batteries for 24v thruster

[Willo B]

Im looking for suggestions. I'm replacing my bow thruster batteries (2 12v=24v 288ah sweeper) flooded with Agm. No room for 6v so looking at two Northstar g31agm 102ah,1150cca. i realize that ill be losing some reserve capacity. Also no 24v recharge except from shore power or generator. Am i going wrong here? Any input appreciated.

 

[john61ct]

You are going to keep existing 24V setup right? Not considering changing that to a different voltage? If you want onboard recharging, look at Sterling DC-DC chargers.

 

[john61ct]

Why are you going to AGM?

Lots more expensive, especially $ per AH per year of lifetime.

Sure you can't make room for GCs?

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, around $400 per 200+AH (4x6V=24V) set

from BatteriesPlus or Sam's Club. Deka-labeled same batts also sold at Lowes.

 

[john61ct]

If you do really need AGM, besides Northstar check out Lifeline and Odyssey

Odyssey's PC-2150 is 100Ah G31 and terrific both for high-amp output and deep cycling longevity if cared for properly.

But pricey, no AGM can compete for value with the Duracell / Deka FLA GCs, nor

Trojan / Crown / Superior / US Battery FLA for that matter.

All these FLA makers can be trusted when they specify a given line is proper true deep cycling.

12V models included.

Rolls Surrette is tops in quality, but much pricier.

 

[Ka_sea_ta]

For a thruster you want a starting battery.... Thin plates high current output.... what I did to charge my 24 volt system was to install a NOCO 24 volt marine smart charger and just powered by the inverter, not the most efficient way but it works well. by the way I used a couple of group 31 batteries.

 

[DavidM]

I think that AGM batteries are fine for powering a bow thruster. Two reasons:


As far as I have been able to determine, there is no difference between starting and deep cycle AGMs unlike FLA batteries.


Bow thruster use is a bit like starting and a bit like deep cycle.


Thus AGMs are perfect aside from the cost.


Look at Yandina's web site for ideas on how to charge your 24V batteries with 12V power.


David

 

[Ski in NC]

My thruster is only 12v, but in my analysis the batt duty cycle is much like a starting batt. You want lots of amps, but for brief moments (well mostly brief). I just use a normal marine starting FLA batt (I think it is Deka) and first one lasted like six years. Eventually volts got low when thrusting so new batt. New one has been ok for last five years.

No need for deep cycle or AGM in my mind, unless you want to spend extra money.

If you don't thrust a lot between periods when dock or genny power is available, a DC charge source is not really needed. The AC based charging should be ok.

I set up mine with a charge link from house batt as I do often run a lot without docking or starting Gennie. Not as easy to do with 24v thruster and a 12v boat.

 

[dhays]

It seems to me that AGM or FLA is just a matter of convenience and access. If you have good access to the batteries where they are installed and don't mind watering them, a FLA battery is going to be a LOT cheaper and work just as well for that type of application. The high charge acceptance of an AGM wouldn't normally be an advantage for a thruster bank.

 

[Willo B]

The only reason for agm is poor location i have to use a mirror to see water levels. The DC to DC sound worth looking in to. It may be easer then changing out one of my alternators to 24v We do stay on anchor a lot. Ill have to price shop some of the other batteries.

 

[john61ct]

The only reason for agm is poor location i have to use a mirror to see water levels.

OK, valid reason for sure there.

Again, the Odyssey, Lifeline and Northstar AGMs are **far** superior for this usage than even good Starters or other-brand "dual use" like Optima. Take care of them well these can last a very long time.

Look for local distribution, don't pay shipping. Check the mfg dates.

Full River is also OK, but personally only if at least 20% cheaper than the top three.

Do not skimp on the amps throughput if you go with a Sterling 12-24V DCDC charger, AGM wants at least .2C, .4C would be healthier.

Yandina's Trollbridge can work OK, but not nearly as good as the DCDC approach IMO, not sure even that much cheaper?

Also note you don't need nearly as fat cable as you would without the DCDC, just look at temp / safety specs, don't worry about Voltage Drop,

that helps pay for the Sterling at least a bit, plus better longevity of the target bank getting its own staged charging profile.

 

[Comodave]

I have an Odyessy AGM for my 12 volt stern thruster. I wanted AGM since it is mounted under our aft cabin berth and I didn’t want off gassing during charging. It has worked very well. It only gets charged on shore power but so far that has been fine.

 

[Ski in NC]

Be careful with selecting a DC-DC charger. You will overload it when thruster is running. Make sure that it can handle an overload or otherwise re-set itself after thruster run.

I solved this issue by putting a relay in my charge link that disconnects the link whenever thruster motor is energized.

 

[Willo B]

Im concerned about having the agm at a low state of charge for 7-10 days wile out and shorting life of battery between bring it up.

 

[john61ct]

Be careful with selecting a DC-DC charger. You will overload it when thruster is running.

Perhaps you were using a dinky unit under 40A?

Sterling goes up to 120A I believe, but obviously should not be bigger than the Alt output.

Also a big enough thruster bank will help. . .

> My thruster is only 12v, but in my analysis the batt duty cycle is much like a starting batt.

