Recharging deep cycle battery from new Yamaha 60HP

[Barry Oliver]

I recently bought a new boat with a 60HP Yamaha. I had a electric motor fitted with a deep cycle battery. I was told that the new Yamaha 60HP motor cannot recharge the deep cycle battery and the only way to recharge it is to put it on a charger when I'm home. The boat has two batteries already fitted and a switch to switch between 1, 2 and 1&2 batteries. My understanding is that I can run the engine on 1 and then switch to 2 if i'm out for a long time not running the engine, as 2 runs the accessories (but not the electric motor). This makes sense because then i don't run down the engine battery- if its switched on 1&2 I can because its just like a big capacity battery. Having the 1/2 isolater switch stops running both down. 

I expect if i've switched to 1 then only 1 will be charged by the engine and similarly if switched to 2, and if i've got the switch on 1&2 both will get charged.

However, I'm at a loss as to why I can't have the engine charge the electric motor deep cycle battery.  Eg have it set up like a 4x4 dual battery system where the deep cycle battery is charged but accessories use the deep cycle and don't flatten the starting battery.  In my case if the switch is on 1 it should charge battery 1 plus the deep cycle, if the switch is on 2 it will charge battery 2 and the deep cycle and if the switch is on 1&2 it will charge batteries 1 and 2 and the deep cycle. BUT the electric motor can only discharge the deep cycle.

 

I spoke to the dealer and was told its because the Yamaha outboard has a rectifier not an alternator like a car...and it will blow up the electronics charging a deep cycle battery...neither of these two things made sense..a rectifier converts AC to DC...has nothing to do with charging...and I didn't understand why it would blow up the electronics...I didn't think he was in the mood to explain any further...so I let it pass.

But alas its still bugging me...can anyone enlighten me here..

cheers

B

 

 

[Allnighter]

I dont know the technical reason either.

But i also have a four stroke yammy connected to a normal 12v battery at rear of boat.

My minn kota is connected to a seperate deep cycle 12v 120ah battery at front of boat.

I can run the minny on spot lock all night without flattening the deep cycle battery.

(This depends on water current, minny can last all night on speed 3 or 4, but if you use the rabbit function or use any speed higher than say 7 for longer periods the electric current draw will flatten deep cycle quite quickly.)

I then recharge deep cycle when i get home with a DEEP CYCLE battery charger, which can sometimes take 48 hours to fully recharge deep cycle battery.

Hope this helps somewhat.

 

 

 

[ellicat]

@rayke1938 may be able to add to this topic.

[Barry Oliver]

Well it certainly means I'm not alone in my setup...:-).  I will have to check the deep cycle battery capacity I don't think its going to be 120ah...you have a kickass battery.

I found on internet that a 55lb minn kota draws max 50amps- so your battery will last a bit less than 2.5hrs on rabbit mode, probably closer to 2 given possible losses.

I saw some report where the slowest speed drew 10amps so that's 12hrs on your battery. I expect the spot lock draw is going to be a function of the effort needed to hold position. In still water it will probably draw very little but if you have a raging tide then probably a lot more...

Anyway, thanks for your input...nice to feel in the same boat as someone else. ;-)

 

 

[Allnighter]

Yes forgot to say mine is 55lb on a 4.2m tinny

And yes your calculations for anticipated run time verse amp draw/ battery life seem correct for what i have experienced with practical real life use for the last 2 years using it.

Who wants to fish in a raging current anyways....

I dont think 120ah is considered kickass, i think this would be considered a minimum, it cost approx $250 a couple of years ago and still lasts ok

So the important thing is to use the RIGHT charger so i was advised years ago, (Jaycar) were most helpful

 

[Old Scaley]

Interesting post. My setup is very similar to @Allnighter. 4.35m tinny with 40hp 2 stroke Yammie on the back and a 55lb MK on the front. The electric runs on a deep cycle 120AH lead acid battery. It is in one of the hatches at the front and I have Anderson plugs on a break in the cable, and an Anderson plug on the 9 stage charger which I bought at Jaycar. Good info above about the current draw because I have never known how much power the electric soaks up. 

Down the back I have a 110AH AGM deep cycle to run the sounder/bilge pump/Nav lights/live bait pump. It is connected to the outboard for charging (motor is pull start) but since I put the deep cycle there I have never been confident that it is charging off the outboard. I had a look in my owner’s manual this arvo and it mentions an alternator but not a rectifier. I will be watching this topic with interest.

[GregOug]

Well, I know absolutely nothing about this topic, but my understanding is that your outboard will charge both batteries regardless of whether the isolator switch is set to 1, 2 or both. The switch only dictates which battery (batteries) discharges (provides) power.

