Battery temp.....

[oscarvan]

Just bouncing this off the brain trust here. Trying to decide if there is an issue, or that it's normal....

The new Rolls bank is warm. As in 95ºF warm, and it's bubbling (Barely audible and not overflowing). Ambient in the generator room is 83ºF so a Delta of 12ºF. New Analytics Systems charger says it's putting 5A in there, which would seem like a normal float charge. Never goes to 0 though.

There are no 32VDC users on.

Thnx.

 

[Photolomy]

Mine goes pretty much to zero and the batteries are room temp. Also, float charge is calculated according to ambient temp, which seems to assume that it doesn't add any temp.

 

[oscarvan]

Mine goes pretty much to zero and the batteries are room temp. Also, float charge is calculated according to ambient temp, which seems to assume that it doesn't add any temp.

I did realize I never hooked up the temp sensor which I did this morning post haste.

 

[Jammin']

Victron Skylla chargers, AGM banks with temperature sensors and Balmer SG200 monitor says it's pretty much at zero amps fully charged. That's also with no real loads on.

 

[Maurice]

My charger has a temperature sensor laying on top of the 8D battery, but I have no idea at what temperature it triggers a change in the behaviour of the charger. Even here in Ontario the ambient can be close to 90F so the engine room has to be a lot hotter than that while cruising, it seems to me. What do I need to watch for?

 

[Captain Ralph]

Read each of the batteries with a DVM. All DCv readings should be real close to each other.
If this is your new 4 x 2 bank, one of the batteries may be having a problem.

 

[oscarvan]

Read each of the batteries with a DVM. All DCv readings should be real close to each other.
If this is your new 4 x 2 bank, one of the batteries may be having a problem.

Yeah, I was wondering that. Thanks.

 

[Photolomy]

My charger has a temperature sensor laying on top of the 8D battery, but I have no idea at what temperature it triggers a change in the behaviour of the charger. Even here in Ontario the ambient can be close to 90F so the engine room has to be a lot hotter than that while cruising, it seems to me. What do I need to watch for?

It doesn't trigger a change in behavior. The change in behavior depends on how much current the battery is drawing from the charger. Once that gets down to 5%, the charger goes into float maintenance mode and lowers the voltage to something like 35.68 volts at 25 degrees celsius. The actual voltage required in float mode depends on temperature. But the difference is very small.

The reason for adjusting the float voltage according to temperature is to not damage the battery.

 

[MadHatter53]

Having two banks of four 8V batteries in series and only one temp sensor where would be the proper location?

 

[Photolomy]

Having two banks of four 8V batteries in series and only one temp sensor where would be the proper location?

In the same room as the batteries. It is really only for ambient temp. The batteries are not supposed to heat up.

 

[Jammin']

I thought the battery sensor was supposed to attach to an inner most terminal of the bank in a location likely to get the warmest.

 

[oscarvan]

OK, I separated the two paralleled port banks and with A hooked up the meters immediately returned to 35.6VDC and 0A.

An hour later....... 8.6X VDC on each of the disconnected bank B batteries......

Then disconnected A and hooked up B...... Within minutes B down to 0A and 35.6 VDC......

So individually they both work fine......

Then paralleled them again...... A few minutes later 35.6VDC 0A As it should be......

I am now really scratching my head.

Taking it out today we'll see what happens.

 

[oscarvan]

And just for giggles here is the configuration..... Hooked up to the charger as a single bank 1. (Starboard bank is bank 2 on the charger). Can the charger not handle this as a single bank? Is it getting confused?

 

[Photolomy]

Is that two (banks of 4 in series) in parallel?

 

[oscarvan]

Is that two (banks of 4 in series) in parallel?

Yes.

OK, so here's the latest. After flushing a head or two it went back to 37.5V 3A and never settled down.....

Now, there's a plate with two screws that hides a switch to switch between 2 or 3 stage charging. I thought the book said it's factory set to 3...... Maybe I remembered that wrong or whatever, but I took the plate off it was set to 2. Switched to 3 and it settled right down.

I always thought 3 was better, but I read up on the difference and according to Analytics 2 is recommended when there are loads, which there are, although none continuous. Water pump, heads, a few LED lights.

Maybe there is just enough resistance in the 32 cells of my configuration to make it think there's a load on it when in 2 stage. I'll be running it in 3 as I definitely don't need warm batteries taking constant 37.5V 3A.

So that's the conclusion of this for now...... I'll try and call Analytics and see if they have anything.

Thoughts?

 

[Photolomy]

I thought the battery sensor was supposed to attach to an inner most terminal of the bank in a location likely to get the warmest.

Yeah, it makes sense to locate it close to or even on a battery. My point was that the batteries are not supposed to heat up during the float phase, which is when temperature is a factor. The batteries should be the same temp as the air around them during the float stage.

 

[Photolomy]

Yes.

