PDS cart w/500A alltrax, gear change or motor upgrade?

[sportcoupe]

Terry convinced me on going 48v so I ordered an on-board 48v charger today. New batteries will be picked up in about a week.

JohnnieB posted an 8v battery AH chart but I can't find it now. Anyone have a copy of it?

[JohnnieB]

Seek and ye shall find.

[sportcoupe]

Thanks Johnnie

[JohnnieB]

Originally Posted by sportcoupe

Terry convinced me on going 48v so I ordered an on-board 48v charger today. New batteries will be picked up in about a week.

Since you spoke with Terry, I suspect you went with Quick Charge for an on-board charger.
(FWIW: If I decided to go the on-board route, that is what I would get.)

If so, be aware that different brands of batteries have different charge profiles and I'm not sure if the Quick Charge chargers have user selectable charge profiles and it may be best to choose a battery brand that likes the profile the Quick Charge charger you get has installed.

The problem I am aware of is US Batteries being undercharged with the Trojan Battery profile.
The manufacturer recommended absorption phase voltage in the US Battery profile is 0.15VPC higher than it is in the Trojan Battery profile, or about 3.6V @ 48V.

[sportcoupe]

I only use Quick Charge if I want an on-board charger.

They have standard and select a charge on-boards, both with user programmable profiles. The options are something like wet cell deep cycle, agm, gel and lithium. I'm unaware of profiles for battery brands. Most likely I'm getting T890's.

[JohnnieB]

With the DPI, the constant voltage in the absorption phase is:
Trojan = 2.35VPC (Mode 2) - 56.4V for a 48V pack
Exide = 2.40VPG (Mode 3) - 57.6V for a 48V pack
Full River = 2.45VPC (Mode 4) - 58.8V for a 48V pack
US Battery = 2.50VPC (Mode 1) - 60.0V for a 48V pack

The constant voltage during float charge is also different in the four modes.

Deep-Cycle Lead-Acid Wet Cell batteries are pretty forgiving for the most part and tolerate a fairly wide range of on-charge voltage, but more tolerant of higher than lower.

If the charger uses a dV/dT algorithm to terminate the charge cycle, the on-charge voltage isn't very critical, but if the charger shuts off when specific voltage is reached, it may become an issue.

The reason I am aware of this is because a forum member (I don't remember who) had some issues with battery lifespan when US Batteries were being charged with a ferroresonant transformer design charger, which was based on the Trojan charge profile and wasn't "fully" charging the batteries.

Attached is a Technical Service Bulletin that artfully talks around the issue.


ADDED: With T-890 batteries you'll be okay. The have the lowest on-charge voltage requirements and even if the charger takes them a bit higher, it doesn't hurt them.

They will tolerate up to 2.79VPC or about 67.0V for a 48V pack.
See attached profile

[yurtle]

I have eight T-105s, and have my DPI set accordingly. Any chance a slightly higher setting may increase longevity?

Gotta live the Red Green!

[yurtle]

I have little experience in lead/acid batteries, but in my Tesla world, I can pump over ten times the recommended energy in a cap. Hipo .1 nF 500,000v DC.

[JohnnieB]

Originally Posted by yurtle

I have eight T-105s, and have my DPI set accordingly. Any chance a slightly higher setting may increase longevity? ..........

Longevity meaning Run-Time or longevity meaning Life-Span?

I don't know for sure, but maybe some of both, or you may lose some Life-Span while gaining some Run-Time.

You can measure gains in Run-Time, but predicting Life-Span is a W.A.G, at best.

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By increasing the SG of the electrolyte, you can store more AH in a battery.
SG tracks At-Rest voltage (VPC + 0.845 = SG), so increasing the on-charge voltage increases the resulting SG, so the AH is upped.

The proportions of Lead and H2SO4 put into a battery are balanced so they run out at about the same time, so increasing the SG would unbalance the equation a bit, but I'm not sure if that will effect Lifespan.

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Your guess is as good as mine.

[TerryH]

Originally Posted by JohnnieB

Since you spoke with Terry, I suspect you went with Quick Charge for an on-board charger.
(FWIW: If I decided to go the on-board route, that is what I would get.)

You'd think the least that those Quick Charge quys could do is send me a little sponsorship love for the drag cart seeing that I'm there entire PR and advertising department.