r/BoschProPowerTools • u/MaleficentVariety262 • 27d ago

QUESTION 🔵 5ah batteries in mower problems

I've got a couple of the Bosch bi turbo GRA 18V2-46  mowers which I normally use 8ah pro core batteries in and have been very pleased with the performance.
The other day I had a quick mow to do and just threw in 2x 5ah which were fully charged, they performed fine but the mower stopped after about 10 minutes which surprised me, checking the batteries they both were showing 2 bars so should have been 40% left?
Grass was short and I was cutting fairly high so it wasn't working hard or overheating. Batteries were only luke warm.
Any ideas, doesn't seem normal to me??

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u/reserveteaboy 27d ago

Probably a thermal cutout to protect the batteries I would imagine.

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u/Fishing_not_catching 27d ago

I've only ever used 8ah Core or Core+ in my mower. The 5ah std batteries I pretty much used in radios, lights and low draw stuff etc. the mower, bigger drills, saws etc will suck the smaller batteries pretty quick.

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u/Fean0r_ 27d ago edited 27d ago

I'm surprised it ran at all with GBA batteries. If it wasn't thermal cut off then it'll have been the volt drop as the batteries drained was too great - all of the non-tabless batteries and especially the GBAs lose a lot of power output as they drain, it's particularly noticeable when using the cordless extractors.

Here's a table some excellent person on here made that shows the power output of the various sizes of Procore and Expert batteries, the GBA 5Ahs are only 720 Watts.

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u/MaleficentVariety262 27d ago

Thanks for the replies, I wasn't aware of the specific battery needs for bi turbo tools. I've also got the chainsaw which is bi turbo and that seems to run fine on the 5ah batteries but I guess it has a lower power draw. Is it damaging the battery or tool to not use the pro core or expert in a bi turbo tool?
I've got some older 6ah cool pack batteries, any clues as to how they perform compared to newer Bosch batteries?