Vehicle batteries

Samven you are confusing gelled electrolyte batteries with agm.

The group 27 northstar will rest fully charged above 13 volts, when healthy.
Mine did, for.6.years, my group31 northstar still does, for the last 3.
 
Samven you are confusing gelled electrolyte batteries with agm.

The group 27 northstar will rest fully charged above 13 volts, when healthy.
Mine did, for.6.years, my group31 northstar still does, for the last 3.
This will depend on the specific chemestry in your battery. What the plates are made from and what the specific gravity of the paste is thay used but the standard for a full charge after the surface charge is removed is 12.8 +- .1. Northstars are very high quality batteries and use very pure materials but even they state in the literature a 100% charged battery after resting will measure 12.95-13.0V. Good luck seeing that for very long in any box store or auto parts store battery.
 
People often erroniously refer to agm batteries as gelcells.

An agm is not a battery with gelled electrolyte. An AGMs liquid electrolyte is absorbed within the glass matt.

When an actual gelled elecyrolyte battery is charged at a high rate, volds can form in the gel.
Voltage, is electrical pressure and more pressure means more amperes will flow.
The battery itself decides how much amperage it will accept, at the voltage at the battery terminals, upto the amperage limits of the charging source.

The healthier the battery, and the more depleted it is, the more amperage it can accept, often exceeding the maXimum output amperage of the charging source.

A well depleted healtjy gel battery hooked to a powerful high amperage source can cause void into form in gelled electrolyte.

This does not happen with agms.
Agms if charges at high rates to high voltages can vent, so instead of 99%+ recomnbination of charging gasses, it might be only 85%. High amp recharge an agm battery at too high voltages too often, for too long, and there is the risk of 'drying' it out.

This becomes more likely as the battery ages, its resistamce goes up and it heats more during charging, creating more pressure and more likelyhood of offgassing.

Most cheap agms say to limit charging amps to 30 per
100ah of capacity


Odyssey, northstar and lifeline basically say no amperage limit, just prevent overvoltage.

Lifeine outright states more charge amperage is better. And in deep cycle service, no less than 20 amps per 100 ah of capacity. Odyssey says no less than 40 per 100.

Not sure what northstar says, I've used odyssey guidance for my northstars.

Tppl agms, the best way to restore capacity is a high amp recharge from a well depleted state, and continue to hold absorption voltage until amps taper to less than 0.5 per 100ah of capacity, then float at 13.6v at 77f.

Low and slow recharging a deeply cycled agm will tickle itnto a premature death.

80 t 100% state of charge is no less than 3 hours...ever, and just gets longer and longer the less healthy the battery.
Higher voltage will not significantly reduce 80 to 100% times.
And 14.8v or higher should not be allowed except with low battery temperatures.

Those agms which say no higher than 27 or 30 bor 33 amps per 100 ah of vaoacity dekanintimidator is one such battery, can and do easily accept more.ampergae than this maximum amperage recommendation.

I often double and triple the maximum recommended charge rate of agms, and get exceptionalnlife from them.
I just monitor them for excessive heating when high amp recharging. Only when they are older, and well depleted, and in high ambient temp, do they get over 105f, in my experience.

Not sure the full charge resting voltage of actual gel batteries. My northstars are 13.06v, the dekas agms are 12.78 to 12.84.
Small loads can drag the Northstar to 12.8, but they always rebounded to above 13 once the small loads were removed.

Watch how much amperage a battery acceptsat the voltage reaching the battery terminals.

Voltage alone can be extradorinarily misleading, and voltage does not equal a fuel gauge or am percentage

Voltage isnonlybuseful as to statenof charge whe no loadsmor charging sourcesnhave beennplacednon the batterynfor many manybhours, and atbthatnpointnitnitnuseful for accurate comparison against that same battery at the same temperature. If i were to compare.my dekas agains the northstars by full charge resting voltage. 25% or greater error would be expected.

Get am ammeter.
 
Some guy a while back said to buy the biggest battery with the lowest cca's because the "plates were bigger" and the battery would last longer. I dunno...?
 
Some guy a while back said to buy the biggest battery with the lowest cca's because the "plates were bigger" and the battery would last longer. I dunno...?
Usually lower CCA=THICKER plates, which should last longer than higher CCA=thinner plates. Seems like a quality manufacturer & attention to electrolyte levels (on a non-maintenance free lead-acid battery) provides the longest life. Along with not operating it in extremely high temperatures & keeping it topped off.
 
