Deep Cycle Battery Charging From Alternator
Hello, May I ask for advice regarding charging deep cycle batteries from the alternator? I have read older threads, and understand opinions vary. The previous two 100Ah deep cycle AGM coach bat...
Forum Discussion
The PD converter algorithm almost meets Lifeline specs precisely, at 77f battery temperature anyway. Seems no aftermarket converters bother with temp compensation, and convincing others to forgo automatic 'stages' for manual voltage adjustment is urinating into the wind in this smart phone 'look at meeeeee!' era.
The PD boost to 14.4v every 18 hours from float(13.2v) is unrequired though, for AGM anyway.
My Thin plate pure lead Northstar AGM loves a high amp recharge from a well depleted state, holding ABSV until amps taper to low levels. It was rated at 90Ah new, I have 65amps of plug in charging source available, and regularly feed it that much, and my alternator can provide even more amperage.
I've never done Lifeline's conditioning procedure.
I have Done Odyssey's once or twice, but not back to back.
https://www.odysseybattery.com/documents/ODYSSEY_Battery_Reconditioning_Charge_Procedure.pdf
I judge performance by voltage retention under load for X Ah removed from the battery, and lately, with ~1100 deep cycles over the last 5.5 years, I can also judge its health, by how low amps taper to. When newer they could taper to somewhere lower than 0.05a at 14.7v with the charging source left at 14.7v, but now after many low and slow solar only recharges it will stop tapering at 0.9a at 14.7v then start climbing again. When I notice this occurence, that night I might intentionally discharge to well below 50% then high amp recharge ( 40 amps minimum) and then amps will again taper to 0.4 or less at 14.7v in a reasonable amount of time.
I've not cycled any other AGM for 5+ years, so I can't say whether what I notice with this Northstar AGM is applicable to other brands.
I do use this Northstar for engine starting too. A volt meter on my dash reveals just how low voltage drops during engine cranking which is ~140 amps of load. A mini load test every engine start, is how I view it. Even well depleted at 1100 deep cycles at 5.5 years of age, it has no issues starting my 5.2 liter v8 in mild ambient temps. When it does I will consider replacement after Odyssey's reconditioning procedure does not seem to be effective anymore.
I will have no Issue forking out the top $$ for a new Northstar AGM once this one can no longer meet my needs. It has been an exceptional battery in deep cycle and dual purpose usage, despite its marketed 'thin plates'.
Its all about proper recharging, and I would not have achieved this lifespan with less than 20% charge rate available, and would not have achieved it had I not been able to hold absorption voltage as long as required for amps to taper to 0.5% of capacity. This requires I use a manual charging source that caters to my whim, not what some beancounter decided was acceptable in some cubicle somewhere.
I do not really adjust voltage for temperature much, but I am mostly in coastal southern California where temperature swings are a tiny fraction that of most every other location on the planet.
High amp recharging will heat the battery. I think this heat helps break up any sulfation which might have been hardening. When over 80f outside I will lower absorption voltage accordingly when high amp recharging from a well depleted state. I've never allowed the battery to get over 105f and that occurence is quite rare, requiring high ambient temps and high amps applied for a long time from a well delpeted state.
As far as I can tell, 'drying out' of AGMS is largely hogwash. I have left mine at 14.7v + cumulatively hundreds of hours after it was already fully charged over the last few years. I can't precisely weigh the battery, but as long as it still mees my needs, I will keep cycling the snot out of it, and regularly apply high amps until amps taper to 0.5% or less of capacity.
The PD boost to 14.4v every 18 hours from float(13.2v) is unrequired though, for AGM anyway.
My Thin plate pure lead Northstar AGM loves a high amp recharge from a well depleted state, holding ABSV until amps taper to low levels. It was rated at 90Ah new, I have 65amps of plug in charging source available, and regularly feed it that much, and my alternator can provide even more amperage.
I've never done Lifeline's conditioning procedure.
I have Done Odyssey's once or twice, but not back to back.
https://www.odysseybattery.com/documents/ODYSSEY_Battery_Reconditioning_Charge_Procedure.pdf
I judge performance by voltage retention under load for X Ah removed from the battery, and lately, with ~1100 deep cycles over the last 5.5 years, I can also judge its health, by how low amps taper to. When newer they could taper to somewhere lower than 0.05a at 14.7v with the charging source left at 14.7v, but now after many low and slow solar only recharges it will stop tapering at 0.9a at 14.7v then start climbing again. When I notice this occurence, that night I might intentionally discharge to well below 50% then high amp recharge ( 40 amps minimum) and then amps will again taper to 0.4 or less at 14.7v in a reasonable amount of time.
I've not cycled any other AGM for 5+ years, so I can't say whether what I notice with this Northstar AGM is applicable to other brands.
I do use this Northstar for engine starting too. A volt meter on my dash reveals just how low voltage drops during engine cranking which is ~140 amps of load. A mini load test every engine start, is how I view it. Even well depleted at 1100 deep cycles at 5.5 years of age, it has no issues starting my 5.2 liter v8 in mild ambient temps. When it does I will consider replacement after Odyssey's reconditioning procedure does not seem to be effective anymore.
I will have no Issue forking out the top $$ for a new Northstar AGM once this one can no longer meet my needs. It has been an exceptional battery in deep cycle and dual purpose usage, despite its marketed 'thin plates'.
Its all about proper recharging, and I would not have achieved this lifespan with less than 20% charge rate available, and would not have achieved it had I not been able to hold absorption voltage as long as required for amps to taper to 0.5% of capacity. This requires I use a manual charging source that caters to my whim, not what some beancounter decided was acceptable in some cubicle somewhere.
I do not really adjust voltage for temperature much, but I am mostly in coastal southern California where temperature swings are a tiny fraction that of most every other location on the planet.
High amp recharging will heat the battery. I think this heat helps break up any sulfation which might have been hardening. When over 80f outside I will lower absorption voltage accordingly when high amp recharging from a well depleted state. I've never allowed the battery to get over 105f and that occurence is quite rare, requiring high ambient temps and high amps applied for a long time from a well delpeted state.
As far as I can tell, 'drying out' of AGMS is largely hogwash. I have left mine at 14.7v + cumulatively hundreds of hours after it was already fully charged over the last few years. I can't precisely weigh the battery, but as long as it still mees my needs, I will keep cycling the snot out of it, and regularly apply high amps until amps taper to 0.5% or less of capacity.
