Amulet
Active member
Chastised on the forum for my folly, and suitably contrite.
Story was: Batteries dead and charger fuse blown. Problem was that the fridge had been left on and no charge for a week. Reading was 7.5 volts on the battery that had been carrying the fridge load and 10ish on the other.
I then put it in on charge followed by blowing fuses on the DC from the charger to the batteries. Increased the fuse size from the recommended 10 amp all the way to 25, and it seemed to be charging. 15ish amps on the lowest battery and 7ish on the other. Not a happy picture, but the charger is thermally protected to the nth. Went home and left it for a few days .. work called - annoyingly.
Having publicised my reckless strategy, I did get forum responses which pointed out that:
1. Maybe the supplier who said use a 10 amp fuse did so for a good reason, like not frying the charger or setting your boat on fire.
2. A battery that reads 7.5 volts is not a flat battery, it is an ex-battery - dead, kaputt, no-more.
On the basis of this I reread the voltage curves for lead acid batteries, and also the manual for the charger. Oh My Gawd I thought - they are right. My boat will burn, or at least my charger will fry, and at best one of the batteries is dead.
Went back to the boat today - took the hoover to clean up the soot from the anticipated fire and all my electrical tools.
When I opened up the boat the monitors were both reading 100% charged and sitting on charge at about 13.4 volts. What the f***. Switched everything off. Let it all settle, then put the monitors back on with a load (cabin lights) to let the monitors recalibrate. Set the whole lot up again. It all looks perfectly normal. I have set it up with "legal" fuse levels, and all looks well. (See picture.)
**1** Can you suck 23 ish amps out of Sterling 10 amp charger? It appears so, in my reckless hands. I'd advise anyone to take the manual and the forumites who spluttered with disbelief at my folly as their guide, not my behaviour. Perhaps, in my absence, the thermal protection on the charger has been cutting in and out and saving my life! I can't know.
**2** How can a battery which read 7.5 volts, and was apparently as dead as Monty Python parrot, have a second life? (a) I misread the monitor? (b) the monitor was wrong? (c) I thought it was on open circuit - but I was confused in my investigation and actually there was a load on it.
Whatever, it appears that God protects idiots, and systems seem to be functioning as normal.
Story was: Batteries dead and charger fuse blown. Problem was that the fridge had been left on and no charge for a week. Reading was 7.5 volts on the battery that had been carrying the fridge load and 10ish on the other.
I then put it in on charge followed by blowing fuses on the DC from the charger to the batteries. Increased the fuse size from the recommended 10 amp all the way to 25, and it seemed to be charging. 15ish amps on the lowest battery and 7ish on the other. Not a happy picture, but the charger is thermally protected to the nth. Went home and left it for a few days .. work called - annoyingly.
Having publicised my reckless strategy, I did get forum responses which pointed out that:
1. Maybe the supplier who said use a 10 amp fuse did so for a good reason, like not frying the charger or setting your boat on fire.
2. A battery that reads 7.5 volts is not a flat battery, it is an ex-battery - dead, kaputt, no-more.
On the basis of this I reread the voltage curves for lead acid batteries, and also the manual for the charger. Oh My Gawd I thought - they are right. My boat will burn, or at least my charger will fry, and at best one of the batteries is dead.
Went back to the boat today - took the hoover to clean up the soot from the anticipated fire and all my electrical tools.
When I opened up the boat the monitors were both reading 100% charged and sitting on charge at about 13.4 volts. What the f***. Switched everything off. Let it all settle, then put the monitors back on with a load (cabin lights) to let the monitors recalibrate. Set the whole lot up again. It all looks perfectly normal. I have set it up with "legal" fuse levels, and all looks well. (See picture.)
**1** Can you suck 23 ish amps out of Sterling 10 amp charger? It appears so, in my reckless hands. I'd advise anyone to take the manual and the forumites who spluttered with disbelief at my folly as their guide, not my behaviour. Perhaps, in my absence, the thermal protection on the charger has been cutting in and out and saving my life! I can't know.
**2** How can a battery which read 7.5 volts, and was apparently as dead as Monty Python parrot, have a second life? (a) I misread the monitor? (b) the monitor was wrong? (c) I thought it was on open circuit - but I was confused in my investigation and actually there was a load on it.
Whatever, it appears that God protects idiots, and systems seem to be functioning as normal.