No, it is pretty easy to draw down to 10+% DoD, which really should get a batt with decent life cycle ratings as I reco above.

 

[john61ct]

Im concerned about having the agm at a low state of charge for 7-10 days wile out and shorting life of battery between bring it up.

Yes, that would really quickly murder even the best deep cycle batt, much less something cheaper.

Try to treat the thruster bank just as well as you do House. Have you got any solar?

 

[Ski in NC]

Perhaps you were using a dinky unit under 40A?

Sterling goes up to 120A I believe, but obviously should not be bigger than the Alt output.

Also a big enough thruster bank will help. . .

> My thruster is only 12v, but in my analysis the batt duty cycle is much like a starting batt.

No, it is pretty easy to draw down to 10+% DoD, which really should get a batt with decent life cycle ratings as I reco above.

When my thruster is running, batt volts go to 10.5. Whatever you use for charging will try to raise voltage up to the normal 13.8 or whatever. My charge link runs through a 10ga cable and 15A breaker from house bank. It trips the breaker if I did not use the relay scheme. It works.

And if you run your thruster enough to take batt down to 10% SOC, you are dogging that thing!! Or you batt is super undersized. I run mine just a few blips at a time to aid maneuvering. If I run it 30sec I did something wrong with my piloting!!

 

[alfamike]

24-Volt - Thruster Batteries -- AGM

FYI - I have both a 24-volt 10-HP bow thruster & 24-volt 13-HP stern thruster.

I use a serial / parallel set up with 4 AGM - Group 31 batteries at each thruster location. I have been VERY happy with them.

Batteries are mounted under the beds, so AGM in a group 31 size was the way to go for me.

I use a Sterling Battery to Battery Charger which works great.
Sterling Part # BB122470

I went with the "ACDelco" brand for the AGM's.

24 Month free replacement warranty.

Pricing is good & durability good.

NOTE: they have both Starting AGM's & Deep Cycle AGM's both. - they are not the same internally !

For the thrusters you usually want the starting type & I prefer a terminal rather than a post battery type hook up .

ACDelco Starting Thruster AGM Battery Part # is: 31 AGM CRT

31AGMCRT= Spec's: -- 110 Ah -- 925 CCA -- RC 190 -- 1140 MCA.

" Technology and Maintenance Council" - (TCM) standards as the benchmark for heavy duty group 31 battery performance - the 31AGMCRT has been tested @ over 850 + cycles of the SAE J2185 cycles operation parameter.
--------------------------------------------------------------------------------------------------------------------------------------------------------------
NOTE: the deep cycle 31AGMDCT is J2185 rated @ 950 + cycles.
Deep cycle AGM PT # is: 31 AGM DCT) - if you wanted deep cycle (31AGMDCT spec is: 700CCA - RC 200 - 100 Ah)

Certainly worth looking into.

Good luck.

Alfa Mike

 

[Willo B]

It sounds like a charge and the a relay would be a nice to have in line. The thruster say a minimum of 400cca or so and only room for two group 31s. So don't have much choice but to keep its use short. More practice on the back and full.

 

[GGroves]

We also have a 10 hp 24v bow thruster. It is mounted under the master v-berth so agm’s are required. Original owner had the thruster installed by Florida Bow Thruster in 2008. Current batteries were Sears AGM (no longer made). Saw FBT at the Annapolis Boat Show and they said they now use Odessy 31M-PC2150ST AGM batteries (x2) connected in series for 24 v. The batteries are next to the thruster motor so lead runs are very short. They installed a Promariner 20 battery charger (115vac). It can charge two banks at once, so it is connected to each battery for 12v. charging. All I can say is it works. Just waiting for spring to get the new batteries.

The Odessey 31M-PC2150ST are dual purpose crank and deep cycle (104 ah).
Gary

 

[john61ct]

When my thruster is running, batt volts go to 10.5

Then your bank is undersized, by definition. Likely not fully charged, maybe never fully charged.

Murderous conditions.

> My charge link runs through a 10ga cable and 15A breaker from house bank. It trips the breaker if I did not use the relay scheme.

Way too small to make a difference.

> And if you run your thruster enough to take batt down to 10% SOC, you are dogging that thing!!

Go back and look, 10% DoD means 90% SoC.

My point is such usage has nothing to do with Starter patterns, absolutely within deep cycling's definition, as your details make even more crystal clear.

Systems design is much better off defined by the worst case scenarios, ignoring the best-case ones.

 

[john61ct]

Odyssey 31M-PC2150ST are dual purpose crank and deep cycle (104 ah)

Yes, a most excellent choice for this use case, and Lifeline and Northstar got the same TPPL tecnology from Enersys, who invented it.

 

[caltexflanc]

I'd get something that matched the thruster manufacturer's specs. A novel concept here. Had a 24v bow thruster on my old Hatteras, 2 flooded standard 8Ds were at the upper end of the specs and that;s what we used, charged by a dedicated charger, all courtesy of a PO. Life was good. Still is for that matter, sans big boat and accompanying thruster, but not as good.

 

[Ski in NC]

Then your bank is undersized, by definition. Likely not fully charged, maybe never fully charged.

