First Top Charge

[sjturbo]

I finally got my volt/amp meter wired in to my Mega Watt and started my first Top Charge. Initial battery voltage was 13.2v. Mega Watt was set to 15v. Turn-on voltage was 14.8v @ 33a. It quickly went to 15v @ 4.8a. Within 15 minutes it had dropped to 3.5a. I thought I would check readings in about an hour? I will also check for modest bubbling. Can I shut off the MW at that time to measure the battery voltage?

[NinerBikes]

MEXICOWANDERER wrote:
The Mega is plenty big enough. I mused this for a bit and came up with an idea. Apply the Mega. 15.0 volts. This time disregard the amperage. Instead monitor the acid in all cells. When all cells are bubbling slightly note the time elapsed between start to finish. This can easily eat a couple of hours, so don't worry. Just ensure you are starting from a level of battery charge that is easily repeatable. That way you can top charge with a timer. I'm soooooo lazy I use an interval timer, but one with a battery backup (I further cheat and use a cheap 12 volt voltage regulator and timer and suck power off the 24 volt bank - not likely to run out of memory). A weatherproof timer is inexpensive and you will look for a lawn sprinkler TYPE timer, which is called an INTERVAL TIMER. While I'm doing important things like reading, snoring, or staring out across the sea the timer and charger is doing it's thing. Not important whether your timer is AC or DC, but it is important that it not lose it's mind (timing cycle) because of a power outage.

Let those batteries bubble a little. If one cell is reluctant, find out why. Usually it is a sign of sulfation. Do an equalization. Then try it again down the road. Bubbling the start of which is an incredibly underused tool in battery management. Use it to VERIFY your perception of state of charge.

APART: I would love to see - it would be my reward to see declarations here "Gee I followed this stuff, it was simple, and it apparently doubled the lifespan of my batteries". Then I will have accomplished my goal. Vamos A Ver.

The increase of sophistication of these threads puts a smile on my face - thanks guys, for the time being, that is reward enough 🙂

Oh come on Mex... I have two H-1 dated 1275's that were deemed in need of recycling by December 2013, thrashed hard for their 500 recharge cycles in golf carts here in So Cal, where they play golf all year round in shorts, every day of the week, every day of the year, rain permitting. They were two years old and pounded on daily when I got ahold of them.

Is squeezing another useful year out of both of them, still with no major signs of quitting, using your technique, considered reward? Let's see how far they go, they are working for me, not me working for them, so that is a win-win. If I get one more year out of them, is that considering their life being doubled by you? There's your sign, I am sure I can get another year out of them, so consider it a success, your advice has worked for me, so far. A good top charge adds so much more capacity to my batteries, the first week or so of camping, not much sag.

Now then... my reward will be you managing to score something simple like spare new batteries and portable chargers for you Galaxy S2 SGH-I777 AT&T smartphone I gifted you while you are down there in Old Mexico. You have your work cut out for you.

[jrnymn7]

AFAIK, that 50a shunt is only good for monitoring the mega watt's amp output. If you're looking to monitor the battery bank, you may need to use a 500a shunt. They usually have 3/8" bolts, so you would just connect a short heavy cable from bank neg to one shunt post/bolt, and ALL other negs to the other shunt post. All other negs would include all loads, as well as the charger's neg cable. This way everything, in or out, will be monitored.

Page 7 of this manual shows how it's done with a Trimetric. Page 8 explains the wiring from shunt to meter:

http://www.bogartengineering.com/sites/default/files/docs/TM-2025Install%20Instructions9-12.pdf

Can you post a link to the meter and shunt you have now?

thanks

[sjturbo]

I just ordered the Freas, looking forward to being able to read through good glass. One of the many puzzles I have not been able to answer is when charging with the Mega Watt how do I need to wire in the volt/amp meter so it is reading what the battery charge is vs the Mega Watt output? I have the meter tied to the shunt on the negative output of the supply now. So how should I have it?
Thanks.

[MEXICOWANDERER]

Jrnymn7,

That is because from the onset I knew the battery was the boss of the game. Diplomas, degrees, and an entire inventory of toys amounted to squat. The battery was and is king of it's own hill and you either play by it's rules or get the hell off the hill.

Out of all the phrases, all of the comments I ever made, my customers made my engineers made there is one that stands out "Why the hell doesn't...?" Electrochemical devices gain personalities. Some are good, some are bad, some are, well, to be frank...seemingly haunted. Trouble in paradise happens when a designer declares "This will make the battery do..." Boy have I got news for them "Let's do this and see what the battery does..." is the correct attitude. Use the number "10" to describe the number of different designs, then multiply by another 10 to gain an appreciation of the different ways a cell can age, then multiply that by ten to assume the number of ways a battery can be maintained and used. The sum is going to be predictable? On paper? Shirley you jest! Actually the number of permutations far outstrips the pitiful numbers written above.

However the owner who bothers to learn just a bit about the "personality" of his electrochemical experiment can indeed predict and calculate to a definite point what to expect. By controlling voltage and time, suddenly the unknown becomes not only wide open, but it becomes easy, furthering the knowledge by learning trends & tendencies of the battery, then makes battery management so easy, it's almost funny.

