What is the best BM out there? No I am not trying to start a fight LOL

[Dzl]

I think Bob is on the right track pointing you towards the JBD BMS sold by Overkill Solar, particularly now that they released such a nice product manual.

When you say you are looking for a lifepo4 charger, what specifically do you mean (AC/wall outlet, solar, DC/cig lighter?) and what voltage?

 

[Dzl]

If you are not in a hurry to have perfect balance but are in a hurry to use your cells then BMS "top balancing" may be the way to go. In the end how much extra capacity will you get if your cells are relatively close to being balanced but not perfect so what if it takes a few weeks for the BMS to balance as long as the capacity is trending up.

I agree with this sentiment.

 

[Bob B]

You'll also get a few laughs while reading the manual Overkill Solar put together.

 

[MisterSandals]

I have 3 banks in which I just allowed the BMS to top balance just fine .

I have come to believe that this is a good practice, especially for beginners with new/unknown cells.
The primary reason for my shift to this has been the number of beginners that destroy their cells with “initial” top balancing and capacity testing (to feel good about the purchase).

When this method does not yield satisfactory results, i think resorting to a “not-so-initial” top balancing in parallel may help. I have not been to this point myself but there are few other options to get the cells in a battery to function better/more similarly.

Of course a bigger and better balancer is a possible solution too.

 

[toms]

REC-BMS with SMA inverters will do everything you requested.

 

[Bob B]

REC-BMS with SMA inverters will do everything you requested.

Do you know what pricing is on the REC Active BMS? I hate it when their website doesn't include pricing. Or maybe you have a link someone selling it with prices on their website.

 

[Deleted member 9967]

In your situation where you need the BMS soon .... and 75A is the largest draw you expect to see ... I would go with the @OverkillSolar 120A BMS.
You can start parallel balancing the cells you have while you are waiting to get it.

Yes I will be doing the parallel balancing for sure. Thanks.

 

[Deleted member 9967]

Do you have an android or Iphone? The reason I ask is the apps are different. I found it necessary to calibrate the charge and load current on mine to make the SOC work right.

Android, but no apps for anything concerning batteries yet.

 

[Deleted member 9967]

I think Bob is on the right track pointing you towards the JBD BMS sold by Overkill Solar, particularly now that they released such a nice product manual.

When you say you are looking for a lifepo4 charger, what specifically do you mean (AC/wall outlet, solar, DC/cig lighter?) and what voltage?

I currently have a charger but it is for AGM's. So I need a charger for Lifepo batteries.
I can use the AGM charger for my batteries but I would have to watch it like a hawk and test a LOT to make sure it does not go to high etc etc.
A wall outlet charger as I will be charging it from my place and a wall socket like regular folks LOL.
Voltage would be 120 as I am in Canada.

 

[Deleted member 9967]

REC-BMS with SMA inverters will do everything you requested.

I have no clue what you just said, sorry.
Not sure how those will work with my lifepo batteries and mobility scooter.
Any links etc?

 

[Bob B]

I think most AGM chargers will be fine and not overcharge .... probably just under charge a little. That's also where your BMS will protect you.

I'm not familiar with the android app .... but I'm sure there are some who are. I just remember that it is different from the Iphone and seem to remember that things like the current calibration may be different.

Here is a link to the manuals. https://diysolarforum.com/resources/overkill-solar-bms-official-manual.87/

There are several other threads if you search overkill solar. I think he is offering discounts for forum members ... maybe message him about that if interested.

 

[Gazoo]

Yes I will be doing the parallel balancing for sure. Thanks.

What charger are you going to use to parallel top balance?

 

[Dzl]

I currently have a charger but it is for AGM's. So I need a charger for Lifepo batteries.
I can use the AGM charger for my batteries but I would have to watch it like a hawk and test a LOT to make sure it does not go to high etc etc.
A wall outlet charger as I will be charging it from my place and a wall socket like regular folks LOL.
Voltage would be 120 as I am in Canada.

Not sure what kind of charge rate you are looking for, but Victron makes some good low current plug in AC to DC chargers. I am certain there are cheaper options that would be adequate, I just don't know of anything personally, its not something I have spent time looking into.

As for BMS, for a mobility scooter the TinyBMS would be worth looking into, it is a bit more DIY-ey than some of the BMS' popular here, but its supposedly high quality with good documentation and has a nice interface well suited for a scooter or bike or EV, plusits made by a European company.

