Battery setup help

[EmpirE231]

Oh for sure that aqua hot is your main issue.  Was the aqua hot left on?  I cant remember if the fan and pump will turn on independent of the main system being powered on.  I have my basement thermostat off since it never gets cold enough to cause problems.

Like others have said you can still get LiFePo4 and just move them to your next coach.  Just not having to maintain the cables alone is worth the price of them. Take these boat anchors out and stick them on a trickle charger in the back 40. When its time to sell swap them back in.  My current bus came with new Golf cart 6 volts.  I swapped them out into my old bus that I sold and moved my LiFePo4 setup over.

2 year of shitty batteries does not sound like fun to me.

The aquahot itself was not on.... it was strange, because I even hit the master battery disconnect in the coach which shut off 12v to everything... and somehow this basement fan was still running.  So that is one less draw for now.

I need to get a video of the buzzing I'm getting from the battery bay to solve that issue.

This weekend will be the moment of truth to see how well this battery bank holds up to 5 days in Glamis.... then I can start making some decisions re: the batteries from there. 

 

[Dockmaster]

If your batteries are all tied together each one will read the same voltage. You have to disconnect all of them to verify what batteries are low or not. 

Sorry but this is not necessarily correct. Multiple batteries in strings can have different voltages based on their conditions. It is not uncommon to see a 6v battery in a string that can be 1 or 2 volts below the rest and causing issues. 
 

Having all your batteries be at the same voltage is a good sign. And having found some continuous draws on your batteries and getting those taken care of is another step in the right direction. As others have suggested, a clamp on meter will be one of your best tools here going forward. 

 

[Lord of the Dunes]

That phenomena is unique to series/parallel connected batteries. The end-to-end voltage of a pair of 6v batteries will be identical to all of the other pairs in the battery bank, while the individual voltages of the 6v batteries may vary slightly. If it was a set of 12v batteries all in parallel, then they would all be the same voltage.

In this example, he has batteries 1+2, 3+4, 5+6 and 7+8. If he checked the voltage across all of the pairs, the voltage would be equal to the entire bank voltage, as jtmoney said, let's say 12.5v for example.

However, due to slight differences in cap. and internal resistance, battery #1 might be 6.3v and battery #2 might be 6.2v, totaling 12.5v. Batteries 3 and 4 might be equal to each other at 6.25v ea., again totaling 12.5v. That's not a problem, but if one battery is 1 or 2v lower than the others, then it's definitely a problem. 

 

[Dockmaster]

 That's not a problem, but if one battery is 1 or 2v lower than the others, then it's definitely a problem. 

This was the whole point I was making. Having them all the same doesn’t mean there is no problem with the batteries. But if he found one or a few that were down a volt or more compared to others, you know there is definitely a battery problem. 

 

[wopachop]

Assuming you fully charged the batteries, testing their resting voltage isnt a great way to determine battery health. Seems like you have 2 issues that could be answered quick and easy. 

1. Turn every switch off. Clamp the main lead. Are you drawing power, or not?

2. Turn your disconnect switches back on. Go inside the RV and apply a very large load to the batteries. Turn on the ACs and/or plug in a household 1500w space heater. Then go measure the 6v voltage again while its under load. A bad battery will sag more. Problem is like steve mentioned you have 4 sets of batteries that will equalize each other. Try to find a set where under load one of the 6v is down at 5.8v while the other 6v is up at 6.2v. (rough estimate of numbers....important part is they are different)

3. The same effect works while charging. The bad battery will spike its voltage before a good battery. If you test them all while charging look for the battery that has a higher voltage than all the others. 

 

[wopachop]

Another thought that the electronic guys might have an answer to. 

Is there a chance his basement fan could run off the capacitors stored energy? After he shuts down the disconnect switch? 

 

[Lord of the Dunes]

This was the whole point I was making. Having them all the same doesn’t mean there is no problem with the batteries. But if he found one or a few that were down a volt or more compared to others, you know there is definitely a battery problem. 

Yes - I wasn't arguing with you. I was clarifying that both you and jtmoney were right - he was thinking of parallel sets of batteries. 

However, voltage differences between batteries can also be an indication of high resistance - poor connections between batteries, usually corrosion on the terminals and lugs. That doesn't appear to be the case on this rig.

 

[Lord of the Dunes]

Assuming you fully charged the batteries, testing their resting voltage isnt a great way to determine battery health. Seems like you have 2 issues that could be answered quick and easy. 

1. Turn every switch off. Clamp the main lead. Are you drawing power, or not?

2. Turn your disconnect switches back on. Go inside the RV and apply a very large load to the batteries. Turn on the ACs and/or plug in a household 1500w space heater. Then go measure the 6v voltage again while its under load. A bad battery will sag more. Problem is like steve mentioned you have 4 sets of batteries that will equalize each other. Try to find a set where under load one of the 6v is down at 5.8v while the other 6v is up at 6.2v. (rough estimate of numbers....important part is they are different)

3. The same effect works while charging. The bad battery will spike its voltage before a good battery. If you test them all while charging look for the battery that has a higher voltage than all the others. 

While I agree with your earlier post about the clamp meter being a great tool to have, I think there are 2 other things he should have and I mentioned them before. In this case, with the large cap. battery cables he has, one might not see any voltage difference. 

Everyone who is serious about their batteries should have a Battery Monitoring System to tell them exactly how many watts have gone into the batteries, how many watts have been discharged and this will tell you exactly what the current State of Charge is.

The other tool is an IR Thermometer. It can be used for a thousand things - to see how well the fridge gasket is sealing, which cylinder on your V8 isn't firing and it will tell you which battery in a large bank is either shorted or open. Due to the 2nd Law of Thermodynamics, which everything is subject to, any battery drawing down the other batteries WILL be warmer or even hotter than the other batteries. Conversely, any battery with increased internal resistance or an open will be taking less charge or no charge at all and will be cooler or colder than the rest. Simply put the batteries at high charge rate and within a minute or two you'll see if there are  any differences between the batteries or if they're all the same and just too old to hold a charge. The temp. is a definitive indication of excessive current draw or lack of current.

 

[Lord of the Dunes]

Another thought that the electronic guys might have an answer to. 

Is there a chance his basement fan could run off the capacitors stored energy? After he shuts down the disconnect switch? 

More likely the basement heat is not connected through the master cutoff switch, this way the other loads won't draw the batteries down in cold weather, but the owner will still keep the batteries from getting damaged in extreme cold conditions.

 

[wopachop]

I guess they expect a rig of this caliber to always be plugged in? The fan that is keeping the batteries warm will eventually drain them dead. 

Think there is a small switch for the fan hiding somewhere? Or do other people with similar setups pull the fuse for long term warm weather storage? 

 

[Lord of the Dunes]

I guess they expect a rig of this caliber to always be plugged in? The fan that is keeping the batteries warm will eventually drain them dead. 

Think there is a small switch for the fan hiding somewhere? Or do other people with similar setups pull the fuse for long term warm weather storage? 

The heater/fan setup should easily run all night with power left over in the morning with a battery bank of that size, assuming the batteries aren't old and losing capacity. If being stored for a while, then it should be plugged in.