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Battery Parameters Help plz!!

@HRTKD @upnorthandpersonal

Hey guys I have another question I hoped you could help me with... The REC Pro people are now saying I should do one big pack instead of the 2 battery packs I have now, and when I get my Eves instead of doing 4 battery packs just one... 4p4s system... Previously I worried about this because having 4 cells as 1 doesn't allow me to see the individual cells... what are you thoughts? The REC Pro teams feels 4p4s is more common now and it's safe...

My preference is to go 4s4p. I prefer to have the monitoring granularity to see what each cell is doing. 4s4p also gives you some redundancy to take one 4s battery offline for maintenance if you have to.
 
REC, just like Orion, have a particular view on this which is, let's just say, biased. There is no 'right' or 'wrong' way, it just depends on what you aim to do. Personally, I like the redundancy of two or more separate packs that can be added/removed on the fly for maintenance, etc. I also like the fact that each cell is monitored individually. Orion is known for a certain document where they argue against this set-up (with some dubious terminology and overall weak arguments). In the past this would be more relevant, but with the wide spread use of decent BMS's, this is no longer very valid. In fact, one of the proposed solutions in the Orion document is essentially what using a modern BMS does. My opinion is that REC and others are going by this Orion document, or that their BMS is more suitable for this kind of set-up and thus recommend it.
Rec said they'd give me a full refund since I was originally sold a system with individual packs not one huge pack... but the reason I went with rec was because they integrate with the wakespeed500 and victron... since I am going with a dual altenator for charging I was worried the JBD bms might not stop the 280amp altenator from charging... thoughts?
 
My preference is to go 4s4p. I prefer to have the monitoring granularity to see what each cell is doing. 4s4p also gives you some redundancy to take one 4s battery offline for maintenance if you have to.
I must have misunderstood, I thought 4s4p was one big battery and not 4 smaller packs... beyond maintenance is there anything else to consider??? The rec integrates with the wakespeed500 and victron and I am hoping that ensures no overcharging with the 280xp dual altenator
 
I must have misunderstood, I thought 4s4p was one big battery and not 4 smaller packs... beyond maintenance is there anything else to consider??? The rec integrates with the wakespeed500 and victron and I am hoping that ensures no overcharging with the 280xp dual altenator

4p4s is one big battery. 4s4p is four individual 4s batteries, that are paralleled.

Your goal of integrating the BMS with other components complicates the landscape. Can the inverter and alternator handle communicating with four BMS? I suspect not, but that's beyond my scope of experience.

My BMS is not integrated with anything else in my landscape. Do I need it? Not so far. Would everything work better if it did? Maybe, but the corner case for that would lead me to think that the rest of your system could be configured better.

My BMS is the last line of defense. I'm not sure that ANY of the configured limits in my two BMS have ever been tripped. The BMS is set to for a high voltage disconnect of 14.6 volts. But my charge devices are set to charge to only 14.2 volts. I have the low temperature disconnect configured the same way.
 
Rec said they'd give me a full refund since I was originally sold a system with individual packs not one huge pack... but the reason I went with rec was because they integrate with the wakespeed500 and victron... since I am going with a dual altenator for charging I was worried the JBD bms might not stop the 280amp altenator from charging... thoughts?

If you want to integrate everything with Victron etc, go with REC. I never had the need for any integration, and the BMS serves only as a protective role for the cells. The charge controller/charger is responsible for the charge parameters, the inverter shuts off at low battery. I've only recently started making a 'supervisor' that knows the state of the entire set-up and can control individual components. The reason it's not done yet is that I don't need it, and it's just something I'm doing in my spare time for fun.
 
If you want to integrate everything with Victron etc, go with REC. I never had the need for any integration, and the BMS serves only as a protective role for the cells. The charge controller/charger is responsible for the charge parameters, the inverter shuts off at low battery. I've only recently started making a 'supervisor' that knows the state of the entire set-up and can control individual components. The reason it's not done yet is that I don't need it, and it's just something I'm doing in my spare time for fun.
So the 280amp altenator is the new component causing the bms switch... the altenator just charges when the motor is running... I guess the rec communicates with the altenator to tell it to slow down.. without the rec I don't know what would slow the dual altenator charging... and let's say the cells are full what would happen to the bms just being pounded with 280amps
 
4p4s is one big battery. 4s4p is four individual 4s batteries, that are paralleled.

Your goal of integrating the BMS with other components complicates the landscape. Can the inverter and alternator handle communicating with four BMS? I suspect not, but that's beyond my scope of experience.

My BMS is not integrated with anything else in my landscape. Do I need it? Not so far. Would everything work better if it did? Maybe, but the corner case for that would lead me to think that the rest of your system could be configured better.

My BMS is the last line of defense. I'm not sure that ANY of the configured limits in my two BMS have ever been tripped. The BMS is set to for a high voltage disconnect of 14.6 volts. But my charge devices are set to charge to only 14.2 volts. I have the low temperature disconnect configured the same way.
The only thing between the dual altenator and the battery is a wakespeed500... I don't think you can communicate with it... rec says their bms can and slow down the charging current based on the cell voltage...
 
The wakespeed500 says it can connect to the smartshunt, but then that wouldn't connect to the victron stuff.. if I attempted to connect it to the victron smartshunt and not a bms
 
I called wakespeed, they said hooking g the ws500 directly to the voctron stuff would not regulate charging, it would have to go to a victron or rec bms... then they said the victron bms is only for victron batteries so .... looks like to charge I would have to have one huge 16 cell 12 volt battery... thoughts?

