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Author Topic:   Battery for Yamaha F70
Keeper posted 12-25-2011 01:19 PM ET (US)   Profile for Keeper   Send Email to Keeper  
I just took delivery of a 2012 Yamaha F70 four-cycle outboard engine I will be installing fairly soon on my 1988 Boston Whaler 15-footer. I won't be running any other electronics. Will an Odyssey PC925 battery be sufficient? I used an Odyssey PC 625 with my previous motor, a Yamaha 70 two-cycle outboard, and never had a problem. The reason I ask: I saw a boat that was in a shop for service and one of the guys told me that the F150 Yamaha four-cycle outboard wasn't getting enough power from the battery and was running poorly. He said it didn't have enough juice to fire the injectors. Thanks for any feedback. PS.
contender posted 12-25-2011 01:43 PM ET (US)     Profile for contender  Send Email to contender     
Keeper: You just spent a bundle, what is another $100 for a brand new battery. The 2 stroke in theory should start easier than a 4 stroke because it fires more. However, I do not think this really holds water if the engine is tuned and running correctly. The other issue is I would check your battery wires, see if they are connected correctly (tight) clean and of sufficient size. Sounds like, I think, something else is wrong with that 150 Yamaha, once the engine starts the alternator should make enough juice to run the engine correctly. I do remember with older Mercury's if the battery was low it would not turn the engine over fast enough to start them. Keeper, bottom line I would just purchase a new battery and the largest one that my battery box would hold with the most cranking amps. Happy Festivus
Keeper posted 12-25-2011 02:51 PM ET (US)     Profile for Keeper  Send Email to Keeper     
Thanks Contender. It's not a money issue, but more of a space and weight consideration. I am going minimalistic on the set-up and want as much weigh and space savings. I actually used that PC 625 with my older 70 Yamaha 2-stroke for almost threee years [without] a problem. Odyssey batteries aren't cheap, I was very happy with their performance. I ran two of the 925's to power my 24-Volt trolling motor with excellent performance! Just want to see how small I can go with house my battery. Thanks


Jerry Townsend posted 12-25-2011 03:45 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Keeper - I suspect you were fed a bill of goods re the battery. That is, as contender has mentioned, low power to the battery is typically from corroded conections, lighter cables which will have more resistence than a heavier AWG-2 or AWG-4. An engine running rough is not going to be caused by the battery. The injectors cannot require all that much current to work.

Check the amp-hour rating on the battery and compare against what Yamaha recommends. We don't know how old the battery is or the amp-hour rating. Typically a battery will last for at least five years - and some longer.

In my case, I always get the largest amp-hour rating battery I can get into the space available. And if a battery is getting on the old side or questionable state - change it. ---- Jerry/Idaho

Russ 13 posted 12-25-2011 05:18 PM ET (US)     Profile for Russ 13  Send Email to Russ 13     
I agree with the battery you have "check up". If your wiring, connections, switch, battery is all in good working condition, you should be fine.
I have had VERY good results with GEL-Cell batterys. Napa sells them, as I am sure many other stores. I relocated mine to under the console, with AWG-4 wiring, soldered and sealed terminals--ZERO problems. Starting and running a 90-HP Yamaha, livewell, and electronics, with a group 24 size Gelcell.
jimh posted 12-26-2011 08:34 AM ET (US)     Profile for jimh  Send Email to jimh     
jimh posted 12-26-2011 08:42 AM ET (US)     Profile for jimh  Send Email to jimh     
Check the owner's manual of your outboard motor to discover the recommended battery to use with the motor. Some manufacturers have very specific recommendations, while others just specify a particular rating in marine cranking amperes (MCA). Once you select a battery by MCA rating, the rest of the features and specifications are up to your discretion.

Since your Yamaha F70 probably cannot be started without a battery providing some current to the engine electronics, it is prudent to invest in a good battery.

zotcha posted 12-30-2011 07:53 PM ET (US)     Profile for zotcha  Send Email to zotcha     
Keeper, I know we've spoken in the past. You are absolutely on the right path. It is possible to run an F70 with something equivalent to a tractor (or something slightly larger) with your new outboard. I've seen it done up in Charleston at High and Dry Boat Works. But, no electronics or live wells. Keep researching, it is possible. zot.

