Rechargeable Lithium AA Batteries

All Summit users operating in winter know the frustration of the low aux battery warning and accompanying beeping. Over the years we have seen how different battery chemistries such as rechargeable NiCad batteries barely seem to last 1hr at -20C before the beeping starts. Some clubs started using non-rechargeable Lithium batteries, and although they worked for the whole day, they were very expensive. The below chart illustrates how different battery chemistries will hit the low battery threshold at different times.

A new product hit the market in 2022 that we were very excited about: rechargeable lithium ion AA batteries. These batteries typically have a micro-USB plugs in the side of the battery.

Zone4 tested the following 3 brands of these batteries (links are just examples of what we bought – not endorsements of that particular source):

We also tested a style from EBL that did not have the plug, but used a proprietary charger for up to 8 at a time.

Our testing involved deploying wireless Summit timers during winter races at temperatures ranging from 0C to -20C. One of the core philosophies of Zone4 is that all hardware should be deployed out in the field at least 1hr before the race. This ensures you have time to fully test and verify all of the equipment and nothing is being rushed out a few minutes before the race. The previous battery life of alkaline and rechargeable batteries made it difficult to uphold that philosophy for Summits and some users were getting into the habit of last-minute deployments and bringing Summits in for breaks to warm up. For our testing, we deployed all Summits at least 1hr before the race with no regard for temperature – we wanted to treat them as we would our GoChip Activators where battery life was designed to far exceed typical daily requirements allowing stress-free deployment.

In all of our testing, both the ELB with a USB plug, and those without never reached their low aux battery warning level. Even when left on late into the evening it took many hours after a race till the warning beep would start. The 2nd best battery was the Keeppower which would regularely last a race day, but not quite at long as the ELB. The HiQuick lasted the shortest.

As for whether we preferred the ELB batteries with the plug vs the proprietary charger, there were pros and cons for each. One one hand, having the plug right on the battery means less equipment to bring and worry about, but there were a lot of USB cables flying around when recharging a fleet of Summits (and of course GoChips phones, battery bricks, etc.) The proprietary charger keeps them all neatly together, but it has to go to every race and forgetting it means you have no way to charge them. So we’ll likely use a combination of these in our deployments this year, but regardless, we are very happy with the performance of the ELB batteries and how it leads to less waste, less stress, and easier timing!

External Power Options

Note that for even longer usage situations, new SRT 2000 units come with an external power jack that can be connected to external power such as a battery brick.

But for upgraded SRT2000 this isn’t an option so as workaround, there is also a workaround using the following product to replace your 2 lower Radio batteries:

This product bridges the one battery with a fake green one, then uses power from the USB plug to feed the clear fake battery: (note the 4.5v is key so it uses the external power before using the top 2 batteries which therefor serve as a backup.) This setup can plug into either a USB wall-wart or a USB battery brick to provide unlimited power to a summit timer. Note that FIS homologation requires that a timer be “able” to be plugged into external power, so although you don’t have to (and we certainly recommend using the AA Lithium rechargeable instead) the following product does meet that requirement for upgraded Summit SRT2000.

Updated on 2022-11-20

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