How many batteries?

[RetiredTorng]

I have two batteries with my Chateau 22E. Just realized there are still cramped space behind the two batteries. Can I add two more batteries behind it? Any disadvantage doing so? Thanks for your advice in advance.

 

[Jimbo57]

You need to get measurements of battery to see if the space you have will allow , on mine there is a brace in the middle holding up 2 chassis batteries above ,it is tight but I have 4-6v golf batteries on lower shelves so it’s a combination of of series and parallel wiring on our Palazzo 33.2

 

[ducksface]

It's barely a diy job.
Will you be doing the installation yourself?

 

[EA37TS]

You need to get measurements of battery to see if the space you have will allow , on mine there is a brace in the middle holding up 2 chassis batteries above ,it is tight but I have 4-6v golf batteries on lower shelves so it’s a combination of of series and parallel wiring on our Palazzo 33.2

The questions are

1. How do you use your rig? Do primarily go to campgrounds with electric or do you primarily boondocking without electric service?

2. If boondocking, what are your power requirements

3. Since newer batteries shouldn’t be combined with old batteries, are you ready to replace the current along with purchasing new.

4. Batteries add weight. Do you have the available GVWR for additional batteries?

IMHO, unless you are boondocking or it’s time to replace older batteries you stay with what you have until an upgrade is necessary. Again, that’s my opinion.

 

[Jimbo57]

The questions are

1. How do you use your rig? Do primarily go to campgrounds with electric or do you primarily boondocking without electric service?

2. If boondocking, what are your power requirements

3. Since newer batteries shouldn’t be combined with old batteries, are you ready to replace the current along with purchasing new.

4. Batteries add weight. Do you have the available GVWR for additional batteries?

IMHO, unless you are boondocking or it’s time to replace older batteries you stay with what you have until an upgrade is necessary. Again, that’s my opinion.

Mostly Glamping by wife’s choice( Happy spouse, Happy House) so full hookups. Our rig has residential fridge, could run generator during day to charge for nights. Yes I just replace 2- 12v for chassis and 4 -6v batteries for coach ,that’s how it came when I bought it used 3 years ago. In the next couple weeks I will fill fuel tanks, fresh water tank and propane is 3/4 full so I can weigh it at a scale. Trying to figure out if there is room for a toad. It’s a Palazzo 33.2 that says GVWR- 26,000 and GCWR- 30,000. I has 6.7 -300hp Cummins diesel 2100 Allison trans. This is an entry level DP. This MH also seems to ride lower with air bags inflated so boondocking on Asphalt/ concrete. Wife heath we are lucky to get out 3 x a year and usually weekends.

 

[EA37TS]

My reply was intended for the OP. My bad.

As a note, we passed on the Palazzo because of the lack of towing capacity. You might check with a Cummins center to see if they can do the uprate from 300 to 340 hp. The 2100 trans might be the factor that won’t allow the uprate. Folks that I know that have updated their rigs said it was the best 300.00 they’ve spent.

 

[Jimbo57]

My reply was intended for the OP. My bad.

As a note, we passed on the Palazzo because of the lack of towing capacity. You might check with a Cummins center to see if they can do the uprate from 300 to 340 hp. The 2100 trans might be the factor that won’t allow the uprate. Folks that I know that have updated their rigs said it was the best 300.00 they’ve spent.

Sorry I read it wrong as for the up grade we live in California and there is this crap called CARB so in Nov. when I get my yearly smog on the RV ( started the year after we bought it) I’ll check with the tech if that raises red flags. If we can’t tow a car we’ll go back to 5th wheel. Again didn’t read post correctly

 

[PreCambrian]

I recently changed out the batteries in my 22E (2022). I thought that I could only fit one more in but decided just to see how my VRLA to LFP conversion worked. Since the new batteries have much more effective capacity I don't see the need to install a third plus it might put additional strain on the alternator (I didn't add a BIM or DC to DC charger).

 

[Chateau_Nomad]

I recently changed out the batteries in my 22E (2022). I thought that I could only fit one more in but decided just to see how my VRLA to LFP conversion worked. Since the new batteries have much more effective capacity I don't see the need to install a third plus it might put additional strain on the alternator (I didn't add a BIM or DC to DC charger).

It would be interesting to see just how many DC amps those batteries would draw when "hungry". If they were depleted to say 20%, how many charging amps would they draw? If you have a DC clamp meter that would certainly make for interesting conversation... AND would answer a LOT of questions from anxiety induced battery threads.

