AGM batteries

[265bhp]

Hi

Have any of you guys had any experience with using higher cranking power AGM style batteries?

Give the space for an E-type battery is slightly limited. I am contemplating a higher CCA rating with an Optima style battery
do any of you have experience with this new technology and also whether the dynamator style alternators that look like the original dynamos are capable of charging the batteries accordingly

Regards
Jonathan

[MarekH]

I run an Optima Red Top. It seems to work just fine.

Starting a carburettored engine is all about having atomised fuel reaching the cylinders. All the battery is bringing to the table is generating the airflow through the cylinders until enough air+fuel "sticks" to fire at least one cylinder. The limiting factor to starting is getting the fueling right and more cranking ability is really about giving yourself a bigger leeway to getting the fueling a bit wrong and not suffering for it.

Having said that, my car is not typical, so may not be the best benchmark. I would have thought a poorly maintained diesel engine owner would be the right person to ask this question.

I have a spare Red Top you can borrow if you want.

kind regards
Marek

[bitsobrits]

I've run an Optima red tops for 20 years now. Just bought the 3rd one a couple of years ago, so the life is excellent. And no need for a battery maintainer during winter layup, though I usually do a 1-2 day "top up" charge in late January if I think of it, and if not the car still starts in the spring! So I'm a fan.

I've also run a gear reduction starter all that time, and the combination yields such a quick start that I will crank it over without the ignition or choke on for several seconds to bring up some oil pressure if the car has been sitting for a couple of weeks.

[lopena]

Yes…I also use an Optima Red Top in my 3.8 E-type.

Interestingly, my last Red Top failed to hold a charge just two months before the (5 year?) warranty expired. Autozone replaced it on the spot without question.

I spray paint them black so they don’t look so jarringly colorful under the bonnet.

Alan
N.J.

[265bhp]

Hi guys

That’s great…thank you

May I also just double check you have not upgraded the alternators that you are using please…some threads on the web suggest alternators for traditional lead/wet batteries don’t either charge enough and/or don't maintain the right amount of charge when running

Many thanks
Jonathan

[MarekH]

Mine is a Lucas which I took out of an XJS. It puts out 14.1v
kind regards
Marek

[bitsobrits]

I have a modern replacement alternator for the last 15 years or so. Something off eBay from East Coast electric in the U.S., 55 amp IIRC, don't recall the voltage output. No issues in all that time.

[Philk]

We put a Duracell DA70L into our 3.8 when it was recommissioned five years ago. Faultless to date. Aside from being a perfect fit with the battery cage top, I also liked the fact that the position of the terminals meant you could rotate the battery 180 degrees and have the positive terminal at the rear right hand corner which is ideal for the positive earth strap. It's decals could also be easily peeled off meaning you could then affix a period Lucas sticker if you wanted to. Whilst not as period perfect as it could be in terms of appearance it is a good quality battery with the correct dimensions.

https://www.duracell-automotive.com/en/ ... /30-DA-70L

[265bhp]

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

[265bhp]

Forgot to add, the old battery was dropping from around 12.6 V to something in the region of 8 to 9 V initially when we did some cranking tests…I checked all the wires behind the dash and thickened a couple of them, also changed the relay unit I had used for the ignition relay upgrade modification as it looked like it had been getting warm in the past…..once all that was done I was getting high 9v values still using the old battery…... With this borrowed battery from Marek not only was I starting at something like 13.4 V, but it was only dropping 10.7 or thereabouts when we tried an initial cranking test.