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battery system upgrade question

7K views 51 replies 11 participants last post by  sailingdog 
#1 ·
I have a 1984 Tartan 3000 with two group 27 batteries. I installed a Xantrex Trucharge 20 battery charger and now I am thinking of what else I should be doing to upgrade the system. I have had several thoughts and I wonder how to priortize them. I don't have refridgeration but I did install radar, autopilot and a chartplotter this year. I intend on mostly day sailing with a trip from Lake Champlain to LI Sound next Spring for some coastal cruising, overnights are a definate possibility.

Some of the questions I have:
1. Should I install a starting battery, and if so any installation advice, and what type of battery. (I believe my battery charger can charge only one type of battery at a time)
2. How do I monitor the charge in the batteries when not on shore power?
3. Should I buy a small gas generator or can I rely on the diesel engine to charge the batteries.
4. Wind generators and solar panels?

So many choices, you can spend a fortune, how do you get what you need for the least cost?

Thanks for your thoughts.

Bud
 
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#2 · (Edited)
Some of the questions I have:
1. Should I install a starting battery, and if so any installation advice, and what type of battery. (I believe my battery charger can charge only one type of battery at a time)
2. How do I monitor the charge in the batteries when not on shore power?
3. Should I buy a small gas generator or can I rely on the diesel engine to charge the batteries.
4. Wind generators and solar panels?
1, It's always good to have a sep. starting battery

2, LED meters for deep cycle batteries?

3, I'm going to get this one, 46 lbs., 1000 watts, 120 and 12V connections.
northern tool com , Portable Generator - 1000 Watt, Model# TG1200 $119

4, flip a coin, both are pricey but make sure you have a minimum of 10 amps. output on the solar panels so they will work well.
 
#3 ·
We added radar and a color chartplotter and I was amazed at their power consumption. It is much greater than a refrigerator. You will want to upgrade your battery system in order to keep up with your electronics. You can gang your two house batteries together and charge them and an isolated start battery from your Truecharge as long as all three are the same type (e.g. all AGM or all gels etc.) They can be of different sizes. What you may find is your underway charging is now woefully inadequate. Consider on getting an externally regulated alternator. You could still get by with a 40 to 55 amp alternator as the magic happens in the regulator. I think that Balmar and Xantrex use the same regulator so you can use either. We installed a Link 1000 to monitor/control our batteries but you could probably get by with a link 10 monitor on your house bank. I found that Jack Rabbit Marine was most helpful when I did my installation.
 
#5 ·
Start with your alternator. With 16-200 Ah already, you should have a ~ 85 amp alternator with external regulator. Throw in a cheap costco starting battery. Adjust your power switch so you switch the output of the batteries, not the charge input. Keep all leads direct and simple and heavy gauge.

Solar and wind are only adjuncts to your power budget and shouldn't be considered as a major source of charge power. Generator probably most effective/less expensive option. Bear in mind the bigger the alternator (within reason) the faster it will be able to recharge the batteries, to the limit of the batteries themselves.

Also realise that with the Ahr capacity you have listed, you actually only have maybe 50-75 Ahr to play with. That's not a lot. You could be down to 50% in a few hours.

The Link system is an awesome battery monitor/charger.

I don't think there really is a cheap way to have lots of power aboard when sailing or on the hook. Who wants a generator running while they're sailing?

Calculate your power budget, lights, electronics, radios etc. and you will quickly see that everything needs power and it climbs fast. You need good battery capacity to keep it all going and a good charging/regulation system to keep it healthy and charged.

Whenever a guy buys new electronics for the boat it's very important to add the cost of increased power capacity that will be needed to let it run. The greater the power draw, the more the item will actually cost you in the end.
 
#6 ·
1981 C&C 34, Pacific Northwest.

Just removed two group 29 deep cycle batteries (90ah each), one starting, one house, and replaced them with an AGM 8D for house (250ah) and an AGM group 24 for starting (Yanmar 3GM). Very happy so far.

