BATTERY?
- Thread starter Guystapo
- Start date
Thanks Dave….it is certainly an old charger. Doesn’t owe me anything.Up grade the charger and you should get 6-8 years from the batteries.
I will look into that as an interim step (and stay with GC2 lead this time around).
Greg
So how would I size a charger for future use and a change to LFP? I would probably use a 280ah battery or 2) 100ah batteries plus my start battery (70 ah LA).Up grade the charger and you should get 6-8 years from the batteries.
Is there a guideline or formula for how many amps the charger needs to be for say a total of 270 ah of batteries?
I seem to remember MaineSail had a guideline, but I cannot find it.
Greg
There is a maximum current that you should not exceed which for FLA is 0.2C or 20% of your rated Ah capacity or the charge capacity of your BMS for FLA. On my 560Ah that is 200A and on my two 460Ah batteries on my motorhome it is 200A each or 400A total. I charge my 560Ah with 190A and my 920 Ah with up to 170A because that is the most I have been able to install.
Remember, that is the max, but you can go much lower, and it really does not have much effect on the performance or longevity. lower charge rates just mean that it will take longer to recharge. I personally like to have enough charger so that I can fully recharge from 5% SOC to 100% SOC in less than 8-hours figuring that is the minimum amount of time I am likely to be on a dock.
That said, I do not like to be on a dock [or in a campground in my motorhome] so I try to maximize my charging to minimize my runtime.
In my opinions, the best bang for the buck currently is the Victron IP22 30A charger. It comes in either a single bank or 3-bank version and sells for about $200. I have two of them installed on my boat for 60A total and they do a fully customizable synchronized charging. It also has the ability to use tail current for final charging the Absorption phase. Compact, powerful and completely silent.
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LA batteries care about current and voltage, too much voltage or too much current are a problem, likewise too little of either won't do a good job of charging a LA. LFP care less about current and a lot about voltage. They do not like float voltages when fully charged. And over voltage charging will damage them.
With a 115a house bank and a 70a start battery, a 20 amp charger would be the minimum. The standard recommendation is 10% of the total capacity. with about 200ah capacity, a 20 amp charger would be necessary, a 30a charger would be better.
30a would also be OK for a 200ah LFP battery bank or even a 100a bank. LFP can easily accept up to 40% of the capacity for charging.The important characteristic is maintaining the voltage profile, not the amperage. A smaller charger, like the 30a will just take a little bit longer to recharge the battery, about 6.5 hours instead of 5 hours to go from 0%SOC to 100% SOC.
If your house and start batteries are connected with an ACR, then the number of batteries that can be charged from the charger doesn't matter, you only need one connection.
Here is a link to your charger's manual. Guest 2614A Owner's Manual (Page 11 of 15) | ManualsLib
On page 11 it shows that your absorption voltage is 14.3v and float is 13.3v. Both of these will work for LFP although I prefer to have a lower absorption of 14.1v to reduce the chance of one of the cells hitting the high voltage limit of 3.65v and going into over voltage protection. Many battery manufacturers recommend a charge voltage of between 14.3v and 14.6v but that means that the BMS will go into protection every charge cycle and I personally do not like that method of balancing.
Even though it would work, I would still install the IP22 30A because your 10A charging max will take a long time to recharge.
It should be noted that none of the ACR's that I am aware of will work with any LFP battery. They combine the two banks when either hit a voltage of over 13.0v. My LFP batteries spend 75% of their life at voltages over 13.0v. The disconnect when the combined voltage drops to 12.75v. My battery is deeply discharged by the time it gets to 12.75v.
These voltages are perfect for FLA but with LFP you are basically connecting them in parallel continuously. Much better to use an ArgoFET combiner that only connects them for charging currents and always keeps the two banks separate.
SI-ACR Automatic Charging Relay - 12/24V DC 120A - Blue Sea Systems
Correct, I was referring to using it with LA batteries not mixed chemistry. A DC-DC charger also works well and allows for more control over charging parameters.
DC to DC chargers is a way to handle charging of the LFP bank but I struggle with the low current that it allows. I want to maximize the current I get from my engine so have installed a 250A large frame alternator on my 23-HP diesel and control it with a Zeus regulator so that I can limit the max output to 190A to keep my batteries happy and reduce the current at higher rpm to retain enough power for my prop. As a result, I am able to charge at 180A at 1900rmp and still make 5.4kts without over stressing the engine. That lets me recharge a fully depleted 560Ah bank in a bit more than three hours. In the 27-years I have owned my current boat, I have used 1900rpm for well over 90% of my motoring. I only rarely go above that because I just do not like the sound.
Both my LFP house and AGM start are charged from the alternator but are kept isolated from each other by an ArgoFET 200-2. Both batteries are very happily charged with the 14.1v absorption / 13.3v float that I have the Zeus set to.
Hayden, that works for you, your sailing plans and your interests, however, Greg's plans are considerably more modest than yours, a simple solution will meet his needs.
I crawled around tracing wires today to try and get a handle on how the batteries, starter, charger and 1-2-B switch were wired…in anticipation of separating the starter batter and wiring it directly to the starter. Then using 1 channel of my existing charger to charge the start battery, and the other channel to charge the house bank. Will go with LA GC2 batteries for now, and when I find a deal on a Victron or Sterling charger, I will use that on the house bank. I would be set to make a move to LFP at some point, but for now, will just separate the 2 battery banks and keep the LA house bank.
What I found is that the 2 channels on the charger are wired to the #1 and #2 post on the battery switch (common I guess). I will reroute the #2 wire to the starter battery directly. The wire to the starter runs to the C post on the switch, so I will pull that and run it to the starter battery directly as well.
My Wind Instrument Raymarine T120 wireless died today…..so that will have to take priority I guess.
Greg
What I found is that the 2 channels on the charger are wired to the #1 and #2 post on the battery switch (common I guess). I will reroute the #2 wire to the starter battery directly. The wire to the starter runs to the C post on the switch, so I will pull that and run it to the starter battery directly as well.
My Wind Instrument Raymarine T120 wireless died today…..so that will have to take priority I guess.
Greg