"Marine" vs Regular Starting Battery

[ERTF]

Two questions:
1. Are "starting batteries" preferred over "deep cycle" for bow thrusters?
2. If so, is there any reason to pay extra for a "marine" starting battery over a regular car starting battery with the same CCA?

 

[DavidM]

There is some debate over #1, but my view is that bow thrusters require heavy current for a short period, not unlike starting but not exactly. You could use either in that service.

For question #2, yes, I think you can use a non-marine starting battery. Supposedly marine batteries are built more rugged to handle the perils of boating, but I rather doubt it, more likely just a label.

David

 

[Comodave]

I use AGM starting batteries for thrusters. High current draw for short periods, just like starting an engine.

 

[bluebyu]

Regarding "marine" battery, speaking with East Penn several years ago, the only difference was the label.

 

[Bacchus]

I agree with DavidM...
Most Marine / RV battys are a compromise between start & deep cycle and not optimum for either. If you are replacing my choice would be AGM and it doesn't matter according to responses I got from Trojan and East Penn. Both indicated their AGM GCs and GP31s would serve start and deep cycle equally well and they spec both AHs and CCA for their AGMs as a result.
I recently moved my main eng start to my AGM thruster bank to leave my house a pure house.

 

[ERTF]

My thruster is 24v, my house bank is 12v. I'm guessing there is no 12v to 24v converter that can handle bow thruster amperage?

 

[CMS]

Two questions:
1. Are "starting batteries" preferred over "deep cycle" for bow thrusters?
2. If so, is there any reason to pay extra for a "marine" starting battery over a regular car starting battery with the same CCA?

The only batteries we will install for 12V or 24v thrusters are TPPL AGM, either Northstar or Odyssey...

 

[DavidM]

My thruster is 24v, my house bank is 12v. I'm guessing there is no 12v to 24v converter that can handle bow thruster amperage?

How do you handle this now. Are the engine alternators and starters 12V?

A typical solution is to use two 12V batteries wired in series located near the thruster and charged with a 12V to 24V charger. No I don't think there are any (reasonable cost) 12V to 24V chargers that can handle the current directly. That is why you need 24V thruster batteries charged remotely with a DC to DC charger.

David

 

[C lectric]

CMS

You are back? HOw are you doing? I am glad to see you on the forum. I hope you are doing well.

 

[ERTF]

How do you handle this now. Are the engine alternators and starters 12V?

A typical solution is to use two 12V batteries wired in series located near the thruster and charged with a 12V to 24V charger. No I don't think there are any (reasonable cost) 12V to 24V chargers that can handle the current directly. That is why you need 24V thruster batteries charged remotely with a DC to DC charger.

David

The previous owner had two 12v batteries in series with an AC 3 x 10a charger that apparently can auto sense 12v or 24v. During the survey, the surveyor opened the compartment up in front if me and said the batteries were agm. Then when i later double checked them, they had unusual tops on that did not look removable so I assumed he was right. There was no voltage monitor on them. Then recently i got back down there while reorganizing under the fwd berth and found the voltages where super low. Pulled the batteries from the boxes and they have a lead acid sticker. The tops are flush, but can be twisted off individually with a socket. They were dry.

Because the battery compartment is located underneath a big storage area, I need to either reposition them to the shelf above so I can monitor water. Or else I need to buy agms. I rarely touch a dock, so my thruster rarely gets used, so it would be nice to just run the thick cables and use my 1100ah bank, but it's not the right voltage...

 

[Comodave]

Part of the agreement when we bought our current boat was that we would have bow and stern thrusters. My wife doesn’t like going out on the bow of this boat. I put in 2 12 volt AGM starting batteries in series and put in a dedicated 24 volt charger for each thruster. The only problem was finding 24 volt chargers in stock. I finally had to put in Mastervolt chargers because I could get them.

 

[utclmjmper]

You can also use a DUVAC system,, that includes an alternator that has split windings and will charge two different systems while keeping them isolated,, one 12 and one 24 simultaneously ( DUVAC = dual voltage automatic control.) Many class "A" RVs have this system installed..>>>Dan

 

[Higgo]

If your lead acid b/t batteries have run dry, chances are they are close to being cactus anyway! If you haven’t already filled them, do so and charge, then test each one for CCA. They might show 12v across the terminals, but until you put them under a CCA test load, you won’t know their true condition .

Having the batteries located forward and independent of house batteries, with whatever charging system works, in my view is infinitely better, particularly not having the cost of the cable run from the stern house batteries as well as the installation hassles.

When I was contemplating my b/t, the cable cost alone (2 @ 45ft run) was around a boat buck 7 years ago! Certainly you need AGM’s forward (with lead acid fume issues in bedrooms).

