1Amp Trickle Charger Putting Out 15.34 Volts

[Northeaster]

Hi Folks,

Have 2 group 27 house batteries at my house for the winter (boat stored elsewhere). I did have them charging on my new Ioata 45a Intelligent charger.
Took the Iota to the boat last week, to charge the start battery and decided to hook up a small 1 amp (Canadian tire) trickle charger to my house batts, just to keep them topped up. I metered the charge after a night of charging, and it read 15.34 volts.
The trickle charger is designed for small flooded batteries (motorcycle, lawn tractor, etc). It's brochure states that it is a manual charger, and care must be taken not to overcharge. It also states it is 1 amp, with a finish charge rate of 0.3 amps.

Note: Learning more about electricity - not there yet!!
Should I be alarmed at the 15.34 volts?
Or, is it at shuch a low current rate (either 1 amp or 0.3 amps) that it woudl not "cook" 2 house batts with roughly 200 amp hours combined capacity?

Thanks in advance, for any clarifications!!!

[s/v Jedi]

If you measured that voltage on the battery, you were overcharging it. However, I think that you measured this on the charger while it was disconnected from the battery and that would be normal.
Measure while charging and voltage should be 13.2 V or close after the battery is fully charged. If it's more, you need to disconnect it.

Nick

[Northeaster]

Jedi - yes, this was measured on the batteries, while charging them.

Does it make a difference that it is only 0.42 amps at 15.34 volts? Is that enough to do harm?

I did remove it for a few hours. Reconnected again, just to see!!

Starts out at around 13.20 volts and 1 amp current.
Then, as batteries are fully charged, amps drop to 0.42a, but voltage climbs to 15.30.

[s/v Jedi]

Originally Posted by Northeaster

Starts out at around 13.20 volts and 1 amp current. Then, as batteries are fully charged, amps drop to 0.42a, but voltage climbs to 15.30.

No, that won't do, you must disconnect it. The voltage and current are determined by the state of charge of the battery. But the voltage determines if it is gassing or not and in your situation it is gassing.

The low amps just means the battery is fully charged. The charger lacks a float-charge state.

It's better to disconnect anyway, let it self-discharge a bit (couple of weeks) and re-connect again. You could use a timer to stop it after so many hours.
When we took the batteries home for the winter, we even discharged them a bit using a small lamp.

cheers,
Nick.

[Northeaster]

Jedi - Thanks for the input! I will leave it disconnected for now, and just use it, or the Iota, if it isn't permanently installed in the boat by then, to top them up in a couple of weeks.