Battery size

bigdee

bigdee

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When I went to take family out on my pontoon this week the battery had died and tested as bad. Since it was too far to drive to get a new battery I used my jump box instead and was surprised how well it turned over my 85 hp 2 stroke. We spent the afternoon cruising without issue. So now I am thinking of replacing that heavy marine battery ( I always remove it to keep it from being stolen) with a garden tractor battery. I have no accessories on board so I don't see why this wouldn't work. Any thoughts? Wally world has 225 CCA lawn tractor batteries for under $30....For that price I would not worry about leaving it on the boat, I don't think a thief would want it anyway.
 
HotTommy

HotTommy

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My limited understanding of "jump box" technology is that it provides a brief output of high amperage. That should allow a well tuned engine that starts promptly to crank and start. But it may not last for more than a few starting attempts before recharging. So my question would be how many amps did your jump box provide to start your engine? That should give you an idea of how many amps your new battery should be able to provide. I wouldn't be confident that 225 CCA is enough without testing it. Unless you plan to augment your 225 battery with the jump box every time.

BTW, I've long thought that weather forecasters should provide two numbers with their forecasts. The first is the probability that the event forecasted will happen, and the second is the probabilty that their forecast is correct. Following that approach I'd give the advice I gave above a 65% probability of being correct.
 
alldodge

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The jump box bats are AGM and in many cases there is two of them inside the box. The AGM can supply more amps then the lead acid. So I would say the tractor might be to little, would suggest looking at a PWC bat
 
Scott Danforth

Scott Danforth

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If you use a jump box more often than once every day, the batteries fail.

Too small a battery and you stress the battery every time you start it.

I wouldnt use less than a 400 cca battery in the boat
 
bigdee

bigdee

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I do not know what the starter current is but it cannot be much more than a similar hp motorcycle which uses a smaller battery than a 275 cca. My jump box is 5 years old and only has a 18 ah battery and it spun my 85 hp yammy with no effort.
 
bigdee

bigdee

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alldodge

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ok, guess get one of those and let us know how it goes by the end of this season.
 
bigdee

bigdee

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AllDodge said:
ok, guess get one of those and let us know how it goes by the end of this season.
Click to expand...

10-4 I already have. Lot easier for a +70 year old man to carry....lol. I always carry a small hand size lithium power jump booster on the boat in the emergency kit. It is only good for starting because the boats 14 volt charging voltage could blow the lithium batteries.
 
HotTommy

HotTommy

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As I stated earlier, I'm not 100% sure that my thinking on this topic is correct, but here's my concern. .... I picked a jump box with an 18ah battery at random on Amazon. That unit is capable of producing 950 amps for a very brief period of time. I calculate it could last about a minute at that level of output. .... 950 amps is plenty to start an engine. I'm not convinced that a 275 Cold Cranking Amps battery is capable of providing anything close to 950 amps to start your engine. ... I hope for your sake that I'm wrong and you get to carry a much lighter battery. But I won't be surprised if its not up to the task. ... I look forward to hearing how it goes.
 
bigdee

bigdee

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OK, I done some research on jump boxes and found some useful information:
1. Peak amps is a meaningless marketing term with no testing data to support it.
2. CA rating on jump boxes is for 5 seconds with a 1 minute rest
3. CA and CCA rating on automotive batteries is for 30 seconds not 5.

My jump box has a 300 CA (not cca) for 5 seconds. Tractor battery has a CA of 275 amps for 30 seconds. I am sure the yammy starter pulls much less than that.....more like 60-100. The day I substituted the jump box I first used it to inflate 2 trailer tires (one was completely flat) and raise and lower motor a couple of time. When I tried to start the outboard the jump box was showing a 75% charge. The boat had sat all winter so it took about 20-30 seconds to fire up and then several restarts after that. So my conclusion is if that little 18 ah battery can do all that a U1 tractor battery 3 times larger should be more than capable.
 
F

Fed

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When I was buying some other parts I picked up a pull cord for my V4 (90HP) it works great and only cost $5.
 
bigdee

bigdee

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Fed said:
When I was buying some other parts I picked up a pull cord for my V4 (90HP) it works great and only cost $5.
Click to expand...

Ha,ha I tried that on my 85 yamaha and it was a no-go for me. You refreshed my memory with the V4. Years back I bought an old boat with a 1971 Evinrude V4, I think it was 80 or 85hp. When I got it home I wanted to try to crank it but it had no battery in it so I hooked up to my riding mower and fired it off....so I guess I just answered my OP.
 
R

Redfred1

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When I saw this thread; it reminded me of a '64 Mustang; small 6 cylinder I had that would crank like a sewing machine and used a L/M battery.Was told it wouldn't last. Sold it with that battery.
My take: I'm not surprised that it works; mainly because it is. Like others; I will be watching for the outcome. I know every member has had horror stories with batteries (Which brand; deep cycle;etc). I too will be watching.
 
M

mgjtkt

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You might want to check the battery size recommended by the manufacturer. I had an 88SPL Evinrude and on those motors there was no voltage regulator, just a rectifier. If you use a small battery it will boil the water out from overcharging. I was told to use a large battery to keep battery maintainence to a minimum.
 
R

Redfred1

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I agree! Right now I have a regular (not D/C) 850 CCA for my 100 Evinrude. Don't think it would spin with a lower amp battery. I have never dealth with the D/C type; I know others will argue and disagree; but thats me. I stick to a battery made by Continental. They deal with Farm and Heavy equipment stuff Example: '01 Mandria tractor. Battery cratered '08. Just replaced again '01-18. hard to believe; but true.
 
HotTommy

HotTommy

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Here's an idea Bigdee - if the small battery doesn't work, get another one and wire them in parallel. It would give you the capacity of a large battery but they would be easier to carry.
 
bigdee

bigdee

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HotTommy said:
Here's an idea Bigdee - if the small battery doesn't work, get another one and wire them in parallel. It would give you the capacity of a large battery but they would be easier to carry.
Click to expand...

Good suggestion Tommy but I think the one battery should work because it worked fine on a V4 Evinrude. I haven't had a chance to get to the lake yet but will I update when I do. LM battery is hotter than my jump box....so we'll see.
 
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