Car battery charger for marine batteries

[Sea Hunt Video]

As the result of several unrelated issues (medical and hurricanes and other) I have been delinquent in keeping my two marine AGM batteries charged. I usually did this by running the Yanmar 1GM for 30-40 minutes once per month with a fresh water hose connected to the water pump intake line.

Today, I tried to start the Yanmar. Battery charge was too low and would not give enough juice.

Can I use a neighbor's regular "automobile battery charger" to charge the marine AGM batteries

Can I charge them together or do I need to separate the charging of each

Are there any special precautions I should take to avoid unwanted issues

Thanks in advance for any and all suggestions, comments, etc.

[tjr818]

Roberto,
Mainsail is the go to guy for this advice, but in part it depends on which type of AGM batteries that you have. I have the Optima Blue top spiral wound AGMs and they can be charged with an Automobile charger, it may not be the best for a full charge, but it should work okay. I ended up installing a Promariner charge that has a specific setting for AGMs. I am glad to hear that you survived the storms, and I hope the medical is resolved soon too.

[swparis85]

An automotive charger should be fine for marine AGM batteries, but check the unit or the manual that it has a setting for AGM.
Some have a switch you need to flip for lead/acid vs AGM charging.
I use a battery tender junior for all my batteries, it has a chip in it which automatically regulates output for all battery types.
Will trickle charge and 'float' mode to keep batteries happy all winter.
I switch it to a new battery every time I'm in the basement.
Do charge them one at a time though.
-Steve

[Sea Hunt Video]

Hilbert, Steve, Tim and all:

Thanks for the input.

Hilbert, I am still not clear on Maine Sail's position on car battery chargers being used on marine batteries. He seems to be a little "on the fence" on this issue.

Anyone have a recommendation for a quality marine AGM battery charger Before posting this thread I tried to read prior threads/posts on this issue. I recall someone mentioned Odyssey batteries and battery chargers. I assume I can use an Odyssey charger (or other make marine charger) on a battery that is not an Odyssey battery.

[hilbert]

I had deleted my post when I realized that your boat was out of the water.

Maine Sail's article, http://www.pbase.com/mainecruising/inst ... ry_charger warns of the dangers of stray current corrosion, Electric Shock Drowning (ESD), ect., when using a non-marine charger.

Most the concerns that he raises are not relevant when the boat is on land. There is still a slight electrocution risk from a faulty car charger energizing the boat's DC ground circuit. This risk can be eliminated by disconnecting the boat cables from the battery while charging.

[hilbert]

Roberto,

For your immediate predicament, your neighbor's automobile battery charger will probably not do any more harm to AGM batteries than a factory Yanmar alternator.
If the automobile charger doesn't have an AGM setting, then use it for hour or two at a reasonable current (10 - 20 amps) until you have enough juice to return to your routine.

Having said that, I don't think that it is advisable to use your Yanmar 1GM for the express purpose of charging batteries. Unless this small motor has an expensive aftermarket alternator and charge controller, it will not properly charge an AGM battery. The charging voltage may be too high and the batteries will never be fully charged with short running times. Then there is the wear on your diesel running at low RPMs (running too long for the good of the engine and not long enough for the batteries to fully charge).

I think that you have posted recently on wanting to use solar to maintain your batteries. A solar panel with a smart controller may still be your best investment.

Jonathan

[Sea Hunt Video]

Jonathan:

Thank you for the clarification and suggestions. I will probably carefully examine the car battery charger to make sure it is OK for my batteries. Hopefully, this won't happen again.

You have an excellent memory. I have been looking for a solar panel to keep my batteries charged up. Unfortunately, I am horrible at making decisions. I "float" between one model and another and never get off the dime.

I had a 32" Sony CRT TV years ago. The tube broke in 1996. Instead of immediately buying a new TV I decided to "study the issue". In the interim I started using a 13" (that is not a typo) Sony CRT TV that I bought in 1994 (again NOT a typo) and was using to edit my underwater video products.

So, for the past 21 years I have been watching TV on an old CRT 13" screen while I study which new TV I want to buy.

I do not hold out a lot of hope that I will make a decision on a solar panel before the end of the year.

