GT4 CAN-ECU, Lithium-ion batteries and Durametric
11-07-2019, 05:10 PM
#31
AGM Battery Substitution
I've installed an H7 AGM battery to replace the Antigravity LI-ion battery... had to experiment sooner rather than later since there are no more track days I can attend this year and the daily menu errors were trying my patience. Nearly two weeks of running the car almost daily and the menu faults (Steering support failure..., Parking brake fault, CEL's etc ) have not resurfaced. This was done without resetting the ECU back to PB-acid since I haven't gotten to a dealer yet to make that happen. I'll do that ASAP.
Without a track day I won't be able to test if the high-rpm miss is gone, but I'll report back in this thread after the first track day I can get to. I have two options for the use of the now underutilized Antigravity battery assuming the ~13.2v resting-voltage isn't a problem. In neither of these two options the charging-profile won't be ideal for the LI-ion battery.
1. I can use the LI-ion battery in my 993 powered 914-6 when it's rebuilt next year. I bought a CTEC LI-ion battery maintainer so it should be fine. Don't know how the 993 DME & alternator will respond to it... anybody tried?
2. The other possibility is to use it in a stock 1979 SC. Don't know about that one either but at least there isn't an ECU to program.
The Antigravity folks did their best. The previous owner installed it to save weight as it was a track-only car. But he didn't take the car to the track for at least a month. So the warranty wouldn't have helped anyway, especially since the battery doesn't seem to be faulty. Even in this case there was no reason for the previous owner to suspect a new battery as the culprit for either the menu-errors or the high-rpm miss... the latter of which has yet to be proven.
My takeaway is that when installing a new LI-ion battery use it immediately... a lot, track or DD. If there are any anomalies the Antigravity folks can have a crack at it instantaneously.
That's all I know right now.
Ron
Without a track day I won't be able to test if the high-rpm miss is gone, but I'll report back in this thread after the first track day I can get to. I have two options for the use of the now underutilized Antigravity battery assuming the ~13.2v resting-voltage isn't a problem. In neither of these two options the charging-profile won't be ideal for the LI-ion battery.
1. I can use the LI-ion battery in my 993 powered 914-6 when it's rebuilt next year. I bought a CTEC LI-ion battery maintainer so it should be fine. Don't know how the 993 DME & alternator will respond to it... anybody tried?
2. The other possibility is to use it in a stock 1979 SC. Don't know about that one either but at least there isn't an ECU to program.
The Antigravity folks did their best. The previous owner installed it to save weight as it was a track-only car. But he didn't take the car to the track for at least a month. So the warranty wouldn't have helped anyway, especially since the battery doesn't seem to be faulty. Even in this case there was no reason for the previous owner to suspect a new battery as the culprit for either the menu-errors or the high-rpm miss... the latter of which has yet to be proven.
My takeaway is that when installing a new LI-ion battery use it immediately... a lot, track or DD. If there are any anomalies the Antigravity folks can have a crack at it instantaneously.
That's all I know right now.
Ron
11-27-2020, 09:53 PM
#33
I installed an antigravity H6 in my 981 GT4 about a month ago, and I just started having these same codes. I did have to use the reserve on the battery about a week ago because an accessory ran the battery dead. I hope the codes don't come back on reset because the battery has already saved me once.
I had asked arcflash before I installed it and they said it should work fine, has anything changed on this issue in the last year?
Edit: I see there's another active thread on this right now. Seems like I should have the latest battery version given when I got it. Sad if my car is going to have issues with it.
I had asked arcflash before I installed it and they said it should work fine, has anything changed on this issue in the last year?
Edit: I see there's another active thread on this right now. Seems like I should have the latest battery version given when I got it. Sad if my car is going to have issues with it.
Last edited by dmaul; 11-27-2020 at 09:59 PM.