Question on charging LiFePO4 to 90% SOC with a charger in an RV

LVLAaron

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Jul 16, 2021
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I'm in a similar boat as you. New camper, lead batteries, similar equipment you listed.

Instead tearing into the factory wiring and changing things, I'm just going to add an AIMS charger to the system and run it in parallel. That way if the camper ever leaves me (crash, sell it, whatever) I can just pull my stuff out and it's still "factory"



Luckily in my unit, under the sink, there is a 120v outlet that only runs on shore power (for the microwave), and the 1000 watt inverter has two sets of lugs so I can just run the aims unit to those and be attached to the 12v system.

I'm fine with the voltages the factory converter reaches, but it's really low output. I get maybe 8-10 amps of charging out of it. If I'm going to run a generator to charge batteries I want to run it as little as possible.
 

chrisski

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Aug 14, 2020
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Instead tearing into the factory wiring and changing things, I'm just going to add an AIMS charger to the system and run it in parallel. That way if the camper ever leaves me (crash, sell it, whatever) I can just pull my stuff out and it's still "factory"

AIMS 12V and 24V AC 75-Amp Converter/Battery Charger
I am getting that piece of equipment.

I will only charge batteries, but not float with that. Purely as back up for my 24 volt SCCs in case of bad weather.

The Gel values are closest to what I wil charge and float my lithium to:

96A47996-EF22-4803-B533-0A3B23C3C6C4.jpeg
 

LVLAaron

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Jul 16, 2021
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I use the Gel profile for my LifePo4 batteries.


My only problem with that charger is it requires battery voltage to start charging (it's 12/24v auto switching, so it needs to sense voltage). This is a real problem if your BMS has disconnected because of low voltage... you wont be able to charge. :/

I have an emergency workaround though. I have a direct connection to the cells that bypasses the BMS that I can use temporarily with a simple switch and direct connection to the cells.
 

chrisski

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Aug 14, 2020
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4,262
I use the Gel profile for my LifePo4 batteries.


My only problem with that charger is it requires battery voltage to start charging (it's 12/24v auto switching, so it needs to sense voltage). This is a real problem if your BMS has disconnected because of low voltage... you wont be able to charge. :/

I have an emergency workaround though. I have a direct connection to the cells that bypasses the BMS that I can use temporarily with a simple switch and direct connection to the cells.
Thanks.

I hope never to get to that point, but you never Know. With my smaller 50 ah battery on the crate build, the batteries died one day when I used it powering the crockpot, but forgot to plug in the solar panels. About five hours later, the BMS shut everything off.
 

Agmills

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Apr 21, 2021
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74
Guys I have a Spf6000dvm with 4875w ( 325w Canadian solar x15) panels directly connected to the pv input so the internal charge controller is producing at max the 79 amps to charge batteries. I have 3x (48v 200ah) Rosen lifepo4 battery banks
( roughly 30kw). On cloudy and over cast days charging drops to like 20-30ah and therefore my batteries don’t get to even 90% buy the evening with loads continuously running. I am aware that the inverter does not want to take anything more than the 5000w to it’s pv input. But I have a Outback fm80 with 2700w ( 9x300w) connect to it. Can I add this somehow to help charge the batteries a bit faster in low light? What , just connect it to the battery banks bus bar? I know it’s too much and would not be utilized if I added the pv output to the pv input of the Growatt as it uses max 80ah. May eventually burn up the mppt charge controller board but can I do as described above and if so how ?
 

HRTKD

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Multiple charge sources can be connected to a system. I've done this on my current system but it's all Victron and those components have a way to coordinate amongst themselves. On an older system that used a 10 amp PWM solar charge controller and a 55 amp AC-DC converter the two charge sources ran fine, though the PWM did tend to defer to the converter.
 

grizzzman

Some say "Why" and some say "Why not?"
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Sep 21, 2019
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There is an alternate way to deal with charging with most any charge source of reasonable voltage. As an a example, I run a ElectroDacus SBMS0 BMS. As I wanted to keep the RV side easily put back to stock.( You never "really" know when an upgrade will happen ) I have the stock system ( including the FLA bank ) run through a KiloVac 500 amp contactor. The charging and discharging limits can be programed in the SBMS0 including as an example 90% charging and 10% discharge disconnect. As a side note the 2000 watt inverter is connected on the FLA bank side. ( No worries about voltage spikes on disconnect or pre-charging the caps on the inverter and there is ALWAYS power no matter what the LFP BMS does)
 
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