Battery Advice for 20hp OB

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Dougcole

Dougcole

Guru
Joined
Jan 21, 2008
Messages
2,167
Location
USA
Vessel Name
Morgan
Vessel Make
'05 Mainship 40T
Hi All,


Just traded in our 2013 Suzuki 20 hp manual start on a 2023 20hp EFI electric start Mercury outboard for our tender and need some advice on battery selection.



We pull our tender (Highfield 340) up onto our swim platform cradle for storage, so I am VERY weight conscious and would like to go with the lightest battery I can find to do the job. I am looking at AGM motorcycle batteries but also possibly considering lithium.


The manual calls for 350 CCA in temps above 0 degrees. AGM batteries seem to take a big jump in size/weight when they go from 300 to 350 cca. Do you think we could get by with 300 cca?


I asked my dealer about it, and he said he thought 300 cca would work fine for our application. As we live in Florida, use the boat primarily in the Bahamas and don't like cold weather, I can't see us using the motor in anything less than 50 degree weather.



I am also kicking around something like this NOCO Lithium battery. 400 cca and weighs under 3 lbs. But I am concerned about it being exposed to the weather and also wonder about how well the OB's alternator will charge it. Any thoughts on this one?


https://www.amazon.com/NOCO-NLP9-Po...anking+battery+for+motorcycle,aps,247&sr=8-24


Thanks.


Doug
 
Might be worth a look at Odyssey Power Sports batteries. I think they're aimed at motorcycles and jet skis and so forth...

Our dinghy motor, Suzuki DF-20A with electric start, currently uses a Deka/East Penn Outdoorsman 11U1L sealed (flooded) maintenance free battery. 350 CCA, 19lbs. Works fine.

But I'll probably look at Odyssey when the time comes... FWIW, it wouldn't surprise me to learn the 350 number isn't magic...

For us, the more important issue is self-discharge rate. Our garden tractor at home has the same battery, and if we don't have snow I have to start the tractor a few times over winter to charge the battery. With the dinghy battery, I've had to bring it home for periodic charging... and this is our first winter with it, so we'll see how that's gone. OTOH, with AGM, I could leave the battery onboard all winter and not worry about it.

-Chris
 
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mvweebles said:
I went with a LFP starting battery for my Tohatsu 20hp. Works fine. A bit pricey at $235, but a very good battery.
Click to expand...

Interesting. 480 cranking amps (probably no matter whether CCA, MCA, HCA, etc.)

-Chris
 
I have a Suzuki 15 HP EFI outboard with electric start. A 275 CCA lawn tractor battery from Walmart works fine. They offer lawn tractor batteries of the same size up to 370 CCA or so.

Ted
 
We have a Suzuki 9.9 EFI with PULL START. Same engine as yours with a different electronic control module. My 120 lb wife can start it with the pull cord. Engine starts first pull every time. So you won’t tax the battery very heavily at all. I wouldn’t be scared to put a small battery in it. You will like that outboard.
 
I had a chat with the manufacturer

Here is what they said,

Hello Iggy, thank you for contacting NOCO Support! The NLP9 is only intended to be used with small power sport applications, like ATV's, snowmobiles, motorcycles, and lawnmowers. We would not recommend and cannot guarantee that it can be used with an outboard motor.
The NLP9 will also need to be recharged to 14.6V when not in use.
 
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Iggy said:
I had a chat with the manufacturer

Here is what they said,

Hello Iggy, thank you for contacting NOCO Support! The NLP9 is only intended to be used with small power sport applications, like ATV's, snowmobiles, motorcycles, and lawnmowers. We would not recommend and cannot guarantee that it can be used with an outboard motor.
The NLP9 will also need to be recharged to 14.6V when not in use.
Click to expand...
I called Anti-Gravity before purchasing my LFP battery. They were a bit sheepish too, mainly because Tohatsu didn't provide specs on AH requirements. These small LFP batteries provide very high cranking amps for short durations so low AH ratings.

Works fine for me.

Peter
 
Huh. Did you tell them it’s a small outboard with less power and displacement than most motorcycles atvs snowmobiles and jet skis? Still think it would work.
 
NWboater2 said:
Huh. Did you tell them it’s a small outboard with less power and displacement than most motorcycles atvs snowmobiles and jet skis? Still think it would work.
Click to expand...

Had that conversation with Anti-Gravity. Without specs, they will go to the largest battery they are pretty sure will work. What they don't know is how much power is needed to (1) start the engine; and (2) tilt the engine. Honestly, I think Tohatsu grossly over-states the AH rating recommendation.

What I wanted was the smallest battery reasonably needed - ideally, something that could be Velcro'd under the OB engine cover. Given the vague information from Tohatsu, means someone has to do some deeper testing to see what makes sense - battery folks won't do it (nor should they be expected to).