Jesus, tells me "You write every day three hours, then go visit the batteries ten minutes, some days not at all?" Truer words were never spoken. Just completed a solar still for mineral free water. Imagine a shallow bowl six feet in diameter. Lined with shiny side aluminum foil. Four inches up reposes 50' of three-eight's inch copper tubing painted flat black. Two window panes cover the coil. Suction is out of a 5 gallon black can. It yields about half a gallon a day, and the spiral needs to be blown down (drained). I use 60ppm "purified" water as feedstock. When I accumulate ten gallons it will be hauled to the gen shed and be set up shoulder high. There are 2 coils, one heating, one condensing.

in closing this little ditty may I remark that I follow each and thread, each comment, every observation, every chart. Time to go - the girls are here and I have only three days left before I have to head back to Baja California. What's on the menu? About 10 lbs of lobster, cold macaroni salad, salsa pico de gallo on tostadas, and cantaloupe agua fresca. At least I got to bring the kids one load of gifts! Thank god for Volaris 99 dollar flights!

[mena661]

sjturbo wrote:
Menna661, Tell me about your batt Bank. As you may have read it took me about 11hr to get my bank to 14.8v. I realize that #4ga ,may have something to do with it but 11hr seems like a long time even with that gauge. What is your starting voltage and how long does your Mega Watt stay at a high amperage? My voltage/amperage started out at 15v/33A. Amperage dropped to the 3-5A range quickly.
So tell me jrnymn7, Is your PS a Turnigy 1080Watt? How do you Top Charge?

I don't use mine for regular charging unless it's from higher SOC's where I don't care about high amps, I use my Iota converter (well....when it was working) or my Black & Decker portable for that. I also don't top charge much cause my float V is good. Mine is used primarily for floating and the occasional de-stratification charge (tall batteries...something you guys don't have to worry much about). For the de-strat charge, I start out with 14.8V and let it run for 15 mins. Typically starts out at 24A and tapers from there.

EDIT: I did do a short boondocker this past weekend. When got home batts were down about 14Ah. Started charge at 14.7V. Amps went up to 36.4 and hung out there for a few minutes then tapered to 29.

[jrnymn7]

Mex,

What I have noticed is no-one comes on the forum complaining about good battery management techniques, like the ones you recommend, resulting in under performing batteries. Otoh, there is no shortage of threads regarding the use of converters resulting in under performance. That, to me, speaks volumes!

[jrnymn7]

Yes, I have the Turnigy 1080w. You're probably familiar with the over-current-protection issue I have with it. I have solved that by simply clamping on my cps1620 for a few minutes. So, yes, a bit of a pita, but no real biggy. I have yet to try it on very-near-full batts. The starting amperage may or may not still spike over its ~60a set point, at power on. If it does, on goes the little gophert for a few minutes.

Lately I've had my 430Ah bank split, so I've been using all 3 chargers to see how each performs. The modified pm4b-45 can be dialed up to 16v, as well as both the turnigy and gophert. So I'm covered either way. But the issue is still keeping up the amps while charge acceptance declines.

Remember, top charging borders on "over charging", as you're trying to force amps into a batt that says its quite near full... kinda like trying to put away that last hotdog in an eating contest.

EQ'ing IS overcharging, and the same issue exists... trying to force feed current into a greatly diminished load... kinda like that Monty Python skit where the waiter offers that really big guy a 'wafer thin mint', after he's already eaten way more than needed. But the gophert, being variable-adjustable, (meaning amps and volts can be adjusted) allows for the amps to decline as usual, but then when they start coming back up as the battery starts to overheat slightly, the amps are limited to my 5% setting, thus preventing thermal run away... at least that's my understanding of what's going on.

So, to answer your question, I do a half-azz top charging like everyone else. The best one can do with a constant voltage charger is bring the batts to a very low amp reading at 15-16 volts. I generally bring mine to about 2.5 amps per 2-6v's, at 14.8v. And if an EQ is in order, I will take them to about 2a at 15v before EQ'ing.

And 'til now, I have always done roughly 80-97's, while boondocking, so a lot of top charging was not needed, but if I switch to say 70-90's next season, I will have to stay up on the top charging, weekly or bi-weekly. I will let the SG readings determine that. Of course, going solar next year will change everything, as well.

[MEXICOWANDERER]

The Mega is plenty big enough. I mused this for a bit and came up with an idea. Apply the Mega. 15.0 volts. This time disregard the amperage. Instead monitor the acid in all cells. When all cells are bubbling slightly note the time elapsed between start to finish. This can easily eat a couple of hours, so don't worry. Just ensure you are starting from a level of battery charge that is easily repeatable. That way you can top charge with a timer. I'm soooooo lazy I use an interval timer, but one with a battery backup (I further cheat and use a cheap 12 volt voltage regulator and timer and suck power off the 24 volt bank - not likely to run out of memory). A weatherproof timer is inexpensive and you will look for a lawn sprinkler TYPE timer, which is called an INTERVAL TIMER. While I'm doing important things like reading, snoring, or staring out across the sea the timer and charger is doing it's thing. Not important whether your timer is AC or DC, but it is important that it not lose it's mind (timing cycle) because of a power outage.

