Need new house batteries, 2008 R25

S

shawnpb

Active member
Joined
Sep 16, 2020
Messages
38
Fluid Motion Model
C-248 C
Hull Identification Number
FMLT2544G708
Vessel Name
MOKUHONU
I have a 2008 R25, wet cell/flooded batteries, model 15020324 deep cycle from West marine. They no longer hold charge. Can I replace the two deep cycle house batteries and leave the other two (starter and thruster/anchor) alone for now? they perform perfectly. Also, I'm sticking with wet cell technology and I read a lot where folks just go to Walmart or similar, spend ~$90 and just replace every 3 years. Does anyone have a MFG & model number of replacement batteries for the West Marine deep cycle units? Thanks a lot!!
 
I just went through this with my R-23. The 2 house batteries and the 1 starting battery were fine but the 1 thruster battery was kaput. The 2 house batteries are considered an independent bank ( bank 1), the single starting battery a separate bank,(bank 2) and the single thruster battery is bank 3. The thruster battery was the only “bad” battery so that’s the only one I replaced. The two house batteries and the thruster battery are all West Marine Premium AGM 92 Ah Group 27 batteries. Everything is working great now.
Cheers,
Karl
 
Going along with the above post, yes, you can just replace the house batteries and if the others are flooded then you need to stay flooded. Group 27 is the usual size. I have known some 25's that had group 31. Group 31 batteries are approximately 13 x 6 13/16 x 9 7/16 inches. Group 27 is 12 1/16 x 6 13/16 x 8 7/8 If the group size is not on the battery then you may confirm from these dimensions. You may have read my other posts on using flooded. I am a proponent because most battery failures are the result of owner error. I would prefer to replace a $90 battery than a $200 plus
 
I've read that you do need to be careful with partial battery replacements. Even though the batteries are in separate banks they will charge as one bank anytime the ACR closes (assuming you have ACRs). While two batteries may be shot, the other two may only be marginally "ok". I would check the specific gravity of the electrolyte in each cell of each battery you intent to keep and do a thorough load test on each battery to get a more accurate picture of the health of the ones you plan to keep.

The risk you take as I understand it (imperfect as it is) is when your marginal batteries are combined with the new batteries for charging, you end up over charging the new ones to bring all the batteries up to full charge (as one temporary bank). What ends up happening is that the new batteries wear faster than they would than if you replaced all the batteries at once.

I believe the process goes something like this: the charger looks at overall voltage (when ACRs combine the batteries into a single bank after sensing a charging voltage) to know how much charge to input, not the voltage of each individual battery. If the charger output is 21 amps, all batteries will get 21 amps. So the newer batteries with a lower resistance will take the charge faster, and "fill up" before the older ones that have more resistance from longer use. At this point the charger is still looking at total volts for the combined batteries which will indicate more charge is still needed because the older batteries still aren’t full. Charging in the newer batteries will continue (because of ACRs being closed) to a level that they get overcharged and damaged over time because the older ones take longer to reach a full charge.

There are other Tugnuts I am sure that can add a more precise explanation. HTH, GF
 
Thank you all! Great feedback and I have also read that combining old units with new units can be an issue when it comes to charging as GaylesFaerie points out. I need to research this a bit more. Maybe I'll get more responses on this topic.
Also, looking for suggestions on flooded, deep Cycle, battery replacements....Interstate, Duracell etc. Thanks again
 
I have four house batteries in our R25 Classic plus a battery for thruster+windlass and another for engine.
We replaced the engine and windlass+thruster batteries in 2020 and the four house batteries in early 2021.
For the house batteries we used these:
https://www.batterymart.com.mx/pdf/27DC115.pdf
Crowns are made in the USA and have a good reputation. At 115 Amp/Hours each they pack a lot of power for a Group 27 flooded battery. The downside is that the Crown 27DC11 batteries are currently a bit hard to find.
For the engine and windlass+thruster batteries, we used the SLI27MA Duracell Ultra BCI Group 27M 12V Flooded Marine & RV Battery from Batteries Plus. The Duracell is made by East Penn Manufacturing and is a very large USA battery company.
 
Thanks again. Has anyone used the EverStart 27DC Deep Cycle, flooded from Walmart....$85. They get decent reviews.
 
When buying batteries retail, you will find that 10 different retailers put their own name or some branding on the battery but technically the batteries are all made regionally by a single manufacturer and sold for re-labeling. Before buying I would inspect the battery closely for the actual manufacturer and use that as the basis for your research or going to their website for the nitty gritty details on specifications, charging, and usage. HTH, Gary
 
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