Trojans behaving Badly

[dmr]

Been on holiday for a week, left boat with batteries (6 Trojans in 12 volt bank) just about 100% charged, isolators off, and possibly small input from small solar panels.

Whilst away recorded -12degC outside and -6 inside, possibly a bit lower than -6 at batteries.

 

Returned home, Smartgage read 100%.

Turned isolators on, within 15 mins Smartgage down to 98%.

Did big engine run early evening. After a while charge tail current down to 4 amps, this is very low, normally see about 12.

Next morning Smartgage read 65%, would have expected about 80% to 85%.

 

Another engine run and measured charge current in each of three battery pairs. Noted significant variation: 27, 24 and 20 amps approx. but this improved as charge progressed.

Did very short equalisation

Batteries appear to now be recovering.

Any good ideas as to what is going on?

My only thought is stratification.

 

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

 

[metanoia]

HISTORY REPEATING ITSELF???!

 

Don't tell me those sneaky sods are hiding in a wooden horse AGAIN?

[Loafer]

At very low temperatures your batteries could be at reduced capacity, as little as 60% that of warm batteries.

 

You were wise to leave them fully charged - they won't freeze at -6.

 

They should recover - how about another equalisation charge? Check the electrolyte after the previous charge, and before you commence equalisation.

 

ETA And try to keep 'em warm.

Edited January 25, 2016 by Loafer

[ditchcrawler]

Been on holiday for a week, left boat with batteries (6 Trojans in 12 volt bank) just about 100% charged, isolators off, and possibly small input from small solar panels.

Whilst away recorded -12degC outside and -6 inside, possibly a bit lower than -6 at batteries.

 

Returned home, Smartgage read 100%.

Turned isolators on, within 15 mins Smartgage down to 98%.

Did big engine run early evening. After a while charge tail current down to 4 amps, this is very low, normally see about 12.

Next morning Smartgage read 65%, would have expected about 80% to 85%.

 

Another engine run and measured charge current in each of three battery pairs. Noted significant variation: 27, 24 and 20 amps approx. but this improved as charge progressed.

Did very short equalisation

Batteries appear to now be recovering.

Any good ideas as to what is going on?

My only thought is stratification.

 

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

 

When we come back to the boat the batteries always go to a lower voltage in the first 24 hrs and then pick up as the week goes on, we also have a small solar panel keeping them charged while we are away.

[nicknorman]

I certainly notice that the first discharge after a long period in float gives poor performance however 1 week isn't that long to be unused. Also, I'd be more concerned about the current split. Are the batteries all the same age (can't remember)?

[dmr]

At very low temperatures your batteries could be at reduced capacity, as little as 60% that of warm batteries.

 

You were wise to leave them fully charged - they won't freeze at -6.

 

They should recover - how about another equalisation charge? Check the electrolyte after the previous charge, and before you commence equalisation.

 

ETA And try to keep 'em warm.

 

I was expecting a reduction in capacity but was surprised at just how much it was.

The fridge might perhaps have taken a bit extra overnight to get back down to its correct temperature, but not enough to get down to 65%.

The low tail current and charging imbalance both surprised me.

It was all rather unfortunate that after this mild winter we chose to go away just when the cold snap came on, and also left the boat in a well known K&A cold spot!

 

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

[Loafer]

 

I was expecting a reduction in capacity but was surprised at just how much it was.

The fridge might perhaps have taken a bit extra overnight to get back down to its correct temperature, but not enough to get down to 65%.

The low tail current and charging imbalance both surprised me.

It was all rather unfortunate that after this mild winter we chose to go away just when the cold snap came on, and also left the boat in a well known K&A cold spot!

 

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

 

I reckon they'll be fine Dave. Just return 'em to normal ops and give 'em one more thrashing Eq for misbehaving!

[dmr]

I certainly notice that the first discharge after a long period in float gives poor performance however 1 week isn't that long to be unused. Also, I'd be more concerned about the current split. Are the batteries all the same age (can't remember)?