Dont use that mode on an AGM. In a traditional lead acid battery there is liquid acid next to the plates and if you hit them with too much voltage they will start to bubble, you can hear them when they are charging, but when you remove the charge the bubbles eventually make there way to the surface and the acid touches the plates. In a AGM there is a mat saturated in an acid paste against the plates, if they start to develop bubbles they get trapped and the acid cant get to the plate anymore so you loose that capacity and AGM cant get stratified, that only happens in the liquid acid because the acid can separate from the water and the heavier liquid goes to the bottom, boiling it mixes them together again. The paste saturated mat cant do this and boiling them depleats there capacity.
I decided to try the repair mode after disconnecting the battery completely but I monitored it with the BM-2 the entire time and was going to stop it if the voltage got excessive. It went the full 4 hours and voltage never went over 14.79v - basically, it just alternated the voltage every 5 seconds or so between 14.4v and 14.6v at the start and by the end of the 4 hours it alternated voltage between 14.4v and 14.79v. Right before it finished there was one spike to 15.2v for a few seconds which came back down slowly over about 30 seconds and then it went into standby mode. The resting voltage afterward with nothing attached to the battery is 13.12v. Resting with the battery terminal connected is 12.83v.
 
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I decided to try the repair mode after disconnecting the battery completely but I monitored it with the BM-2 the entire time and was going to stop it if the voltage got excessive. It went the full 4 hours and voltage never went over 14.79v - basically, it just alternated the voltage every 5 seconds or so between 14.4v and 14.6v at the start and by the end of the 4 hours it alternated voltage between 14.4v and 14.79v. Right before it finished there was one spike to 15.2v for a few seconds which came back down slowly over about 30 seconds and then it went into standby mode. The resting voltage afterward with nothing attached to the battery is 13.12v. Resting with the battery terminal connected is 12.83v.
This is very good info, thanks for getting back to us. You never know exactly what these charger are doing unless you have the time and equipment to monitor them. It seems they have taken a safe approach to avoid any damage. I have seen some of the less expensive chargers run up to 15.5v in AGM mode, the same exact profile they use for wet cell. It seems they just put another led on the front but did not change anything inside.
NOCO seems to live up to their reputation.
 
When a lead acid battery sits and rests 85 to 95% charged, never getting to 100%, it becomes more and more time consuming to get it to 100%.

4 additional hours held at 14.8v might not be enough.

If amps tapered to 0.4 or less when held at 14.8v, then one can assume it is fully charged, or very nearly so

If one only assumes 4 additional hours at 14.8 musy have fully charged any specific battery, without knowing the amperage accepted at that voltage

They then are making a hopeful assumption.

Get an ammeter.
Unless bliss via ignorance, floats your boat.

A true full charge is the best thjng one can do for their lead acid battery.

Accomplishing this takes a lot.of time, and more so when it has spent a lot.of time undercharged.

Get, and use an ammeter.

Any proclamations as to state of charge or charger efficacy, without an ammeter, are misleading guesses, at best.
 
When a lead acid battery sits and rests 85 to 95% charged, never getting to 100%, it becomes more and more time consuming to get it to 100%.

4 additional hours held at 14.8v might not be enough.

If amps tapered to 0.4 or less when held at 14.8v, then one can assume it is fully charged, or very nearly so

If one only assumes 4 additional hours at 14.8 musy have fully charged any specific battery, without knowing the amperage accepted at that voltage

They then are making a hopeful assumption.

Get an ammeter.
Unless bliss via ignorance, floats your boat.

A true full charge is the best thjng one can do for their lead acid battery.

Accomplishing this takes a lot.of time, and more so when it has spent a lot.of time undercharged.

Get, and use an ammeter.

Any proclamations as to state of charge or charger efficacy, without an ammeter, are misleading guesses, at best.
I don't know if I'd say ignorance is bliss but the thing was a couple of hundred dollars (not a huge deal) and at some point, I just need to get on with my life, as my time is more valuable than an AGM battery.

Thank you to everyone who took the time to help me.
 
I don't know if I'd say ignorance is bliss but the thing was a couple of hundred dollars (not a huge deal) and at some point, I just need to get on with my life, as my time is more valuable than an AGM battery.

Thank you to everyone who took the time to help me.
I am willing to spend $$ on a smart charger but not really interested in building a battery charger using a variable power supply and more. Then closely monitoring it.

But if you can show me a smart battery charger that can do a better job that some of the higher end Battery Minder chargers then I would listen.
 

This may be the good News we've all been waiting for. More power and perhaps a feeling of contentment while driving in that rush hour traffic!
 
Hmmm…Noco says repair mode can be used on an AGM. My resting voltage is down to 12.72v this morning. Just leave as is?

Don't have a NOCO, but a CTEK and it has a setting for AGM batteries the same setting that ought to be used even on reg batteries when around 0 centigrade. It does start at a higher level.
 
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