At least that was my takeaway. So I went with a relatively large capacity LFP battery - good news is it's clearly smaller and lighter than it's AGM equivilent.

Peter
 
Doug

My boat may be capable of carrying slightly more weight on the transom than yours, but I don't concern myself over a few extra pounds in the dinghy. All in, I think mine weighs 750# and sinks the stern of the boat by 1 to 1.5" when lifted. I try to travel with a full tank of gas in the dinghy, but no extra jerry cans. My battery is a motorcycle sized AGM, so only weighs a few pounds, not a significant contributor to the overall weight. I don't think I could detect the weight difference if I was to switch to LFP.
 
For me, the biggest benefit for LFP for outboard is small size because I have a traditional 310 dink without console to hide battery. But there's also benefit to LFPs very low self-drain rate. Dinghys often sit for months without use - FLA (and AGM brethren) drain at a few percentage points per month. After 6 months, may need to be recharged before use. A friend keeps a trickle charger on his replete with orange extensive cord across deck.

Peter
 
mvweebles said:
Dinghys often sit for months without use - FLA (and AGM brethren) drain at a few percentage points per month. After 6 months, may need to be recharged before use.
Click to expand...

I haven't had to recharge AGMs; self-discharge seems to be pretty non-existent for the ones we've used. Longest for our AGM generator battery on the previous boat was probably about 5 months, no noticeable issues.

-Chris
 
ranger58sb said:
I haven't had to recharge AGMs; self-discharge seems to be pretty non-existent for the ones we've used. Longest for our AGM generator battery on the previous boat was probably about 5 months, no noticeable issues.

-Chris
Click to expand...

I don't recall where you are located, but the heat/humidity of Florida is really hard on batteries for some reason. Also, I keep a car (AGM battery) in the cellar of my cabin in Colorado that is closed-up over winter. If I don't keep a trickle-charger on the AGM, it will be D-E-A-D (as in cannot be revived) by spring.

For me, price premium of LFP wasn't that much for such a small battery. Easy choice.

Peter
 
mvweebles said:
I don't recall where you are located, but the heat/humidity of Florida is really hard on batteries for some reason. Also, I keep a car (AGM battery) in the cellar of my cabin in Colorado that is closed-up over winter. If I don't keep a trickle-charger on the AGM, it will be D-E-A-D (as in cannot be revived) by spring.

For me, price premium of LFP wasn't that much for such a small battery. Easy choice.
Click to expand...


We lived in Florida for a while, but didn't have AGMs then... and our more recent experience is on the Chesapeake... where heat and humidity sometimes seems worse than in Florida (July and August)... but also where our AGM very-little-self-discharge experience has been about over winters.

Don't know how much our experience might be impacted by AGM brands...

The price for your LFP outboard battery didn't seem all that high to me. Looks like a decent choice.

-Chris
 
Thanks for all of the great advice everyone.


@Carl (Cigatoo). Yes, we had a pull start Suzuki 20hp before, ran it for almost ten years and loved it. It is a great motor that was running perfectly when we traded it in last week. I actually had another 'zuke 20hp, but this time electric start, on order but decided to switch to the Merc. My same dealer, who is a very trustworthy honest guy (I've bought 4 motors and a flats boat from him) sells both Merc and Suzuki. He told me that from a reliability standpoint the merc and the 'zuke are identical, both excellent. I like the features on the Merc a little better (center mounted tiller, shifter on the tiller, placement of the flush port, spin on oil filter) and it was $300 cheaper than the 'zuke, so I went with it.
 
I reached out to Noco a couple of days ago about their Lifpo4 battery for a small OB and below is my chat transcript with them. Pushed them pretty hard on if it would work, I think I eventually got a yes, albeit wrapped in corporate cya.