OK, so here's the latest. After flushing a head or two it went back to 37.5V 3A and never settled down.....

Now, there's a plate with two screws that hides a switch to switch between 2 or 3 stage charging. I thought the book said it's factory set to 3...... Maybe I remembered that wrong or whatever, but I took the plate off it was set to 2. Switched to 3 and it settled right down.

I always thought 3 was better, but I read up on the difference and according to Analytics 2 is recommended when there are loads, which there are, although none continuous. Water pump, heads, a few LED lights.

Maybe there is just enough resistance in the 32 cells of my configuration to make it think there's a load on it when in 2 stage. I'll be running it in 3 as I definitely don't need warm batteries taking constant 37.5V 3A.

So that's the conclusion of this for now...... I'll try and call Analytics and see if they have anything.

Thoughts?

My charger has 3 stages, Bulk, Absorption and Float. The charger determines the stage by how much current the battery is pulling which is related to how charged the battery is.

Bulk is full voltage and current and stops when the battery is 80% charged.

Absorption is full voltage but limited current and stops when the battery is 95% charged.

Float is limited voltage but full current (potentially) and it stays that way till I recycle it.

In float, the only reason there is hardly any current is because the voltage is just above the battery's voltage and the battery therefore draws hardly any current. However, the charger is still capable of delivering its full current capacity if a load is applied. Thus, when I flush a toilet, the power is coming from the charger, even though it is in float mode. The charger's fan kicks on, because of the current draw, but the charger keeps the voltage at float voltage (which is still a tad above the battery voltage). And the charger never leaves float mode.

Your charger may be different, but it seems that in setting 2, your charger is never entering float mode with all of the batteries connected. It is strange that it did with just one bank connected. As I said above, you can put all the load you want on the charger in float mode. Maybe setting 2 is such that if you had constant loads, it knows this, and delays going to float mode to account for the constant loads, and with the extra batteries it never reached that point.

Also, even if it goes into float mode a little prematurely (the batteries aren't 95% charged), they will still charge because the uncharged voltage will be less than float voltage and current will flow into the batteries until they are charged. But it will be slower than at the other stages where the charger voltage is higher.

This is from my manual ...

If a load is applied during the absorption phase, the charger may revert to the bulk phase depending on the total current draw. When the charger switches to the float phase, it will remain in that phase regardless of current draw. The charger is still able to deliver full output current when in the float phase. To re-initialize the three stage process shut the charger off momentarily, then back on again.

 

[oscarvan]

My charger has 3 stages, Bulk, Absorption and Float. The charger determines the stage by how much current the battery is pulling which is related to how charged the battery is.

Bulk is full voltage and current and stops when the battery is 80% charged.

Absorption is full voltage but limited current and stops when the battery is 95% charged.

Float is limited voltage but full current (potentially) and it stays that way till I recycle it.

In float, the only reason there is hardly any current is because the voltage is just above the battery's voltage and the battery therefore draws hardly any current. However, the charger is still capable of delivering its full current capacity if a load is applied. Thus, when I flush a toilet, the power is coming from the charger, even though it is in float mode. The charger's fan kicks on, because of the current draw, but the charger keeps the voltage at float voltage (which is still a tad above the battery voltage). And the charger never leaves float mode.

Your charger may be different, but it seems that in setting 2, your charger is never entering float mode with all of the batteries connected. It is strange that it did with just one bank connected. As I said above, you can put all the load you want on the charger in float mode. Maybe setting 2 is such that if you had constant loads, it knows this, and delays going to float mode to account for the constant loads, and with the extra batteries it never reached that point.

Also, even if it goes into float mode a little prematurely (the batteries aren't 95% charged), they will still charge because the uncharged voltage will be less than float voltage and current will flow into the batteries until they are charged. But it will be slower than at the other stages where the charger voltage is higher.

This is from my manual ...

If a load is applied during the absorption phase, the charger may revert to the bulk phase depending on the total current draw. When the charger switches to the float phase, it will remain in that phase regardless of current draw. The charger is still able to deliver full output current when in the float phase. To re-initialize the three stage process shut the charger off momentarily, then back on again.

Agreed with all. However I was familiar with three stage charging not two, and yes according to the book that's the setting you want with a (continuous?) load on it. Again it appears that with both banks connected it had enough "going on" to think there was a load on it and amperage and voltage staid up. It's been behaving just as advertised in three stage mode now for 24 hours. I think I can sign this off.

(Again the 2/3 switch is hidden behind a plate with 2 screws....)

 

[oscarvan]

As far as where to mount the temperature sensor I offer this out of the Rolls manual:

 

[Captain Ralph]

Good to read it's working. I remember now that a few modern chargers do allow for a one or two level charge. Same on my inverter/charger.

My old and simple Raritan charger/coverters are just set to the float level and deliver what is required to get them there if low.

So, What is your next high adventure project?