BMS communication with alternator voltage regulator

[Lsantana]

I am currently designing/building the electrical system for my sprinter conversion. The bank consists of 16 280ah 3.2v LiFePo4 prismatic cells which I plan on charging with a 2nd alternator. I am trying to make it a 48v system and am wondering if the Overkill BMS has the ability to communicate with the alternator's voltage regulator to discontinue charging when the parameters are met, full charge, low temp etc. I was told by the vendor to make sure the BMS I choose has this ability, since the alternator may be damaged by a sudden cut-off.

 

[Rocketman]

Overkill does not.

Batrium watchmon does. (But it’s a lot more expensive). (If looking at Batrium look at the watchmon5 - it will do 15 cells - which is still 48v). If you are using Victron it can also connect to the Victron CAN-Bus.

There is an alternator protection device from Sterling (I believe) that I would also look into as well.

 

[Lsantana]

Overkill does not.

Batrium watchmon does. (But it’s a lot more expensive). (If looking at Batrium look at the watchmon5 - it will do 15 cells - which is still 48v). If you are using Victron it can also connect to the Victron CAN-Bus.

There is an alternator protection device from Sterling (I believe) that I would also look into as well.

Thank you, I'm going to look into that right now. Are there any cons to dropping that cell, aside from the slight drop in amp hours?

 

[Rocketman]

Are there any cons to dropping that cell, aside from the slight drop in amp hours?

I think that would be the only one.


Here is a thread from someone doing a project in a sprinter van. It might help on other items.

Component Review for Cabinet Design

I'm focussing primarily on the floor plan/design of my Sprinter build so, this is a fairly crude look at my electrical cabinet design so far. While I've put some thought into the current placement of components, this review is not so much for that. I'm primarily concerned with the dimensions...

diysolarforum.com

 

[Lsantana]

I think that would be the only one.


Here is a thread from someone doing a project in a sprinter van. It might help on other items.

Component Review for Cabinet Design

I'm focussing primarily on the floor plan/design of my Sprinter build so, this is a fairly crude look at my electrical cabinet design so far. While I've put some thought into the current placement of components, this review is not so much for that. I'm primarily concerned with the dimensions...

diysolarforum.com

Thank you! Being a newb I have much to learn. I looked up the Sterling device and it only works with 12v and 24v systems, from what I read.

I am starting to question the benefit for me going with a 48v system. Cost seems to be somewhere around 2k vs a 24v systems. Halfing the cable size from a 12v system which is what I used in my last van build is a no brainer for me, specially since I didn't use a 2nd alternator, hence my ignorance on the matter. Cable size is my main reason for going 24v/48v since I am also going to Victron Quattro 5K insted of the Victron MultiPlus 3k in order to be able to use the induction stove top and ac at the same time. The negatives I've found so far are a more expensive alternator. I've heard a 48v alternator is easier on the engine but not sure that to be true.

What are your thoughts?

Also wondering if would still need the Watchmon5 or will the balmar bms regulator on a 24v alternator kit leave me more options...

 

[Rocketman]

Which Quatro were you think of the 3000 or 5000?

I would go with the Multiplus 3000 (save the money). If the only reason to go higher is to run the A/C while cooking, then Run the A/C before... switch on a fan & cook, then when cooking is done back to A/C. Or go find a cooler place to park it. Or cook outdoors.

Using an A/C without being plugged in (or a generator) I think will be problematic. There is not a lot of room for solar, on those Vans. So you will have the A/C on for many hours, but then need to recharge, and that will take a LONG Time to recharge (regardless of which voltage you choose), but it totally can be done.

Have you figured out how long you can run the A/C and other loads under each battery size? And how long it will take to recharge?

 

[Lsantana]

delete

 

[Lsantana]

Which Quatro were you think of the 3000 or 5000?

I would go with the Multiplus 3000 (save the money). If the only reason to go higher is to run the A/C while cooking, then Run the A/C before... switch on a fan & cook, then when cooking is done back to A/C. Or go find a cooler place to park it. Or cook outdoors.