[FONT=&quot]
default-avatar-80.png
[/FONT]
[FONT=&quot]Doug Cole[/FONT][FONT=&quot] [/FONT]
[FONT=&quot]Apr 3, 2023, 14:49 MST [/FONT]
Chat started: 2023-04-03 09:12 PM UTC
(09:12:20 PM) Doug Cole: Hi, I am considering a NLP9 as a starting battery for the 20hp outboard in our tender. But I have a couple of questions.
1. How waterproof is it? This is an open boat, so it will get wet. What happens if the boat fills partway with rainwater and the battery is submerged?
2. Do you make a waterproof box that will work with the NLP9?
3. Will the 12/145 alternator on my outboard charge it safely?
Thanks.
(09:14:11 PM) *** Sierra joined the chat ***
(09:14:42 PM) Sierra: Hello Doug, thank you for contacting NOCO support! Unfortuantely the NLP9 is not a starter battery so it will not work for this application.
(09:15:25 PM) Doug Cole: do you have a battery that will work? I need 300 cca
(09:17:44 PM) Doug Cole: Are you sure they aren't a start battery? Your website says the following:
(09:17:48 PM) Doug Cole: They are designed to withstand 50,000 start cycles and 2,000 charge cycles, making them the highest performing and longest-lasting batteries for any motorcycle, ATV, UTV, PWC, scooter, or snowmobile.
(09:18:22 PM) Sierra: The NOCO NLP Batteries do not have CCA ratings. Cranking amp ratings were created for lead-acid batteries. Since Lithium batteries have different characteristics, this test does not apply to them. To determine which NLP model may be a suitable replacement for your battery, check if the model of your current battery is on the list of lead-acid battery models each NLP can replace, found on each NLP model's product page.
(09:19:15 PM) Doug Cole: Thanks, but that doesn't help me. I am starting from scratch with a new motor. There is no existing battery.
(09:19:53 PM) Doug Cole: is it a deep cycle battery? Why would a motorcycle or PWC need a deep cycle battery?
(09:20:41 PM) Sierra: No it is not a deep cycle battery. This is a battery for very small applications.
(09:21:05 PM) Doug Cole: Like starting a small outboard motor?
(09:22:23 PM) Sierra: No it would be more for ATVs, snowmobiles, lawn mowers, and motorcycles.
(09:23:14 PM) Doug Cole: But all of those have motors about 20hp. What is the difference?
(09:25:24 PM) Sierra: We cannot guarentee that it will work for this set-up as it hasn't been tested but if you would like, you can purchase the battery and test it, then return it within the 30-day return period if it does not work.
(09:25:48 PM) Doug Cole: OK thanks. That is very fair and I appreciate the offer.
(09:26:22 PM) Doug Cole: Can you speak a little bit as to it's water resistance? will it hurt it to get rained on?
(09:27:19 PM) Sierra: It can get rained on but you don't want to submerge it under warranty.
(09:28:38 PM) Doug Cole: OK, got it. Thanks for your help!
(09:28:52 PM) Doug Cole: do you make any sort of battery box for it?
(09:30:23 PM) Sierra: We may have a battery box that it can fit in.
(09:36:43 PM) Sierra: Unfortuantely we do not have a battery box for this battery.
(09:41:48 PM) Sierra: I haven't seen any activity for several minutes now, are there any other items I can assist you with today?
(09:49:54 PM) Sierra: I haven't heard from you for a while now, I do apologize, but I will need to close our chat to assist other customers in the queue. Please chat back with us once you are available, your chat history will be saved and viewable by any Support Agent. Thank you for contacting NOCO Support. Have a great day!
(09:49:56 PM) *** Sierra left the chat ***
 
EarthX

Hi Doug,

We have been using an EarthX battery on a 20hp Tohatsu for about 2 years. Weight and size was our priority. Our tender can sit unused for some months and we have been pleased with its performance. The battery has been maintenance free. A link to our model is below.

https://earthxbatteries.com/product/etx680c/

Good Luck
 
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NWboater2 said:
Huh. Did you tell them it’s a small outboard with less power and displacement than most motorcycles atvs snowmobiles and jet skis? Still think it would work.
Click to expand...


If your asking me? Yes I did. I mentioned a 20hp motor.
 
Believe the issue with electric start outboards 20 hp and under is that alternator output voltage is not well regulated such that lithium batteries may be over charged. For this reason have opted for a lawn and garden wet acid battery even though heavier for my 20hp Suzuki efi.
 
Jc180 said:
Believe the issue with electric start outboards 20 hp and under is that alternator output voltage is not well regulated such that lithium batteries may be over charged. For this reason have opted for a lawn and garden wet acid battery even though heavier for my 20hp Suzuki efi.
Click to expand...


This is one of my biggest concerns as well. But the Noco battery is marketed as a start battery for motorcycles, jet skis, lawn tractors etc. None of those have a more sophisticated charging system than an outboard do they?
 
Dougcole said:
This is one of my biggest concerns as well. But the Noco battery is marketed as a start battery for motorcycles, jet skis, lawn tractors etc. None of those have a more sophisticated charging system than an outboard do they?
Click to expand...

I am thinking, that it would be under charged.
 
Dougcole said:
This is one of my biggest concerns as well. But the Noco battery is marketed as a start battery for motorcycles, jet skis, lawn tractors etc. None of those have a more sophisticated charging system than an outboard do they?
Click to expand...

I actually have a LI-ion Noco starting battery for my Honda ATV, but it has a separate regulator and Noco is marketed for this application. However, my Suzuki Shop Manual (page 0A-6) recommends a lead acid starting battery going on to say “ The use of Maintenance -Free, sealed, or gel-cell batteries is not recommended because they may not be compatible with Suzuki’s charging system.” No mention of Li-ion, but I assume they be an issue as well. Interestingly, this same caution is not published in the Suzuki Owner’s Manual.
 
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