I've had trouble running down my cranking battery from prolonged use of gadgets and livewell etc.

I bought a inexpensive Schumacher jumpstarter which said 600 amps but when I tried it it just barely cranked the outboard. I tried to jump a friends Harley and it wouldn't even turn it over.

What size should I have bought for a 150 merc?

good fishing folks

4-6 gauge wire booster cables.

I would suggest in getting a better battery.

Make sure the cranking battery is in good health. If not, get a new one. I’ve gotten in the habit of trickle charging the cranking battery just like I do with the TM and graph batteries.

If you got a merc just buy the biggest you can get and bring jumper cables aswell

We jump larger trucks with a noco gb50. It's small, light weight 1500 amps. They are around $150.

I have a NOCO 40 and it is good.. Buy the NOCO 70 and you can start a BIG truckso your boat will be good.

jumper cables won't help if there's no other boats around and I hate asking for help. I have a good cranking battery but I'm going to have my alternator checked.

I thought I may need a more powerful jumpstarter.

Thanks for the help fellas.

I think they were talking about jumping your cranking battery from your trolling motor battery. Usually there is enough “juice” in your trolling motor battery to get your motor to crank. I added 2 “On/Off” switches and ran a cable from the “Positive” of my trolling battery to the switch then ran a cable from the switch to the “Positive” of the cranking battery. I did the same thing for the “Negative”. If I ever have to jump the motor, I just reach in the battery compartment and turn on the “Negative” switch then the “Positive” switch, that acts as a built in jumper cables. Once I crank the motor, I cut off the Positive THEN cut off the Negative. Some will connect the Negative cables directly to each battery without a switch, BUT I DO NOT RECOMMEND that. In theory, it’s supposed to be ok but I have seen electrical issues and electrolysis when the Negative is wired directly. You also NEED to jump from the trolling motor battery that has the negative that connects directly to the trolling motor.

NOCO GB40

If you watch them on Amazon you can get them for $69.95.

Your battery may be good, but is probably to small. If your running big graphs, poles, and live wells, anything under a 29 series is asking for trouble.

HUH??

If you have a trolling motor, you have a secondary electrical system to "jump" your motor off

I have owned several, and like the GB50 best. Unless you have some large diesels to crank, the GB50 is more than adequate. The GB70 is a bit bulky and heavy. Using my GB50, I've started a 5.3L gas engine several times with no recharge, and even a 6.2L gas engine. It will crank a Merc 250 without issue. I've never seen anything Junkmacher.... I mean Schumacher made that wasn't carp!

If your starting battery is a starting and not a combination battery, expect it to last half its normal life if you have so much drain that you are constantly pulling it down that much. They just are not designed to be drained like that.

I would run a 27 or 31 group dual purpose battery. It will start your motor fine and will last longer.