 

[Deleted member 9967]

I think most AGM chargers will be fine and not overcharge .... probably just under charge a little. That's also where your BMS will protect you.

I'm not familiar with the android app .... but I'm sure there are some who are. I just remember that it is different from the Iphone and seem to remember that things like the current calibration may be different.

Here is a link to the manuals. https://diysolarforum.com/resources/overkill-solar-bms-official-manual.87/

There are several other threads if you search overkill solar. I think he is offering discounts for forum members ... maybe message him about that if interested.

Yes the problem with the AGM chargers is that they do not "terminate" properly. I am not certain of the exact science behind it. But basically as it reaches the top end it just keeps going and going eventually ruining the cells. So yes, I will have to watch it carefully and stop it well before it reaches 3.65. Probably more like 3.4 or do you suggest another voltage?

Thanks for the link yet again Bob. Wow you are helpful with those tonight.

Also thanks for the insight to a deal as well.

 

[Deleted member 9967]

What charger are you going to use to parallel top balance?

Just the same one I am currently using for my AGM batteries.
I thought I mentioned that I need a charger for lifepo. Hmmm, maybe not.

 

[Deleted member 9967]

Not sure what kind of charge rate you are looking for, but Victron makes some good low current plug in AC to DC chargers. I am certain there are cheaper options that would be adequate, I just don't know of anything personally, its not something I have spent time looking into.

As for BMS, for a mobility scooter the TinyBMS would be worth looking into, it is a bit more DIY-ey than some of the BMS' popular here, but its supposedly high quality with good documentation and has a nice interface well suited for a scooter or bike or EV, plusits made by a European company.

Thanks DZL
The 15 amp charger will take a while to charge my 280Ah battery, but it is an option. Thanks

 

[Craig]

Yes the problem with the AGM chargers is that they do not "terminate" properly. I am not certain of the exact science behind it. But basically as it reaches the top end it just keeps going and going eventually ruining the cells. So yes, I will have to watch it carefully and stop it well before it reaches 3.65. Probably more like 3.4 or do you suggest another voltage?

Thanks for the link yet again Bob. Wow you are helpful with those tonight.

Also thanks for the insight to a deal as well.

I like 3.4 as there is little energy to be gained by charging higher

 

[Deleted member 9967]

I like 3.4 as there is little energy to be gained by charging higher

Fair enough. I don't think so either.
Thanks

 

[Dzl]

What charger are you going to use to parallel top balance?

Just the same one I am currently using for my AGM batteries.
I thought I mentioned that I need a charger for lifepo. Hmmm, maybe not.

I think you guys are not talking about the same thing.
Sherilyn, I still think you may not be clear on what people are generally referring to when they talk about 'manual top balancing', 'initial top balancing' or 'parallel balancing'. This involves putting your cells in parallel, charging with a CC/CV power supply until cells hit 3.65 (or 3.6, or 3.55, etc) and current tapers down to a predetermined cutoff point, at which point the pack is balanced.

You almost certainly cannot use your AGM charger for an initial top balance because it is most likely a 12v charger, and your cells in parallel are only charged to at most 3.65V. Adjustable CC/CV benchtop power supplies are commonly used for this process.

I believe you may be planning to skip this part of the process (a manual top balance) which is probably completely fine so long as you understand the caveats Craig and I mentioned earlier (namely you will be operating at reduced capacity for some number of days, weeks, or months until the BMS can bring your cells into balance). As Craig said if your priority is to get things setup ASAP, this is probably the way to go for your situation.

 

[Gazoo]

Just the same one I am currently using for my AGM batteries.
I thought I mentioned that I need a charger for lifepo. Hmmm, maybe not.

From everything I have noticed everyone is using bench top power supplies or single cell LifePo4 chargers. We top balance to 3.65 volts....right?

I don't know of anyone using an AGM charger to top balance. I don't know if it's possible. But if it is I would be extremely careful and overly cautious because you have no way to limit the voltage.

I am planning to top balance to 3.55 and may go up to 3.6 volts depending. I am going to connect my cells in parallel and let them sit for a day or two. Then charge in steps. I do not want to end up with a bloated cell due to overcharging and I figure charging in steps will help prevent that. Even though I have a power supply/charger I can't watch them like a hawk all the time but I will be watching them like a hawk when the cell voltage is near the end of charge....lol

I am thinking if I was in your shoes I would not top balance. Instead focus on a decent BMS and charger.