Using a Guest 10 amp charger now but thinking of the Truecharge 20. My DC demands are pretty light.

No refrigeration, no water system, no radar, but do have an autopilot (~1.5 amps), laptop (~1 amp), TV/DVD (~2 amps), and an Espar heater (20 amps to start, 2 amps to run). All lighting is LED which has an insignificant draw even with all lights on. All of this worked okay with the old batteries but I wanted more capacity.

Have 40 watts of solar panels and this keeps up pretty good when the sun shines. If it's cold out the heater gets ahead of the solar panels because it's also usually not sunny either.

Installed a Microlog battery monitor from SailorsSolutions.com. Very happy with it. You can monitor the charge current and discharge current simultaneously along with the voltage on two batteries. It also has an alarm for low battery voltage but the set-point is not adjustable.
 
#7 ·
Above is good advice except I would question why someone's view that radar/charplotter consumption seem excessive - should only be a few amps most.
Figure out what your avg daily power consumption is.
Size the house battery bank accordingly so as to not consume more than 50% of it between recharges.
For recharging, use above to calc est recharge time for a decent alt/regulator setup and replace both.
Stay away from the cheap portable gensets - either Yamaha or Honda make quality productsl the rest have poor reputations.
Install at Link10 if you want a battery monitor or simply use the voltmeter for gross estimates of charge state
Solar panels should be sized similar to what you figured above for daily consumption as you don't want to continually underchage the bank
 
#8 · (Edited)
It all adds up. If you want an eye-opener, do an energy audit. This is what I'm looking at:
<O:p
E80 chartplotter - 1.7amps<O:p
RD218 RADAR Scanner - 2.3amps<O:p
Miltech AIS - .5amp<O:p
ICOM 602 VHF - .5amp<O:p
Instruments - 1.2amps<O:p
Autohelm (avg) - 1amp<O:p
Running Lights - 1.5amps<O:p
Total - 8.7amps<O:p
<O:p
My refrig cycles at 5.5 amps but runs less than half the time so for comparison purposes it averages 2.5 amps.
</O:p
Now assume that I also have a red light or two on down below and we're listening to the CD player to break the monotony, and you can see that I'm burning close to 100 amps while sailing overnight. My trusty Link 1000 has confirmed all of this. The important thing ito remember is you are burning way more energy than you realize and a monitor that can read amps is essential when you are running a big electronics package like I am.
 
#9 · (Edited)
I think your house bank is probably a bit on the small side, given that you have radar, autopilot and chartplotter. If you're planning on adding a stereo, laptop or refrigerator....you'll definitely want a bigger bank.

I would add a starting battery and a BlueSea Dual Circuit Plus battery switch. This switch isolates the house and starting sides normally, but allows you to combine the two banks if needed to start the engine. BTW, it is available in a combo package with an ACR battery combiner. This would allow you to charge both battery banks while leaving the banks isolated in normal use. The ACR will detect charging level voltage on either side-charging both banks if either bank has a charging source.

BTW, the Xantrex TrueCharge 20+ can charge three battery banks. However, all three banks need to be of the same chemical makeup...ie all should be wetcell or agm...don't mix types. Even if it couldn't, the ACR would allow you to charge both banks with a single charger-but also allows the alternator to charge both banks while not needing the battery switch in the combine position.

A small gas generator isn't a bad alternate charging source, and far better than running the inboard diesel under a light load. You might want to look at a wind gen or solar panels if you're going to be at anchor a lot.
 
#10 ·
You've already made a good upgrade by adding the TrueCharge. I agree, your current battery bank is a bit on the small size, but not desperately so for how/where you plan to sail. My approach to upgrades like this is to replace components as they fail or reach the end of their useful life, rather than throwing away equipment that still works fine. This is what I'd do in your shoes, in this order:

1) Swap your Group 27 batteries for Group 31s, preferably AGMs. The 31s fit in the same battery box as the 27s, but you'll immediately have 25-35 more reserve ah. But I wouldn't do that until the Group 27s began showing signs of anemia. OR, explore the possibility of even larger batteries if space permits, but be mindful of weight and trim issues.

