Charger won't start charging.....

[TownesZ21]

Hey guys. what do you do when your batteries are completely discharged and a smart charger won't charge? Presumably because it can't tell there is a battery connected?

Old days a standard charger would get you started and give them enough juice for the smart charger to read. Unfortunately, don't have one anymore and can't find one.

[iabass8]

jump them off your vehicle. I've never done it but if you don't have access to a jumper box, a vehicle is the only thing I can think of. Do yourself a favor and get a noco GB40 off amazon . It has an override mode to jump a dead battery to get it some juice.

[TownesZ21]

Not sure I'm in on the vehicle idea, but if I picked up a jump start pack how would I go about it? Would the charger need to be plugged in? Could that damage anything or would simply activating the jump start function give it enough juice for it to work after I disconnected it again later?

Haven't used a jumpstart pack before.

[jbh3]

A portable 12 volt charger would also work. Let it charge each battery for an hour or so. Then plug your on board charger in. A jump starter is a good thing to have on board for sure. I have a Weego 66, also off Amazon.

[iabass8]

Not sure I'm in on the vehicle idea, but if I picked up a jump start pack how would I go about it? Would the charger need to be plugged in? Could that damage anything or would simply activating the jump start function give it enough juice for it to work after I disconnected it again later?

Haven't used a jumpstart pack before.

I not totally on the vehicle option either but you said you don't have another charger. A weego or Noco GB is a small, portable jumper. Comes with cables that plug right into it. Hit the power button and it jumps the batteries. You don't leave it on the batteries. The Noco GB40 has a mode that will jump a dead battery and give it enough juice to work. When you jump it, just take the cables off the battery and plug the batteries back into your charger. There's dozens of videos on youtube about them.

[TownesZ21]

Need some clarity, picked up a Noco tonight and tried the override mode for a while. Obviously this use is different than starting a car, but so far it hasn't worked. Left it on that mode for about 10 min and then tried to charge normally, no difference and still didn't work. I did put a tester on it when it was on, pushing a little over 10v with the Noco vs almost nothing without.

Do I put the Noco on for an extended period per battery and hope it gives them enough juice that my dual pro will recognize them, or do I try to turn on my dual pro and the Noco at the same time..... Thinking that might work, but also thinking two sources of power flowing in at once could be dangerous for the battery or in general...

Thoughts?

[blkfalc4]

"Almost nothing"......Sounds like new batteries may be in your near future.

[billnorman1]

When you jump the battery under charge, the charger "sees" the jumper source and thinks it's O.K. to turn on. Then remove the jumper.

[Jonestrollingmotor]

You're going to have to disconnect wires, jump to a good battery and let the charger charge both in parallel. Once the charger gets the battery charged enough to see it, remove the slave battery.

[375VTROCKET]

Hook some jumper cables to your vehicle and boat battery after disconnecting the wires of the dead battery let the vehicle either run or not and the dead battery will leech power from your vehicle battery. I would leave the vehicle running and do it but that is just me.

[Jonestrollingmotor]

Hook some jumper cables to your vehicle and boat battery after disconnecting the wires of the dead battery let the vehicle either run or not and the dead battery will leech power from your vehicle battery. I would leave the vehicle running and do it but that is just me.

The problem with jumping from the auto is the vehicles alternator will "think" that it's charging a dead battery and start trying to charge "wide open" meaning if it's a 160A alternator it will try to send all 160A (or max it can do) to the battery. This creates an abundance amount of heat and could damage the vehicle alternator. The alternator is meant/designed to maintain the battery under normal operating loads, not to charge batteries.
John

[blkfalc4]

Agreed John, IMO, if getting "almost nothing" the batteries are beyond help at this point to be considered for any reliability out on the water. While you may be able to salvage them short term, the life cycle has been trashed. They'll give up the ghost again at the worst possible time.
Replace them and don't let them get that low in the future.
Again, if it was me.