Murderous conditions.

> My charge link runs through a 10ga cable and 15A breaker from house bank. It trips the breaker if I did not use the relay scheme.

Way too small to make a difference.

> And if you run your thruster enough to take batt down to 10% SOC, you are dogging that thing!!

Go back and look, 10% DoD means 90% SoC.

My point is such usage has nothing to do with Starter patterns, absolutely within deep cycling's definition, as your details make even more crystal clear.

Systems design is much better off defined by the worst case scenarios, ignoring the best-case ones.

Hmm. Responses below:

1. Batt volts at 10.5 under thruster load is not indicative of a problem. Batt is well charged, healthy and thruster performance is good. Could it be better with a bigger batt? Sure, a few more rpm. But I do not need it. And as a planing boat, I pay for increased weight.

2. Murderous conditions? Hyperbolic much?? The charge link is 10ga, amps limited to 15A, but it works absolutely fine with the relay that disconnects charge link with motor running. Breaker does NOT trip. A half hour after using thruster the thruster batt is right up there at the same voltage as house bank. In bulk mode it is 14.4v, after that 13.5v and charge amps basically zero. Battery is happy there.

3. My mistake about SoC vs. DoD. Just using gut feel math my thruster does not draw batt more than 10% of capacity on normal use. That does make a start type battery inappropriate. And batt life seen confirms this. Six years is not too bad.

4. I am fully aware of system design criteria, I have done it for a living for 30yrs as a mechanical engineer. On a planing boat you want to minimize weight (just as you would on an aircraft). If you designed everything to the worst case conditions, the boat would be a pig. Or the plane would not fly.

 

[ranger58sb]

Current batteries were Sears AGM (no longer made). Saw FBT at the Annapolis Boat Show and they said they now use Odessy 31M-PC2150ST AGM batteries (x2) connected in series for 24 v.

The Odessey 31M-PC2150ST are dual purpose crank and deep cycle (104 ah).

The Sears Platinum Plus line of AGM batteries were OEM Odyssey PC-2150 (Group 31) and PC-1500 (Group 34) respectively.

The "ST" is about specific terminal type or configuration, I think. IIRC, Odyssey offers a few choices there...

I'd think the PC-2150s would seem to be a very good choice for a thruster (huge cranking amps, very good longevity), especially if the batteries are installed in living quarters.

-Chris

 

[saboga]

I like the idea of a relay to cut out the charger when the thruster is running.

With a big enough relay (and with enough DPDT contacts), it would be possible to wire it so that when the thruster is not running, the batteries are connected in parallel and being charged by the 12v charger. Then when it's activated, the relay disconnects the charger and reconnects the batteries in series for 24v to power the motor.

That would work. Just have to draw out the wiring diagram!

 

[alfamike]

12 / 24 realy

I also have a 12 / 24 - Parallel / Series relay. Let me know if you need one, I have a couple spares.

They use them on Big Rigs & heavy duty equipment.

12-volt wiring of the two 12-Volt batteries in parallel for recharging & then when you hit the starter, relay flips, & they go to series wiring & you have 24-volts to run the starter or thruster.

No Electronics to fail.

Works great.

Alfa Mike

 

[boatpoker]

I also have a 12 / 24 - Parallel / Series relay. Let me know if you need one, I have a couple spares.

They use them on Big Rigs & heavy duty equipment.

12-volt wiring of the two 12-Volt batteries in parallel for recharging & then when you hit the starter, relay flips, & they go to series wiring & you have 24-volts to run the starter or thruster.

No Electronics to fail.

Works great.

Alfa Mike

Done it this way since 1994. No problems.
I got my series parallel switch from a farm equipment place, $54.00 for a switch from a Russian Belarus tractor which starts on 24vdc but then everything else runs on 12vdc.

 

[Ski in NC]

Yep, 12/24v relays are common out there. Some marine diesels above 10 liter use these too. I think it would be relatively easy to wire in for a thruster. Might need some diodes to fire the coil from the p/s run signal.

 

[saboga]

Here's a link to a 12/24 relay. Charges the batteries in parallel at 12v, then puts them in series for 24 v for heavy duty starters or bow thruster applications.

12/24 Volt DC 1500 amp Series Parallel Solenoid Relay.

 

[ranger58sb]

Realize OP is starting with a 24V thruster... and don't mean to hijack, but didn't get any comment in the other thread I started about thruster options.

I'm still in "decision" mode, wondering if there's any reason I should prefer a 24V thruster over a 12V version, assuming all other things being equal. I wrote:

I'm still kicking this around, although given the state of my wallet just now I'm probably not seeing an imminent installation...

But seeing the discussion in the current thread Willo started with questions about batteries for a 24V thruster, leads me a a question of 12V vs. 24V selection...

Assuming batteries installed within 2' of the thruster... is there any significant advantage to a 24V unit over a 12V unit? Using the Side-Power SE100 12V and 24V models as examples, both spec to the same thrust: 100 kg at 10.5/21.5V, or 116 kg at 12/24V.

Our ride is essentially a 12V boat, and I'm thinking a 12V thruster would simplify requirements for charging sources...​

Thoughts?

-Chris