Charging LiFePo4 battery

[TahoeT]

I just finished building my 280amp Lifepo4. However, found that Overland Solar panels only have
2/1/2' feet of cable. I ordered 6 feet of SAE to SAE extension cable. My cells are currently about 13.25 volts. I set my Victron controller at bulk 14.0. I plugged the camper in to shore power and believed it would top off at 14.0. Shore power did not change my voltage and both my BMS (Xiaoxiang blue tooth) and Victron 100/30 show no current coming in?? All four cells remain at 13.25. I won get my SAE cable until Thursday...hoping my solar panel will show a positive current. I believe 13.25 is correct voltage as check with my monitor, victron and my voltmeter. Is something wrong....my wiring I believe I installed correctly using all negatives to the shunt...etc.

2012 Kestrel
100/30 Victron Controller
120a 4S 12 volt BMS
4 prismatic cells 280amh
Aili battery monitor with shunt

 

[rando]

I think we need some more details here - when you say you plugged the camper into shore power - you mean you are using the stock IOTA converter? That should bring the batteries up to 13.7 or so, so there is something not right there. You would not expect to see any current on the Victron, as it only shows current from the solar panels, but you should see it on the BMS. I wonder if you popped the fuse on the iota - the lithium cells can draw a lot of current.

Can you disconnect the battery and see what the output from the iota is with your multimeter? It should be 13.7V.

 

[TahoeT]

Thanks Rando, I will check it out. The BMS is telling me the battery is at 62% and showing no charge. I went with the single Lifepo4 battery as you suggested. Tim

 

[Zirdu]

TahoeT:

I would be interested in a report on the details of the 280 amp hour battery you built. The final size and weight, final price, the source and price of your components, how you connected the cells together, how you balanced them, etc. etc.

 

[TahoeT]

Popped the fuse and its looks good. My friend who is pretty good on electrical side and owned a Grandby for 10 years believes the converter is 12 volt and not able to charge the Lithium battery beyond 13.25 volts. Tomorrow I will get my SAE cable and be able to hook the solar. I will find out then if I can reach my 14.0 Bulk rate. Rando: thanks for info on the Victron blue tooth. Tim

PS: Unhooking my battery is somewhat difficult with numerous wire connections in a small space. Will do that if problems persist.

 

[rando]

The converter should output a constant 13.6V at up to 30A, so it will charge your LiFePO4 battery up to 80 - 90% SOC. The converter actually does a pretty good job of charging lithium batteries. I use a bulk charge of 13.8V and a float of 13.3V on my lithium setup and it has worked very well for the past few years.

There is definitely something wrong if you don't see any current into the batteries and you are not seeing the voltage rise with converter powered on. DIY lithium can save a lot of money, but you really need to have a good understanding of how the system works, or it will lead to frustration, or worse. For safety sake you definitely want to have a way to quickly disconnect the battery, either a quick disconnect plug, or a high current circuit breaker with a manual override.

 

[TahoeT]

I was informed that my converter may only provide 13.2 or defaults to that number. There is a part called a "plug" which will enable my IOTA to secure a higher voltage--14.0 range. I have no idea what a plug is or how to install it. I am awaiting that info on DIY solar. Anybody here heard of the "plug." The plug is somehow attached or becomes part of the IOTA I think. If I find out anything about the "plug" i will share it with you. Thx Tim

 

[Vic Harder]

https://www.batterychargerdepot.com/IOTA/IOTA%20-%20Dual%20Voltage%20Jack.htm

 

[TahoeT]

Thanks Vic I'll check that out. Hope you are well. Tim

 

[PaulT]

More info here on IQ4 modules.
https://www.iotaengineering.com/IQ/#!/

Paul

 

[rando]

The Iota DLS-30 defaults to 13.6V:
https://www.iotaengineering.com/pplib/dls30spec.pdf
With the 'dual voltage jack' installed it ups this to 14.2V.

However, it would also be worth giving this document about charging LiFePO4 charging a read:
https://www.powerstream.com/lithium-phosphate-charge-voltage.htm

This is the important bit:


You need to multiply these by 4 to get the pack voltage, but what this is telling you is that even at 3.4 x 4 = 13.6V your battery will get to 99% SOC. Point being, you should be fine with the Iota as is and nothing is gained except increased heat in your batteries and decreasing their lifetime by charging at 14+V.

 

[TahoeT]

Thanks everyone for your information, suggestions and websites for booster components. I got my SAE extension cable yesterday and I am now on full solar. One question remains: I was told that all you need to do is put in BULK number for Lifepo4. You do not need to program in a float number. Is this correct? I set my Bulk for 14.0. I have a Victron 100/30 smart controller and a 4S 12volt BMS with blue tooth. The Victron has a float mode so I decided I should use it for the time being. I set it at 13.6. I would imagine that Lifepo4 will be the norm in the next 5 years... Tim

Rando: Regarding your earlier suggestion to buy one large amp Lifepo4 battery in which I did.....I will let know if that single 280ah battery has the storage power to handle my Isotherm 85 frig. On a boondocker next week in the middle of the desert. thx Tim

 

[veryactivelife]

I would check with the battery manufacturer for recommend settings as they vary from battery to battery. My LiFePO4 batteries are Lion Energy and they recommended Bulk/Absorption of 14.6V and float voltage of 13.8V.