2) Upgrade your alternator to a higher output Balmar or equivalent with smart external regulator (e.g., MC-612) and temperature sensing. Again, I would wait until the alternator reached the end of its useful life (if it's the original alternator, I wouldn't feel too bad about doing it with the battery upgrade).

3) Add a group 24 starting battery (same kind as house bank, i.e. AGM, Gell, or Wet).

The reason for doing #3 last is so that you have adequate alternator output to charge the larger battery bank.
 
#11 ·
Link 10 and regulator

Good to hear you guys talking about upgrading the battery system as Im in the middle of the process and kind of winging it.
Most of you suggest the Link 10 but I was thinking of the Link 20, which monitors both banks. Is the general feeling that one doesnt need to monitor the starter bank or is it just not worth the extra cost?
And George B said that the "magic" happens with the regulator. I too have a 50 amp alternator with internal regulator. Will an external regulator significantly change my recharge rate or in some other way provide a benefit without a higher amp alternator.
 
#14 ·
scosch...Having GEL and AGM together is not a good idea at all. YES you need external 3 stage regulation for EITHER Type.
You only need to monitor your house bank as long as you have a combiner switch and run off your house at anchor. You will draw nothing from your starter battery except in starting and can easily test state of charge with a simple voltmeter or voltmeter readout while monitoring the house bank with your Link10.

How big is your house bank and what type of battery is in it? Are you prepping for full time cruising or just weekend/vacation sailing? What is your daily amp hour usage when at anchor?? Will you be plugged into a dock for charging or on the hook/mooring?
Need this info for proper advice.
 
#15 ·
Thanks for asking camaraderie,
I have a 200 A house bank, AGM, and a 75 A start battery, GEL. I had heard that it wasnt good to have two types but thats the way the boat was set up when I got it. I figured if I was slowly killing the Gel battery, so be it. I have a Trucharge 40 for when Im at marina (which is most of the time). Im trying to set up for 2-3 week trips but more than a weekend but not cruising. I have frig, lights, chartplotter, radar, autopilot. So while at anchor Im using maybe 5-10 amphr in evening with lights and less during the day. When sailing with radar and autopilot, use goes WAY up. Could be 30 if radar is radaring and autopilot is struggling, even more at night.
I have a 50 amp alternator and no external regulator.
Does this info help with suggestions from you.
 
#17 ·
First, don't mix battery chemistries...it's really bad for the batteries, and gel batteries are about the worst IMHO.

Are you saying that you use only 5-10 amp-hours all night? I find this very hard to believe given you have a refrigerator, and most of them draw more than that. Add the cabin lights and nav lights, and it goes up even more.

You really need to come up with a fairly accurate electrical budget, preferably a worst case scenario one that overestimates your electrical usage, rather than underestimates it. Then you have to figure out how many days you want to go before having to recharge the batteries. Multiply the number of days by the daily usage and then double it to get a rough idea of the size of the battery bank you'll need as a minimum. Then figure out passive recharging systems you have or are going to add and how much usage they'll offset under the least optimal conditions and subtract that from the battery bank size.

Ideally, you don't want to run your battery bank down below 50% very often. The batteries last far longer if you don't run them down below 50%.

BTW, do you have a battery combiner?? If not, getting one might not be a bad idea. Also, get a good external voltage regulator for the alternator. Not only will it help the batteries charge more efficiently, it will help prevent the alternator from frying them.
 