Feel free to email. Michael.

Keeper posted 12-31-2011 12:40 AM ET (US)     Profile for Keeper  Send Email to Keeper     
Thanks, Michael. My buddy just got a [lithium] battery and he is very happy. [The cost of a lithium battery is] too rich for my blood. It's cool to see the technology heading in the right direction though. Thanks, and I will hit you up in the next couple weeks to let you know what I find.--Keeper
jimh posted 12-31-2011 11:53 AM ET (US)     Profile for jimh  Send Email to jimh     
I cannot see any application for a lithium battery in a boat. The cost of the lithium battery is about twenty-times the cost of a conventional battery, and the principal advantage is saved weight. Saving perhaps 50-lbs of weight in a boat battery at a cost of $1,800 does not seem like a reasonable value to me, and I suspect most boaters would agree with me.

The requirements for a cranking battery for a Yamaha F70 are not likely to be particularly special. I cannot see any reason why a Yamaha F70 would need an unusual marine cranking battery to be started and run.

Keeper posted 12-31-2011 12:07 PM ET (US)     Profile for Keeper  Send Email to Keeper     
I think there is a market for Lithium batteries in marine application. Aaaron Martens shaved over 200-lbs of battery weight in his boat. Some people do like to spend the money on stuff like this. Eric
jimh posted 12-31-2011 01:25 PM ET (US)     Profile for jimh  Send Email to jimh     
Eric--I don't think too many people will be interested trading $1,800 to save 50-lbs in a battery. However, if you think that a $2,000 battery will be the best way to start a 70-HP outboard engine, don't let me hold you back.
jimh posted 12-31-2011 01:28 PM ET (US)     Profile for jimh  Send Email to jimh     
Eric never did mention what the specifications were from Yamaha for the starting battery of an F70. If we knew the battery specifications it would be possible to recommend a specific battery for that service.
Keeper posted 12-31-2011 03:04 PM ET (US)     Profile for Keeper  Send Email to Keeper     
I've been looking for the battery requirements from Yamaha. Unfortunately I haven't' been able to find it on their website, etc.
The shop where I bought the motor is closed till Tuesday.
The motor was just shipped to that facility, so I don't have the owners manual yet either.
I'll advise as soon as I learn more.
jimh posted 12-31-2011 03:57 PM ET (US)     Profile for jimh  Send Email to jimh     
Yamaha can be a bit coy about providing the owner's manual on-line. Try aspx?ls=outboard

jimh posted 12-31-2011 04:00 PM ET (US)     Profile for jimh  Send Email to jimh     
The on-line F70 manual says re battery:


Battery requirements

Specifications of Battery

Use a fully charged battery that meets the following specifications. The engine cannot be started if battery voltage is too low.

Minimum cold cranking amps (CCA/SAE): 380.0 A

Minimum marine cranking amps (MCA/ABYC): 502.0 A

Minimum reserve capacity (RC/SAE): 124 minutes


Do not use a battery that does not meet the specified capacity. If a battery that does not meet specifications is used, the electric system could perform poorly or be overloaded, causing electric system damage.

Keeper posted 12-31-2011 05:14 PM ET (US)     Profile for Keeper  Send Email to Keeper     
Thanks Jim,
It looks like I am gonna go with the Odyssey 925 like I planned.
The dealer is near my house, and I was very happy with them before.
I'll post up a report as the build progresses.
Thanks again !
jimh posted 01-01-2012 05:14 PM ET (US)     Profile for jimh  Send Email to jimh     
Also consider the Sear DIEHARD Platinum marine battery. I think they are actually made by ENERSYS, who also makes Odyssey. See my earlier article on that topic at

At one time I thought that Sears would be a retailer whose universal presence would make them a preferable vendor, although the recent news that Sears will close 100 under-performing stores might question that judgement.

Jerry Townsend posted 01-01-2012 11:54 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
I have used the Sear's DIEHARD top quality batteries for years - and will continue to do so.

Their closing 100 stores is a drop in the bucket - and that number includes their K-MART stores. --- Jerry/Idaho

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