The future of Dry camping and charging with LiFePo battery

And I though charging LFP batteries was complex................

From my perspective a lead acid battery is a technology that's 150 years or more old and long past it's glory days. The sooner we can get the lead out the better.

I KNEW that would stir up your battery acids there mexicowanderer.

Hehehe,

Trojan, meaning James, is ASSSSSSSSSSSuming customers do not have access to a constant CURRENT charging device. Stepped voltage equalization is better than nothing. But for accuracy and kindness to the battery nothing on the face of the earth matches EFFICIENCY and EFFECTIVENESS 5% of amp hour capacity CONSTANT CURRENT from otherwise full-charge status toward 16.0 volts max.

Eleven hundred cycles huh? That's = to a full 50% discharge and full recharge every day of the week for 3.014 years. I'll leave it to the reader to judge.

What everyone seems to be missing here is the formula itself. 5% amperage is continued until such time as gravity in all cells reaches original density OR (The word "or" is significant. It does not mean -and- or -until- or anything else but alternative other)...

Sixteen volts is reached. Without question the lower the voltage reached to equalize the cells the better it is for the battery, the user and the power bill. The formula SPECIFICALLY does not state to continue to sixteen point zero zero volts DESPITE the gravity reading. Again, keep dipping the weak sister cell.

Constant current chargers that are large enough to imply 11 amps through 3 or 6 cells of golf car batteries DO NOT GROW ON TREES. They are hideously expensive. A large power supply can do it. So can the DC to DC converters and 12-volt light bulbs or that special 600 watt 12 booster with a CURRENT LIMITING cermet potentiometer.

"James" is not aware that such a thing is possible these days. You can call hum back and ask him if you wish.

I do try my best to offer shortcuts and better battery management on this forum. I did not spend 30-years as a hired-gun employed by battery manufacturers to play the part of peer with their engineering departments.

The FIVE PERCENT FORMULA minimizes antimony poisoning as well as cleans sulfation better than any other protocol I have ever tried. It is not my formula. I adopted it from BCI who in turn adopted it from BuShips manuals for lead acid battery management for submersible vessels during WW II.

APPLICATION engineers always try and put their signature mark on statements of fact. James did not give bad advice. He merely did not give the best advice. He thought it very unlikely anyone would have access to equipment that would mimic BCI desulfation protocol.

TOP CHARGING on the other hand IS MINE AND MINE ALONE formula for minimizing the need for formal equalization and it too recognizes the need to MINIMIZE antimony poisoning. Antimony poisoning is CUMULATIVE. Once those atoms migrate from the positive plates, the plates SOFTEN and decompose much easier and much faster. The atoms migrate to the negative Pb dioxide plate and foster intercell leakage as well as hinder the electrochemical effectiveness of the lead dioxide plate.

Remember, APPLICATION ENGINEERS are salesmen who have studied the manuals. Genuine engineers do not answer phones, and I can guarantee you if you telephone a battery company and ask for a DESIGN engineer:

a) 10,000 excuses, and endless phone shuttling but you will NOT talk to a genuine engineer. They hold the keys to the box with the family jewels.

b) If by a miracle bordering on the 9th wonder of the world, you do get to talk to a genuine engineer, his answers to your questions will be QUITE DIFFERENT from those of an educated salesman, (oops I mean applications engineer).

Because I am free from constraints of non-disclosure, have zero to gain when I am correct and my reputation to lose if I am wrong, it tends to to make me damned sure that my information is full and correct before I respond to a battery issue on this forum, within the confines of a solar voltaic home, million dollar Swan cruising sailboat or hundred foot yacht with helicopter pad.

The battery industry is incredibly complex, competitive and regulated. Over regulated. OSHA and EPA have made sure OEM walks a fine line. They are forced to use recycled impure lead. Customers, as "James" pointed out can be ignorant jerks. Too many people pontificate over lead acid batteries when they have no clue whatsoever of the entire picture. Trojan and James are forced to try and distill a complex subject into terms and actions the average Joe can understand and utilize. I'd last 4.6 minutes at that job. I'd be invited to leave at gunpoint.