@HRTKD @upnorthandpersonal

I like the idea of checking individual cells, but I like the idea of being able to charge more...
 
Alternator charging has been covered ad nauseum on the forum.

I have OEM dual alternators in my F-350 for an advertised 397 amps. However, I'm unlikely to see that full amount. In normal use, the two alternators switch back and forth, giving each one a chance to cool down.

I disconnected the truck's charge circuit from the LiFePO4 batteries in my trailer. I don't like the charge profile and the battery bank simply doesn't need the charge. If I did need a charge from the truck then I would be using a programmable DC-DC charger. You already have the Orion. Maybe add a second or third one?
 
Alternator charging has been covered ad nauseum on the forum.

I have OEM dual alternators in my F-350 for an advertised 397 amps. However, I'm unlikely to see that full amount. In normal use, the two alternators switch back and forth, giving each one a chance to cool down.

I disconnected the truck's charge circuit from the LiFePO4 batteries in my trailer. I don't like the charge profile and the battery bank simply doesn't need the charge. If I did need a charge from the truck then I would be using a programmable DC-DC charger. You already have the Orion. Maybe add a second or third one?
I do have the Orion, but the dual altenator gives me 280amps potential... that would be a silly number of orions and seems more complicated... the dual alternator allows me to charge outside my vans system.
 
A current isn't pushed, it's pulled. If the battery is full, you don't pull any current any more, so nothing is being pounded with 280A.
Then why the heck would wakespeed say the rec bms will tell the unit to drop the charging current? That's strange, no ?
 
Then why the heck would wakespeed say the rec bms will tell the unit to drop the charging current? That's strange, no ?

The same reason a BMS can talk to a solar charge controller: to give fine grained control over the charge parameters, e.g. lowering the max output power when the battery is nearly full during cell balancing. These are all nice to have features, but not really critical to have. I assume that Wakespeed works similarly to how solar charge controllers work in that it has a charge and cut-off voltage and the like? If that is correct, you can use it just like you would a solar charge controller: set the charge voltage limits, float limits, and be done.

Lots of people, including myself, operate our batteries this way. The BMS is just a failsafe, last line of defense, to protect the cells. All the other parameters such as charge profile should be configured in the charge controller (or the Wakefield in your case) and should be of no concern of the BMS. It's just a nice to have feature that the BMS can throttle the incoming power when it's trying to balance etc.
 
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So what did you end up doing? I'm building the same system - wakespeed, 16 304Ah, nations 280. I'm looking at the Tao BMS and Rec...
 
So what did you end up doing? I'm building the same system - wakespeed, 16 304Ah, nations 280. I'm looking at the Tao BMS and Rec...
The nation's took two months to ship so I just got it. I went with the rec and have sourced everything... so I'll hopefully start connecting everything today... I went with 16 eve 310 ah, all the cells tested at 320+...

I hooked the rec up last night and got the wifi module going... we got a snow storm yesterday so I'm not terribly inspired to work on the van
 
I hooked the rec up last night and got the wifi module going... we got a snow storm yesterday so I'm not terribly inspired to work on the van

Plus it was 13° F this morning. I was going to lug a chop saw and drill press to my storage lot so I could fab up some bus bars to the exact dimensions needed. I think I'll keep the equipment at home and just wing it. If I'm off by 1/2", no big deal.
 
Plus it was 13° F this morning. I was going to lug a chop saw and drill press to my storage lot so I could fab up some bus bars to the exact dimensions needed. I think I'll keep the equipment at home and just wing it. If I'm off by 1/2", no big deal.
I have all my tools in my bus, but there is no heat, so yeah I'm with you
 
It's interesting reading all this, as I hadn't seen the thread until this morning.

I was asked last summer to help a friend upgrade his 40' sailboat's house electrical system. The prime motivation was to upgrade to 12V 560Ah (4S2P) batteries, but in the process he decided to upgrade to mostly Victron stuff: A Smart Shunt battery monitor, a Multiplus Compact Inverter/Charger, 2 MPPTs, a Cerbo GX, and a GX Touchscreen. He's was upgrading to a Wakespeed WS500 alternator regulator.

I knew from reading about it that a risk in charging LFP from an alternator can be that the BMS cuts of charging so that there is a sudden drop to zero on the current, which can cause the alternator to burn up in short order. The system we're doing will have two DC-to-DC chargers from the LFP to other banks on the boat, and I've read that can be enough to prevent a problem. In addition, I believe the Wakespeed also does something to deal with this risk, like maybe cut the stator field current. I don't really know anything about the Wakespeed (or alternators) so I'm not sure about that.

Mostly because I already knew them, I went with two 4S 150A JBD BMS's. I was building the battery bank when I decided to start asking about what I needed to know to have the Wakespeed show the amps out of the alternator on the Cerbo, and how best to display battery status.

Almost immediately I started getting some real REC enthusiasts (maybe zealots?) that I was doing it all wrong, and that I needed to go 2P4S and use a single REC BMS, because it could integrate with the Wakespeed to "manage" the current coming from the alternator. This kind of puzzled me because I thought (as @upnorthandpersonal said) the LFP's kind of manage it themselves. They will take as much as then need, and when they are full they don't take much. I did know that the passive balancing can perhaps work better if the current is decreased near the end of the charging, so that the final absorption phase takes a little longer.

I mostly gave up asking questions, because it seemed like if I didn't agree to go REC everyone that it was going to be terrible.

He's now in the process of completing the installation. The Wakespeed connectivity to the Cerbo GX is one of the last things (he needed a longer cable). I'm still not certain that the Wakespeed will provide the alternator current to the touchscreen display, but I guess we'll see.
 
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