Hybrid Battery problem

Is this for business use? Why not get a new one or a Dorman battery with a 3 year warranty? It would be a tax deductible expense. Can you afford to have the cars not working?

 

For prior experience I could tell you that the copper links, daisy chaining the batteries modules, could be corrode and/or not making proper contact.
If they are not in pristine conditions, I would use a wire brush wheel and buff all of them, and the battery modules terminals also.

 

cell replacement is a tricky affair. there are threads here that can help you. you do need to test them under load and balance the replacements with special chargers. it is painstaking and time consuming, but cheap, if you don't count the man hours.

 

I am not really a battery expert but I am an electrical engineer. Probably the easiest thing to do is put a load on all of the cells and quickly discharge them together down to 40%. Then point an IR temperature gun/reader (less than $100) at each cell for a few seconds and see it one of them is hotter or colder that all the rest. Then measure the voltage on all the cells. Then charge the batteries to 80% quickly and again measure each cells temperature. My bet is one of the cells has a high source resistance and is not charging or discharging as well as the others.

The new cell you put in should have similar charge/discharged characteristics to the old cells remaining and be charge to the same level as the rest of the stack.

Let me know it this works out.

Barry Gamble

 

Good suggestion that may also confirm "mrbighs" suspicion about "dirty" contacts. With higher current demands even a relatively small amout in added resistance, internal to the cell or connection to it, will cause an increase in heat (them electrons will work up a sweat). A tell tale sign at a connection is a discoloration of the metal at the connection. With copper and brass it will present as being a bit darker. If caught early enough a good buffing with a green scotch brite pad will usually do the trick. Don't use steel wool because you'll have conductive dust getting where you might not want it. Any connection between components is a potential problem waiting to happen.

I repair guitar amps as a hobby. In the old vintage ones (I prefer to work on) the components fail because all the connections are point to point soldered except for tube sockets On the newer ones, I have fixed over half were plug type connection issues and those were repaired by simply disconnecting and reconnecting every plug in there.

 

Time to invest in dielectric grease?

 

Yes. Much better than the current formulation of DeOxit. The old stuff would melt oxidation right off a connection, was like a very light machine oil and pretty much stayed on forever. Back in my Xerox days of the 80's the EPA banned it and force a reformulation in the states. Xerox had a work around and got the original formula from Xerox of Canada at about 70.00 for a little 2 or 3 oz. bottle but 1 bottle would last for a good year or 2. I work on machines that have thin, coaxial communication lines with push on, F type connectors that go from board to board throughout. We were having lots of random comm faults and using that stuff cured it. However, nothing but a file, and that's if you catch it soon enough, will renew a burnt connection.

I do tend to ramble, don't I? I always figure everybody enjoys electronics as much as me. My wife can attest to that.

 

Did you try getting an OBDII reader and the torque app. It will show you cell voltages and resistances. Definitely worth the investment to diagnose. OBD reader is only $15 on amazon. Most people already have an android smartphone, but if not, android tablets are going for $60 in places, don't need a fast or fancy one.

Since you run a business, i would always just have one pack on standby so you don't lose business while fixing one up. Once your fleet starts hitting over 200k miles each, you'll start to need to replace a few modules here and there.

 

If you want to find a bad module you need to load test it, here's how you do it (all the info of rebuilding is in this thread):
Gen II Prius Individual Battery Module Replacement | Page 13 | PriusChat

Issue will be to check the capacity of the old modules (need to run charger cycles on them to find remaining mAh) then make sure any new modules match within 500 mAh.

If you need help, just post up and we can walk you though it.......BTW mini VCI w/Techstream helps alot too.