Lithium battery discussion - Printable Version
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RE: Lithium battery discussion - encantotom - 03-29-2024
Finished it today. 100amp hours is just fine. I don't use it for more than 10 minutes ar a time. Used big zip Tues to hold them together and trim tape to hold the bms on the batteries. Used velcro to hold the charger down.
It's like a race lift now. Onthe bms bluetooth app it was drawing 65 amps driving and 185 amps going up
I am 400 bucks all in including the daly bms and the victron 8a 24v bluetooth charger
Way cheaper than 500 for 4 cheap golf cart batteries
Tom
RE: Lithium battery discussion - Jack Houpe - 03-30-2024
That looks great Tom you'll be very happy with those batteries.
RE: Lithium battery discussion - Richard - 03-30-2024
First there was lawnmower racing, now lift racing………………
Seriously, Tom, do you have the charge profile that the supplier recommended? If so, just out of curiosity, would you publish? I am interested in charge voltage, absorb voltage if used, float voltage if used, and what criteria does the charger use to change modes, i.e time, voltage, returned amps?
RE: Lithium battery discussion - Jack Houpe - 03-30-2024
If it where me I would use 28.4v charge and 28v float. I would set the BMS to shut down at 3.2v per cell and 25.6v low voltage shut down. Make sure to set the low temp cut off at 34F to be safe.
RE: Lithium battery discussion - encantotom - 03-30-2024
Ha. Never gets below 60 to 65 degrees in my shop. Or above 95.
I will look at the settings. I don't intend on keeping it plugged in all the time
Tom
RE: Lithium battery discussion - smagown - 03-30-2024
Where is the old work boot?
RE: Lithium battery discussion - higherwireinc - 03-30-2024
Hey Tom, glad that worked out for you with the 100Ah pack. I'd be interested to see the power draw it pulls while going up. While these are high-drain cells, we typically recommend continuous loads of no more than 50% of rated capacity (50a for these 100Ah cells, as an example).
In general, LFP will spend 80% of its depth of discharge (DOD) at 3.2v per cell. We recommend setting cutoff at or just above 3.0v per cell, since you lose very little capacity. Similarly, we recommend setting float to 3.4v/cell and bulk/absorb to 3.5v/cell. Equalize is not required, but you can fully charge to 3.6v/cell periodically; the battery management system (BMS - red box in Tom's battery photo above) will slowly top balance by burning off energy from the highest-voltage cells. This is only required if cells become imbalanced. We're more conservative than other manufacturers simply because we test and renew the cells from other applications (typically forklifts), which leads to inherent but small imbalances in the system. Limiting to 80% also extends battery life considerably.
I've attached our (51v) charging recommendations, along with a graph showing the general (12v) voltage curve of LFP vs. lead acid. I'm happy to answer any other questions.
RE: Lithium battery discussion - encantotom - 03-30-2024
hi trevor, thanks for the info.
the bms said that when i was driving it was drawing 65 amps and going up 180 amps. my shop is only 70ft long so there is not alot of driving...ha and i go up maybe 4 or 5 times at most and that is when we take down and put up the Christmas tree. if i am using it to work on the coach for some reason it goes up and down a few times and then drives 40 feet.
my usage is very low.
tom
RE: Lithium battery discussion - encantotom - 04-18-2024
i am going to go ahead and do a homebuilt battery pack and rec system bms. trevor is helping me get going.
i will do a 1200 ah 12p4s setup. will take a while to get it going as i am having cataract surgeries over the next few weeks.....then i will be able to see what i am doing.....ha
will keep you informed.
tom
RE: Lithium battery discussion - folivier - 04-19-2024
Just a tip but wrap whatever wrench you'll use to connect the bolts to each cell, either shrink tubing or tape. It'll save those new eyes from all the pretty sparkles if you ground out your wrench.