trevmar
Posts: 35
Joined: Sat Jan 21, 2017 8:08 pm

12 volt AGM battery

Thu Nov 14, 2019 9:43 pm

Much has been said about the reliability of these batteries, but on a temporary basis ONLY what are the downsides to substituting a "conventional" SLI 12v battery? (if it fits mechanically)

I realize SLI batteries don't like deep cycling, but everyone has left their lights on at some stage, or parked an ICE car for a month............


Come to that, what about using a Harbor Freight AGM battery - much cheaper at $70, albeit only 35 A-hr.

marspilgrim
Posts: 60
Joined: Tue Jul 30, 2019 10:13 pm
Location: Chicago

Re: 12 volt AGM battery

Thu Nov 14, 2019 10:12 pm

I haven't tried it but I am positive that in a pinch a lead acid would be fine, like stranded in a ghost town and you want to get home. That said, long term I'd stick with a AGM with the same rating that came with the car, the way the engineers designed it. I know they're expensive though but fortunately we can't leave our lights on. :) Leaving the car sit for a long period it is worth investing $100 in a good battery tender but the real concern would be the primary battery.
2017 Bolt EV Premier

SparkE
Moderator
Posts: 1133
Joined: Sun Sep 11, 2016 5:53 am
Location: SF Bay Area

Re: 12 volt AGM battery

Fri Nov 15, 2019 12:32 am

AGM batteries are supposed to be more resistant to sulphation.

shmuelyosef
Posts: 1
Joined: Sun May 03, 2020 7:34 pm
Location: SF Bay Area

Re: 12 volt AGM battery

Sun May 03, 2020 7:38 pm

marspilgrim wrote:I haven't tried it but I am positive that in a pinch a lead acid would be fine, like stranded in a ghost town and you want to get home. That said, long term I'd stick with a AGM with the same rating that came with the car, the way the engineers designed it. I know they're expensive though but fortunately we can't leave our lights on. :) Leaving the car sit for a long period it is worth investing $100 in a good battery tender but the real concern would be the primary battery.


What is considered a "long time"? In the current pandemic scenario we often go for a week without driving the Bolt (2019) an rarely drive more than 2-3 miles as we are under lockdown in California.

Any recommendations besides the BatteryMinder?
(I already have one on my VW GTI which NEVER gets driven in this scenario)

SparkE
Moderator
Posts: 1133
Joined: Sun Sep 11, 2016 5:53 am
Location: SF Bay Area

Re: 12 volt AGM battery

Sun May 03, 2020 9:51 pm

Recommendation :

Regularly unplug the trickle charger from the VW, and plug in the Bolt. Do it at least overnight, once a week, when not driving the Bolt at all (or almost not at all).

Or, better yet, swap the trickle charger to mainly be on the Bolt, and plug in the VW overnight once a week. The Bolt is a computer on wheels, with wireless and satellite receiver active. Unless your VW was built in the past 4 years, the drain the the 12V battery is likely a lot less than on the Bolt (and since the VW's 12V battery has to crank an engine, it probably has much more capacity).

SparkE
Moderator
Posts: 1133
Joined: Sun Sep 11, 2016 5:53 am
Location: SF Bay Area

Re: 12 volt AGM battery

Sun May 03, 2020 9:58 pm

But if you insist on buying another trickle charger, I own this one. Very gentle (0.8A), AGM-safe, perfect for gentle overnight "top-up" charging :

https://www.amazon.com/CTEK-56-865-Smar ... 002QUT8IC/

https://www.amazon.com/CTEK-56-865-Auto ... 006CQ9BMO/

(same unit, different vendors)


Although if I were buying now, I'd probably buy this one (although about $35 more). Will charge at 4.3A *and* 0.8A, and has other useful functions (including adapting charge profile based on temperature) :

https://www.amazon.com/CTEK-56-959-CHAR ... B00GODGN9E

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