New T105s

[jckm2000]

 

Ok, got my new batteries in, wired up to the genny (24v DC) voltage is up to 30.5v with genny running, seemed a bit quick, taken off one or two of the caps and the electrolyte is bubbling/fizzing. Is that ok? Never noticed before with the old batteries.......

[bottle]

No wonder they are bubbling that voltage is very high unless you are doing an equalisation charge and new batteries should not need it.

The charger needs looking at, setting correctly I would think.

[jckm2000]

I think there may be something wrong with the genny actually, it has two knobs on the control panel, one for amp output and one for volts. When I fitted it I could set the voltage to 28.4 etc, now it doesn't change anything.

What's also confusing is that the old batteries electrolyte never seemed to need topping up and I've been charging upto 30.2 for 18 months or more......

 

Apologies for the cross-posting

[dmr]

Trojans do like a bit of bubbling, it stirs the acid up.

30.5v is maybe just a little high but not excessive. Have a look at the "ideal" charging curve in the Trojan user guide, they suggest finishing every charge with a little tickle at between 29.4 and 32.4volts. Almost no chargers are this clever.

If you are an off grid liveaboard running your engine for a couple of hours each day then your 30.5 volts is probably fine, especially in the winter, however if you charge at this voltage for many hours then you will loose some water and might slightly shorten the life of your batteries.

 

29.6 is the recommended voltage in most situations.

 

 

.........Dave .

[blodger]

Perhaps you could drop the voltage a bit with a heavy duty diode to avoid messing with the genny?

[jckm2000]

We have 540w of solar and run the genny for about 1-2 hours per day in winter. I'll have a look at the genny (German ex military diesel) tomorrow.

 

I'm just terrified of damaging my eight new T105s !!!

[bottle]

I think there may be something wrong with the genny actually,

 

 

Being pedantic it is still the charger (side) that needs looking at.

[dmr]

We have 540w of solar and run the genny for about 1-2 hours per day in winter. I'll have a look at the genny (German ex military diesel) tomorrow.

 

I'm just terrified of damaging my eight new T105s !!!

 

Eight! thats equivalent to 1000 amp hours at 12volts!!!.

 

You said bubbling/fizzing? What does it actually look like? Can you see just two or three bubbles rising in a cell at any given moment or is it more like a jacuzi ??

 

..................Dave

[jckm2000]

Somewhere between the two, a just opened bottle of coke....

[smileypete]

What sort of charge current are you seeing when they're gassing?

 

cheers, Pete.

~smpt~

[jckm2000]

18Amps (@24v) at the time. My genny does 45-50amps when batts are low......

[dmr]

This does not sound quite right to me, what do you think Pete???/

 

I equalise at 15.5volts (=31v in your case) and usually see about 12 amps (I think) which is 6 amps per battery against your 9 amps.

All I see is a gentle stream of bubbles, just a handful, rising to the surface.

in the winter I sometimes charge at 15volts (=30 in your case) so will cettainly match your charge current and again don't see any great amount of bubbling.

Do you see the bubbling in both of your "batteries".???..that is regarding your system as two "batteries" each made up of four trojans in series

 

...........Dave

[smileypete]

Well 18A into 900Ah is a charge rate of C/50, at which point the batts could be considered fully charged, according to The Battery FAQ:

 

http://jgdarden.com/batteryfaq/carfaq9.htm#charged

http://www.batteryfaq.org/

 

As Dave says bit of bubbling towards end of charge is good as it stirs up the electrolyte which helps stop it stratifying (acid at bottom is much more concentrated than at top).

 

Maybe it's partly because they're new? 900Ah is a pretty biiiig bank, if the OP is charging from 45A genny a charge from 50% is going to take about.... 12 hours!

 

cheers, Pete.

~smpt~

[jckm2000]

Thanks for the replies. The genny does 45-50 amps @ 24v (90-100 amps @ 12 therefore).

 

 

I'll have another look today.

[smileypete]

Yeah I got that totally wrong serve me right for posting late =), so it's 18A into 450Ah of batts which is C/25 so some way off full charge.

 

Maybe keep a close eye on the water levels at least initially. If you have a hydrometer how about give the batts a FULL charge then make a note of the SGs, I take it the batts have some sort of marker in the topping up hole and when fully charged the acid level is at that level, as it should be for a new set of batts (it will drop as the batts discharge which is why they should only be topped up after a FULL charge).

 

A DC clamp ammeter is very handy for diagnostics, it'll show how much current is going into each string, also might be interesting read the voltage across each batt in the string not just the whole bank.

 

cheers, Pete.

~smpt~