Let those batteries bubble a little. If one cell is reluctant, find out why. Usually it is a sign of sulfation. Do an equalization. Then try it again down the road. Bubbling the start of which is an incredibly underused tool in battery management. Use it to VERIFY your perception of state of charge.

APART: I would love to see - it would be my reward to see declarations here "Gee I followed this stuff, it was simple, and it apparently doubled the lifespan of my batteries". Then I will have accomplished my goal. Vamos A Ver.

The increase of sophistication of these threads puts a smile on my face - thanks guys, for the time being, that is reward enough 🙂

[sjturbo]

Menna661, Tell me about your batt Bank. As you may have read it took me about 11hr to get my bank to 14.8v. I realize that #4ga ,may have something to do with it but 11hr seems like a long time even with that gauge. What is your starting voltage and how long does your Mega Watt stay at a high amperage? My voltage/amperage started out at 15v/33A. Amperage dropped to the 3-5A range quickly.
So tell me jrnymn7, Is your PS a Turnigy 1080Watt? How do you Top Charge?

[jrnymn7]

sjturbo,

Like with all things electrical, big amps cost big bucks. This includes buck and boost converters. It gets to a point where the buck/booster gets as expensive as another charger.

I had recommended a bucker for getting V down to 8v for EQ'ing individual 6v batts. But for top charging the full bank, you may be better off boosting that PD 9270's output? See Mex's 'Playing with dc-dc Boosters' thread.

But you'd still be into a fairly high amperage booster, so it will get costly. Notice the one Mex links to is limited to 12a max output; perfect for a 220Ah bank. This is where bank splitting comes in. It eliminates the need for such high amperages (12a vs. 24a, in your case) But, of course, it all depends on how accessible your bank is, and how much time you want to spend re'and re'ing wires.

I went with a 60a adjustable 13.6-18v power supply, so that I can do regular top charging without overtaxing it's duty cycle. But it still doesn't compare to the versatility of the cps1620.

But it still doesn't deal with the constant current issue. It's one thing to supply power to a constant load, such as a string of led lights, it's a whole other thing when dealing with an ever decreasing load, such as a battery that's being charged. I'm still trying to figure what would best solve this issue. How does one maintain that 5% rate throughout, without continually raising the voltage?

[mena661]

sjturbo wrote:
Morning MW. Thanks for the kudo's! Since it appears that for Top Charging the Mega Watt is somewhat inadequate for my bank, (recommended 5A/100ah, constant for 470ah ~ 24A), is there a "bucker" up to the job or should I look at an alternative? I'll be ordering the Freas today. Thanks again!

The MegaWatts come in 30 and 36A. Plenty for your bank. I use the 30A on mine and it's larger than your bank. The smaller chargers just take longer to get things accomplished but when you're on shore power, that doesn't matter much. If you're boondocking then you need the bigger chargers.

[mena661]

jrnymn7 wrote:
Thanks, Mex,

I was wondering if the resting V could hold strong while SG drops.

Most definitely! I've seen 12.8V on my batts with a 1.265 SG. Voltage doesn't tell me squat! I get more info looking at amps draw. If I see anything more than 0 amps on my Victron on float (technically this would be net amps), either I just came back from a boondock trip and the batts are not 100.000000000000000% full (after charging, batts on float I'll still get some NET charging amps for a day or two even if SG says they're full) OR I have a problem (had to fix TWO different wiring issues). I ONLY use voltage to see if the charger is running properly.

[sjturbo]

Morning MW. Thanks for the kudo's! Since it appears that for Top Charging the Mega Watt is somewhat inadequate for my bank, (recommended 5A/100ah, constant for 470ah ~ 24A), is there a "bucker" up to the job or should I look at an alternative? I'll be ordering the Freas today. Thanks again!

[MEXICOWANDERER]

And again, I'll point out that battery management is like learning to use a computer - confusing and frustrating at first, then a laugh-a-minute later. One a person "knows their battery bank" it's more effort to go out and fetch the paper from the driveway than to manage batteries. My son-in-law has a 6th grade education from rural Mexico. His intelligence is plenty high. He has learned how to manage batteries correctly and he loves it. The community now refers to him as a "Battery Guru".

I remember the look of horror on the face of the battery store owner when Jesus hauled in a 500-amp carbon-pile and Freas hydrometer to check group 27 batteries before he purchased one for his "lancha". Out of a stack of 7 batteries, Jesus, culled six, and cherry-picked the best of the breed.

Once-per-month top charging: Recommended constant 5 amp per 100 amp hours input for one-half hour via a trusted (battery backup for memory) interval timer, is plenty. That will free a lot of your time.

Storage temps of less than 0 C need a full forty minutes of 5% amperage. Pianotuna could use almost an hour a month. And a hot water bottle 🙂

[jrnymn7]

Thanks, Mex,

I was wondering if the resting V could hold strong while SG drops. I will keep a better eye on SG's this winter, while the batts are "hybernating", and if necessary, hit them with a good stirring.