[Andy Denmark]

Roberto,

I'm a big believer in anything Charles Industries makes for marine battery chargers. AGM's do require a different charging algorithm for permanent installations and Charles products are superior to most others in this regard. This holds true with their lead acid chargers as well.

In an emergency using an automotive charger will work for AGM's but they won't achieve 100% charge and there's enough voltage differential between AGM and flooded batteries that you wouldn't want to make a habit of this. This is especially true if charger is an "automatic" type that senses voltage to cut off. The point here is to not overcharge.

Another factor for an automotive charger is that it needs to have a 3-prong plug for grounding safety. If the plug is 2-prong then the possibility of a ground fault problem is amplified. That said, I wouldn't use any shoreside charger without a good quality GFI between the charger and power source.

The other factor, already mentioned, is unhook the battery being charged from boat cables while you're charging it to protect electronics from spikes, etc. while hooking up things.

Of course, the best answer is to get a good quality AGM charger and permanently install it.

Just sayin'... my $.02 worth

Andy

P.S. An 85 watt Kyocera solar panel keeps my 2 batteries at 100% charge and only maintenance is occasional addition of distilled water. Rhiannon is totally independent of shore power with this simple setup

[Sea Hunt Video]

Andy:

Thanks for the info and advise.

I will look at Charles chargers and Kyocera solar panels.

[Andy Denmark]

Roberto,

Two birds with one stone ...

I have a 10 year old 37" Sony Trinitron TV I'll sell you for $100, you pay packing and shipping. This will fix your TV problems, too. No charge for consulting.

Now that NFL is not worth watching, I have no use for TV that my 13" Sony and rabbit ears won't solve.

Andy

[barfwinkle]

I have been looking for a solar panel to keep my batteries charged up. Unfortunately, I am horrible at making decisions

We know

[Maine Sail]

Andy:

Thanks for the info and advise.

I will look at Charles chargers and Kyocera solar panels.

Charles is done producing marine chargers and I never was a fan of their three position "dip switch" based rather dumb so-called "smart" kitchen-timer chargers.

What you are looking for are the charge VOLTAGES for absorption & float. If you spent the money on an AGM product don't cut any corners on the charger.

This article is more than just about installing a charger it helps lay out what you should look for and watch out for.

https://marinehowto.com/installing-a-ma ... y-charger/

I know I have likely beat this horse to death but the battery type (in words on a charger eg; AGM, GEL, Flooded) is quite often pretty irrelevant. What is relevant is the batteries recommended absorption and float voltage.

For example an Odyssey AGM is optimally charged at a 14.7V - 14.8V temperature compensated absorption voltage and 13.6V for float. The Charles chargers, when set for AGM, will charge at 14.2V and this will help to destroy an Odyssey or Northstar AGM.

Soap Box:

As a group boaters really, really, really need to stop looking at the words or charge profile on a chargers pre-set list, and instead look at the VOLTAGES behind the words or word defined charge profile. AGM, GEL, Flooded, FDC etc. are words and they mean absolutely nothing without knowing the VOLTAGES behind those words. A flooded setting on some chargers will literally destroy some flooded batteries. An AGM profile on some other chargers will literally destroy AGM batteries.

One manufactures voltage for AGM will NOT always be the same as the next thus boat owners should only focus on the VOLTAGES the words represent. Sometimes you can also see different absorption times behind the words and this too is very useful information. For some AGM batteries you will be much better served using the FDC setting than an AGM setting but a custom setting will always better be able to match the manufacturers recommended absorption & float voltages.

For example Trojan's are best charged at 14.8V absorption & 13.5V float for a PSOC type of use (marine use is almost always PSOC). If an installed starting battery can also be charged at 14.8V & 13.5V then the charger can charge both even if one is flooded and the other AGM.

All batteries should be charged temp compensated especially AGM's & GEL..

VOLTAGE (and time or timer algorithm) is the key not the words or a "charge profile" simply given a name or acronym.[/I]


While a smart charger may have outputs for "three-banks" most are still one charger with one single voltage setting used at a time. You can't for example put a GEL battery that needs 14.1V on output #2 and a Northstar that needs 14.7V on output #1 and then set the charger to FLOODED because you will cook the GEL battery. If you set it to GEL then you chronically under charge the Northstar and also ruin it.

