gnarledwolf said:
Nah... bought it last year in Quartzsite. We were trying to put through a quicker charge up with a bypass... but it was only to be for a few hours... then we got called away and forgot, THEN the sun came out of hiding and reached the battery... after that we got a few good weeks of charging... but it slowly died off after that. Problem is we really don't know, we only get about 5 hours charging time around here so our battery might only be getting a top charge then dropping back down. Going to have to take it back to the desert and give it a few good days of charging to know for sure.
Matt
Well, not sure what is really going on with your discharge/recharging pattern, or what happened with your bypass procedure and the sun unexpectedly coming out.
AGM batteries are often seen as a super battery, but the fact is that they require full charges more often and also require the occasional higher amp recharge.
Deny them both of these and they will fail faster than a flooded battery would in the same usage.
So any recovery at this point will not be best accomplished by a few days in the desert with more low and slow solar, it would be most likely to occur by a high amp recharge, say 30 amps per 100AH of capacity, and then hold a voltage of 14.4v to 14.8v for 4 hours after the battery first achieves 14.4v via the high amp recharge. Then a 50% discharge that night then another high amp recharge.
Accomplishing this high amp recharge is not really easy to do without either having a fast spinning alternator hooked to battery over thicker cabling, or being able to plug in to the grid and have a larger plug in charger. It might not recover any capacity either.
If one can
never accomplish a high amp recharge, then a deeply cycled AGM battery is not going to achieve many cycles before its capacity diminishes to a point of near uselessness, even if it reaches 100% often.
I find my Northstar AGM, after 5 low and slow solar only recharges to 100% charged, starts getting punch drunk and I have 200 watts feeding 90AH of battery in a sunny environment. NOt the cloudy olympic pennisula some 1500 miles further from the equator.
When punch drunk I will discharge to ~50% again and then first thing in the morning, apply 40 amps via my plug in charging source or 60+ amps from the alternator, and this is like a six pack of redbull energy drink, but without the burnout once the caffeine and sugar wears off. Performance is restored. If I go say 15 cycles of low and slow only recharges then 2 high amp recharges each morning work better to restore performance.
If I drive every morning, even just 12 minutes worth of 60+ amps, then low and slow solar the rest of the day, then punch drunkness does not happen or is practically unnoticeable.
Not sure of your set up, but a pair of jumper cables hooked from vehicle to punch drunk drowning AGM could help restore some capacity. BUT the AGM will likely max out the alternator and cause it to reach 220F or higher, which is very hard on alternator. Idling amperage is not very high on most vehicles, and airflow at idle is not enough to allow alternator fan spin fast enough or engine fan to evacuate engine heat. And of course idling wastes fuel, and money, which could be better put toward a new battery.
not sure what is best plan of attack for you, or how much effort you wish to put into trying to restore capacity of this battery nor how effective it would be.
Just that the higher amp recharge is the most likely way to restore capacity on a chronically undercharger and slowly recharged AGM.
Bypassing a PWM solar controller is not really going to add any extra wattage to the charge current. Bypassing is usually done when the PWM controller cannot be programmed to seek a higher voltage such as for equalizing a battery.
If your bypass, in combination with the sun baking the battery, caused it to dry out is unknown. Voltage would have to had been in the 15's and battery temperature at 95 degrees plus for a while for significant water loss to occur.
If dried out somewhat, the voltage held under load could easily improve as the electrolyte is now stronger, which of course also chews up the plates faster too.
Best of luck, but any future battery will also live an abbreviated life unless you can improve your charging regimen or reduce the amount of energy you remove from it each night.
