Importance of a fully charged battery

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AnglerC
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Importance of a fully charged battery

Post by AnglerC » 12 Sep 2016, 12:59

An oversight on my part left me on a like with a 40 horse OB Evenrude and a battery so low it triggered the low battery alert on my fishfinder.

This was the first time I had had it back on the lake since I had the carbs done in late June. (long story).

Needless to say the motor was cutting out or bucking at low rpm and died frequently. It did not do it at higher rpm. Before the carbs were done it did the same thing but also did it at higher rpm.

So my question is. Was it giving me fits due to a low battery or is it not repaired after the carbs were done?

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lovedr79
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Importance of a fully charged battery

Post by lovedr79 » 12 Sep 2016, 13:16

i would try it with a full battery before i took the carbs back off. i have seen some ATV's run like crap with a dead battery. one inparticular would idle all day long. tuoch the gas it would die. for giggles i got out jumper cables and a car battery. ran like a champ.
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jbird68
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Re: Importance of a fully charged battery

Post by jbird68 » 12 Sep 2016, 20:21

Do you need a battery once the motor has been started? Why would it affect the way the motor runs?

Sincerely,

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Texas Prowler
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Re: Importance of a fully charged battery

Post by Texas Prowler » 12 Sep 2016, 22:19

A bad battery would do that to any engine. Try having the battery load tested. That will tell you what you need to know about it.

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Pappy
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Importance of a fully charged battery

Post by Pappy » 12 Sep 2016, 22:40

NO, a bad battery will NOT do that to any engine.
Your Evinrude 40hp needs NO battery to run at all. You can rope start it and run.
This engine as well as most if not all carbureted engines use a mag CD style ignition that generates its own power to run once the flywheel is turning.

Now, on to your issue. You have, on that engine, (3) seperate circuits on your carburetors. These circuits control idle, midrange, and high speed fueling.
Your issue suggests your idle circuits are either plugged up again or improperly adjusted or the Sync and link needs to be done.

Texas Prowler
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Re: Importance of a fully charged battery

Post by Texas Prowler » 12 Sep 2016, 22:49

Not trying to argue but read the first sentence... Either it's not getting a charge or can't be changed.

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Pappy
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Importance of a fully charged battery

Post by Pappy » 12 Sep 2016, 22:57

Now we are getting off track. He indicated he started the engine with less than a fully charged battery.
The engine ran.
This same engine is made in a rope start, tiller operated configuration. No battery required on that engine and the same ignition system.

The charging system on that engine is totally separate from the ignition system. The charging system has zero to do with ignition.
I gave you the explanation on how the system works in a short version. Read it again. Needs no battery to run.

lovedr79
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Importance of a fully charged battery

Post by lovedr79 » 13 Sep 2016, 08:00

if there is a completely DEAD cell or two in the battery this would cause the "loop" to be incomplete. some ignition systems have to have a complete loop to run causing havock on the ignition.
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overboard
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Importance of a fully charged battery

Post by overboard » 13 Sep 2016, 08:24

I would have to agree with Pappy! Just for piece of mind put a fully charged battery on it, I doubt if that will solve the problem and you will be looking at the carbs.
Some electric start motors come with a rope and can be started if the batter is stone dead, those motors can be started and will run just fine without a battery. My 100hp Mariner has a starter rope in the cowl from the factory, I hope I never need to use it! :lol:
Just a thought, even though the carbs were done they could have been recontaminated.
Just saw the above post, I don't know what a dead/shorted cell would do, but would be worth checking the battery out first and then go from there.

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Pappy
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Importance of a fully charged battery

Post by Pappy » 13 Sep 2016, 10:01

lovedr79 wrote:if there is a completely DEAD cell or two in the battery this would cause the "loop" to be incomplete. some ignition systems have to have a complete loop to run causing havock on the ignition.
Give us an example of that in the vintage the OP is running. Looking forward to your reply.

Hint. On an Evinrude that is normally started by a battery just remove the battery altogether and start the engine with the rope.

lovedr79
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Importance of a fully charged battery

Post by lovedr79 » 13 Sep 2016, 10:12

I can tell you for a fact that a 1971 Honda SL70 with battery and kick start will not run without a battery. I do not know all of the specifics of the OP's OB. More importantly is what has the OP done since they started this thread.
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DaleH
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Importance of a fully charged battery

Post by DaleH » 13 Sep 2016, 12:41

overboard wrote:Some electric start motors come with a rope and can be started if the batter is stone dead, those motors can be started and will run just fine without a battery.
You meant to add, of course ... provided that the key switch was still turned to 'ON' ...
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Texas Prowler
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Re: Importance of a fully charged battery

Post by Texas Prowler » 13 Sep 2016, 15:41

Pappy since I've had my 73 50hp Johnson I've started it with a known bad battery. It has a bad cell. I've had it load tested. Just because it started doesn't mean it isn't bad. Again not arguing just pointing out facts. Just thinking outside of the box here as there are other possibilities. The op wouldn't even have to buy an extra battery to test this theory.

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Pappy
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Re: Importance of a fully charged battery

Post by Pappy » 13 Sep 2016, 19:32

Texas Prowler wrote:Pappy since I've had my 73 50hp Johnson I've started it with a known bad battery. It has a bad cell. I've had it load tested. Just because it started doesn't mean it isn't bad. Again not arguing just pointing out facts. Just thinking outside of the box here as there are other possibilities. The op wouldn't even have to buy an extra battery to test this theory.

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Okay lets go back to basics here.
Go back and read the OPs post again. The issue was that the engine ran rough at low RPM and the OP wondered if the low battery was the culprit.

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Importance of a fully charged battery

Post by turbotodd » 13 Sep 2016, 19:44

lovedr79 wrote:i would try it with a full battery before i took the carbs back off. i have seen some ATV's run like crap with a dead battery. one inparticular would idle all day long. tuoch the gas it would die. for giggles i got out jumper cables and a car battery. ran like a champ.

yep. Kawasaki Prairie 300 and 400, Bayou 300 and 400, some Honda ATV's, Kawi Prairie 360, 650, 700, many kawi motorcycles (750 vulcan I'm working with currently, requires a GOOD battery to run properly), etc etc. I haven't heard of any outboards requiring a battery to run properly. Doesn't mean that they will ALL run right without a good battery, just means I've not heard of it (yet). Maybe the bigger motors. EFI anything for the most part, requires a battery-with the exception of a very few machines....Merc 25hp EFI is one of them, and now the Suzuki outboards (both are batteryless EFI). Lot of the motocross bikes 250cc and 450cc are EFI and no battery but the technology behind this is still a little behind, in that you can't slowly kick it over and expect it to start...it takes a swift kick of the start lever (or a swift pull of the starter rope).

Those are the ones I know of off the top of my head based on my personal experience with them.

Most everything is a CDI style ignition, especially the newer (1980 and newer) japanese stuff. There are two main types of CDI systems. AC-cdi and DC-cdi. AC will have a coil on the stator assembly that powers the CDI (aka source coil). DC CDI systems require 12v to run properly, usually in the form of a good battery.

Most older carbureted outboards don't NEED a battery to run correctly, but if the system is electric start and has a charging system, it's hard on the regulator/rectifier to continue to use the motor without a battery.

In the original poster's case I doubt the low battery had anything to do with the running problem, but I'm not an Evinrude guru either. Could be a hundred things causing the poster's problems. Timing, carb(s), linkages, etc.

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