Premium AGM batteries for track/race use (Braille, Odyssey, Northstar X2, etc.)

Ironically, most (if not all) of the chargers on that list can not supply the current that Odyssey recommends for optimal charging: at least 40% of the battery C10 rating e.g. at least 40A for a 100Ah battery. The minimum allowable charging current is 10% of the C10 rating.

LOL yes, I noticed that. But they can do above the 10%.
 
Here is the said list of approved chargers for Odyssey:

What is special about Odyssey charging and float requirements?
I have two Battery Minder chargers, both approved by Odyssey. One is specifically for AGM batteries https://www.batteryminders.com/2012agm-12v-charger-maintainer-sealed-agm-lead-acid-batteries, the other is for all types, with three settings, an AGM/Flooded setting (yes, they combine them), a lithium, and an "Odyssey" setting. https://www.batteryminders.com/batt...tainer-desulfator-lithium-charger-maintainer/
 
Have you considered the optima batteries? They were at one point the battery of Choi when I raced in the scca.
 
Have you considered the optima batteries? They were at one point the battery of Choi when I raced in the scca.
Optima has developed a reputation for poor quality and life over the past decade, which is a shame, they used to be great. Early failures, a single deep discharge would permanently lower CCA and leaking through the two black vents caps on top. I personally had three red tops develop leaks out the vent caps, even though the battery was performing fine. I gave up and moved on to other AGM brands
 
......What is special about Odyssey charging and float requirements?
I have two Battery Minder chargers, both approved by Odyssey. ...
Odyssey requires a float voltage (at 77F) of 13.6V, preferably with temperature compensation. I bought a Battery Minder 2-3 years ago, but returned it because the float voltage on the Odyssey setting was only 13.2V
 
Odyssey requires a float voltage (at 77F) of 13.6V, preferably with temperature compensation. I bought a Battery Minder 2-3 years ago, but returned it because the float voltage on the Odyssey setting was only 13.2V
Actually Odyssey claim a typical AGM voltage rate recommendation of 13.5 to 13.8V in their instructions for use: "The trickle charge voltage measured at the battery terminals must be between 13.5V and 13.8V." https://www.odysseybattery.com/wp-content/uploads/sites/2/odyssey-battery-owners-manual.pdf That recommendation is common to many AGM battery manufacturers and the industry as a whole. But that is for float or trickle, is the charging algorithm recommendation different perhaps?

My Battery Minder 2012 AGM does a temperature compensated (48F garage) float voltage of around 13.54 to 13.65. It will go higher when it drops into the 30s. Are you saying at warmer temps it will be at 13.2V? I'll have to monitor that as we move into summer. But you may be onto something, as the BM manual states that at temps from around 70F it should be 13.6V and it temperature compensates higher, or lower from that set point. So if temps are in the 40s, I should be seeing 13.8V or so.

I have not checked the float voltage on my Battery Minder 128CEC2 yet (which has the Odyssey specific setting), as I only received it yesterday.
 
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My buddy had a 12248 Bminder when they first came out 2007ish without the optional temp sensor.

IIRC it frustratingly seemed to revert to GEL setting after a certain amount of time, when set to float AGM/WET, and i believe this was 13.2v, but its been 15 years.

I used to borrow it for extended periods when my marine flooded group 27s started showing obvious performance loss. It Never made any improvement, even when I'd take it out of service and let it 'pulse' for 6 weeks.

AGMS have so little self discharge, that they should ONLY be held at float voltage when there is a significamt parasitic load on the battery which will discharge it.

Their Ideal float voltage when there is a parasitic load on it, is dependent on the amount of load.
Too low and the battery will discharge ever so slightly
too high and it will over charge slightly.

The bigger the load, the higher the float voltage should be so the charger provides the all the juice to the load, rather than the battery providing some of it.

Finding the exact perfect float voltage, for a specific battery, can be done, but is in the curious OCD enthusiast department. When a manufacturer provides a wide range like 13.5 to 13.8 it is more or less a 'good enough' to prevent premature warranty returns in the expected use of a majority of users uses. They are not going to provide the asterix and the reasoning behind it, as the average consumer would say Ahh haa and buy a product without the enlightening , or more likely confusing, asterix.

If one wants to find ideal float voltage for their battery they need a precise ammeter and an adjustable voltage power supply, time and curiosity, and it would help to have battery in climate controlled environment once ideal FV is established. Even then, Ideal float voltage will change as the battery ages.

