Voltage on FLA batteries

[spudsdailey]

I have 6 Trojan FLA batteries, L16-AC's. They provide about 1300 ah. No problem charging from engines, however I am a little concerned on shore power.

I have a new Magnum inverter/charger that puts in max, about 135 amps. After the charger goes through its cycles, the batteries get to 100% SOC. I assumed they go to float, however, it appears that the charger turns off, and the batteries over 12 hours go from 13.4 volts to 12.7 at which time the charger turns on and brings them up to 13.4. During this process the SOC may read as low as 98%. There is very little if any load on the batteries while on shore; perhaps bilge pump occasionally.

Is this proper, or is there a setting on the charger I need to adjust?

Your thoughts are appreciated.

[motion30]

My Magnum charger never shuts off it goes into float at 13-3 and stays there for as long as it has power. I believe there is a problem with your charger

[john61ct]

Originally Posted by spudsdailey

it appears that the charger turns off, and the batteries over 12 hours go from 13.4 volts to 12.7

This part is normal after charging finishes, settle to "resting", quickly with loads present.

But you want Float to carry the loads so the bank stays Full, and your charger has all the settings available to enable that, including adjusting Float V higher if the bank chemistry calls for that.

Do you have a remote for it?

Read the manual of course.

[smac999]

there are many different magnum versions. every year the programming was different.

the older ones were horrible at charging.

the newer ones have a "final charge" setting. from there you can set the float on and off once full. I'm guessing this is your issue if it's a new one. it's designed for if you have multiple chargers. (it will let the other ones take over)

some of the older ones would just say "full battery" and not float as well.

if you have a 1300ah bank. you should really add a 2nd charger. 130a is too small. are you on a 30a or 50a shore cord? if only 30 you'll probably stuck with the one charger.

[spudsdailey]

Thank you for your input.
The Magnum is brand new. I think 130 amps charge is fine. This is on a powerboat; I have twinn Cats with larger alternators that both charge the house bank. So when I am back at dock, the bank is usually 100% SOC. I do occasionally anchor for a night or two and charging with the generator does take a bit of time. However, that is a separate issue.

I am more interested if my current charger should cycle on and of in float, or should I program it to keep the charge at say 13.3?

[sailorboy1]

You should ask your question to the manufacturer!

[S/V Illusion]

Originally Posted by spudsdailey

Thank you for your input.
The Magnum is brand new. I think 130 amps charge is fine. This is on a powerboat; I have twinn Cats with larger alternators that both charge the house bank. So when I am back at dock, the bank is usually 100% SOC. I do occasionally anchor for a night or two and charging with the generator does take a bit of time. However, that is a separate issue.

I am more interested if my current charger should cycle on and of in float, or should I program it to keep the charge at say 13.3?

What model Magnum charger is it?

[john61ct]

Float all the time is not required.

But when loads are present the charger should be carrying them so not wasting bank cycles.

What batteries?

You may need the remote to really tweak things, but if it isn't an expensive fussy chemistry, likely can do without.

[spudsdailey]

The batteries are Trojan L16-AC, 6 volt 435 Ah. I have 6 of them.

The charge/inverter is a Magnum Energy MS2812.

[spudsdailey]

By the way I have the ME-RC remote that controls the inverter/charger.

[john61ct]

See your chargers manual, and the FLA charge specs from Trojan here

https://www.trojanbattery.com/pdf/Tr...UsersGuide.pdf

Note 12V = 6 cells, so multiply voltages given by 6.

Note the standard terminology is

Bulk / CC is "striving" to reach the voltage setpoint

Absorb / CV afterwards, holding V while trailing amps decline

Only drop to Float after the Full point is reached, aka endAmps, .01-.03C

If this does not match your docs, best to "translate" when asking Qs here.

Trojan also likes a higher V "finishing charge" to mix the electrolyte, your charger may not accommodate both setpoints, I would then just use the higher spec for Absorb.

Discussions as to details, interpretations
https://www.google.com/search?q=site...+float+voltage

Pay particular attention to MaineSail

http://www.cruisersforum.com/forums/....php?p=2648005

[sailinglegend]

Originally Posted by john61ct

Float all the time is not required.....

This is a very dangerous statement!!!!

Please can you justify this without irrelevant links in your post below. Indeed some of those posts clearly disprove your statement above. You should read your own links!