One other D31 brand you may consider is Optima Bluetops. I originally had a single battery running the thruster and windless, but added a second in parallel 5 years back. They both are still going strong! I actually used the windless cables to run a new charger wiring which is located down the back which made things much easier!

Good luck with the project! Cheers

 

[Leo Reise]

On our boat, bow thruster has a single series 24 - 12 V start battery CCA 850. Our start battery is a series 31 - 12V rated CCA 950. The stern thruster however needed CCA to be 1700. It has 2 series 31 12V rated CCA 1000 each in parallel.
I think the answer to the question might be “ It depends”.

 

[Kuncicky]

If your lead acid b/t batteries have run dry, chances are they are close to being cactus anyway! If you haven’t already filled them, do so and charge, then test each one for CCA. They might show 12v across the terminals, but until you put them under a CCA test load, you won’t know their true condition .

Please pardon the ignorance, but why would the batteries be close to being cactus anyway? I had always thought that if one added water, and then charged them back up, that all would be well. Not so? And what is a CCA test load and how would one go about doing it.


If it is not already apparent, I have some batteries that were completely dry, and I am in the process of dealing with them.



Bill

 

[Higgo]

Bill, like one of the prior threads said, it depends! You may be lucky and get your batteries back, but it depends on their age, and how much water you need to add to top them up.

If they had been connected to an automatic charging device, the acid can be significantly reduced as well as they get warm/hot charging, evaporating the liquid over time. Water top ups over time, reduce the acid concentration.

One time, I had to add about 1.5 gals of distilled water to a large 200ahr battery to get the liquid above the plates. Putting a multimeter across the terminals after charging it showed over 12v, I thought I had managed to save it, but turn the key (a start battery) , all it did was go “click”!

Just because a battery shows 12+v across the terminals, doesn’t mean its condition is good. Starting an engine for example draws an incredible amp charge to do so, so it’s the Cold Cranking Amps (CCA) left in the battery that determines its condition.

An initial test can be done with a hydrometer, but Google CCA battery testers and you should be able to pick one up for $50. Old testing devices used to “short out” the battery for 10 sec or so, stressing the battery even more. But the latest testers can read the battery condition without that old shorting stress loading.

So the net net is that you won’t know until you try to top up the batteries, charge and see! Try it and let us know, but if they have been left for a while without sufficient acid covering the plates, my experience over the years was that they didn’t have the stored amps or they failed very quickly thereafter!

After charging, try it and see or if you don’t have a tester that can read CCA’s, take it to your local battery store. I’m sure they’ll be happy to sell you another if it’s failed! ). Good luck with it! Cheers

 

[Comodave]

Actually the acid doesn’t evaporate but rather the water does. The acid has a much higher boiling point than water so the water goes first.

 

[Kuncicky]

Bill, like one of the prior threads said, it depends! You may be lucky and get your batteries back, but it depends on their age, and how much water you need to add to top them up.

If they had been connected to an automatic charging device, the acid can be significantly reduced as well as they get warm/hot charging, evaporating the liquid over time. Water top ups over time, reduce the acid concentration.

...

An initial test can be done with a hydrometer, but Google CCA battery testers and you should be able to pick one up for $50. Old testing devices used to “short out” the battery for 10 sec or so, stressing the battery even more. But the latest testers can read the battery condition without that old shorting stress loading.

...
Good luck with it! Cheers

OK, thanks for that. These batteries were close to being dry, were indeed on an automatic charger, and are a little over four years old. So sounds as if there is a good chance they bit the cactus! Oh well. "A boat is a hole in the water into which one pours money," so they say.


Bill

 

[Higgo]

Actually the acid doesn’t evaporate but rather the water does. The acid has a much higher boiling point than water so the water goes first.

... then the acid if they were almost dry..... I stand corrected Dave.. Suffice to say my experience has been adding copious quantities of water to an almost dry battery has little chance of success and bringing them back to life.

 

[SteveK]

I have recycled batteries to a local supplier and in discussion they told me that they bring a lot of them back to life by over charging. I am sure they have a system in place that expands. They are then usable again.
Equalizing batteries may be the same/similar system.

 

[Kuncicky]

Just because a battery shows 12+v across the terminals, doesn’t mean its condition is good. Starting an engine for example draws an incredible amp charge to do so, so it’s the Cold Cranking Amps (CCA) left in the battery that determines its condition.

An initial test can be done with a hydrometer, but Google CCA battery testers and you should be able to pick one up for $50. Old testing devices used to “short out” the battery for 10 sec or so, stressing the battery even more. But the latest testers can read the battery condition without that old shorting stress loading.

Thanks again for that good info. I did indeed find a CCA battery tester on Amazon, and ordered it. A Konnwei KW208, for $29.95. Looks like a really good accessory to have on the boat, and for a very reasonable price.




Bill