#18 ·
Thanks so much for your replies. I now have a "On Off 1,2, Both" switch with 2 Group 27 wet cell batteries. Can I add a group 24 or 27 to this setup thus having a starting battery and 2 house batteries, using the same switch? Do I need to wire up the Xantrex 20 battery charger to seperately charge the newly added battery? (the charger can charge 3 banks). When the engine is running does the alternator charge all the batteries regardless of what position the switch is on? It appears that when on shore power I have to have the switch on "both" to charge the batteries with the battery charger. Would it be better to charge the batteries seperately by turning the switch to "1" then "2" or just leave it on "Both", I remember someone saying that charging/using all the batteries at once can be problematic as battery characteristics change over time and one battery can draw power from the other. Am I going crazy here and making things too complex?
 
#20 ·
RALPH...
Can I add a group 24 or 27 to this setup thus having a starting battery and 2 house batteries, using the same switch?
Yes. Put your starter on position #1 and the other 2 batteries on position #2. Note that mixing old and new batteries will reduce the service life of the new battery. Your house bank batteries should be of the same size and type, your starter battery needs to be the same typ but not the same size. Do I need to wire up the Xantrex 20 battery charger to seperately charge the newly added battery?
The short answer is NO provided that it is already wired to charge battery 1 and 2 on your switch which from your description I believe it is.
When the engine is running does the alternator charge all the batteries regardless of what position the switch is on?
No...sounds like your setup charges from the alternator...to the battery switch and then to the selected batteries. Leave the switch on both when you want to charge both house and starter batteries. NEVER change the switch with the engine running...and always switch to your house bank only when at anchor to insure your starting battery will have enough juice to get you going.
It appears that when on shore power I have to have the switch on "both" to charge the batteries with the battery charger. Would it be better to charge the batteries seperately by turning the switch to "1" then "2" or just leave it on "Both"
Leave it on both.
I remember someone saying that charging/using all the batteries at once can be problematic as battery characteristics change over time and one battery can draw power from the other. Am I going crazy here and making things too complex?
A bad CELL in one battery can draw down all other connected batteries so this is what you are probably referring to. During charging you won't have this problem so leave everything on both.
 
#34 ·
Ralph,

I was looking over Camaraderie's reply to you and was puzzled by your question of what battery to select (i.e., 1-Both-2) when charging from shore power. Did you install the charger so that it is wired through the battery switch? That seems peculiar, are you sure it's set-up that way? We have the same charger as you and it is hard-wired directly to the battery bank. On our boat, we leave the battery switch on "OFF" while away from the boat (for safety reason, to shut down our DC sytem), but the charger continues to charge both batteries (it is wired throught he AC/shore power panel).

Also, perhaps I misunderstood the context, but I don't entirely agree with Camaraderie's advice to never switch the battery selector while the engine is on. Most battery selectors, such as those by Guest and Perko, have a "make-before-break" wiper switch design that maintains the connection while switching. So there in no problem selecting between "1-Both-2" or "1-All-2" while the engine is on. However, you MUST NOT switch to "OFF" (unless you have a bypass installed on the alternator, such as the Zap-Stop) because you can fry the alternator diodes. So some folks don't like to switch while the engine is on for fear of accidentally going to "Off".

I hope this helps...
 
#21 ·
I understand most of your points. Thanks!
Oooops. Me bad. I meant to convey that I probably use 5-10 A/hr at night, not 5-10 AHr. Two nights on the hook with lights and fridge and I can see Im at 50%.
I can see that more AHr are necessary, especially if sailing at night.
You mentioned a couple of things that I dont understand though.
You said I can keep my existing 50A internally regulated alternator if I switch to wet cells for the house (and eventually to the start bank too after Ive killed the AGM that you suggested putting over there to replace the GEL)
Why is that? Are you suggesting that for cost effectiveness? I thought wet cells benefited too from a more sophisticated multistage charger. And wouldnt a larger alternator get it done quicker? Or are suggesting to keep the old alternator only if I add a gas generator (which isnt immediately appealing on my 30' boat, storage for generator and gas is limited and they are quiet but still kinda annoying).
Thanks again and Ill check back in this evening.
 