True. I was thinking of going with the 5000 Quattro, but yes i agree the 3000 Multiplus would be sufficient. The increase in the charge rate of the 5000 Quattro is very tempting, although my access to larger plugs is limited and when i do have it is usually overnight which defeats the purpose of charging faster but i can see times when that would be useful.

Using an A/C without being plugged in (or a generator) I think will be problematic. There is not a lot of room for solar, on those Vans. So you will have the A/C on for many hours, but then need to recharge, and that will take a LONG Time to recharge (regardless of which voltage you choose), but it totally can be done.

Have you figured out how long you can run the A/C and other loads under each battery size? And how long it will take to recharge?

The air conditioner on my current build, a 13,500 btu Penguin ii, draws between 1,300W & 2,160W while the compressor is engaged depending on ambient temps. I usually see about 1600W on average as the van and night cools the compressor draws less. Just the fan draws about 480W, but I am eliminating that by going with a separate control panel for it so that it shuts off when the compressor is off. The compressor in my experience, depending on the setting and ambient temps, runs about 35% of the time on warm nights, I'm from South Florida so that is somewhat often. So for example at 12v it draws about 150a. The bank consists of 1120ah÷160a= 7 hours runtime. I figure it will be good for about two 2 full nights.

I have considered using solar but due to my consumption rates it almost seems futile and not worth the extra $$.

Again all your thoughts are welcomed and very much appreciated.

 

[Rocketman]

Two disadvantages of going with the 5000 vs the 3000, first I believe the 5000 is larger (and in a van -every inch counts. Second, the idle load is larger. Just something to think about.

You may want to consider a panel, - if camping when the a/c is not needed - it will keep the battery up. Also when stored it will keep the battery up.

 

[Lsantana]

Two disadvantages of going with the 5000 vs the 3000, first I believe the 5000 is larger (and in a van -every inch counts. Second, the idle load is larger. Just something to think about.

You may want to consider a panel, - if camping when the a/c is not needed - it will keep the battery up. Also when stored it will keep the battery up.

Thanks, that makes sense. As for 48v vs 24v, do you think the additional cost is worth it? The 48v Quattro 5000 is actually the same size as the 24v 3000 MultiPlus. But the one factor I am yet to figure out is the appropriate BMS for a 24v system. 2 Overkills may not suffice and I am unclear if I will still need the signal for the alternator regulator from the battery's bms or if the Balmar regulator already handles the issue. Although if it doesn't the Sterling device you suggested would work.

Can you suggest a BMS to handle my intended loads @24v comfortably or would you go with the Watchmon5 as well?

 

[Rocketman]

Actually I think the Watchmon7 is for 24v. I like the Batrium bms’s (I am installing a Watchmon4 on my MotorHome this spring). I also have an Overkill in a portable pack. The things I really like about the Watchmon’s. Lots of additional signal wires (control, fans, heaters, contactor, etc). Ability to connect to my CCGX, and the CCGX can control Victron’s charging and discharging.

One thing I tell people- Remember you are the system engineer- it is your job to make sure everything can and will work together BEFORE you buy anything.

I just had a thought on the Multiplus 3000. Look at the spec sheet and make sure it will still handle the loads you must have when it gets hot. It will derate the current when it gets hot.

 

[Lsantana]

Actually I think the Watchmon7 is for 24v. I like the Batrium bms’s (I am installing a Watchmon4 on my MotorHome this spring). I also have an Overkill in a portable pack. The things I really like about the Watchmon’s. Lots of additional signal wires (control, fans, heaters, contactor, etc). Ability to connect to my CCGX, and the CCGX can control Victron’s charging and discharging.

One thing I tell people- Remember you are the system engineer- it is your job to make sure everything can and will work together BEFORE you buy anything.

I just had a thought on the Multiplus 3000. Look at the spec sheet and make sure it will still handle the loads you must have when it gets hot. It will derate the current when it gets hot.

