Sizing Chargers to the pack size

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echuckj5
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Sizing Chargers to the pack size

I read a lot about chargers failing.

I used to be in a business that did a lot of land surveying. The instruments used in the field used 12 volt agm batteries. These batteries were used hard. In very harsh conditions on construction sites. 365 days a year. Only tough chargers could tolerate the field conditions of the temperatures in the summer on the ground close to 110 degrees and in the winters cold, wet and muddy conditions found on these construction sites. These batteries were being used or being charged, all of the time. The sophisticated chargers I used were made by zivan. They were very smart, it did not matter what state the battery was in, cold, hot, discharged, it sensed the batteries condition and charged the batteries properly every time.

Now, I used to own a boat with gel cell trolling batteries. Big heavy 90 pound batteries. Again, tough chargers to charge these after a day fishing.

Now, I certainly did not think a little tiny 1 lb 5 amp charger, my soneil 2409 is a 4.5 amp charger, was going to last long with daily charging a 864 watt hour pack 2 times a day. That I got 8 months use with this charger on this bike actually surprised me. Actually it shocked me! I only bought it because it was the only charger I could find that could be left hooked up to the battery all of the time. It has no cooling fan, it ran very hot every charge. I thought, based on my previous experience charging batteries for 25 years, that the little soneil did an outstanding job! Except for the fact that the soneil charger does not sense the internal temprature of the battery it is charging, I would certainly purchase these in the size necessary for my pack.

A charger needs to be matched to the size of the battery to prevent overloading and overheating the charger so that it can charge properly. I suspect I should be using chargers with an output of about 36 amps for my agm battery pack of 864 watts. When I was in contruction and in my boating experience, the chargers always cost more than the batteries. Good chargers lead to good battery life. Cheap chargers lead to very poor battery life. And, cheap chargers don't last long.

In my experience, the charger is as important as the battery, and, in my opinion, the charger should cost more than the batteries they are charging. I used cheap chargers and burnt up quite a few batteries, I learned my lesson, I never lost a battery when using a good charger.

Chuck

echuckj5
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Re: Sizing Chargers to the pack size

I guess I posted this fishing for comments on what others are using for chargers that are portable enough to be carried on the bike permanently and have good life for lead battery packs. Anyone use the larger soneils with cooling fans?

chuck

[b]AGM BATTERIES[/b]

Alphi
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Re: Sizing Chargers to the pack size

I use NIMH Batteries with a "Universal Smart Charger" you can pick these babies up on ebay for $17 USD.
they are so small that I managed to buy 3 and tape them together so that trickle charge my battery pack which is also split into 6 even 12V parts. They trickle charge at 1.8A and .9A respectively.

This can manage to charge a 72V 18.2 AH NIMH pack in about 5-6 hours.

If I used 6 Chargers I could half that.. time.. and they still would only take up a small space on my ebike.

They work well with NIMH.. and apparently there is a LI-ION version too.
They are also very light weight..

reikiman
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Re: Sizing Chargers to the pack size

Actually it shocked me! I warned you against licking the charger terminals. But did you listen to me? Nooooo..... That's what you get from licking the charger terminals -- a shock.

A charger needs to be matched to the size of the battery to prevent overloading and overheating the charger so that it can charge properly.

Okay.. so, seriously..

Yes, choosing a charger has a couple characteristics. But I think the size of the battery pack isn't the best attribute to choose on.

If you're gonna carry this on an electric bicycle then the charger should be small enough to carry, right?

Different battery packs can be charged at varying rates. Some packs can only be charged at a low amp-rate, while others can be charged at a high amp-rate. You mention a "36 amp charger" and that's a pretty darn high rate ... The chargers I'm accustomed run from 3 amps to 8 amps. My biggest charger is 15 amps.

The charging rate determines the the time to recharge. You say your pack is 864 watt-hours, assuming that's a 36 volt pack then you have 24 amp-hours. A 4.5 amp charger should take 7 hours to charge that pack assuming it's fully discharged.

And, yes, good quality chargers will do a better job than cheapies.

- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
- Electrified Electra To

echuckj5
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Re: Sizing Chargers to the pack size

reikiman,

This post is a little wrong. I never had any luck with gel cell trolling motor batteries in series. It did'nt matter how I charged them. The first set of gel cells I owned was a very large set of 36 volt batteries with balancers, circa late 80's. The gels did'nt last a day. Running a 3 hp minn kota trolling motor. Had a lot of luck with deep cycle wet cells. I ran the gamut, used every battery out there, lead acid. Lot's of marina grade chargers. Most were ##$$%%!!.

A good battery with a cheap charger will not last as long as a good charger with a cheap battery. My experience. For what it is worth.

When I built my first e bike, I needed a small, portable charger. Soneil, from my reading, was highly recommended. I'll never recommend them. Bought a 24 volt 5 amp charger. That charger's voltage was all over the place, got hot. I had to monitor it constantly to prevent damage to the 2 odyssey pc 625 18ah batteries that it was responsible for charging. Horrible charger. I cannot think of a charger that I have owned that performed worse.

The soneil model 2409, had trouble with overheating with a 432 watt hour pack. When I upgraded to a 864 watt hour pack, forget about it. On a 24 volt pack, the charger would show up to 32 volts, I had to watch that charger constantly. 32 volts is high for deep cycle wet cells. I kept a fan on it, monitored it like a mother hen.

That soneil lasted about 2000 miles, 8 months. $100 down the tube.

Anyway. The Odyssey batteries, 18ah, each, can be charged at up to 50 amps, each, as long as the charge voltage does not exceed 14.7 volts. The manufacturer says that there is no amp limit. The 50 amp is from the battle bot websites, where fast charging is important. They found that rates of greater than 50 amps harmed the odyssey 18ah battery. If I could find a charger, I could charge these in 10 minutes. I have never found a lead battery out there that outperforms it.

I was only inferring to lead chargers. These cheap series chargers for lead, portable that they are, aren't doing anything good to the batteries. I've used balancers on lead batteries, never had any luck with em. (on marine batteries). Good batteries, good 12 volt chargers, not series chargers, Thats was my point. Cheap batteries, cheap chargers, good luck.

chuck

[b]AGM BATTERIES[/b]

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