#22 · (Edited)
All batteries, AGM, Wet Cell or Gel, will benefit from a three-stage intelligent charger, provided it is set for their chemistry type. This is why mixing different types of batteries is a really bad idea.

Unless you run your refrigerator only at night, which I kind of doubt, the fact is that you're probably over using the house bank you've got currently. The problem is even worse if you've been sailing with the radar on, since that increases the daily amp-hour usage from the estimated 50-75 amp-hours to probably 100-125 amp hours, given a full day of sailing.

Unless you've got AGM house bank batteries or get a larger house bank, going to a larger alternator isn't going to help much. Wet cells can only accept a maximum of about 25% of their amp-hour rating in amps... so a 200 amp-hour bank, like the one you have will only accept 50 amps maximum or so... and only during the bulk charging phase. Batteries basically charge in three stages... BTW, charging wet cell batteries at more than C/10 (their amp-hour capacity divided by ten) for any significant period of time will boil off electrolyte and is not really a good idea.

The first is bulk charging, where the charge acceptance (amperage) is fairly high, and the batteries provide little resistance to the charging process. Going any larger on the alternator will cause the batteries to boil off electrolyte during this phase, and increase the amount of water you need to add to the cells.

The second is the absorbtion charge phase, where the charge acceptance rate drops considerably. This phase starts at about the 80% charge level and continues until the battery is fully charged.

The third is the float or maintenance charge phase. This occurs after the battery is fully charged and basically is to offset the self-discharge that normally occurs in rechargeable batteries.

I hope this helps.
 
#23 ·
Scoche..you said:
You said I can keep my existing 50A internally regulated alternator if I switch to wet cells for the house (and eventually to the start bank too after Ive killed the AGM that you suggested putting over there to replace the GEL)
Why is that? Are you suggesting that for cost effectiveness?
YES and because you are not full time cruising and don't need to spend another $7-800 bucks + install for a week or two of extended cruising a year. Your charger at the dock will maintain your batteries properly.

I thought wet cells benefited too from a more sophisticated multistage charger. And wouldnt a larger alternator get it done quicker? Or are suggesting to keep the old alternator only if I add a gas generator (which isnt immediately appealing on my 30' boat, storage for generator and gas is limited and they are quiet but still kinda annoying).
All batteries benefit from a 3 stage but they don't need one 100% of the time. Your alternator is DESIGNED to work with wet cells without damaging them and as long as you do a lot of dockside charging normally...motoring and using your alternator is no problem.
I suggest adding a gas generator cause using a diesel to charge your batteries is BAD BAD BAD for your engine if it is not in gear....AND because that will allow you to use your 3 stage charger at anchor.

The only reason to add a larger alternator and separate regulator in your circumstance is if you are going to stay with AGM's which can take a higher charge rate AND need 3 stage regulation underway AND if you will be motoring a lot.
 
#25 ·
If you want to monitor both banks,, get a Xantrex Link20. See this thread regarding battery monitors.
 
#26 ·
"Magic" Explained. (Warning: I am not a licensed electrician, nor do I play one on TV. I do not have access to my notes and I'm posting from memory. I did however, use the services of a licensed engineer when I did my installation.) The stock alternator on practically all marine diesels are the standard automotive alternators ("Motorola") that have output of around 40-50 Amps. They are internally switched (regulated) by a series of diodes. Designed to replace the relatively few amps used during the starting process, they step down to a float charge rather quickly (I recall something like 15 minutes? I think it is determined by the temperature of the alternator case?). They also use a relatively low charging voltage which is inefficient when you are charging deep cycle batteries.<O:p</O:p
<O:p</O:p

