AGM Batteries

Need some help with a technical problem - ask away and let's see if we can all help.

Moderators: hot66, impmad2000, Nige

Post Reply
jtparr
DDK 1st, 2nd and 3rd for me!
Posts: 2230
Joined: Mon May 24, 2004 10:54 pm
Location: london/surrey

AGM Batteries

Post by jtparr »

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
1974 2.7 Carrera
(full restoration. now as an RS Touring)
1963 3.8 E Type
( 11 years in the making…………………….)
1952. XK120…the next one ……….……..)
Kneeslider
DDK slapper chatter
Posts: 401
Joined: Tue Oct 01, 2013 5:04 pm

Re: AGM Batteries

Post by Kneeslider »

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.
'65 356 SC
'91 Ducati 750/900ss mongrel
1963 Velocette Viper (mostly) with '39 KSS OHC engine
'05 997 C2
1954 FB Mondial 200 Extra Lusso
jtparr
DDK 1st, 2nd and 3rd for me!
Posts: 2230
Joined: Mon May 24, 2004 10:54 pm
Location: london/surrey

Re: AGM Batteries

Post by jtparr »

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.
1974 2.7 Carrera
(full restoration. now as an RS Touring)
1963 3.8 E Type
( 11 years in the making…………………….)
1952. XK120…the next one ……….……..)
User avatar
PeterK
DDK rules my life!
Posts: 1068
Joined: Mon Sep 01, 2014 3:04 pm
Location: GU51 - Fleet, Hampshire, UK

Re: AGM Batteries

Post by PeterK »

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.
'79 Targa - restoration now mainly complete & being driven
viewtopic.php?f=28&t=59756
wildtexas
DDK slapper chatter
Posts: 481
Joined: Thu Apr 20, 2006 1:10 am
Location: N. Ireland

Re: AGM Batteries

Post by wildtexas »

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
jtparr
DDK 1st, 2nd and 3rd for me!
Posts: 2230
Joined: Mon May 24, 2004 10:54 pm
Location: london/surrey

Re: AGM Batteries

Post by jtparr »

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
1974 2.7 Carrera
(full restoration. now as an RS Touring)
1963 3.8 E Type
( 11 years in the making…………………….)
1952. XK120…the next one ……….……..)
NurLinks
DDK Fanatic
Posts: 83
Joined: Thu Mar 20, 2014 9:20 pm

Re: AGM Batteries

Post by NurLinks »

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.
1986 911 3.3 Turbo, 1973 911 RSR Replica, 1974 FIA spec 3.0 RSR (in progress)
1993 928GTS, 1971 Alfa Romeo Giulia
jtparr
DDK 1st, 2nd and 3rd for me!
Posts: 2230
Joined: Mon May 24, 2004 10:54 pm
Location: london/surrey

Re: AGM Batteries

Post by jtparr »

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… :bounce:

All the best
Jonathan
1974 2.7 Carrera
(full restoration. now as an RS Touring)
1963 3.8 E Type
( 11 years in the making…………………….)
1952. XK120…the next one ……….……..)
Post Reply