[Alex2505]

Hi Barry the rectifier as you say converts AC to DC . As I understand it you need a regulator to control the voltage range ( Between say12- 14.4 volt. I had a Suzuki 30 HP electric  start (2008 model) years ago with a rectifier. at WOT I was seeing up to 16 volt charging the battery. as the dealer said not ideal for electronics or the battery. I'm no Auto elec but this is how it was explained to me. 

 

the screen shot below shows the new 60 HP yammy has a rectifier regulator @ 16 amp I'm not sure why you can't charge as it will already be charging your start battery.

 

• ngine Type4-Stroke, SOHC In-line 4
• Bore x Stroke (mm)65 x 75
• Fuel Tank Capacity (l)
• Displacement (cc)996.0
• Recommended Maximum RPM5000-6000
• Fuel ManagementEFI
• IgnitionTCI
• Lubrication SystemWet-sump
• Alternator Output12V - 16A with Rectifier Regulator
• Gear Ratio1.85 : 1
• Starter SystemElectric
• Operation MethodMechanical Control (Optional Tiller Handle Available)

[Allnighter]

A quick google search confirms for deep cycle agm batteries, the slower the charge rate will extend battery life.

Excess heat build up inside deep cycle battery if charged too quickly may also be an issue.

[Barry Oliver]

The plot thickens!

I have just run an 'out-of-water' current test and this is what I found:

Rabbit mode/10= 5amps

9=4amps

8=3.5amps

7=3amps

6=2.4amps

5=2amps

4=1.9amps

3=1amp

2=0.68amps

1=0.37amps

I will test this next time I'm out. It won't surprise me if these current draws are x10 with load (in water pushing boat).

The engine is a 55lb Minn Kota Riptide Terrova. I have a 120ah battery. That's isolated from the rest of the electrics.

Once I get underload current draw I'll post them here.

In relation to the total electrics this is the story-

1. the electric motor battery is totally isolated from all other electrics (so the battery needs to be charged after each trip and won't be charged by the outboard alternator). The reason for this is most likely that the electrics needed to charge the deep cycle from the outboard without flattening the starter are not worth the effort in such a harsh environment like salt water. Also most outboard don't have big alternators which might be also relevant. Charging a deep cycle battery can take a lot of energy and you don't want to risk any problems with your starting batteries. The exact reason isn't clear yet but these two are good enough for me.

1A. Running deep cycles below 80% discharge reduces their life. Some say down to 50% is ok. Seems to be a bit subjective. So a 120ah battery only has only up to 60ah usable before damage is likely to occur. This means if you run it down more than 80% its going to fail earlier than otherwise. How earlier? How long is a piece of string? Anyway once I get a better idea of current draw under load it will give me better idea of run-times.

2. The isolating switch for the outboard battery: 1, 2 and 1&2 are that..isolating..if you are switched to 1- then only 1 will be charged by the outboard. If you are on 2 same idea- only 2. If on 1&2 both will be charged. However never have it switched to 1&2 because if you get a fault in one battery it will destroy the other. Run your whole trip on only 1 or 2. If you put it on 1&2 you are basically running on only 1 battery albeit a big one. On 1&2 you have the same risk as one battery. If you are out and on 1 and your battery goes flat (for whatever reason) you can switch to 2 and start or vice versa. If you are on 1&2 and you flatten them...call Marine assist or get out your hand starter cable or maybe use your deep cycle as a last resort...:-) Take note GregOug.

Its a good idea to swap between 1 and 2 on different trips, and keep each battery in peak charge. If you don't go out often then keeping both batteries charged is good practice.

Anyway, I hope this helps someone as well as me..:-)

 

 

 

[GregOug]

32 minutes ago, Barry Oliver said:

The plot thickens!

I have just run an 'out-of-water' current test and this is what I found:

Rabbit mode/10= 5amps

9=4amps

8=3.5amps

7=3amps

6=2.4amps

5=2amps

4=1.9amps

3=1amp

2=0.68amps

1=0.37amps

I will test this next time I'm out. It won't surprise me if these current draws are x10 with load (in water pushing boat).

The engine is a 55lb Minn Kota Riptide Terrova. I have a 120ah battery. That's isolated from the rest of the electrics.

Once I get underload current draw I'll post them here.

In relation to the total electrics this is the story-

1. the electric motor battery is totally isolated from all other electrics (so the battery needs to be charged after each trip and won't be charged by the outboard alternator). The reason for this is most likely that the electrics needed to charge the deep cycle from the outboard without flattening the starter are not worth the effort in such a harsh environment like salt water. Also most outboard don't have big alternators which might be also relevant. Charging a deep cycle battery can take a lot of energy and you don't want to risk any problems with your starting batteries. The exact reason isn't clear yet but these two are good enough for me.

