R-27OB Battery

M

marksandyham

Well-known member
Joined
Feb 6, 2021
Messages
77
Fluid Motion Model
C-28
Hull Identification Number
FMLT2704E819
Vessel Name
John 10:28
MMSI Number
338323603
My engine battery needs replaced because my boat spends time inside out of the water and not connected to shore power, resulting in the 24/7 loads will draining the battery combined with the OnBoard charger being incorrectly set up to deliver only 6 amps from the factory (per the dealer mechanic).

I tried many locations locally (Lake Erie North Coast of Ohio) including my marina who can usually always find parts and could not find an exact or functional replacement battery. Factory is a UB121100/D5751. UB121100 comes in many variants, the variant with the "L" terminal is the D5751.

This is because the battery terminal is a bolt thru tombstone shape. Many choices with standard marine battery connections 9post and threaded stud) or bolt in top. There are three cables two on one side and one on the other on negative side. Have not checked the positive side yet. I know ABYC standard is four but would rather use exact replacement.

The bolt appears larger than the standard marine stud.

Any one have any suggestions on sourcing a 12v 110AH Deep Cycle AGM battery with the "L" terminal
 
marksandyham":t9z5frpt said:
My engine battery needs replaced because my boat spends time inside out of the water and not connected to shore power, resulting in the 24/7 loads will draining the battery combined with the OnBoard charger being incorrectly set up to deliver only 6 amps from the factory (per the dealer mechanic).

I tried many locations locally (Lake Erie North Coast of Ohio) including my marina who can usually always find parts and could not find an exact or functional replacement battery. Factory is a UB121100/D5751. UB121100 comes in many variants, the variant with the "L" terminal is the D5751.

This is because the battery terminal is a bolt thru tombstone shape. Many choices with standard marine battery connections 9post and threaded stud) or bolt in top. There are three cables two on one side and one on the other on negative side. Have not checked the positive side yet. I know ABYC standard is four but would rather use exact replacement.

The bolt appears larger than the standard marine stud.

Any one have any suggestions on sourcing a 12v 110AH Deep Cycle AGM battery with the "L" terminal
Click to expand...

The engine battery should not be a 110ah Deep Cycle AGM battery with L terminals. The UB121100 is a deep cycle battery that the factory uses for the two house batteries and the thruster battery.

The Yamaha F300 requires 680 CCA to start. The UB121100 Deep Cycles offer 550CCA, as they are deep cycle and not engine starting batteries.

The engine starting battery that came with my RT27-OB from the factory is a Centennial, C-31-9ST, and is rated for 950 CCA. It also uses normal threaded terminals, not the L-shaped (tombstone) style that the deep cycle batteries use.
 
My Cutwater 28 came with the UB121100 for the engine battery so I ended up redoing the cables with a bus bar so I could use standard thread in terminals. The factory wiring had 5/6 connections at the terminals so a bus bar was required to fit them all properly. Plus I’m pretty sure you should never have more than 4 connections per terminal anyways. I went with the Odyssey AGM 31 series for the new engine battery.


Sent from my iPad using Tapatalk
 
Interesting. My R-27 is a 2019 Hull FMLT2704E819. So apparently the factory installed the wrong battery or they believe it is capable of starting the motor.

I hope the factory will comment.
 
Hi Mark,

The current starting battery for the R27 Yamaha is a Group 31, 930CCA part number C31-9ST, available at Battery Systems. Not sure about your batteries, but this is what we have in our system at this time. Hope this helps.

Cheers,

Ralf
 
Thanks Ralf.

I have 4 of the UB121100 AGM Deep Cycle batteries on my boat. Is it possible that the early R27OB were built with this battery? It has not been a problem until this year when it was out of the water and inside with no solar. No issue with engine starts.
 
Hi Mark,

Unfortunately there is no way I have of being able to tell. I suppose it's possible, depending on how Reed Yacht Sales ordered the boat. But I can't check that. It shouldn't be much of a problem. Also considering the age of the boat, the batteries will soon be in need of replacement regardless.

Cheers,

Ralf
 
Mark,
Like you I have a 2019 R-27OB which also came from the factory with four UB121100 Universal Batteries. I am in the process of replacing the engine start battery with a Duracell Group 31 AGM Commercial Battery from Sam’s with 950 CCA. The House Batteries were previously replace with Lithium as part of my conversion from a generator to battery/converter on my Luxury Edition. The thruster will continue to operate on the original UB121100 until it’s time to replace. Good luck.
 
Thanks Larry
 
Ralf,

If the current starting battery from the factory for the R-27 Yamaha is the Centennial Group 31 Commercial C31-9ST, what battery is the factory currently using for the Thruster battery? I prefer to stay with factory specifications when possible. Maybe also provide the current house battery for those with the Northwest Edition (the Luxury Edition is now Lithium). Thanks

Larry Davis
2019 R-27 OB
Perdido Key, FL
 
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