The external regulator allows you to adjust both the charging voltage and the cycle time to float. For example, my Xantrex regulator is set for bulk charging at 14.5 volts and cycles over to "float" after 50 minutes. I have a temp sensor on the alternator that protects against overheating. I can even equalize (@15.5volts) my batteries using the alternator only! Gels, AGMs and deep cycle batteries all are charged using different voltages which can be programmed into the unit (that is why you do not want to mix battery types!)<O:p</O:p
<O:p</O:p

Before external regulators, the mantra was to buy the largest alternator that would fit on your engine. As you can see, you can improve your charging immensely just by upping to the proper charging voltage and extending the bulk charging cycle. Big alternators are going to rob HP off of small engines. I've noticed a measurable increase in fuel consumption when I installed a 105 Amp alternator on my 35 HP engine. I do have a "cut off" switch on the Xantrax that can completely shut off the alternator (and let it freewheel) when I need to put all of the HP to the shaft.<O:p</O:p
<O:p</O:p

One more thing&#8230; The positive wire off of the alternator to the Batts is woefully undersized. You need to up it several gauges in order improve your recharging efficiency.


I have seen people at anchorages using a Honda generator plugged into their shore power to recharge their batteries. The Achilles' heel is their shore charger. A 20 Amp shore charger is great at your berth when you have all the time in the world to recharge. But, on the hook, you will be running that Honda for at least several hours.<O:p</O:p
 
#31 ·
...Big alternators are going to rob HP off of small engines. I've noticed a measurable increase in fuel consumption when I installed a 105 Amp alternator on my 35 HP engine...
Thing to remember about this is the energy - you will need so many watts to replace what has been spent. The engine converts chemical energy to kinetic, and the alternator converts kinetic to electrical. The amount of energy required is constant regardless of the alternator size- it's equivalent to the amount drawn from the batteries. A small alternator will have to run longer (and so will the engine) to fully charge the system; a larger alternator will need to be run for a shorter time, but will load the engine more.

In general, it would be better to have an alternator that loads the engine more because an unloaded diesel idling will glaze it's cylinder walls.
But overall the fuel consumption shouldn't really change. There might be something else going on.

The other thing to be aware of is future changes/expansion. For a few hundred bucks more The 2000R has a ton of features and saves you the cost of a smart regulator. If you are talking about spending lots of time on the hook while cruising, it is probably a good idea to spend the bucks and get a good system set up. There's lots of better ways to save money on a boat.
 
#27 ·
A few points...If you have a proper regulator, you can't really have excessive alternator capacity. While it is true that batteries have a finite rate that they will accept a charge due to inherit aspects of their chemistry, boiling of the electrolyte occurs as a function of voltage. Excessive voltage will cause this (such as during equalisation) but a good regulator will feed the battery it's upper limit of voltage, and the battery itself determines the current draw.

The thing about battery bank size (and corresponding alternators) is that paper will show you have say 200 Ah of capacity, that is theoretical only. Batteries have internal resistance, they quickly lose max efficiencies, and there are always resistances in the circuits. In terms of actual available power to run appliances, your 200Ah bank may only be able to provide 160Ah. divide that by the 50% rule and you can see there isn't a lot there.

As for alternators, again you have resistances and power losses in the circuits, and the concern is that while motoring you won't be able to supply power at the max rate that the battery bank is able to absorb it, which isn't good for the batteries, and you can end up with an only partially charged bank when you shut down.
A good alternator means running the engine less. It's true you can't force more power into the battery than it will accept without doing damage, but most stock alternators were designed to charge the shallow-cycle starter battery only. One engineer I refer to often recommends an alternator rated about 1/3 the bank capacity. 300 Ah bank = 100amp alternator.

The circuit configuration you have now puts your alternator at risk. Use a diode isolator and connect the alternator output directly to the batteries , and switch the output of the batteries to house/start that sort of thing. Right now if someone changes the switch while motoring, you will fry your alternator. If something goes wrong with the switch (very common) you will fry your alternator.
Shows how poorly these systems are designed.
 
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