Help - Reviving Batteries

[Presto]

Hi All,

I have two batteries in my boat that are pretty much dead. They have done very little in their life, but have stood for around 10 months with no activity. They are both an NS70 type battery and currently read around 3 volts (with no load).

When I stick the charger on them, it does nothing, as it's one of those that only pumps out a charge when it recognises the battery (yes, it's a cheap charger!!).

Does any one have any tips on how I could try to revive them? I understand they could well be screwed having sat flat for some time, but I want to at least try to breathe some life into them before I give up.

Do you think attaching them to the car (with jump leads) and leave it running may get enough life into them for the charger to do something?
Scrap the charger and get a decent one?
Forget the problem and drink beer?

Any help appreciated!

[rrturboD]

I'd try a more sophisticated charger, see if you can borrow one. Or at least connect your charger and leave it overnight.

I sell Optima batteries to lots of boat owners. The Red Top batteries have a shelf life of over 12 months, so hold their charge for that time. I can verify this with my own use in a classic car that get used very irregularly. Let me know if you want an optima!

[bee utey]

Connect the jumper leads to the flat battery, after a few minutes put it back on the charger. If the battery has any life in it getting it up to 12V will allow the charger to start.

[stikman]

If you have no luck and can drop them to me (work in Milton - Brisbane, home Redbank Plains - Ipswich) I will put them on my charger which has given me some little success with flat/old batteries. No promises but more then happy to give it a go for you.

[Presto]

If you have no luck and can drop them to me (work in Milton - Brisbane, home Redbank Plains - Ipswich) I will put them on my charger which has given me some little success with flat/old batteries. No promises but more then happy to give it a go for you.

Thanks for the offer!
What charger do you have? I'd consider buying a decent charger too!

[Presto]

I'd try a more sophisticated charger, see if you can borrow one. Or at least connect your charger and leave it overnight.

I sell Optima batteries to lots of boat owners. The Red Top batteries have a shelf life of over 12 months, so hold their charge for that time. I can verify this with my own use in a classic car that get used very irregularly. Let me know if you want an optima!

I've just got an Optima for my D3 and already see the value! ...the boat unfortunately is getting ready for sale, so an Optima is not an option.

[Presto]

Connect the jumper leads to the flat battery, after a few minutes put it back on the charger. If the battery has any life in it getting it up to 12V will allow the charger to start.

I will try this tomorrow, to see what results it brings!

[drivesafe]

Hi Presto, I would not connect a battery that is that low.

If the battery was around 8+v then you could do that but at 3 volts, the battery could quite literally explode.

Two suggestion.

If you have a large solar panel, say 60w or bigger, connect the panel directly to the battery ( with no regulator ). and give it a few days of sun light to try to get a charge into it.

If it charges, let it charge to 16v and just keep an eye on the battery’s temperature. It can start to warm up, this fine, just don’t let it get hot to touch.

What this does is if the battery can be charged, the 16v will boil the battery and and possibly reverse some of the sulfation.

Another safer and simpler set up is to get a large wattage globe like a 100w driving light globe and connect one side of the globe, via some wire, to the positive terminal of your cranking battery, and the other side of the globe to positive terminal of your stuffed battery.

The neg of your stuffed battery should be earth as normal.

Only connect the two batteries when you are going to do some driving. As you connect, the globe will light up but will act as a current limiter and as you drive, it will pass a small current load through the stuffed battery and if you drive long enough, the globe will slowly get duller if the stuffed battery takes any charge.

This will take a few hours of driving but if you connect up every time you have to do some driving, you will bring the battery voltage up.

Once the voltage is around 8+ volts, you can then connect the stuffed battery without the globe and you will then charge as normal.

If your Optima is fully charged, you could use the globe set up, running off the Optima without having to drive. You can safely discharge your Optima but don’t use your cranking battery unless the motor is running.

[Presto]

Update - I connected up the battery to the Optima for a couple of hours without the engine running, that brought up the voltage to around 9v. I then connected it up to the charger and left it on trickle for 24 hours. It's been off the charger for around 5 hours now and still reads 13v without any load. I'll put some load on it to test over the next couple of days

Starting on the second battery now