lipo question

[saleens7]

is ti possible to charge two 4s lipos in parallel, but run them in a series without any bad side effects? the triton can only take up to 5s lipos, but ill be needing to charge up to 8s...

[LJH]

S7,
I have been charging a lot of pack lately in a P configuration.....one thing you have to do though is make sure both pack start at the SAME voltage. I have been charging packs well under 1C and they are still very well balanced.

Cheers,
Jim

[saleens7]

how would i do that...i dont have anything that will do that or tell me that...unless the triton can...how do you make sure the lipos are at the same voltage?

[SweetZ28]

I would not do that one pack will get discharged before voltage peak no good for lipos unless you want a fire?

Even if they start at the same voltage... all batteries take a charge diferently so it's dangerous....

[Darin Jordan]

I charge my packs all the time in parallel with no problems... I start the day with the packs equally charged individually and balanced, then parallel them and run them that way the rest of the day...

These are NOT like NiMH where there is a lot of variance between cells... Thus far, the packs are VERY predictable, and since I treat them as a set, they get equal treatment... and stay at equal conditions... I used to separate them and charge separately, but the packs would charge almost identical amounts, so I just leave them parallel...

Also, modern Lipo charges will NOT charge over the set voltage (usually 8.4V for 2S, etc...) unless you tell them to, so when the peak hits the peak, they stop charging... or go to cv mode where they just hold the peak voltage on the cells and let them take in whatever they will take...

The key is to make sure you START with cells of the same condition. Then make sure your charger is set properely.... You shouldn't have a problem... Especially if you keep it at 1C...

[NorthernBoater]

I charge my packs all the time in parallel with no problems... I start the day with the packs equally charged individually and balanced, then parallel them and run them that way the rest of the day...

When you are charging them in parallel are you using a balancer on pack when you are out at the lake?

[saleens7]

umm...im going to try to explan my situation a little better....i want to use two 2s2p packs from maxamps...they will be used on my SV.....a 2s2p pack is just basically two 2s packs wired in parallel and shrinkwrapped together, and since they are wired to be as one pack, it would basically be just a high capcity 2s pack....so the only way i can charge and discharge the pack is at the same time....i was planning on use twin 4s packs in parallel, but now ill be using two 2s2p pack in a series...so now the only way to use the 2s2p pack is by using the two paralleled 2s packs at the same time since they are wired to be a single pack....uh....im confusing myself trying to explain it....lets just call it a self-answering question and forget this thread:D

[LJH]

I have charged pack in paraelle 100's of times with no issues. It is best to use packs that have the same amount of cycles on them and are in the same condition. I use a DMV to get the exact voltage of the pack. Once charged my packs ate within .02V of each other. If you run the packs together it should be no issue charging them together. I was a VERY early adoptor of Lipo's when they first came out my first pack, which I still use, is a Kokam 700mah pack that I bought back in early 2002. I have dozens and dozens of lipo packs ranging from 2S 300mah too 4S4000's. One thing that I have noticed that really seems to help the longevity is charging at a lower rate then 1C, I have never ballanced a single cell in my life but I do keep an eye on individual cell voltage and with quality cells I have never had an issue. I have a couple TP2100PL packs that I use in a 50" edge that pulls 40A WOT. While I am never at WOT all that long the cells are still doing well after 100 or so cycles. People make Lipo's sound like they will explode at any minute but as long as you know what to look for and follow propper proceedures they can be very safe.

Cheers,
Jim

[saleens7]

i know the exploding lipos are exaggerated alot, but as long as you take all safety precautions, you probably wont ever have a lipo blow up on you....ill charge in a lipo sack and once a week will chare the lipos below their 1C rating....

i wonder if the triton can measure the voltage of each pack...ill have to look that up...