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09-26-2022, 07:03 AM #21
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"C" is a rating of how "fast" one can charge/discharge. 1 C is the capacity of the battery in 1 hour. So charging at "1 C" means going from fully discharged to full in one hour. A 100 amp battery would need a charge rate of 100 amps to do that. A 50 amp would need 50 amps, etc. (In reality it takes somewhat longer).
Back in the day, old Nickel Cadmium batteries, for example, could not be charged faster than 1/10th C - 10 hrs, or in reality overnight. Any more would damage them.
I have some small versions of what we use in our campers that are rated to take a charge at 4C - meaning 15 minutes! But even if the camper batteries were so rated, it might be hard to find a 400 amp charger (!)
Anyway, if told to charge a 100amp battery at .5C, that would mean use 50 amp charging (.5 x Capacity), and it would then take 2 hours.
Same math for discharge - what rate can a battery dump all of its power? Some other lithium chemistries can dump at 60C - all their amps in 1 minute. Yow!
What is used in the camper is actually way over qualified in many cases. They can routinely be charged in an hour, and discharged fully in an hour with no harm at all. The issue comes in having enough charging power (external/solar) to do that and having wiring heavy enough to handle such large amounts of current.2017 Imagine 2670MK
2012 F-150 SCrew, Eco, 4x4 6.5 box
Max. Tow, HD Payload, Airbags, ProPride hitch
(Previous: Jayco 26.5RLS Fifth, Revolution Pinbox)
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09-28-2022, 02:34 PM #22
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09-28-2022, 08:19 PM #23
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I looked these up and you cannot charge them below 32F!!!
I live in MN and that would be a problem.
Anyone with cold temp experience?2018 Ram 3500 with AS69RC Aisin transmission and Companion RVK3670 sliding hitch
2018 Grand Design Solitude 310GK
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09-28-2022, 08:54 PM #24
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Yes, that is one of the limitations of LiFePo4 batteries, they can't be charged below 32 degrees, however, you can discharge them below 32 degrees. This only becomes a limitation if you actually camp in cold weather, or you have a Solar system that could possibly charge your batteries when the temps are at, or below, 32 degrees while your camper is in storage. If you are just storing the batteries they can be stored inside the camper (or on the tongue) in the cold, just read your owners manual to ensure that they don't experience temps below the maximum allowed.
There are two ways to combat the "no charge below 32 degree" limitation: one, you can install the batteries inside a heated space within your coach (most common for 5th wheels is a heated hold area, for travel trailers the most common heated area is underneath the dinning table benches or bed), two, you can install a thermostatically controlled heating pad that can keep the battery temps above 32 degrees.
There are also batteries that have internal heating elements that automatically keep the batteries above freezing.
On my system, I installed the batteries inside the heated hold (under the steps leading to the bedroom), additionally, I configured my system to prevent charging below ~ 34 degrees. No temperature limitation on discharging below 32 degrees. Note: the 34 degree limitation is a protection against my Solar system charging the batteries while the coach is in storage (I leave my Solar and 12v system active while the coach is stored).Last edited by SolarPoweredRV; 09-28-2022 at 09:01 PM.
David and Peggy
2019 Ford F350 Lariat, 6.7L Diesel, Dually, Long Bed
Running with 20k Reese Goosebox (Love It) and Ford Factory "Puck" system.
Stopping with 8,000 lb Disc Brakes and Titan Hydraulic over Electric Brakes system.
Powering all this fun with 1200 Watts of Solar, two Tesla, Model S, battery modules, 24 volt Victron Inverter.
2018 Solitude 310 GK
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09-28-2022, 10:44 PM #252019 GMC 3500 SRW Sierra Denali Duramax
2020 Reflection 315RLTS
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09-29-2022, 03:34 AM #26
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C is the rate of charge/discharge (how many amps over a set time period)
Check out https://diysolarforum.com/members/will-prowse.1/ for a more thorough explination2019 Grand Design Reflection 320MKS
2010 Ram 3500 dually
Home is where I park it.
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