sunshine_eggo
Happy Breffast!
If you have to force yourself to read something, read the guide.
This newbie just got his EVE 280 amp hr cells.
- Thread starter Clavebob
- Start date
If you have to force yourself to read something, read the guide.
Being retired and living on SS I went for the cheapest cells. I bought the B grade. Hope I don't regret it. I expect good things from Overkill. I have yet to capacity test the cells. So I don't know what the SOH is.
By 'The guide' ? What's that?
sunshine_eggo
Happy Breffast!
Top Balancing LiFePo4 Cells using a low cost benchtop power supply.
To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...
diysolarforum.com
Orange button at top right of that page.
Generally, the "B" grade fall a little short on capacity. The 280Ah might be 270-ish. Generally, the EV grade 280Ah are likely 290+, but there's variation in batches, and they can't recycle them, so they sell to the "gray" market.
MANY folks have "B" even when they were told they have "A", and in most cases, they're all humming along well.
I've had my share of disasters caused by not waiting for the 'smart' guy to come help me. I burned up the motor controller on my sailboat electric motor conversion. 'Magic Smoke' ! I suffer from 'I can do it myself' syndrome. Sometimes I can. In spite of watching countless hours of videos I never picked up on that fact.. that a cell can over-volt real fast. No damage done I am fairly certain. I will set it up to slow charge with my Dr Meter power supply. First I have to figure out how to use it.
I've got a power supply hooked up to the cells. They are in series. I'm charging at 3.55 volts. The read out on the Dr Meter says it's only outputting 2.34 volts but my amp meter says it's abut 4.7. I would expect it to output the max of 5 amps. Anyway it's top balancing. I have it set up so it is outputting constant voltage. That's correct, right ? I want to be sure not to over volt.
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,843
Are you using the wires and the alligator clips that come with the power supply? If you are you need to change them, it should be in CC mode (current set to max) right now if using the correct wires and terminals, there are many thread about not getting enough current while charging, I.E.
Thicker Wires Top Balancing makes huge difference!!
I made thicker leads for my Bench Top Power supply, and this made a huge difference while charging the batteries. Went from 3.6 amps in Constant Voltage with the tiny terminals that came with the power supply to 10 amps in constant current mode for the 10 AWG wires. This should cut down charge...
diysolarforum.com
sunshine_eggo
Happy Breffast!
That's why you read the guide where it tells you to upgrade the leads.
Remove leads. Set to 3.65V. Replace leads. Might hit 5A.
Alkaline
Solar Addict
Yeah you're right. The stock leads are crap. But that wasn't the problem. I had to readjust the meter. Now output steady 5.2 amp. I did up grade the leads. Got carried away. I have three set of leads now. I checked the amps on the different leads. The amp output gets divided. That surprised me. I reckon it figures that it does. Volts stay the same. It was Will Prouse BTW, that suggested to make a 12 V battery and bulk charge it to 14 .2. So it doesn't take a month of Sundays to finish. I was reminded of that when I saw one of his video I'd seen in the past.That's why you read the guide where it tells you to upgrade the leads.
Remove leads. Set to 3.65V. Replace leads. Might hit 5A.
I upgraded the leads. The voltage reading on the Dr meter is correct. The voltage showing is not the limit it's set at. It's doing it's thing at CC. The voltage showing will- is rising as the cells charge. I'm going to turn it off when I go to bed, just to be safe. Not sure I trust this Dr Meter guy yet.Are you using the wires and the alligator clips that come with the power supply? If you are you need to change them, it should be in CC mode (current set to max) right now if using the correct wires and terminals, there are many thread about not getting enough current while charging, I.E.
BTW, set the Voltage before connecting the power supply to the battery.Thicker Wires Top Balancing makes huge difference!!
I made thicker leads for my Bench Top Power supply, and this made a huge difference while charging the batteries. Went from 3.6 amps in Constant Voltage with the tiny terminals that came with the power supply to 10 amps in constant current mode for the 10 AWG wires. This should cut down charge...
sunshine_eggo
Happy Breffast!
Divided?
Yes. He did. So does the guide I linked, but both recommend use of the BMS to protect the cells.
Browneye
Dr. WattSon
My diy battery has yet to be capacity tested. It just works, there’s enough extra I don’t worry about it. Use it, solar recharges it.
My cells came from Docan, overkill bms. It all works!
My cells came from Docan, overkill bms. It all works!
I thought I should post my results now that I've got all the components together. After top balancing with a power supply the BMS took no time to finish the balancing of the cells. So, no magic smoke ! I want to recommend the power supply I ended up getting. I returned the Dr Meter power supply. It's dangerous to use for top balancing because you can't lock the Voltage setting. I think maybe one of the dogs might have moved the V dial with their tail or nose ?? Luckily the voltage got set low not higher. This is the unit.
I installed the cells in an old milk crate. I'll post some photos once I have it all put together. Still got some fiddly bits to put together.
Kungber DC Power Supply Variable, 30V 10A Adjustable Switching Regulated DC Bench Linear Power Supply with 4-Digits LED Power Display 5V/2A USB Output, Coarse and Fine Adjustments with Alligator Leads. (SPPS-S)
The leads are nice. No need to upgrade. It completely silent. The fan never turned on at the low power settings. It's a keeper.I installed the cells in an old milk crate. I'll post some photos once I have it all put together. Still got some fiddly bits to put together.
Would like to know how to make contact with Steve from technical support if you wouldn’t mind sharing ?The overkill manual also has some good explanation and examples supporting top-balancing. The how and why, and what can happen if you don't.
I still had to do quite a bit of bleeding down of high cells at high-knee - near full charge. I used a 12V headlamp bulb during the last few amps of charging to even all the cells up - right at about 3.55 or so. Even still, If I try to charge past about 14.2V or that magic 3.55Vpc or so, one will or more will tend to reach full charge and its voltage will shoot up - bms will shut down charging. Which is not a great way to manage your battery charging. So you set your peak voltage and duration on your charge source so it gets your pack to full charge without cells going over the volt max you've set in your BMS. The closer matched the cells are the more even they'll be near full charge - same can be done for near full discharge, but most don't need to bother with that.
Overkill by default sets nearly everything up for you and tests it. Another value-added perk for sourcing from them, plus you can call Steve for technical support if you have trouble. Try doing that with alibaba.
MrM1
I'm Here, But I'm Not All There
Steve ? At Overkill Solar? You just need to send them an Email. They get back in a day or 2. I smoked a BMS 3 weeks ago. User error. My eyes aint what they used to be. Anyway, reached out to Overkill ... and on their direction, purchased a new replacement BMS, sent in the old burnt one and got a full refund. You can send it in and they will swap it out, but if you need it fast, it's best to purchase a replacement.
But they respond to email.
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