The other battery is 11.5V? If they are SLA batteries then if you don't charge this battery soon you're going to lose it too... Have you not been periodically charging these sla's? ..They are not going to get charged from power occasionally being dumped back into them... which by the way is not very much anyway...

The battery's are connected in parallel with the 12 volt power supply, so whenever the robot is turned on, I presumed the battery's should be charging. I must admit though I don't know much about battery's and how they should be charged. Maybe this set up will not work with regards to battery life.

I should also point out that I have connected the battery's and the power supply using Dave's MOSFET and Diode circuit so the Sabertooth is not back fed by the battery when the robot is switched off thus draining the battery and still allows a path back to the battery for re-gen voltage if the motor is rotated while off.

If I upgrade to the 2x32 Sabertooth I can forget about the battery's.

Steve

Power supplies are not battery chargers... You need a proper SLA battery charger...

So is the failed battery the likely cause of the sabertooth failure?

Not sure, but I do know your battery died from the lack of charging....

Do you know if I replace the Saberteeth and reuse the already tuned Kangaroos if I will need to redo the auto tunes?

Hi Steve, What an odd issue.

I can say this, I've had this same setup in the leg section in my B9 with a 12v SLA battery for the past few years in my leg section and have never charged it. It's charge level stays at about 11v and I have no issues. Before I switched over to the 2x32 sabertooth in the torso section I also was running this setup for a long while with no issues. I never charged them and they stayed about 11v by just receiving the regen power from the Sabertooth.

With that said, RR is right about SLA'a needing to be charged. Lead acid batteries must always be stored in a fully charged state and be periodically recharged even when not in use. Leaving them discharged is a sure way to ruin them. Continuous over charging or under charging is the worst thing for a SLA battery. It's possible in this setup that you overcharged this battery. However like like rr said there is really very little Regen power going back into the battery. Again, how much is to much?

Now, we'er not talking bout discharged batteries here. You "are" charging them and if your other circuit and my setup is any comparison to go by the level should stay about 11v on a 12v battery. This has been a constant in my system for years now and I've never had a battery fail. I'm not sure that just one volt low or high will really make a big difference in the battery life (but I'm not 100% sure). I would say there is more risk of overcharging in this system.

Also, something else to keep in mind when thinking this through. There's a lot of talk now everywhere and on this forum about LIPO batteries. Don't confuse the two. SLA's don't have the same issues as LIPO' s when you discharge them. With LIPO's they certainly die when you drop below a certain level. This is not an issue if you kill a SLA once on a while. I cant tell you how many times I've had to jump start a completely dead car battery that's been drained from the cold or a short somewhere in the car and have it last for years after that.

I really think you have something else going on here that has nothing to do with discharged batteries. If this was a undercharging issue I'd think the battery would fail over a longer period of time. The flag for me is that you have a very low voltage reading on your SLA. The other SLA in your other system is preforming nicely and has been. Here's my thoughts on possible causes:

*You battery just failed on it's own. This happens. Do you have a battery store near you? We have them here (Batteries Plus) and they gladly test suspected failed for you and give advise. If you end up getting a new battery make sure it's got a "minimum" capacity of at least 1.3Ah. *If the battery has failed (or even if it can be saved) it could have been caused by a short. I know you said you checked for this but what about the cutoff circuit you built? Could something in that be shorted or have a failed part? *The Sabertooth failed on it's own. I've been reading posts from people that have recently had one fail. Unless you accidentally shorted out the power input I don't think there is anything your little setup could do to kill this tank of a controller. It protects it's self pretty well.
*The Kangaroo failed. Same as above. Just a note and question here; Do you have 5v feeding "into" the 5v port on the control side of the Roo? This is a 5v "out" port and you'll kill the Roo if you feed power "into" this port. *There is something shorted in your circuit or power supply. Battery, homemade shutoff circuit, wiring, power supply, Sabertooth, Kangaroo. Dont forget to check the wiring between the Roo and the EZB.

Try removing or replacing parts of your setup to see if you can get the red led to go off. I'd start by making sure everything in the circuit is attached and ready then : *Removing the homemade shutoff. *Replace or remove the battery. *Move the Roo then Sabertooth one at a time to the working circuit. When you move the Roo and attach it to the other Sabertooth did it's LED turn red? When you move the Sabertooth in question to the new circuit does it's red led go off? When you attach a known working Roo to the Sabertooth in question does the red LED got off? Be advised that when swapping around devices that may be bad you may cause damage to something in the working circuit. However because of the nature of this circuit and the protection built into the Roo & Tooth I think this is unlikely. Still if the red led comes on when it shouldn't remove power as soon as possible.
*Try running the Sabertooth without the Roo attached. You may need to place the dip switches in the proper setting.

In the long run I would advise replacing all your Saberteethes 2x12 with the 2x32's. I loved being able to remove the SAL's and not have to worry about things like what your going through, a failed battery down the road or ever an acid leak. Running a power resistor across the power input/output of the 2x32 as a voltage clamp was so much cleaner and less hassle. The hardest part was finding the proper value to use. That was more or less trial an error.

EDIT: One more thing to answer your question; I've found when ever you change anything including adding a different Sabertooth you need to do a re-tune of the roo. This may not be the case if you swap out like for like between 2x12's. My experience was when I upgraded to the 2x32. I'd advise to see if your motor is acting as it should after the swap and before you re-tune. You might get lucky. I never did though.

Good luck ad have fun!

Standard charge level for a healthy 12V sla is between 12.4V and 12.6V... 11V is too low... eventually it will croak from not being charge as opposed to old age... If you don't believe me Google it...