- February 15, 2016 at 9:59 am #2943
Hi – I have another, very important problem with my Saberteeth 2×12. I am using 8-cell LiFePo4 batteries to drive my 24V DC motors by the Sabertooth 2×12. When fully charging the batteries, I get an initial peak voltage of 29.2V (8×3.65V). The error LED on the Saberteeth glow constantly and the Sabertooth does not work until the voltage drops below 28.2V; which covers with the max voltage setting I read in the DEScribe tool. Is there any remedy for that other than limiting the power supply?
Please help me as quick as possible, since I am in big time hurry to deliver my 12 robots to my client. Thank you!February 15, 2016 at 11:13 am #2944
The 2×12 is not rated for that voltage. The Describe allows you to put a max voltage of 28.32. The hardware cannot tolerate that high of a voltage. The 2×12 is only rated for 6-24 nominal. It says 30V absolute max, but we its hit or miss trying to get it to work above 28V. We have tried to get them to work with LiFePO4 batteries too, and usually not successful. Unfortunately the only solution is 2×32, it’s rated for 6-30V nominal.February 16, 2016 at 9:04 am #2947
Thanks for answering quickly. I already damaged two Saberteeth because the battery had 29.2V after full charge. There is now a short circuit between B- and B+. Do you know which part has blown-off in this case? Is it one of the IC or maybe just a capacitor which I could replace by myself?February 16, 2016 at 9:14 am #2949
The MOSFETs are what is limited (at least that is my understanding). If you have a short between B+ and B-, I doubt there is much that can be done. Dimension Engineering is pretty forgiving with their warranty if you want to contact them, they will probably replace them. However, they will likely keep having issues with the LiFePO4 batteries. We have not had much luck with the 2x12s running so close to the max. the 2x25s handle it much better, but the 2×32 is what should be used (our understanding is the 2×32 was created due to the higher peak voltages (25.6V nominal for LiFePO4). The older controllers like the 2×12 were really intended for lead acid (24V nominal) and 6 cel lithium Ion (22.2V nominal)
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