yahmaha 99 starting battery size

[Rainh2o]

I can't seem to find the exact owners manual for my motor. It's a 9.9 EX, and I was wondering, what the min size amperage battery would be needed to start it? I was looking at my lawn tractor battery the other day and it is rated for something like 365 cranking amps and the size of it would be great to mount closer to the motor on my catalina 25, and it would get my motor off the house batteries. Its smaller size might make it easier to recharge with the motor as well. The closest thing I found was for a newer 9.9 that said it needed 290 cranking amps.

 

[thinwater]

In 30 years of running small outboards I have never understood why you would separate the house and engine bank. Keep them balanced and charged together. More capacity and better battery life.

It's not like you can't hand-pull the engine if the battery is flat (which will not happen if you want them to last). With bigger inboards I do understand the purpose.

 

[Chris & Lenore]

I have the same engine but manual start. It starts on one pull - bring it up to compression and a quick six inch pull and it starts. Once and only once it took two pulls (in six years use).
I have an electric start kit for it but nothing could convince me to install it. Maybe if I didn't have to remove the pull start to have electric.
My wife can easily start it too...

Chris

 

[Benny17441]

With 365 cranking amps I do not see why it would not start your motor; after all that battery is likely to have more capacity than the ones in those portable and rechargeable power packs. Not that I think it would make a difference but it would be good to know if the rating is for CCA (cold cranking amps) or at what temperature was the rating given. The smaller battery will have less capacity and if the engine requires repeated cranking before it starts might be something to consider. But if it starts quickly you should not have a problem.

 

[thinwater]

I have the same engine but manual start. It starts on one pull - bring it up to compression and a quick six inch pull and it starts. Once and only once it took two pulls (in six years use).
I have an electric start kit for it but nothing could convince me to install it. Maybe if I didn't have to remove the pull start to have electric.
My wife can easily start it too...

Chris

I believe you can still pull start if need be; though the original rope is removed, you can still take the cowl off, wrap a line around the flywheel and pull, and there is an emergency rope supplied for this use. I know, I've pull started electric Yamie 9.9s (the battery on mine died on the delivery trip--the boat had old batteries). The only down side is that the rope has to be re-wound for each pull. Common practice is to give it a little starting spray to make sure it starts the first time. No problem.

The new 9.9 electrics have a manual pull too; the best of both worlds!

I would install it. It's nice.

 

[Crazy Dave Condon]

any 9.9 with electric start should have it's own battery if on a dual battery system as it will supply enough to start the engine and then when the engine is running, it is rechargaing that battery. The purpose to separate the batteries is due to the fact that many pleasure sailors will turn the batt. selector to all which if not careful sometimes drain both batteries to the point you cannot start the motor electrically or by battery which will then require yanking that rip chord.

This then brings up to a second issue. You have to make sure the motor is maintained and if not, long bursts to start that engine if it will start. Causes not to start include bad fuel, fuel left in the carb for a long time fouling up the carb to require cleaning out, fouled spark plugs, loose or corroded wires, and so on.

My suggestion is keeping one battery for the 9.9 making sure it is being maintained properly to insure a quick start.

 

[thinwater]

any 9.9 with electric start should have it's own battery if on a dual battery system as it will supply enough to start the engine and then when the engine is running, it is rechargaing that battery. The purpose to separate the batteries is due to the fact that many pleasure sailors will turn the batt. selector to all which if not careful sometimes drain both batteries to the point you cannot start the motor electrically or by battery which will then require yanking that rip chord.

This then brings up to a second issue. You have to make sure the motor is maintained and if not, long bursts to start that engine if it will start. Causes not to start include bad fuel, fuel left in the carb for a long time fouling up the carb to require cleaning out, fouled spark plugs, loose or corroded wires, and so on.

My suggestion is keeping one battery for the 9.9 making sure it is being maintained properly to insure a quick start.

This is just a difference of opinion, but...

In my experience most small outboards are often not run enough to keep the battery up against self discharge. 10 minutes at 0.5 amps (0.08 amp-hours) is simply meaningless. Thus, the house battery and the engine battery are seeing different cycles. The boat will need to be on a charger, either plug-in or solar. By keeping them combined, the strain of over night loads is evenly spread and the batteries can be maintained in a uniform manner. It also takes very little juice in a the combined bank to roll-over a 9.9.

Will the sailor run the bank dead over night? Well, that's just bone head and I have not experienced it. But I have pull started the engines (there are 2) both for practice and when the OP pitting me with old batteries on the delivery trip. It was not a big deal.

Like I said, just an opinion which I have followed for a very long time.

 

[Rainh2o]

Thank for the replies. Think I'll give it a try. I have two marine batteries on board as house batteries. I know the motor would never charge either one of those, not enough power to do it and I dont yet have solar panels, its in the books but not just yet. The lawn tractor size battery might get enough juice back into it from the motor though after running it for 20 mins like we usually do to get out of the marina and onto the big lake. Ill have to keep an eye on the charge state for awile to be certain though. The reason I want to do it is redundancy, if for some strange reason I do kill my house batteries I will still be able to start the motor easily. Sure I could pull start it and it does start usually with just a bump of the starter, so even hand pulling it wouldn't be bad, but goofing around with a rope and pulling the cowl off over the water just sounds like the very last thing I want to do unless I had too. Hand pulling it would be my 3rd and last redundancy.

 

[Brian D]

FYI, I use GP24 x 2 for my Y9.9 that is electric start. Might be an overkill but at least it will start. LOL. The house is GP27DC x 2. I also have solar on the boat to keep the batteries topped.