Float voltage when held for 12 to 36 hours after a period of time held at absorption, can get the 99.1% charged battery to 100%, and this is good for the battery's ultimate longevity and performance.

Float voltage held after this time, for ideal longevity of the battery, needs to be spot on ideal for that specific battery's temperature, and the amount of potential parasitic load on that battery.

Long term floating can lead to issues when the voltage held is outside ideal, but good enough is likely only missed when the battery is held well outside ideal in significantly hotter or colder temps than the 77 to 80F all manufacturer voltage recommendations are based upon.

When the AGM battery has NO parasitic load, holding it at an unideal float voltage is not doing the battery any favors, and even holding it at ideal is not beneficial after true 100% state of charge is attained.

but most applications the vehicle will present some degree of parasitic load.

I bump my unused AGMS to 13.8 for a few minutes every few days....see how long it takes the ammeter to lower down to low levels, then bump voltage upto absorption, watch how long it takes amperage to lower to similar levels, just to sake curiosity, then let batteries sit, perhaps check OCV every week.

I got a 4 year old UB12180 , 18 amp hours when new. It is in serious decline now, able to provide only 6.2 amp hours before voltage tanks below 10.5, and takes 8.8 amp hours before amperage at 14.7v to taper to 0.19, at which point it starts rising again as the battery heats.

This battery if fully charged and left disconnected from all loads will hold 13.5v for a hour, be 13.3v after 6 hours and 2 days later be at 13.11v.

It is fully charged, but is down to about 30% of its original capacity.
it requires I return 130% of the energy removed from it, to return it to full charge, whereas a healthy TPPL AGm is about 105%, and a flooded about 110 to 112%.

if I leave it at absorption too long it starts heating exponentially.

Even at float it sucks up a steady 0.11 amps and that seems to keep it a few degrees over ambient.

ALL AGMS at near end of life are prone to similar.

One interested in batteries and their performance throughout their lifespans should really monitor amperage flow at the pressure one is holding the battery at, unless they also like to drive without speedometer odometer or fuel gauge.
Those who believe voltage = a definitive state of charge, or state of health, or remaining capacity are misinformed.

Voltage is but one clue.

There are inexpensive adjustable voltage "12v" power supplies meant for LED lighting that can act as battery floaters, for those insisting on finding and holding ideal float voltage.

I played a LOT with a cheapo model and it was a great learning experience, but then went with a Meanwell Rsp-500-15, modified its voltage adjustment potentiometer, added more heatsinking and ventilation, and it will output upto 40 amps, seeking and then holding any voltage I choose between 13.12 and 19.23v.
It's got a ammeter, voltmeter, watt hour and amp hour counter on it, as well as an 'Ideal diode' so that shoud the 120vac power fail, the fans cannot drain the battery.

I can easily adjust voltage to the hundredth of a volt, and watch the amps fly, or trickle. The battery itself decides the flow at the pressure I choose.

40 amps is just enough to keep my group 31 Northstar happy in Deep cycle duty.
I also have a 100 amp adjustable voltage power supply.
Sometimes i combine them for close to 140 amps, but I need two different 15 amp household circuits to power them both into a healthy depleted battery.

The Northstar-31 had no issues gobbling up 136 amps when depleted 67 of its 103 amp hours.
 
Actually Odyssey claim a typical AGM voltage rate recommendation of 13.5 to 13.8V in their instructions for use: "The trickle charge voltage measured at the battery terminals must be between 13.5V and 13.8V."
The 13.6V at 77F float specification comes from the latest Odyssey June 2021 Technical Manual. The manual also specifies a temperature compensation of +/- 18mV per degC variation from 25degC. The optimum charge voltage is 14.7V at 77F (25degC).

Odyssey used to recommend 6 hours of float charging after the bulk and absorption phases have been completed, but I don't see that recomendation anymore in the latest tech manual. They also used to recommend a temp comp of 24mV per degC.

 
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My Battery Minder 2012 AGM does a temperature compensated (48F garage) float voltage of around 13.54 to 13.65. It will go higher when it drops into the 30s. Are you saying at warmer temps it will be at 13.2V?
Yes, that is how my new Battery Minder 128CEC1 was acting, with a float voltage of 13.2V at the reference temperature of 77F. That is 0.4V below what Odyssey specifies as optimum. At 48F the Odyssey recommended float voltage would be 13.9V. I contacted them about the float voltage being too low in the Odyssey mode, but they ignored my inquiry. So I returned it to Amazon.
 