I have the Multi Plus 12v 3000 and I love it. I originally bought it in 2016 to run my AC with a 2000 Honda generator, splits the load and charges bank when the compressor is off. My bank consists of 6 6v gc2 interstate 210ah batteries for 630ah. The performance with the generator was excellent but the bank couldn't handle the ac on its own for long since after about an hour the voltage drop was significant. So for my new system I wanted to go big and not have to worry about running the generator. Stealth is priceless out east. Of course growth comes with more complications. But I really enjoy it and am really grateful for your feedback and all the info in this forum.

Just spoke with Nations alternator and their 24v doesn't require communication with the banks BMS and they have a 48v coming out in April... excited about that.

So far I am just committed to the 16 3.2v cells since I already it ordered ahead of time along with the van, since they take a while to get here. I still have time to decide on the voltage. 48v seems tempting but going with 24v appears to be a better option since i don't need to take the risk of new technology and its more compatible with solar it appears, and going with Multi Plus would offset the cost... lots to think about.

For now I'll be researching the Watchmon line... thanks again!

 

[lachness]

Victron is about to release a 48vdc MultiPlus II 3000 with 120Volt AC output.

I am looking for a BMS that can shutdown the alternator also.

Good Luck.

 

[Springbok1817]

True. I was thinking of going with the 5000 Quattro, but yes i agree the 3000 Multiplus would be sufficient. The increase in the charge rate of the 5000 Quattro is very tempting, although my access to larger plugs is limited and when i do have it is usually overnight which defeats the purpose of charging faster but i can see times when that would be useful.

The air conditioner on my current build, a 13,500 btu Penguin ii, draws between 1,300W & 2,160W while the compressor is engaged depending on ambient temps. I usually see about 1600W on average as the van and night cools the compressor draws less. Just the fan draws about 480W, but I am eliminating that by going with a separate control panel for it so that it shuts off when the compressor is off. The compressor in my experience, depending on the setting and ambient temps, runs about 35% of the time on warm nights, I'm from South Florida so that is somewhat often. So for example at 12v it draws about 150a. The bank consists of 1120ah÷160a= 7 hours runtime. I figure it will be good for about two 2 full nights.

I have considered using solar but due to my consumption rates it almost seems futile and not worth the extra $$.

Again all your thoughts are welcomed and very much appreciated.

Just a thought on the a/c system. I'm installing a 48v mini-split heat pump in my van. It's actually designed for off-grid telecom centers and runs directly from 48v DC without an inverter. The EER is almost 3 times what an RV a/c is, the Penguin II is about 8 EER and the one I'm using is 19.3 EER. Normal operation it pulls less than 500W and full power is 980W for a 12k BTU (1-ton) system. The only problem was finding a location for the condensing unit. I have it mounted through the floor of the garage in my 170 Ext. Sprinter. I have the head unit (evap and blower) installed above the drivers/passenger's seats. I also have 4-365W solar panels for a total of 1460W of solar!

 

[Lsantana]

Thank you for sharing, I'm going to check it out.

 

[rotortalk]

Regarding the alternator shut off, I have multiple charging sources, (solar, alternator, Quattro and Skylla) and I'll never know what if anything is going to cause an overcharge. Plan is to set everything at a safe charge voltage and 99.99% of the time they charge source will deal with it, but in the event that the BMS wants to cut it off, I'm using the charge enable pin on my BMS (via a relay) to cut the FIELD voltage to the alternator. It will stop it charging safely. Same pin also tells the Quattro to stop charging, via an aux input.

 

[fpat99]

Hi Lasantana,
I am also trying to decide between a 24V or 48V system for my Sprinter Van build. One thing I found in favor of it is that 48V capable solar panels are available. For example:

https://a1solarstore.com/trina-410w-pv-module.html

And as you pointed out, there are 48V alternators and regulators available. Have you made a decision to move forward with the 48V system? Have you finalized your configuration?

Regards,
Frank