Frost vs No Frost

[Joseph_Grey]

We have been having some pretty cold days over the last week and I have been burning quite a bit of propane keeping the van warm.  The other evening while changing propane tanks though I noticed something odd about my batteries.  The two batteries on the drivers side appear frost free while the two on the other size seem frosted from the water level down.   The two sides *should* really be equal butI realizer there could be a ton of environmental factors that could be causing a slight temperature difference from side to side.  Even at eight below if the drivers side was parked in the sun, it might be a little warmer.  If my insulation isn't quite as good on that side, I could be leaking warm air into that space from the interior of the van, etc.  But I am concerned maybe the batteries are not getting charged as well on that side and I am getting some freeze-up.

Should I be worried about this difference?

--jg

 

[Weight]

Could be your charging current is not balanced. It is worth while to check.

 

[Canine]

Joseph, can you take a picture of the tops of the batteries so we can see how they are connected? It looks like you are running four, 6 volt batteries connected in series/parallel. Assuming this is accurate, I'm going to give a couple of scenarios that may be a problem.

When the loads/charging wires are connected, they should all be on the same terminal. You should not have the wire from the charge controllers connected to a different terminal than the wires for your inverter or any other device that creates a load. Always have all the connections on the same terminal. Always.

When you connect two, 6 volt batteries in series, you are in effect making one 12 volt battery. When you connect the wires from the CC, inverter, etc., the POSITIVE connections should be on one battery (the one pair of 6 volt batteries) that is on one side of the van. Then the NEGATIVE connections should be on the other battery (the other pair of 6 volt batteries) that are strapped in on the other side of the van. The connections should NOT be on the same battery (the same pair of 6 volt batteries). This may explain why one side is frosted. If the connections are on one side of the van, that set is getting the highest discharge and the highest charge with the batteries on the other side getting a lower charge, which would mean less heat for that battery which could account for the frost.

Keep wires the same length. Make sure you have good connections. If you can't provide pictures, try to provide a diagram for us to see exactly how the wiring is connected.

 

[jimindenver]

I would like to know the voltage of each pair of 6 volt batteries. A charged battery will not freeze so I suspeck the set getting the frost is undercharged.

 

[Joseph_Grey]

I would say bingo on guess two. So is there likely damage to the frosted batteries?

Thank you!

--jg

 

[Canine]

Joseph, it's hard to say if the batteries are damaged without doing a specific gravity test. A quick test, like jimindenver said is to do, is a super quick, easy voltage test on each battery. If the voltages are off, that doesn't mean the batteries are for sure damaged, but will inform you at the least the batteries aren't being charged properly for some reason. Just because they have frost doesn't mean they are damaged, so there easily could be no problem. But make sure you wire them up the best way you can. I hope my previous description sans pictures was clear. (I can provide a link if you have any questions at all. Let me know.) When the batteries aren't connected in the most balanced way, some batteries will get used harder and will wear out sooner. It doesn't necessarily mean you are abusing the batteries, but at the least you aren't using them in the most efficient, proper way possible.

 

[Weight]

Unless the electrolyte is frozen, that can happen if the batteries are dead un-charged, the battery is likely not damaged. The temperature of a fully charged battery can fall below the temperature where frost could form on the case, Just like any surface, dependent on the dew-point and temperature.

 

[John61CT]

Wiring 4x 6V batteried as 12V (2P2S configuration) should follow this:

Yes the interconnecting wires should all be the same gauge and length, and all loads and charge sources should use the same two posts.

Here's some variations and more background details

http://www.smartgauge.co.uk/batt_con.html

And I would call different batteries in a bank getting worn out unevenly as "damage", certainly accelerates wear overall, but if they haven't been wired incorrectly for more than a few months maybe not too significant.

Whatever you do, treat the bank as a whole as to when to scrap it, do not add new batts to an old bank even when everything's wired correctly.

 

[Weight]

Where was it determined that any battery was worn-out? Or wired in any specific way?