I also note that you repeatedly don't follow the original posters question - in this and many other threads. He told you he had L16s in #1 - you joined this thread in #3 but still in #8 you had to ask "what batteries"?

Research shows that you make about 50 posts a day on Cruisers Forum alone and are active on about 25 other forums. This explains why you can't keep in touch with the OP's post and the thrust of the threads. You always have to push 'other' irrelevant ideas of yours - like endAmps - which has now after much criticism changed here from 0.005C to 0.01C to 0.03C which you say is 'Full'! This is wrong - it may be 'cruising full' as Maine Sail would say but not truly 100% full which banks need to achieve as often as possible - at least every 10 days - by checking that the 'return amps' has reached 0.005C endAmps.

So please John stop being just a compulsive poster with so many thread drifts.

So let me clarify for the poor readers who don't understand most of your posts that endAmps is the actual current going into the battery bank, not the current generated by the charge source. The battery is "full' when endAmps is 0.005C or 0.5% of the battery capacity at greater than 14.4v at 77F. So a 400Ah bank would show 2 amps charging at absorption voltage.

The trouble is ALL chargers will drop down from absorption mode to float mode early and let float continue the charging to fully charge the batteries. Most default settings for absorption time need to be extended so that the charger drops down to about 95%-98% of full - maybe 0.02C o 0.03C - I'm not absolutely sure on these figures and would welcome clarification.

Chargers do this because they are designed to charge batteries and not 'overcharge' them. This final process can take many hours and is why most boats can't get to 'fully' charged on solar or engine alone.

To verify 'fully' charged the best way is to check return amps=endAmps by turning the charger off - waiting a few seconds - and turning it back on. It will immediately go back into bulk mode and almost immediately into absorption mode. If the return amps for the 400 Ah bank is showing say 4 amps, that 0.01C then the batteries are still not 'fully' charged so leave the charger on. If endAmps has been achieved at 2 amps then the 400 Ah bank is fully charged.

But now you have a problem that the bank should not be left in this state of being fully charged AND sitting at absorption voltage - this will 'overcharge' the batteries. Its not over current that overcharges batteries - they decide that themselves - its over voltage. If you did this every day and the bank sat at 14.4 volts for only two hours before switching to Float for days or weeks this would dry out the batteries which is very dangerous for sealed 'leisure' batteries that can't be topped up. This is a complex subject but I suspect cheap sealed Flooded Lead Acid batteries is what the majority of weekend cruisers reading these forums have.

So turn off the charge source and only switch it back on after loads have reduced the capacity considerably. Its a shame that most chargers can't do all this automatically, or allow you to jump straight to float mode to maintain the load demands.

[john61ct]

Float is not - in itself - necessary.

In itself, if no loads, and if the charger is configured to turn back on when the need arises.

Depends on the batteries, healthier for some to not Float.

With **those** batteries, yes Float should be (re-) enabled.

[Stu Jackson]

Originally Posted by sailinglegend

>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
This is a complex subject but I suspect cheap sealed Flooded Lead Acid batteries is what the majority of weekend cruisers reading these forums have.

>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>

That was a very astute and comprehensive post. Thanks.

One thing caught me right there at the end and in the quote. If this "issue" is leaving the boat plugged in and the charger is in float, then this is NOT an issue for "...the majority of weekend cruiser..." because they can and do.

What most all of these "How to charge" topics have been directed towards are active cruisers who 1) don't plug in; 2) want to minimize run time for generators.

In that case, generally, the "smarts" of the charger seem to be less important than its size, because knowledgeable cruisers who are into battery charging tend to have learned this.

Weekend warriors, not so much, but then, they don't have to because they stay plugged in all week and their batteries DO get full.

Two different audiences, although the ww can learn from this, too.

[sailinglegend]

Originally Posted by john61ct

Float is not - in itself - necessary.

In itself, if no loads, and if the charger is configured to turn back on when the need arises.

Depends on the batteries, healthier for some to not Float.

With **those** batteries, yes Float should be (re-) enabled.

I still don’t understand how you justify your comments about float is not necessary, it’s just an unnessary confusion for most readers here.

If the charger keeps ‘turning back on when the need arises’ - is that at say 12.8v - then it goes straight up to absorption voltages when it should go to float voltages because the battery is almost fully charged. Staying up at absorption voltages for say three hours or longer every day when the batteries are fully charged is dangerous for the life of the battery - but I know from previous threads that you don’t appreciate that. Maybe you could explain why that is ok?