1A. Running deep cycles below 80% discharge reduces their life. Some say down to 50% is ok. Seems to be a bit subjective. So a 120ah battery only has only up to 60ah usable before damage is likely to occur. This means if you run it down more than 80% its going to fail earlier than otherwise. How earlier? How long is a piece of string? Anyway once I get a better idea of current draw under load it will give me better idea of run-times.

2. The isolating switch for the outboard battery: 1, 2 and 1&2 are that..isolating..if you are switched to 1- then only 1 will be charged by the outboard. If you are on 2 same idea- only 2. If on 1&2 both will be charged. However never have it switched to 1&2 because if you get a fault in one battery it will destroy the other. Run your whole trip on only 1 or 2. If you put it on 1&2 you are basically running on only 1 battery albeit a big one. On 1&2 you have the same risk as one battery. If you are out and on 1 and your battery goes flat (for whatever reason) you can switch to 2 and start or vice versa. If you are on 1&2 and you flatten them...call Marine assist or get out your hand starter cable or maybe use your deep cycle as a last resort...:-) Take note GregOug.

Its a good idea to swap between 1 and 2 on different trips, and keep each battery in peak charge. If you don't go out often then keeping both batteries charged is good practice.

Anyway, I hope this helps someone as well as me..:-)

 

 

 

What you talkin’ ‘bout Willis? Lol.
 

Understood about 50% but did understand about only switching to one battery. Thanks.

[Old Scaley]

Thanks @Barry Oliver. That info is great and I am looking foto your results in an on-water test. I have read before about not running deep cycles below a certain level but still not sure how to know when you have hit that level?

[ellicat]

1 minute ago, Old Scaley said:

still not sure how to know when you have hit that level

You can get an in-line meter. I have one I'll show you Tuesday.

[Barry Oliver]

Most sounders have a voltmeter which will tell you battery voltage. Mind you, not much good if your electric motor is on a different circuit.

This is the voltages discharges:

% of Charge (discharged DOD)             Volts

100              0                               12.7

90                10                             12.58

80                20                             12.46

75                 25                           12.40

70                 30                         12.36

65                 35                         12.32

60                  40                       12.28

50                   50                       12.20

Discharged   >50                     11.90

My minn has a battery level indicator. I found this:

"For my motor, four is 12.8v or better, three lights is 12.6v two, 12.5, and one light is 12.3v. "

If true, then the lowest light indicates about 60-65% of charge, which makes sense.

As ellicat implies- easy enough to get an inline voltmeter - Jcar or something similar sell them.

Raises a question of how long your deep cycle battery would last if discharged regularly...probably depends upon the type and quality of battery and how long it was left discharged.

How long is a piece of string?

However a mate of mine had a deep cycle last 10yrs from carefully managing it. I also read a marine battery has an expected life of 1-6yrs. I expect if you discharge to more than 50% regularly its going to be 1yr, and 6yrs if you don't go below 80% or thereabouts and recharge soon after discharge.

I found this:

"Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film. The graph above shows how lifespan is affected by depth of discharge. The chart is for a Concorde Lifeline battery, but all lead-acid batteries will be similar in the shape of the curve, although the number of cycles will vary."

 

Cheers

B

[Barry Oliver]

Here you go. Did a test today off Manly. 10kph wind from the E smack in the middle of an outgoing tide. Boat facing into wind. (kph is kilometers per hour)

I used a clamp meter at the battery.

Rabbit mode/10= 43 amps (draw)= 4kph (boat speed over ground)

8=24amps= 3.2kph

7=18amps=2.6kph

6=12amps=2.4kph

5=8amps=1.93kph

4=4.8amps=1.44kph

3=2.7amps=1.12kph

2=1.1amps=0.8kph

1=0.5amps=0.5kph

On the anchor lock, as you'd expect, current draw varied. Today it was from 0-5amps- this is going to be much dependent on wind and current. If there's no current and no wind then you'd expect the motor to draw zero current. If its blowing a gale with a current its going to draw 43amps (and it still may not hold your position).

If you have a 120amp battery and you only want to go to 80% discharge you have 24amps so on rabbit mode you'd get half an hour or about 2k.

If on 5, you'd get about 3hrs and about 6k.

On anchor lock you'd get quite a few hours, but as mentioned its going to be a function of wind and current. If it consistently drew 2.5 amps then you'd get about 10hours.

Done!

Now I just need to catch some fish and/or go boat camping. :-)

 

 

[Old Scaley]

Thanks @Barry Oliver, that is fantastic info. Very helpful.