 

[Joseph_Grey]

So how really critical is that element of having the interconnecting wires be the same length? Unless I make them all long, I have two batteries on one side of the van and two batteries on the other.

--jg

 

[John61CT]

It is important for optimal lifespan.

But not as important (probably) as:

battery quality, true deep cycling

not going below 50%, or only rarely

getting to true 100% Full (as per endAmps) most cycles

keeping up with watering if FLA



Perhaps more important than:

commission charging and proper break-in period treatment

regular equalizing if indicated by mfg

high amp rate charging if AGM


So if the above hasn't been so, maybe just wait until you buy the next bank, may well be sooner rather than later anyway

 

[Canine]

So how really critical is that element of having the interconnecting wires be the same length?  Unless I make them all long, I have two batteries on one side of the van and two batteries on the other.

--jg

I'm not sure if you are saying all the same length. The 2 wires connecting the batteries in series should be the same length as each other, which are short ones, around 8 inches long. Then the two wires connecting the pairs together in parallel should be the same length as each other; since they are on opposite sides of the van, they will be long ones which will be around 5 feet long. The wires coming from your solar panels and charge controller don't matter as much. The quality of the connections should be equal as well. This way the electricity all travels the same distance and the batteries are as balanced as possible.

Imagine if you had one leg significantly longer than the other. Not only would that be awkward, one leg would be working harder to compensate for the other one. Then that leg would wear out faster then think of the difficulty you would have! Unless you wore the long leg down to the same length as the shorter one, then you would be fine, and this would be a terrible analogy. Anyway, you see what I'm saying.

I'm not sure if the wires to your inverter should be equal. Or other loads even. Someone here could probably clarify that.

 

[John61CT]

Good point, yes all the series jumpers should match, all the parallel ones should also, but they don't need to match each other.

As a side note, if you're going to more batt-units per bank, you should parallel all the batts first to maximum amps, then use serial to get to target voltage.

Not recommended to go past 3 paralleled. Need more capacity at a given weight, look at lower-voltage cells, 2V x6 to get 12V is common but 3V and 4V exist too.

 

[John61CT]

Positive and negative lengths on loads should ideally be identical, but likely not that important.

Some people even rely on chassis / frame for negative return, but not me.

 

[Weight]

I think the ugliest bear in the room would be the size of the cables connecting one side to the other. having the bank divided by distance causes miss balance of voltage resulting in uneven battery conditions. Larger cables can help overcome this problem. The cables across, positive and negative don't have to be exactly the same length, but they will as they need the same distance. I think I would bring both 12V negatives to the chassis as well as cabled across to the other pair.
I have seen many battery banks composed of many more than 3 sets of 12 volts. Especially in maritime use. And both lead acid and lithium.

 

[John61CT]

Yes, many things are often done that are not optimal, our understanding of technology is improving all the time, and it takes time for word of non-critical improvements to spread.

The design has inherent balance problems leading to shortened life.

But then most banks suffer from shortened life from all kinds of reasons, and it's not all from ignorance, many owners just don't care.

Your rig, your money.

 

[Canine]

John61CT, the comment where you posted the diagram and information was excellent! That really helped this thread. Very clear and good context, too.

 

[tx2sturgis]

Burning propane causes condensation and frost on any interior surface that is below freezing.

With a nod to all the electrical considerations above, it still might just be the fact that the frosty side is colder, or getting frosty and not melting off as rapidly due to air movement or adjacent surfaces not being as warm.

Be sure to check all the above posted recommendations but don't overlook the 'environmental' factors you mentioned. 

A small fan moving air around might be needed (due to dripping condensation) or possibly, better ventilation of the vehicle.

 

[B and C]

From the pictures, it looks like multiple ground wires (maybe + wire too?) off both banks. This looks to me like it is miss-wired. It needs to be wired like the schematic.

 

[jimindenver]

Did I miss the simple voltage test results?