revtothelimit - motorbike forum

Is Go-slow still around?
I bought a 50amp charger with "battery repair technology" for my two 110ah leisure batteries (220ah total) because my solar panels struggle for a couple of months in winter.
If batteries are low it starts charging around 30-35amps at 13.8v, as the hours pass the amps slowly drop and the volts rise, all seems fine apart from when its dropped to about 10amps charge the volts are about 15.5v.
From what I understand 15.5v should be boiling the batteries, yet they stay stone cold!
I've used the charger for a couple of months and the batteries are performing perfectly.
So what's occuring here? Should I be concerned?
Cheers. ☺

10 A isn’t a big charge rate into 220 AH worth of batteries, so it’s not too surprising that it’s not warming them up.

They probably are gassing a little bit when they’re fully charged and the 10 A is still going through them, but that’s not literally boiling.

5.5 is what the charger is putting out...the batteries will be 14.2.

David wrote: Fri Feb 19, 2021 5:04 pm 5.5 is what the charger is putting out...the batteries will be 14.2.

Eh?

15.5 is very much on the high side, unless it's about -10degC when they're being charged.
That said, even if the batteries weren't accepting charge at all it'd be like having the heat off a 75W bulb radiating from a fairly big, black (presumably) surface area, so wouldn't expect it to get all that hot, but them staying cold is a good sign.
Voltmeters on chargers aren't always the best and you'll lose a bit over the charging leads anyway....possibly the point 'David' was trying to put across, although I doubt they'd drop more than a volt, especially if they're specced for 50A charging.

Personally I wouldn't charge up 220Ah worth of leisure batteries at more than 20A.

There's a good chance you have AGM batteries in a camper, does your charger have an AGM setting? It will be written on the battery if it's AGM or gel, if so a standard charger may damage them.
I'm assuming your batteries are in parallel and not series, if they are in series you'll need to charge them 1 at a time.

Thank for the replies so far, my batteries, lead acid sealed, parallel connected, were brand new 6 months ago because the solar panel controller failed and pumped 18-20v into the old batteries for a day, which cooked them, they were very warm!
The charger only displays amps, the volts readings are from my multimeter directly on the battery terminals whilst charging. (Tried another meter to confirm mine was accurate).
I'm still confused, 15.5v going in yet batteries stay stone cold?!
I can only guess that it's something to do with the chargers claimed "battery repair technology" doing it's thing....

Intelligent chargers normally push high power in for a while and then tail off towards the end, they can also go very slow for maintenance with a variety of V and A. Did you get instructions with the charger as they usually tell you what charge it applies in different modes. 15.5V is fine for charging.