 

[PreCambrian]

I actually wrote a response to a post on this very subject recently. I can't remember if it was Thor Forums or iRV2. I did measure this and the two 100Ah LiTime Batteries, Group 24, with BMS, Bluetooth, etc. only took 80A at 20% SOC. So I didn't add a BIM. This was just slightly more than the two VRLA batteries that I replaced took to charge at 50% SOC (although they didn't hold a charge very well at the time I tested them, just prior to being replaced). These LFP batteries also started my Onan generator, which required 55A continuous to start. The 80A was less than I expected based upon the comments of others. It might have taken more but I only took the rpm up to 3000, which is more than the E350 typically operates unless I am going up or down a steeper hill.

 

[ducksface]

The bms will decide. It is probably written on the top of the battery.

 

[Chateau_Nomad]

The bms will decide. It is probably written on the top of the battery.

My 100Ah SOK batteries only spec the recommended and maximum charging current, which is 50 amps. So, they are assuming the charging is being supplied by a charging device that's capable of limiting the current.

Please correct me if I'm wrong... but I understand that an alternator will try to produce (to a point) as much current as you ask of it... and with lithium batteries having such low resistance, they can "ask and receive" a LOT more current than a legacy lead-acid battery. I can find no data stating the BMS in my SOK batteries will actually limit incoming current... it's up to the current supplier to do that. HOWEVER, the BMS will limit current DRAW... the reverse of charge... out vs. in.

Ultimately I think this is the source of the controversy around the Li-BIM 225 and other current limiting devices. ???

 

[ducksface]

400a of lithiums has drawn a max of 140a per my xantrex 3012 guage.
They generally draw closer to 50a(this makes me a bit angry)
My 200a of wet cells would draw a consistant 150a on the same system.

 

[16ACE27]

My 100Ah SOK batteries only spec the recommended and maximum charging current, which is 50 amps. So, they are assuming the charging is being supplied by a charging device that's capable of limiting the current.

Please correct me if I'm wrong... but I understand that an alternator will try to produce (to a point) as much current as you ask of it... and with lithium batteries having such low resistance, they can "ask and receive" a LOT more current than a legacy lead-acid battery. I can find no data stating the BMS in my SOK batteries will actually limit incoming current... it's up to the current supplier to do that. HOWEVER, the BMS will limit current DRAW... the reverse of charge... out vs. in.

Ultimately I think this is the source of the controversy around the Li-BIM 225 and other current limiting devices. ???

As I understand it, the purpose of the BMS is to protect the battery. It will limit both the charge and discharge current to/from the cells to the maximum allowed by the BMS programming. Why would it rely on an external regulator to do its job? That doesn't make sense.

 

[Chateau_Nomad]

As I understand it, the purpose of the BMS is to protect the battery. It will limit both the charge and discharge current to/from the cells to the maximum allowed by the BMS programming. Why would it rely on an external regulator to do its job? That doesn't make sense.

Not sure. But why would the manufacturer state maximum charging amperage if the BMS limited it anyway??

On that note... my inverter/charger is adjustable. I have it set at something around 40 amps. I might try draining the batteries somewhat (so they'll accept a charge), then crank the charge current up to around 60 amps. Then look at the Bluetooth app and see what they're accepting. You may be absolutely correct if it's not over 50 amps... worth testing...

 

[16ACE27]

Not sure. But why would the manufacturer state maximum charging amperage if the BMS limited it anyway??

On that note... my inverter/charger is adjustable. I have it set at something around 40 amps. I might try draining the batteries somewhat (so they'll accept a charge), then crank the charge current up to around 60 amps. Then look at the Bluetooth app and see what they're accepting. You may be absolutely correct if it's not over 50 amps... worth testing...

Well, further research indicates you may be right in a lot of cheaper BMS applications. Certainly, the Interweb's tribal knowledge in Forums believe that is the case.
BUT, like in many things, it depends on the details.
Overcurrent protection is provided in many cases for charging the same way as for discharging - by turning the battery off.
There may or may not be an automatic reset in the BMS to reinitiate the charging, and this protective action may not occur until double the rated charging current is reached.

But quality BMSs "must know what the limits are and will command decisions based upon the proximity to these thresholds. For example, when approaching the high voltage limit, a BMS may request a gradual reduction of charging current, or may request the charging current be terminated altogether if the limit is reached."

Certainly, a balancing BMS has the capability to stop charging individual cells and direct charging to lower cells to balance the battery as the battery pack approaches full charge.

The linked article below is a good read on BMS application and where the quoted text above comes from.

What is a Battery Management System (BMS)? – How it Works | Synopsys

Battery management system (BMS) is technology dedicated to the oversight of a battery pack, which is an assembly of battery cells, electrically organized in a row x column matrix configuration to enable delivery of targeted range of voltage and current for a duration of time against expected...

www.synopsys.com

 

[ducksface]

The old truths become lies if the new truths aren't referenced.

Duckism