Recently in Lead (SLA, AGM) Category

I had hooked up one of my larger SLA batteries to a winch to move some logs around. I thought that the 30 amp PowerPole connectors on the battery leads were maybe a bit undersized for the winch, but was lazy and went with them anyway.

I originally thought one of the PowerPoles wasn't properly seated and it melted down. That's perhaps one of the problems with the small PowerPoles, there isn't a clean "click" confirmation of seating.

Closer examination of one of the melted PowerPoles showed however that the tongue that grips the connector had arcing on it; obviously it had shorted and overheated, causing a melting of the connector. Very strange.

Closer examination of the crimped connector showed that the connector itself was bent upwards. What I now think happened was that the main body of the plug was bent and not seated in the plastic case, and this caused the mating connector's plug to wedge itself between the tongue and the plug (instead of on top of the plug), causing sparking and overheating.

Revised bill of materials (BOM) (dated 2009.09):

[moved to after the jump]

This is the post-flameout, rebuilt Piaggio Boxer EV. I changed the battery carrier from a top-mount system to saddle bags. This lowers the center of gravity and makes it easier to handle. I'm going to replace the seat with something more classic looking.

I welded the saddlebag carriers myself from steel tubing with my MIG welder.

The Electronic Speed Controller (ESC) is sitting on top. It's the replacement HV-110 that I received from Castle Creations with additional capacitors soldered in parallel on the input lines.

It's sitting in a Lexan enclosure that I bodged together. Unlike the old metal enclosure with a single temperature controlled fan, the new enclosure uses two fixed speed fans that pull the air across the ESC and the voltage converters (sitting below). They also are assisted by draft air when the vehicle is at speed.

This photo was taken a few minutes after a short run, the temp of the caps is 34 centigrade which is nominal. Anything less than 60 centigrade I think will be ok. The caps are rated at 85C.

Although the angle of the photo above makes it look like the ESC could short out on the voltage converters, it's actually held a centimeter or so above and everything is well insulated.

I just bought a used iMax B6AC charger (LiPo/Li-Ion/NiMH) to complement my previous Turnigy Accucel-8 charger. I had trouble finding the user manual but finally located it. I'm posting a copy here just in case anyone wants it:

• iMax B6AC Charger User Manual (pdf)

And here's a little comparison table that I drew up comparing the iMax with the Turnigy units:

	iMax B6AC	Accucel-6	Accucel-8
Max Power	50 watts	50 W	150 W
Max Current	5.0A	5.0A	7.0A
Max LiPo Cells	6	6	8
Max NiCD/NiMH Cells	15	15	27
Max Pb	20v	20v	36v
Power Input	100-240 VAC 11-18 VDC	10-18 VDC	10-18 VDC

My Piaggio hit the dust a few weeks ago. I went to school with no problems and was on my way back when I heard a loud pop, lost power, and an acrid smoke started pouring out of the ESC/electronics components.

I finally got around to taking the electronics out this weekend. It looked like the Phoenix HV-110A hit the dust.

I was using 2S Pb (SLA) and my max watts were under 100A the entire time (according to my wattmeter). The HV-110 burst into flames when the moped was being driven under relatively light load. This is despite it being force cooled and the ambient temp here relatively cool. Also, the system was under a 90A circuit breaker which didn't trip.

I've contacted Castle Creations and hopefully they'll let me know what happened in more detail and perhaps help me towards a (beefier?) replacement.

I just had a nice conversation with one of the staff at BatterySpec.com, which is where I bought my Tempest TR22-12 sealed-lead acid (SLA) battery. I had inquired about a warranty exchange. They denied it but they gave me a really good reason why -- which is why I'm giving them two thumbs up.

The reason my TR22-12 died on my Piaggio is because I had it in a 2 serial 2 parallel configuration with slightly lower capacity Rhino batteries. I had them configured as a bank of Rhinos and a bank of Tempests. The internal resistance of the Tempests is lower than the Rhinos, so the Tempests were discharging faster and this is why one of them failed.

If anything, I should have done a mixed bank of Rhino-Tempest paired with another Rhino-Tempest. This would have protected the Tempests. But in general, mixing different capacity batteries is a big no-no -- which is why my warranty claim was denied.

In any case, my TR35-12 should be good for its purpose so we'll see where to go from there!

All in all, I'm very happy with BatterySpec and glad that they took the trouble to call me to tell me why my warranty claim was denied and why I shouldn't be doing what I had been doing.

I stopped riding about a month ago because I had severe sciatica. It's getting better now and so I thought I'd get back on the horse. One thing I had noticed last month is that my Piaggio was barely making it to work where previously it had been able to go there with energy to spare. I thought it was simply the cold weather.

For a related project, I bought a relatively sophisticated balancing charger, the Turnigy Accucel-8 150W 7A Balancer/Charger. One of the reasons I got this particular unit was that it could charge up to 36 volts of SLA; 32.4 volts of NiMH; or 8 cells = 29.6 volts of LiPo. Most other intelligent chargers I've seen can't handle this high a voltage. I want to experiment with switching over to NiMH or LiPO but I didn't want to have to take the packs apart to charge them.

One of the interesting aspects of the charger/discharger/balancer is that it has an accurate ampere-hour gauge, so you can tell exactly how many Ah you are putting in -- or taking out of the battery. I used this to test the various batteries I have in my stable and found quite a few bad packs.

What surprised me, though, was that one of the SLAs that I had been using in the Piaggio had gone bad. My original setup was 2S2P or two parallel sets of 2 serial 12 volt batteries:

 Battery 1: Rhino SLA17-12  (rated 18Ah) = 10.508 Ah @ 2A discharge
 Battery 2: Rhino SLA17-12  (rated 18Ah) = 10.485 Ah @ 2A discharge
 Battery 3: Tempest TR22-12 (rated 22Ah) = 12.092 Ah @ 2A discharge
 Battery 4: Tempest TR22-12 (rated 22Ah) = 1.880 Ah @ 2A discharge

Yikes!!! Very bad. And I had used it for less than two months... But no wonder I wasn't getting any mileage. I was going to just replace the battery with another similar sized one when I decided to see how many Ah were in the larger batteries that were in my power scooter.

 BigBatt #1: Tempest TR35-12 (rated 35Ah) = 30.612 Ah @ 2A discharge
 BigBatt #2: Tempest TR35-12 (rated 35Ah) = 30.539 Ah @ 2A discharge

Wowza..... This blew my mind a little.

• Revelation 1: The big batteries were getting significantly closer to their nominal ratings than the little ones.
• Revelation 2: Two big batteries had more amp-hours than four little ones == 30 Ah @ 24 volts vs. 22 Ah @ 24v
• Revelation 3: The big batteries were 11.8 kg each x 2 = 23.6 kg
• Revelation 4: The little batteries were 6.8 kg each x 4 = 27.2 kg

This all added up to .... it was better to use two big SLAs rather than four little ones because: 1) I would gain 50% more amp-hours; 2) it was lighter; 3) it was smaller; 4) and in hindsight, it would have been much cheaper.

That was easy enough to accept but it meant that I would have to redesign the battery carrier system. This was something I had been planning on doing anyay. More posts to follow.

Bill of Materials for my mo-ped conversion after the jump.