raw newbie battery pack questions

[64ragtop]

I just acquired an electric trike in running condition, but with no documentation. it came with an active battery pack consisting of three 12 volt sla batteries that seems to have been created in the "necessity is the mother of invention" school of engineering. It also came with a battery pack that fits into the frame for a much neater appearance. I think the second pack was maker supplied and the first - - well....it was providing motive power.

For some silly reason mostly having to do with an air conditioned workspace - I live in Austin, Texas, and our temperatures have been flirting with the 100 degree (F) mark for about two months - I decided to try to figure out the maker supplied battery pack first. it consists of a charger port, three 6DZM-10 12 volt 12 amp hour batteries in series and an output contact set that matches contacts inside the rack the battery pack slips into, and the wiring and jumpers needed to place the batteries into a series configuration.

using an old, but trusty analog volt-ohm meter, I measured approximately 36 volts at the charger input, and the same at the output terminals. I also measured approximately 12 volts from each battery. When I attached the battery charger, however, I measured 13.25, 13.0 and 16 volts on the three batteries. Since I am not conversant with any oriental alphabets, I suppose the led changing from green to red is the expected behavior. The other led remained red, the fuse didn't blow and the charger only got s bit warmer than room temperature. I'll take all of this as "normal" until I learn otherwise.

So, first question: what do the varying voltages on the batteries while connected to the charger mean?

Second: should all three batteries in a series configuration to drive a 36 volt motor and controller be equal in amp hour ratings.

Third: any other insights and wisdom is much appreciated.

Thank you!

 

[Link]

First: Means that 16V batt has a pretty high internal resistance and probably crap.

Second: Yeah.

Third: Meh...

 

[Anonymous]

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[64ragtop]

Thanks for the replies, folks. I finally found my little cheap digital volt/ohm meter, and pulled the charger off the battery pack. An hour later, the batteries read 12.7, 12.4, and 11.9volts. the low volt one is the one that had the high reading on the charger. So, battery #3 is crap. Can I replace the one and expect the other two to behave?

On a related matter, I'm thinking the "contact on installation" (for want of a better term) is probably not reliable, or at least would need pretty consistent cleaning to assure good contact. Another concern is that they could also be intermittent on rough surfaces and that this could stress the controller. Maybe I should sacrifice the convenience for a more reliable power connection???

And on a semi-related matter, this is a Chinese tricycle that bears some resemblance to a Worksman Industrial Trike called the Mover, with an even larger cargo platform. The only English language words I've found on it are "Sanhuan" "Century Star" and the phrase in the dashboard that reads: "The electricity move the bicycle" Any ideas where I might find more info? I've looked at scores of Chinese sites, til my eyes glazed over and been rather amazed at the seemingly unrelated products featured on many sites (bicycles, shoes and hair straighteners, kinda stuck in my memory). But no industrial looking electric trikes.

The good news is that it ain't rocket science, and with a bit of help, I can rework it from the ground up! I'm mighty glad I found this site, 'cause it looks like lotsa help is right here.

Thanks again!

BC

 

[Anonymous]

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[64ragtop]

What's the downside of just replacing one of the three batteries? If I replace one, will the life of the other two be shortened? Digi Key's pricing for the two best replacements are about $150 and About $170 for three. I'm a disabled vet on a fixed income trying to save money after two successive $64 dollar fillups to my truck. If I was going to replace all three, would the extra 2 amp hours claimed for the Panasonic batteries justify the extra $21 price? Is there any way to determine the characteristics of the Chinese charger (constant current or whatever else) , or reason to replace it with one with known "better" characteristics?

Thanks for the input! I'm learning but this is a whole new electronics area for me.

BC

 

[dogman dan]

Depending on how far you need to go,

Use the other pack, no problem carrying it on a trike.

Replace the batteries in the stock container with sla's whatever sise fits inside. Then use one pack, then the other, they do need to be the same sise to paralell connect em.

Get a Ping 36v 20 ah lifepo4 on ebay. Mine will take my trike about 15 miles including serious hills and very little peadling.

 

[Link]

That third batt is definitely junk. The other two will probably be okay for a while longer. But, if you can use this thing to replace that truck sometimes, you might as well replace all three. You'd save money in three fill-ups. If you can use it to replace the truck a lot, then you can get some lithium and get better range out of it.

The contact is probably okay if it isn't loose. Replace it with some PowerPoles if you're paranoid.

 

[dogman dan]

Link is right about the pay off. I bought two ebikes, spending allmost $2,000 and I am about to break even compared to the cost of using a subaru to get to work. Every day I ride puts $12.50 in my pocket. With a truck, you will be pocketing about $20 a day or more. I'm taking about the total cost per mile, which makes $4.00 gas look cheap. Not having to buy a new truck soon, Priceless. A really good litium battery will let you really put the truck away since you can ride farther. 20 miles on an ebike is really no sweat at all.

 

[Rassy]

Hi Ragtop. I just read through these posts, and I think there are some real good "long term" answers to your questions. But to get started, IMO, you have everything you need. First, I would charge all six batteries individually, probably with a 2 amp setting on a car battery charger. Then I would take what I thought were the best three batteries (IMO, for what you are doing it will not hurt to mix and match them, assumming they are all 12V batteries), and see how they work under load. Now you can play with the trike, find out if it works okay, etc., before you spend real money on it.

I do not think you should spend any money on even one replacement SLA battery. When you are able, use that money towards a "Ping" type LiFePO4 battery.

 

[Beagle123]

I would try charging each baattery separately with a 12v charger to make sure that they're in balance. Then when they're all charged to 13v, go for a long ride and test when you get back. If a battery is bad, it will be lower than the others.