Here is a prime example of ignore the words (Flooded, Sealed, AGM GEL) and focus on the recommended VOLTAGES



Here are some manufacturer suggested charging voltages:

AGM's - Which AGM Preset works?

Lifeline AGM = 14.4V & 13.4V = AGM Preset #1
Odyssey TPPL AGM = 14.7V & 13.6V = Neither AGM Preset
Northstar TPPL AGM = 14.7V & 13.6V = Neither AGM Preset
Firefly AGM =14.4V & 13.2V = Neither AGM Preset
Mastervolt AGM = 14.4V & 13.2V = Neither AGM Preset
Full River AGM = 14.7V & 13.7V = Neither AGM Preset
Rolls AGM = 14.7V & 13.7V = Neither AGM Preset
East Penn/Deka AGM = 14.6V & 13.6V = Neither AGM Preset
US Battery AGM = 14.4V & 13.4V = AGM Preset #1
Trojan AGM = 14.4V & 13.5V = Neither AGM Preset

As can clearly be seen this chargers "AGM setting" (words) FAILS for 8 out of 10 AGM brands! This is why boaters should always focus on buying chargers that have a custom voltage setting. Please do not focus on the words but instead focus on the voltages that the words are representing..

How about Trojan Flooded batteries? Which Flooded preset works for Trojan flooded batteries??

Trojan Flooded = 14.8V & 13.5V = Neither are ideal. So you use custom and set it at 14.8V and 13.5V

How about Deka / East Penn Flooded

Deka Floded = 14.7V & 13.8V = Neither are ideal. So you use custom and set it at 14.7V and 13.8V

* This is but one example of one charger but one that has 11 separate charge voltage settings to choose from PLUS a custom setting.. Some so called "smart chargers" are so dumb as to only have three options AGM, GEL or FDC.

[Andy Denmark]

I just called Charles Industries and confirmed what Mainesail says. Charles is no longer in the battery charger manufacturing business. That's too bad because I always considered their products to be pretty much top of the line and significantly better engineered than most of their competition.

Out of curiosity, I asked if they had sold that product line to someone else to manufacture and they did not --- they simply ceased manufacturing all battery charging equipment.

Thanks for that information, Mainesail, and a good technical treatise. As usual, you are spot on!

[Paul D.]

Roberto,

I installed a Charles 2000 SP charger a couple years ago replacing the Ferro resonant "dumb" charger after a friend left it on when using the boat. It had a pretty close to ideal voltage rating for the lead acid setting. It has performed just fine since, charing the two Trojan T-105 6 volts I use for the house bank. It is not however what charges the batteries the most. That duty falls to the 60w Kyocera solar panel run through a charge controller. With this set up, including a Xantrex Echo Charger between the house bank and a 12v start battery, the batteries have lasted 10 years, just replaced them a couple years ago. I leave them fully hooked up to solar panel over the winter with the panel somewhat hobbled by facing it mostly away from the sun, thus acting as a trickle charger. I check the electrolyte levels twice a year.

This set up, along with a smart regulator and alternator for the motor which I have not installed yet, was recommended to me by Hamilton Ferris.

I think a great way to get you out of your waiting place (God knows I've been there too!) would be to call them up, speak to Ham or someone who deals with Marine rigs, and just tell them your gear, how you use your boat etc. I bet they would recommend an ideal charging/monitoring set up for you that would not cause a run on your bank. They did that for me and I have not looked back. I also second MaineSail's plaintive cry to understand charger voltage settings and your battery needs as opposed to relying on simple setting switches.

http://www.hamiltonferris.com

[Sea Hunt Video]

Sorry for the delay in responding. My computer caught a virus or malware or something. Took a day for a buddy to find and destroy it.

Thanks to all for so much input and advise. It is very much appreciated. Sadly, it is also mostly way over my head.

I think my plan is to buy a quality marine battery charger suitable for an AGM, hook it up and get some juice back into my two 12v AGMs. I will then keep this battery charger in reserve. I will then invest in a quality solar panel (like Kyocera) with a quality charger controller. Living in South Florida the sun should provide all the juice I need 24/7/365.

Thanks again to all for the great posts, suggestions and comments.