A common question with the Bosch 36v Litheon tools has been, which battery should I get the SlimPack or FatPack? Also, why are there two different batteries options? Both batteries provide 36 volts of power for the most heavy-duty applications and both batteries are lithium ion so there is little power fade during usage. However, there are some good reasons to have the two sizes.
The difference comes down to simply run time vs. weight. In the chart above you can see the SlimPack is tested to run about 15% longer than the Bosch 18v battery. (Remember the power of the 36V is still significantly greater) The FatPack has a 100% longer run time than the Bosch 18v battery. The down side to the FatPack is it weighs 1 lb. more and costs almost 50% more. Currently the SlimPack BAT818 is $99.50 and FatPack BAT836 is $142.50.
Clearly it comes down to preference but typically the SlimPacks are used more commonly with drill/drivers in applications where weight might be a concern. The FatPack is typically the battery of choice and our recommendation most of the time.
One final advantage for both of these batteries is Bosch’s Provantage warranty of 2 years. If you are going to rely on these tools this is a huge advantage. The warranty will replace the battery and will do so within 48 hours. Obviously no one has been using these for 2 years (they haven’t been around that long) but so far we have not heard any negative feedback on battery problems or fading battery life which we can’t say about the discount brands.
If you need help or have any questions please talk to the professionals at Ohio Power Tool.