JumbleDuck
Well-known member
Hello, folks.
My house bank died today. It's 2 x 60Ah (all that will fit) Varta lead acid, ten years old. Yes, I know, should have replaced them ages ago and will do so asap but ... I'm at Ulva Ferry, a long way from suppliers. If possible I'd like to continue until I am in easy reach of one of Tayna's couriers, and with care one battery will be fine.
There is a noticeable difference between the two batteries. With the engine running and the batteries linked the forward one is taking 11A and the aft one 3A. On a small mains charger, 3.3A fore and 0.5A aft. With the batteries unlinked, either separately takes 3.8A from the charger.
So ... is the battery taking the much higher charging current when they are linked the dud (perhaps because it is less charged) or is the battery taking the much lower charging current when they are linked the dud (perhaps because it has a higher internal resistance)?
If further tests are needed I have ... a standard multimeter, a clamp on DC ammeter, a 3.8A battery charger (Lidl!) and an electric outboard which draws ~30A from a well charged battery. Getting the batteries to the outboard with prop immersed would be fiddly but perfectly possible.
For now I have the aft battery on charge, but only because I am more suspicious about the amp hungriness of the other.
Advice and informed opinions would be very welcome.
My house bank died today. It's 2 x 60Ah (all that will fit) Varta lead acid, ten years old. Yes, I know, should have replaced them ages ago and will do so asap but ... I'm at Ulva Ferry, a long way from suppliers. If possible I'd like to continue until I am in easy reach of one of Tayna's couriers, and with care one battery will be fine.
There is a noticeable difference between the two batteries. With the engine running and the batteries linked the forward one is taking 11A and the aft one 3A. On a small mains charger, 3.3A fore and 0.5A aft. With the batteries unlinked, either separately takes 3.8A from the charger.
So ... is the battery taking the much higher charging current when they are linked the dud (perhaps because it is less charged) or is the battery taking the much lower charging current when they are linked the dud (perhaps because it has a higher internal resistance)?
If further tests are needed I have ... a standard multimeter, a clamp on DC ammeter, a 3.8A battery charger (Lidl!) and an electric outboard which draws ~30A from a well charged battery. Getting the batteries to the outboard with prop immersed would be fiddly but perfectly possible.
For now I have the aft battery on charge, but only because I am more suspicious about the amp hungriness of the other.
Advice and informed opinions would be very welcome.