DDK - Die Deutschen Klassiker

Hi guys
Have any of you folks used AGM style batteries in your classic cars
I need to increase the cranking power for the E Type, as it doesn’t like cold winter starts but I’m not sure batteries like the Optima ones are going to be able to be recharged with standard alternators.
I would ask on the Jaguar forum, but they’ll probably scorn it because it’s not standard, so I thought I’d start here with you Maverick lot…!

Best
Jp

I've had a 6v Optima on my 356 for a number of years. My charging system is the stock dynamo and mechanical regulator. I normally make sure that the output from the dynamo is regulated to 7.2-7.3V. It seems to work fine, and is a maintenance free solution when compared to lead acid batteries. It also manages to hold a charge pretty much indefinitely, providing there is no residual current drawdown when connected to the car. which is a definite plus.

thanks..good to read

Any of you guys out there using 12v with a positive experience..?.. from my limited understanding of things electrical, the web seems to suggest that AGM batteries are not often best served by alternators designed for conventional batteries that they either don’t charge quickly enough or to the right voltage levels.

Any real world experiences will be greatly appreciated.

Many thanks.

I’ve got an Optima on my Targa, along with a high capacity alternator from Jonny. The alternator is (AFAIK) the same technology as the original (no additional smarts in the regulator), so charges the same (just faster). If the car is not being used for a week or so, it goes into the garage and I connect to an AGM capable trickle charger.

However, between these brief rests, and while staying away from home (CLM last year was my longest spell away from the trickle charger), all the battery gets is sleep and then charging by the alternator. I’ve had no issues with the battery.

I ran an optima on my 912E in the states around 2006. Never had issues with it under or over charging.

In honesty, whilst a fresh battery will help turnover and starting, it sounds as though you could find out where the resistance in the wiring system is causing your cold start issue.

I don’t know e types, does the current for starting run through the ignition switch similar to a 901 series ?

Starter relay ?

Matt

Hi Matt
I did some testing and found 2 wires that benefitted from being thicker, which did seem to improve things, but the 550CCa / 60Ah battery was still dropping from 12.6v down to roughly 10.4 once cranking
The E Type has a limited battery compartment so the max i can find is 640CCA / 63AH in wet battery tech…the red top AGM optima’s for example raise that to 730CCA which is quite a bit more..hence the thinking

Hi Jonathan, I have a Red Top AGM in my 911. Very good cranking power and when not used it holds power/capacity really well over long periods. Much better than the (new) conventional batteries in my other cars. The standard alternator charges the AGM without any trouble.

Thanks everyone…I borrowed an Optima 4.2RTR battery today and what a difference…it’s too snug a fit to be used, so I have just ordered the RTR3.7 version which is around a cm shorter and 730CCA compared to the 817

The friend has a series 3 EType and just a regular alternator originally from an XJS

Either way it’s a big difference from the 550 I have currently

Should be here Tuesday so next weekend I can get out and about again…

All the best
Jonathan