Lithium ion jump starter or spare battery?

[Poly2096]

Hi all,

 

Im keen to hear everyone's views on what would be better? I currently run a single battery for our 4.5m boat. So trying to work out a backup plan whilst adding as little weight as possible. 

 

Cheers

[zmk1962]

Hey @Poly2096, I think you need to share a bit more than just the length of your boat mate. Like what type of boating do you typically do.  I presume your prime concern is starting the motor, so do you fish next to rocks or in areas that may be a bit dangerous - so need to be able to flick a switch to the reserve battery and start cranking... or do you have time to expose the terminals and attach a jump starter and crank.

Its all depends on what you typically do - and how quickly you need to be up and going?

Cheers Zoran

 

PS - there was a fair bit of discussion on dual battery set up considerations in this post - I fished/boated for many years in a 15ft runabout with single battery set up (the backup was the pull start on the 40HP outboard). It really depends on what you do and how quickly you need to recover:

 

Edited January 3, 2019 by zmk1962

[Poly2096]

thanks for the reply Zoran. We have a 4.5m polycraft, 50hp motor. We will be fishing mostly in pittwater so have time but that said we do fish close to the points and when the wind is whipping across the bay we could end up on rocks pretty quickly. Ultimately in pittwater we can just throw the anchor down and work on getting the motor started after that. thanks for the link to the other chat. i hadnt seen that one despite searching quite   a bit 

[JonD]

I've carried a small lithium jump starter for two years, it's been used to start other people's boats and 4x4's that have had their lights left on at the ramp all day. At no point has it ever struggled on any jumpstart but it was quite an expensive one at $200.

Over the years ive always had dual battery's in my vehicles and boats, now I only use singles. The local 4x4 centre ( Totally Equipped) adviced me on not fitting a dual system to my latest vehicle and use a mini jump starter if I ever needed. The same goes for my local outboard mechanic, he said forget the dual system on my boat, he also uses one of the mini starters himself on customers boats.

The local marine rescue see them as a god send when attending rescues which are just flat batteries, now they simply pass a little jump over to the boat in need.

 

[fragmeister]

I have a dual system in the boat and a lithium jump starter for emergencies (usually to help other people out!)

Actually, the boat has 4 batteries in total. This is why I chose them which may or may not be relevant to your circumstances but it may be worth something to someone.

Battery 1 is a 75 Ampere Hour cranking battery which I use as the primary starting battery. Cranking batteries do not like being discharged below 80 per cent charge regularly so they are not ideal for running lights, GPS equipment, bait tanks etc unless your motor is running to keep them topped up. 

Battery 2 is a 70 Ampere hour deep cycle battery which I switch to when  I am stationary for a long time or doing an overnighter. Deep cycle batteries can handle being deeply discharged without any detrimental impact on their serviceable life.

Battery 3 and 4 are 100 Ampere hour deep cycle batteries in series for my 24Volt Minkota. They are 5 years old and still going strong.

A typical Lithium Jump Starter has a capacity of around 20 Ampere Hours compared with a typical boat battery of say 60 to 90-ampere hours. The cold cranking amps on these units are about 50 per cent lower than a marine battery.

I have found that Lithium starters are great for starting a boat which has a flat battery but not so much one that is flooded or wet etc and needs a lot of cranking to get going. The small leads and contact surfaces on the connectors can rapidly overheat and increase the contact resistance and decrease the starting current.

Some are much better than others and like Jon's, mine was a few hundred dollars. They do work, but I would always trust a properly maintained dual battery system over a single battery and a Lithium Jumpstarter.

Cheers

 

Jim

 

 

 

 

 

[Davison]

I run a second battery and a jump starter. There's comfort in knowing you can leave electronics running at anchor without wondering how low the battery is getting. The mini jump starter lives in the cab as a last resort.

[JonD]

Not sure how many people use the settings on most plotter sounders to give a permenant reading of the battery voltage.

Remember the original question was for a small 4.5m boat which I assume would have a small easy pull start outboard. 

Any battery system whether single, double or even more needs to be installed in aluminium boats in a way not cause ellectricle corrosion https://bbsc.org.au/resources/Documents/Marine-Galvanic-Corrosion-Made-Easy-SYC.pdf.

 

[fragmeister]

All good points Jon...

It is certainly a more expensive option running dual batteries when correctly installed in particular as it's not just the second battery but the wiring, battery switch and, ideally some way of isolating the system for external charging.

As you mentioned, in smaller boats with pull start outboards a jump starter and a single battery is probably the best low cost option.

Cheers

 

Jim

 

 

[zmk1962]

33 minutes ago, fragmeister said:

As you mentioned, in smaller boats with pull start outboards a jump starter and a single battery is probably the best low cost option.

Agree.... especially if its not being used for "Open Waters" .  Ran that way for many many years with my Savage, single battery and 40HP Tohatsu.

Cheers Z

[Nolongeramember]

On 1/3/2019 at 8:59 PM, Poly2096 said:

thanks for the reply Zoran. We have a 4.5m polycraft, 50hp motor. We will be fishing mostly in pittwater so have time but that said we do fish close to the points and when the wind is whipping across the bay we could end up on rocks pretty quickly. Ultimately in pittwater we can just throw the anchor down and work on getting the motor started after that. thanks for the link to the other chat. i hadnt seen that one despite searching quite   a bit 

I would just get a jump starter as a back up. I have a 60HP and only run one 100ah battery. It powers all my electrics (bait tank, sounder, bilge etc)

What I think is important is to not neglect things just because you have a back up. Make sure everything is in good working order. 

Check and monitor voltages. You should be able to bring this up on your sounder. Make sure engine is charging the battery by confirming 14v when running. Keep battery in good order and replace when sluggish or old. Don’t wait until it lets you down. Check and charge if necessary, before every trip. If starter motor or something is not 100% get it fixed. Don’t wait until you are stranded to do something about it.

Use common sense. If the engine has not been run for a long time, don’t run your sounder and bait tank constantly for hours and hours. 

Almost all break downs can be avoided. 

 

[Poly2096]

Thanks a lot.