Charge rate?

[bobsyouruncle]

I've heard a lot of what seem to be contradictory statements about charge rates for batteries. On the one hand many people state that the best way to treat your batteries is to only charge them at a 1c rate and on the other manufacturers give higher ratings to their batteries and many people state that charging said batteries is perfectly fine.

I have a few 3s lipos that are rated to a 5c charge rate and was hoping someone could help clarify for me whether or not I would really be harming my batts to charge them at the max rate as 1c charging is a throwback to earlier generation batteries and an anecdotal preference. Or is it true that 1c charging is really the "best" way to charge your batteries to prolong life?

I had another question as well.

I recently picked up an Icharger 3010b and a dell 6650 900 watt ps.

My question is: what gauge wire is sufficient to parallel charge 6 3s batteries? My current charging lead has 18 gauge wire and my batteries have 12 gauge. Is it ok to run 500-600 watts through 18 gauge wire, or should I upsize?

[Gregor99]

Its true that slower charging is better for your batteries. However with modern higher C batteries, the more damage done to the packs during regular discharges. So while charging at 1c may help prolong the life of the pack its not significant enough to give the user any reasonable amount of benefit.

The manufactures charge rate race is a lot like the C ratings. The charge rate and the C ratings must be competitive with other brands. In fact, I have seen one vendor raise the charge rate spec on a pack after a competitor introduced packs with a higher charge rate. What changed? The pack? Not likely.

All that said, there are diminishing returns in increasing the charge rate. 2c is twice as fast as 1c. But 3c is only a little faster than 2c. 5c is not significantly faster than 3c. Personally I use 2c for my slow rate and 3c for my fast rate. Occasionally 4c, but that is rare. 5c and higher for testing purposes.

Your charger can deliver 30 amps. I would use 14 AWG or larger. Most parallel cables premaid are either 10 or 12 AWG.

[RedOctobyr]

Originally Posted by bobsyouruncle

I recently picked up an Icharger 3010b and a dell 6650 900 watt ps.

My question is: what gauge wire is sufficient to parallel charge 6 3s batteries? My current charging lead has 18 gauge wire and my batteries have 12 gauge. Is it ok to run 500-600 watts through 18 gauge wire, or should I upsize?

Originally Posted by Gregor99

Your charger can deliver 30 amps. I would use 14 AWG or larger. Most parallel cables premaid are either 10 or 12 AWG.

As Greg said, you'll max out at 30A total. What size are the shorter section of wires going from the charger itself, to where it splits out to the 6 different leads? 12-14AWG?

I'm making an assumption that you're talking about a parallel cable, with an initial length of thicker wire, which then splits out to 6 thinner sets of leads. Those first sections of wire will see all the current. After that, it will get split up.

(If my assumption is wrong, and you have 18AWG leads even right where it comes out of the charger, then that's too thin for 30A. For instance, maybe you have a parallel board, not a parallel cable, where there is only a single set of leads, and those are only 18AWG)

For 3S 2200s (making an assumption on size), 3C is 6.6A per pack. With 6 packs, you'd max out at the 30A output. But even if only charging 4 packs, at 3C, 6.6A through 18AWG isn't a problem.

Per this:
http://www.powerstream.com/Wire_Size.htm

18AWG can carry 16A for short distances. 14AWG can do 32A.

If the primary leads of your parallel cable are preferably 14AWG or thicker (like 12AWG), I'd say you're OK for 30A total. Worst-case, during a charge, feel the wires. If they're a little warm, that's usually OK. If they're hot, you have a problem, and need to change something.

[bobsyouruncle]

I'll just play it safe and resolved the connectors onto new wire. Thank you both for that information that is helpful.

Where is a good place to get silicone insulated wire?

[RedOctobyr]

I get mine from HobbyKing. They have a decent selection in the US, and more at the international warehouse.

http://www.hobbyking.com/hobbyking/s...0&currentPage=

[bobsyouruncle]

I thought of something else....the ps supplies 72 amps of current maxed out. Is that the number you use to determine wire size from the ps to the charger. I guess your kinda locked into the charger size and that should be sufficient?

[Gregor99]

Originally Posted by bobsyouruncle

I thought of something else....the ps supplies 72 amps of current maxed out. Is that the number you use to determine wire size?

I size my supply wiring and connectors based on the max the charger will pull for my charging scenarios. For the 3010b that's 36 amps on 24v and 50 amps on 12v.

I'd also check http://www.monoprice.com/ for wiring. Note the copper is better than aluminum.