Installed a battery capacity indicator


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ksquared
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Installed a battery capacity indicator

Post by ksquared »

meter2.jpg
meter1.jpg
Just thought I'd share this. I had one of these indicators on the bench from another project & thought why not install it on my CBX. I got it via eBay for about $5. The installation was simple and required no modifications to the bike. That means it can easily be removed with no evidence of it ever being there. It is accurate for voltage measurements (not hard at that resolution) but I don't have any details on how it calculates capacity percentage. It's not a load test so it has to be based on measured voltage. The meter has a switch to select capacity, voltage and off. Of course you would want to leave it off unless you are checking the battery. I think the device consumes around 20ma at 12v. So to use it, I have to remove the left side cover.

FYI another way to check the health of a lead acid battery is measuring its internal resistance. This can be done with a suitable ESR (Equivalent Series Resistance) meter. As the battery condition worsens, its internal resistance increases. ESR meters are primarily used to test capacitors but the one I have works well on batteries too. They are also good for measuring low resistance values. The one I use can measure down to .01 ohms.
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79 CBX - 75 CB400F - 71 SL350 - 07 Buell XB9R - 03 Harley V-Rod

Larry Zimmer
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Re: Installed a battery capacity indicator

Post by Larry Zimmer »

Most interesting. Thanks.
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Re: Installed a battery capacity indicator

Post by divan »

Thanks much for this tip. A voltmeter mounted here is also a quick way to check the charging system output without having to remove the seat to get at the battery or probe the sensing (black) wire at the regulator/rectifier connector. Overcharging (up around 15 volts) is generally more common than undercharging (less that around 14.0 volts) and one common cause of overcharging is voltage drop in the black wire circuit, caused usually by excess resistance in connectors or in the ignition and/or kill switches -- or frayed wires. The black wire handles all of the switched 12v throughout the harness, and it's spliced 4 ways (in one splice) internally in the harness. The lead wire into the splice comes from the ignition switch (fed by the red wire back to the main fuse and starter relay/battery source); one branch wire runs though the 9P connector on into the kill switch, where the black/white wire carries the current back through a connector and to the coils. A second wire at the splice junction runs through another connector into the handlebar fuse block, distributing current to the 4 fuse circuits. And the third wire at the splice junction runs back into the regulator/rectifier connector and into the unit, serving as the battery voltage sensor (AKA the "signal wire"). That's a lot of switches and connectors (not to mention the 3-way wire splice) where voltage can -- sometimes cumulatively -- drop. So a little gadget like this can help keep an eye on our aging wires.

Added note: the black wire actually has a 5th splice, but that occurs at the harness entrance to the kill switch, with one branch going to the kill switch and another going to the starter button switch. But since the starter button switch wire is only energized when the button is pushed it isn't involved in regulator sensing when the bike is running. Since this splice is soldered (not just a barrel crimp) it's less likely to have poor conductance -- but it could.)

For reference I've attached a photo of that in-harness splice. This winter I decided to rebuild my harness and discovered what you see in the photo. Three stands you can see were broken at the splice. If you look closely you can see that the barrel splice was not crimped properly and probably damaged these strands -- time and vibration did the rest. There were also two more strands broken, which can't be seen in the photo -- same cause. I'd had a small but not critical voltage drop in the ignition circuit for a few years and could never find the source in switches or connectors. Probably had a bit of overcharging as well.
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Re: Installed a battery capacity indicator

Post by Larry Zimmer »

Many thanks. These are the type of gremlins that can be most elusive when trying to trouble-shoot electrical issues. Just as a reference for folks, if memory serves me correctly, charging voltage should be of the order 14.1-14.3 volts at the battery terminals. Approx 3000 rpm is a good check point. Any better info on these points, do please correct me. Please!
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Re: Installed a battery capacity indicator

Post by daves79x »

I might be wrong, but that splice does not look factory at all. Are you sure it hasn't been butchered in the past? Points are all good though.

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Re: Installed a battery capacity indicator

Post by divan »

Absolutely OEM, Dave. I'm the 3rd owner of the bike, and the harness, when I bought it, was intact OEM, no tape ever removed, label still in the tape, etc. That was 1993, and in '96 I went through all the connectors (which were in good condition, just never maintained) and cleaned terminals and connectors, applied dielectric grease, and put it all back together. Pretty easy to tell the harness had never been touched. Because I haven't been able to ride for a couple of years, I decided to remove and rebuild the harness, partly because of some minor voltage drop across a couple of circuits, partly because I wanted to integrate some mods I'd been reading about in the Forum (ignition and volt meter relays, Kawasaki alternator conversion, all using cross-linked wires, and secondarily because I'd become curious to see how all of those splices in the wiring diagram were actually made, and where the splices lived in the harness. Looking back at my notes, I counted 15 crimp splices joining a total of 45 wires, spread all through the harness. There are also a couple of solder splices inside the spark unit and the one at the kill switch. Three of the crimp splices had broken strands: the 3-way green/red (starter safety circuit); the black 4-way; and a huge 5-way green/ground splice, which had two 14 ga and three 16 ga wires stuffed into one barrel. In my re-build I broke up the 4-way and 5-way splices, replaced the green/red splice, and then cleaned and soldered all of the splices and insulated them with adhesive shrink tube, instead of the blue tape used originally. I don't know -- maybe the guy at Sumitomo or Yazaki (wherever the harnesses were assembled in '78) was having a bad day.

Here'a a photo I took of the ground splice being unwrapped, and another of the some of the tape wrap on the harness (the orange tape isn't OEM -- it's self-fusing tape I used at the harness/frame clamp points, to prevent chafing). It looked pretty good on the outside, but it was clear that 40 years of heat etc -- especially where the harness runs around the engine -- had done a number on the adhesive.
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Re: Installed a battery capacity indicator

Post by daves79x »

If that's what you found, that's what you found. I've had a bunch of harnesses apart over the years, but the last has been a while, and I don't remember any crimped connections as you show. Must have just forgotten what I did and found. Carry on!

Dave

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