling propane once a month at $18 and installing a propane locker with monitoring devices will soon cost more than going the electrical re-charge direction.

Plus re-filling propane once a month at $18 and installing a propane locker with monitoring devices will soon cost more than going the electrical re-charge direction.

Depending on how you run the numbers I figure its $5.00 to at least $10.00 for every hour of noisemaker time.

Just 4 hours a day is at least $20, what a months worth of propane costs.

I tried for a long time to create an acetylene gas generating system to feed a range and fridge (lighter than air) , but no go.

The IOTAs are not marine chargers and likely do not have the proper isolation of AC and DC circuits. I don't see any indication they are UL 1236 rated, and they don't include marine as an application. As usual, there's no free lunch.

FF said:

Depending on how you run the numbers I figure its $5.00 to at least $10.00 for every hour of noisemaker time.

My Genny burns half a gallon an hour. Your figures are just a little high.

Just 4 hours a day is at least $20, what a months worth of propane costs.

Anchoring out 2-3 times a month and it's cheaper to go with electric. But your point is well made once the anchoring times go much above this.

I tried for a long time to create an acetylene gas generating system to feed a range and fridge (lighter than air) , but no go.

Click to expand...

I know there is a reason, but why not natural gas. It should work well with all propane systems with minor mods.

caltexflanc said:

The IOTAs are not marine chargers and likely do not have the proper isolation of AC and DC circuits. I don't see any indication they are UL 1236 rated, and they don't include marine as an application. As usual, there's no free lunch.

Click to expand...

George, I need to look into that.

There was a guy on this forum who wrote blogs about everything he had done to his boat. Was very active, but left in a huff, I don't know why.
Anyway I read his blog on chargers and he used IOTA's, 2 of them and was happy.

timjet said:

I know there is a reason, but why not natural gas. It should work well with all propane systems with minor mods.

Click to expand...

Very few places that supply CNG in the US. It is a great fuel, that takes a lot of pressure to keep it liquid. It is used in Europe quite a bit.

OK, I have to replace 300 amps per day, so recharging twice a day is 150 amps per charge. I only want to run the genny 1.5 hours at a time or 3 hours a day. A 100 amp charger minimum is necessary. But that is still probably not enough. If a charger will bulk charge my AGM's to 80% before going to an absorbtion phase and AGM's will accept 80% of their capacity during a bulk charge then if my figures are correct I will be replacing 120 amps during each 1.5 hour charging cycle. In this case I will have to run the engines/alternators every other day or so to regain those lost amps and bring the batteries up to full charge.

So sticking strictly with battery chargers there are a few options.

• If I keep my current 30 amp Charles charger to maintain the engine and genny start batteries, adding a new 100 amp charger (for the house bank) will require adding the wiring and circuit breaker to add the new charger. There is a cost and my time associated in doing this. Also I will have to look at the power draw of the new charger along with my current charger to make sure I don't exceed the capability of my genny. A 100 amp charger draws from 15-18 amps (I think) Each circuit of my genny (there are 2) is 30 amps.

• Replace my current 30 amp charger with a new 100 amp 3 bank charger. I will have to check the wiring gauge and circuit breaker to make sure they are robust enough, but the whole process is a bit easier than the option above. The downside is the genny start and engine start bank will take some of the amps, so I will not get full charger output capacity to the house bank on most chargers.

The 100 amp chargers I've look at:

• Victron 100 amps, 3 banks, 15amp input. $1087

• Mastervolt 100 amps, 3 banks. Intersting in that this is the only one that stated the output of the 2 smaller banks. 10 amp each and the main bank gets the full rated 100 amp output. $1375

• GoPower; 100 amp single bank, marine rated $339 This is an interesting option at a third the cost. It only has one bank but I could keep my other charger for the other 2 banks.