I spoke to your buddy James over there in Santa Ana at Trojan Headquarters yesterday... about all kinds of golf cart batteries, equipment, leases, and charging them back up.

He says a 30 point spread in SG should be aquired before performing a 16.0V Equalize charge. He also said that if 14.8V won't bring your SG up above, 1.240 to 1.250, bump the voltage up for float V to 15.0V, and if that still doesn't get the SG up, bump it up to 15.3V float V. And if that still does not get you to a SG of 1.275, then go full monty to 16.0V and watch your battery temperature, making sure you at all times keep it below 115F when doing so.

Golf cart batteries are measured in number of holes of golf you can play on them. A Golf Cart battery has a prerequisite to not slow down or drop V over 36 holes between nightly recharging. Obviously, most managers of golf carts don't know or care about this when they get busy... and end up playing 54 or 72 holes, with unfavorable battery life results to the batteries before getting their overnight charging.

James said that indeed, while not published, 15.0V or even a bit more in 50F temps, is fine, as long as your battery does not have a roilly bubble going on inside the cells, champagne bubbles are fine. T105's are designed to handle plenty of plate shedding deposits at the bottom of the battery cell, before problems arise and the cells get build up between the plates and short out internally.

Trojan expects about 3 years or 1000 to 1100 two full rounds or 36 hole golf course cycles per 24 hour period before performance starts suffering on a golf cart battery.

Another very juicy tidbit for all you solar panel hounds / freaks that are measuring your amps in and amps out while recharging /discharging. Battery charging is only 80 to 85% efficient, you lose 15 to 20% of your amps going in recharging... so if you took 100 amp hours out, and you metered it, it will take you 115 to 120 amp hrs from your solar panels, going back in to replace the electricity and overcome thermal losses and chemical resistance to recharge back to where you originally were.

I can get gold cheap. Two dollars

A microgram...

mena661 wrote:

NinerBikes wrote:
you get that in an 18650 liIon now. 2500mAh or 2.5 amps for $4.00 per cell. Problem is it's a 3.7 v cell.

Maybe use a small DC-DC converter on the output?

well, put 3 or 4 in series... and you are at $16 for 15V and 2500mah... that won't fit Mex's cutoff for cost effectiveness.

NinerBikes wrote:
you get that in an 18650 liIon now. 2500mAh or 2.5 amps for $4.00 per cell. Problem is it's a 3.7 v cell.

Maybe use a small DC-DC converter on the output?

MEXICOWANDERER wrote:
Lithium would be IDEAL in the following situation:

Me carrying a battery into a hotel room for BiPAP backup. There the weight is critical, the battery maintains voltage to the bitter-end, and has a fast recharge time. But this cheapskate would hesitate even if the batteries were 50% of their current price to outfit an RV with them. I have my own cost/benefit ratio and five dollars per ampere hour is the maximum. Some folks who have a Money Is No Object budget will scoff at my financial derivitive.

you get that in an 18650 liIon now. 2500mAh or 2.5 amps for $4.00 per cell. Problem is it's a 3.7 v cell.

Reed, that was informative. So my take away from it was that Lifepoxy batteries like to be kept middle of the road in charge. You have a 90%-10% state of charge being best for them. If the are sitting pretty close to 3.4 per cell or around 13.6v's for 4 cells. You are doing good. Stay away from voltage peak when climbing and stay away from the voltage drop cliff when discharging. Keep at least 12.0v in them for min state of charge and 13.8 to 14.0v for max state of charge.

Lithium would be IDEAL in the following situation:

Me carrying a battery into a hotel room for BiPAP backup. There the weight is critical, the battery maintains voltage to the bitter-end, and has a fast recharge time. But this cheapskate would hesitate even if the batteries were 50% of their current price to outfit an RV with them. I have my own cost/benefit ratio and five dollars per ampere hour is the maximum. Some folks who have a Money Is No Object budget will scoff at my financial derivitive.