Lifepo 4 battery - 100 amp hr £140

[fishplug]

Ah! yes. Gotcha. Sorry, I misunderstood your question.

As Bigtwin pointed out those numbers are a bit odd.

Preferred minimum charging current: 60A

Maximum charging current: 300A

What they're saying is that the standard current you should charge the battery at is 20A (or 60A on the 300) and the maximum is 200A (or 600A on the 300).

By comparison, my 300Ah Fogstar Drift Pro puts the max charging current at 150A and the standard at 60A.
My 100Ah Li Time has a max charging of 100A and a standard of 20A

The standard charge current is typically 20-30% of the battery's capacity but charging them for long periods at a higher current can damage them. That's why a good BMS would definitely be limiting that higher charging capacity.

Sticking 600A into a battery that has a normal charge rate of 60A doesn't sound like a great idea to me. Again, I'm a long way from being an expert so I'm happy to learn from others if I've missed something.

 

[Raul]

Ah! yes. Gotcha. Sorry, I misunderstood your question.

As Bigtwin pointed out those numbers are a bit odd.



What they're saying is that the standard current you should charge the battery at is 20A (or 60A on the 300) and the maximum is 200A (or 600A on the 300).

By comparison, my 300Ah Fogstar Drift Pro puts the max charging current at 150A and the standard at 60A.
My 100Ah Li Time has a max charging of 100A and a standard of 20A

The standard charge current is typically 20-30% of the battery's capacity but charging them for long periods at a higher current can damage them. That's why a good BMS would definitely be limiting that higher charging capacity.

Sticking 600A into a battery that has a normal charge rate of 60A doesn't sound like a great idea to me. Again, I'm a long way from being an expert so I'm happy to learn from others if I've missed something.

Also, take in consideration BMS limitations, even if the drift battery is 300Ah, max may be limited by BMS as well at 150A. I guess if you stick a 300A bms on it, it may well be ok for up to 300A.

 

[fishplug]

As I said, my knowledge of them is slightly limited but I would have thought that if the battery ideal charge rate is 60A and that charging at high amps can reduce the battery lifespan then having a BMS that limits the charge rate to 150A is sensible.

I'm sure you could shove a 300A charge into it with a different BMS, but I'm not sure it would be a good idea!

 

[oldiesontour]

In practice the max charge rate is unlikely to be a problem... haven't heard anybody with a motorhome with a 300amp B2B or Mains charger and it would be a big roof for solar to deliver 300amp !
The talk of 2000 ,3000,even 8000 cycles is also fairly academic for most as calendar ageing is likely to kill the cells before capacity drops sufficiently to need to replace them(I did say for most... meaning motorhomes).
More likely to matter to MHs is discharge rates ,often a single 100ah will have a max discharge rate of 100amp (continuous) not enough for a 2000w inverter,the 100amp may in cheaper BMS's be pushing it to it's design/construction limits generating considerable heat.
Although I will never draw above 170amp I built my batteries with 200amp quality BMS's
these are not much more than cheaper 100amp basic(no Bluetooth no heating)units
mine were £60 each and with 2 batteries give a true 400amp continuous so I could have used slightly cheaper 100 amp (X2 =200amp)
to supply my max 170 draw.

 

[jongood]

As I said, my knowledge of them is slightly limited but I would have thought that if the battery ideal charge rate is 60A and that charging at high amps can reduce the battery lifespan then having a BMS that limits the charge rate to 150A is sensible.

I'm sure you could shove a 300A charge into it with a different BMS, but I'm not sure it would be a good idea!

I like a bit of redundancy but find it starts to get untidy when going to 3 so if I wanted 300ah I would look for 2x150ah and pay attention to the discharge rate.

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[oldiesontour]

I should add the problem with unknown (even if there's a u tube teardown) is they can't see inside the cells and many have no manufacturers info.U tubers will be very critical of general build quality BMS quality etc but these bits are cheap and easy(ISH) to replace...it's the cells that are the main cost.
Having said that I would see no business sense in building a very expensive plant to produce Lipo4 cells then cutting corners to produce significantly inferior cells But time alone will tell...after all some very big names sometimes do APPEAR to (air bag ECUs, Adblue,etc,etc)

 

[bigtwin]

More likely to matter to MHs is discharge rates ,often a single 100ah will have a max discharge rate of 100amp (continuous) not enough for a 2000w inverter,the 100amp may in cheaper BMS's be pushing it to it's design/construction limits generating considerable heat.

Indeed, my earlier post (below) was quoting discharge specifications but I failed to make that clear in my post and, consequently, many misinterpreted it as referring to charging.

The discharge information is a little odd, and vague.

For example,

• the 100Ah battery states Std/Max as 20A/200A
• the 300Ah battery states Std/Max as 60A/600A

that seems both inadequate (Std) and highly suspect (Max).

Personally, I’d steer clear.

Ian

Ian

 

[Sewdhull]

Long story short, 0.5C charge and discharge and you wont go wrong. Inverters have a continuous rating ( usually for a period of time) and a burst or max rating for coping with devices that draw more current on start up than when they are running (Fridges and motors)


The life prismatic cells used in these batteries will generally have 0.5 to 1C charge and discharge rates because of chemistry. Manufacturers can and will put their own specs on them because the batteries will perform way beyond the standard specs, but at the expense of battery life. Obviously go too far and the batteries will fail...

Larger single batteries would be my preference unless you want a 24v system which is easier on the batteries.

Some batteries are constructed for high discharge currents ( I have some Headway 15ah cells which are rated for 10C so 150A, and some Eve cells which are rated at 0.5C on a 315A cell so again 150A ish)

You always want the biggest inverter you can get, but for more than 3KW I go for 24v or more supplying it.