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My 2017 Corvette, when tested for parasitic draw according to the GM procedure, is 20-30mA. Newer cars are probably even more.
 
Yes, that is how my new Battery Minder 128CEC1 was acting, with a float voltage of 13.2V at the reference temperature of 77F. That is 0.4V below what Odyssey specifies as optimum. At 48F the Odyssey recommended float voltage would be 13.9V. I contacted them about the float voltage being too low in the Odyssey mode, but they ignored my inquiry. So I returned it to Amazon.
So my observations with both of the Battery Minders I purchased: when used in the AGM settings, the base line float voltage if temperature compensation is turned off is 13.2 volts (or at 70F with temp comp on). This is contrary to the user manual that states the base line float voltage is 13.6 volts. When you activate the temperature compensation, then that adjusts the voltage higher if cold, or lower if warm. In an upper 40F garage I am seeing between 13.54 and 13.63 volts. If temps drop into the upper 30F I see voltages approaching 13.7 volts.

When using the "Odyssey" setting, the float operation is unchanged.

I called Battery Minder today and spoke with "Wayne". He says what I am seeing is "normal operation". They have changed the algorithm to a 13.2 volt base line float voltage. It will temperature compensate up or down from this base voltage at 70F or if temp comp is turned off. He says the change was made a year or so ago and was done to reduce incidences of overcharging and damage to batteries. He claims this will still adequately charge an AGM battery, while minimizing the risk of overcharging or losing electrolyte (moisture) whether in a flooded or AGM battery.
The "Odyssey" setting simply takes the battery to a higher voltage during the charging phase, per the Odyssey recommendation. I asked why it doesn't float at a higher voltage per Odyssey's and many AGM manufacturer recommendations, and he again stated that overcharging is a concern and this lower float voltage will avoid that.

In reviewing my older battery chargers compared to my newer ones, I do note that all my older ones float at 13.6 to 13.8 volts and all the newer ones float at 13.2 to 13.3 without temperature compensation.
 
I spoke with Bruce Essig at Odyssey years ago, and he was rather adamant that if one could not Float their battery at the recommended temp compensated voltage, to not float it at all.

When I fully charge my Northstar, holding absorption voltage until amps taper to really low levels, or start rising again, then float my Northstar too low, it discharges slightly.

I know this as when I bump pressure back upto 14.7v, it takes a period of time before amps again taper to the low level that caused me to declare fully charge previously, then turning voltage down to the too low of float voltage. This indicates the battery was discharging slightly, when floating too low

for those insisting on exact float voltage and with a tinkerer mindset:
hook this Buck converter to the output of an old 19.5vDC Laptop power supply:
61mTGHw788L._AC_SL1000_.jpg


Say the supply is rated for 6.5 amps output. This device will step down the 19.5v to whatever one chooses, via one potentiometer, and the other potentiometer allows one to limit the maximum amperage

put this on the output of the buck converter so you can see voltage and amperage and amphours/ watthours.

They get a little inaccurate under 0.4 amps, reading low, but is 'good enough' depending on where one sets that line.


it should be noted that on each and every AGM i have cycled to death, at near end of life, amps will not taper to the low levels they once did.
At too high a float voltage in this end of life stage, the battery will warm up, and the amperage required to maintain that voltage, will keep rising, even with the warming battery, and then that same float voltage would be too high even if the battery was still healthy.

Too high a floast voltsage on an end of life AGM battery, can lead to thermal runaway, which can be dangerous.
think of all the AGM in the Uninterruptible power supplies that are melted and stinky.

Too low a float voltage is safer, on an end of life battery.
Makes charger manufacturer retained lawyers happy, but makes newer healthy batteries age faster.
 
I think what is most annoying about Battery Minder, is they changed the float algorithm at least 1.5 years ago, but have not updated any of their documentation on their website or in the Instructions for Use included with their battery maintainers.

Wayne at Battery Minder, did say if I wanted a unit that floated like the original documentation, at 13.6 volt base line, with temperature compensation, he could recommend one of their "Aviation" rated models, which apparently follow a more strict protocol.
 
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