• IOTA makes a 75 amp single bank charger with a controller that will allow connecting 2 chargers in parallel. This would be 150 amps but each charger consumes 18 amps and I would have to watch carefully my amp usage when the genny is on. As George mentioned above, these units are not marine rated. Total cost of 2 chargers and controller is about $450. There is also the redundancy of 2 chargers. I would have to add the wiring and CB for 2 chargers and keep my current 30 amp charger for the engine and jenny start banks.

What do you guys think?

timjet said:

...The 100 amp chargers I've look at:

• Victron 100 amps, 3 banks, 15amp input. $1087

• Mastervolt 100 amps, 3 banks. Intersting in that this is the only one that stated the output of the 2 smaller banks. 10 amp each and the main bank gets the full rated 100 amp output. $1375

• GoPower; 100 amp single bank, marine rated $339 This is an interesting option at a third the cost. It only has one bank but I could keep my other charger for the other 2 banks.

• IOTA makes a 75 amp single bank charger with a controller that will allow connecting 2 chargers in parallel. This would be 150 amps but each charger consumes 18 amps and I would have to watch carefully my amp usage when the genny is on. As George mentioned above, these units are not marine rated. Total cost of 2 chargers and controller is about $450. There is also the redundancy of 2 chargers. I would have to add the wiring and CB for 2 chargers and keep my current 30 amp charger for the engine and jenny start banks.

What do you guys think?

Click to expand...

I'd go with the 2-IOTA chargers. Most 100 amp chargers run off a less than 10 or 12 Kw generator will not give you the rated 100 amps.

Tim:

If your driver is convenience then I would go with the Mastervolt principally because it has 3 isolated outputs. You probably will have to upgrade the AC breaker to at least 20 amps and 12 gauge wire and the DC wiring to at least #6 for the house bank. The other two can be 14 gauge if these are limited to 10 amps.

Don't know anything about GoPower. Maybe Chinese- some ok, some bad.

I agree that the IOTAs are an installation hassle. Contrary to another poster they are UL listed, just not marine rated. Marine rating doesn't mean much as there is no standard that defines it.

Two IOTAs draw a maximum of 36 amps AC. That is probably at a .8 or .9 power factor so at worst it is 36*120*.9 = 3900 watts which is pushing your generator's rating. But you will probably never see 18 amps each, more like 15 amps. But this does mean that one leg of your generator can't have any other load on it while you are charging.

You will probably have to install a 40 amp AC breaker directly off of one leg of your generator, probably the one that feeds the A/C and feed the IOTAs from that with #8 wire. The DC output wiring will have to be at least #4 for 150 amps.

It is doable, but it probably needs a marine electrician to wire it properly. And it needs careful power management to avoid overloading your genset.

Another way is to parallel two 55 amp IOTAs. The maximum current draw for two is just 27 amps, which means that you can wire them to your existing 30 amp breaker on the generator's A/C leg. After some reflection, that would be my preferred choice.

David

And Tim, you were asking about settings for AGM on a battery charger and if you need a charger that has an AGM setting. My boat, luckily, has an 80 amp Charles....I guess between your boat and mine they wised up a bit. It does NOT have an AGM setting. When I was buying my AGMs from Sears(built by Odyssey), I called Odyssey to see if my charger was sufficient. And basically it is all a matter of if the specs of the charger meet the specs of the batteries. In my case, it did. It was not optimum, but it was within the general parameters. AGM desulphate on the charge cycle. If there is not enough charge current then they don't desulphate properly.

Anyway, people complain about the cost of things and then bitch when they cannot get any support when they "cheap out". I called both Charles and Odyssey. Both on the upper end of their respective markets. I got an English speaking human being(at both companies based right here in the good ole USA) that was extremely knowledgeable and very eager to go through all of the steps with me in properly sizing my charger to my battery bank(My charger still needs to be bigger but that is beside my point here). So FWIW, Charles is based right here in the USA and made right here in the USA. They have an excellent track record of products that work...and products that work for a very long time. And if they don't, they have excellent service and support to get you back up and running.

Just my very recent experience. I am not singling out Charles...just using them as an example. You get what you pay for!!! And the USA still knows how to make good ****!!!