 

Four newer ones, plus two of the old ones in a semi split bank. I was surprised at the charge current imbalance on the new ones as they are correctly (symmetrically) wired. The older two show a higher tail current but I expect that.

I will check the current split again in a few days when things have settled down, have not measured it before on the new batteries.

I don't measure things much of late, or even bother to check specific gravities, I just assume that Trojans (and Smartgage!) will work correctly.

 

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

[Loafer]

I would certainly bother to check your electrolyte levels. If it's down to below the plate tops, they'll be dying.

[cuthound]

As Loafer says it is probably temporary capacity reduction due to low temperatures.

[WotEver]

As Loafer says it is probably temporary capacity reduction due to low temperatures.

99%

[MtB]

 

Next morning Smartgage read 65%, would have expected about 80% to 85%.

 

 

 

Another faulty SmartGauge?

 

[Loafer]

 

 

Another faulty SmartGauge?

 

 

Tin hats everybody!

[metanoia]

Another faulty SmartGauge?

 

They've got a lot to answer for...................

[Loafer]

They've got a lot to answer for...................

 

But they HAVE provided a lot of entertainment among the more argumentative cognoscenti!

Edited January 25, 2016 by Loafer

[MtB]

First rule of fault diagnosis:

 

If the instruments reads wrong, first check the instrument!

 

But they HAVE provided a lot of entertainment among the more argumentative cognoscenti!

 

 

No they haven't...

[metanoia]

But they HAVE provided a lot of entertainment among the more argumentative cognoscenti!

THAT'S entertainment?

 

ETA: check your instrument

Edited January 25, 2016 by metanoia

[Loafer]

THAT'S entertainment?

 

 

That's very subjective, but for me it certainly was! It had the added bonus of being quite educational, too.

[dmr]

 

 

Another faulty SmartGauge?

 

 

It did briefly cross my mind, I did think that maybe the battery voltage had changed due to the cold and upset it.

So....I did have a very quick look at the voltage when the batteries were down at 65%. It was 12.0 volts with a load of about 10 amps (measured at the distribution board) so I reckon the Smartgage was about right.

 

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

HISTORY REPEATING ITSELF???!

 

Don't tell me those sneaky sods are hiding in a wooden horse AGAIN?

 

That's a rather intellectual comment for this forum, I was rather expecting some silly replies about American condoms!!!

 

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

[WotEver]

First rule of fault diagnosis:

 

If the instruments reads wrong, first check the instrument...

I believe he did. It correlated to the voltage. The only problem appears to be very cold batteries.

 

Tony

[metanoia]

That's a rather intellectual comment for this forum, I was rather expecting some silly replies about American condoms!!!

 

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

I'm an old fashioned kinda girl, Dave - and most of them on here have their heads up their a..es (or battery monitors anyway) - so well over their heads!

[Top cat]

If the concern is that low temperatures have depressed the voltage leading to instrumentation errors then a cheap digital thermometer with its thermocouple right by the batteries would enable you to apply the corresponding fiddle factor. The SoC charge table I use has a wide range of temeratures.

I found out how temperature affects batteries the hard way when I fitted our solar controller in the cabin rather than adjacent to the batteries in the engine bay.

 

Top Cat

[MtB]

That's a rather intellectual comment for this forum, I was rather expecting some silly replies about American condoms!!!

 

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

 

 

Well it went right over MY head!

[dmr]

 

 

Well it went right over MY head!

 

We better meet up for a few beers at the Waterfront then, in addition to teaching you electronics looks like we need to do some Greek Mythology too!

 

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

[ROBDEN]

 

 

That's a rather intellectual comment for this forum, I was rather expecting some silly replies about American condoms!!!

 

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

 

I'm an old fashioned kinda girl, Dave - and most of them on here have their heads up their a..es (or battery monitors anyway) - so well over their heads!

Love it............have a greenie.

 

Rob....