12.5 Volts Fully Charged?

[Meck]

Hello all,

I don't have a very strong understanding of the electrical system on our new catamaran, but I've got a Tecsup "Switch Mode" battery charger and when I'm hooked to shore power the charger will charge the house bank but it says that the the charge is at 100% when the bank is reading only 12.5 volts. So by the time the voltage makes it to the fridge and freezer the units start dropping cycles because of low voltage.

Is there anyway to adjust or is it even safe to charge the house bank above 12.5 V? I just need to find a way to get more voltage inside the boat...

If anyone has an idea for me it would be much appreciated!

Cheers,

Meck

[GordMay]

You're right that 12.4V does not represent a charged battery, and that you should expect to see no less than 13.8V during charge.

You don’t say which model of Tescup charger you have; but here’s a manual for their “HI-TEC 200W - 300W SWITCH-MODE BATTERY CHARGER”

You can select the charging curve characteristics by
(according to battery type) choosing profil A-B-C or D (see tables page 15), position correctly the 2 switches on the front as written on the cover.

Manual Goto ➥ http://www2.kegel.de/tecsup/pdf/char...00-300-use.pdf

Or Manufacturer ➥ TECSUP - battery chargers: high quality chargers made in france in high and low frequency

[MarkJ]

Originally Posted by Meck

So by the time the voltage makes it to the fridge and freezer the units start dropping cycles because of low voltage.

,

Meck

Hi Meck,

I solved this problem by changing the connections into the fridge compressor and increased the size of some of the wires from where they conected to the main DC power wires.

12.5 was all I could get for 100% full on my old batteries too. But they lasted for 12 months more so I was happy I have recently changed them over inicreasing from 110 ampo hours to 300 and fully charged is higher now at 12.6+

12.5 would still be 85%

Mark

[limmer]

when we are plugged into shore power we never see less than 13.5 on the house bank. which is telling me that the bank is charged and is in float mode or trickle charge. From what I understand A fully charged battery is 12.5?. But you are right when plugged into shore you should see more voltage.

[onestepcsy37]

a fully charged 12 volt battery should read 12.73 volts, according to the trojan battery users guide. a reading of 12.5 volts indicates 80% of full charge.

while your charger is running you will get a higher voltage reading - that's how a battery is charged - sometimes as high as 14.6 volts, depending on the charger regulator, although 13.8 is probably more common.

for a good guide to deep cycle batteries go to www.trojanbattery.com and download their users guide ( i think its in the 'technical' section). it's an excellent guide and i refer to it often when checking my battery state of charge....

[CharlieJ]

Remember; voltage as an indicator of state of charge is temperature dependent. < 20C; higher voltage indicates fully charged. > 20C; lower voltage indicates fully charged. Oh, and do not forget that the voltage reading must be taken after the battery has been quiescent for 12 to 24 hours for the voltage to SOC table to provide accurate results.

[Jentine]

I would be more concerned with the state of the specific gravity of each cell. If you can't raise the voltage above 12.5v, you probably need to equalize the batteries. Your specific gravity of a fully charged battery should be above 1.260. Anywhere between there and 1.300 is ideal.

[Meck]

Fantastic! I flipped the toggles on the tescup charger to the correct configuration for the lead calcium battery bank and am now seeing charging states into the high 13's. and the refrig units are much happier! Cheers, Meck