Parallel Charging | Quick Tip | Motion RC

If you want to be able to charge more batteries at once, try parallel charging. Links to parallel balance boards here: www.motionrc.c...
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#parallelcharging #lipo #rc

[@og_myxiplx]

Parallel charging is great, but this video misses a whole bunch of safety tips. I've been parallel charging 6 packs at a time per charger for 5+ years now and it can mask issues with packs, so there are additional checks you *must* get in the habit of carrying out yourself if you're going to do this safely. While parallel charging, your charger can no longer monitor the individual cell voltages of the packs (a problem in one cell of a pack will be masked by the healthy cells from the other packs), and it can lead to cells being over-charged and catching fire since your charger can no longer detect an over-voltage state. The biggest cause of fire when parallel charging is connecting a bad pack among a bunch of healthy ones. You also don't ever want to connect a pack that's at 3.7V straight to a pack at 4V or 4.1V, you'll cause a brief spike as a ton of current flows straight from the high voltage pack to the low voltage one. The packs should be at a similar state of charge, ideally around 0.1V difference between them, and you want to start by connecting the pack with the lowest charge to reduce the current spikes hitting each pack as the higher voltage packs are connected. The good news is that it's easy to counter all of the risks; simply check your packs *before* you charge them. A battery checker like the CellLog 8S which shows the voltage of each cell, is ideal. Over the years I've found the safest parallel charge procedure is: 1. Check your batteries, ensure all the cells are balanced. If any packs show a bad cell (one cell > 0.1V different to the others), put it aside to charge individually. 2. As you check the batteries, line them up from lowest to highest charge. 3. Connect the lowest charge battery as per your charger's best practice (either balance leads first or main leads, depending on the charger). 4. Now connect the next lowest battery, but now you always connect the main leads first (they're thick enough to safely absorb any current flowing between the packs). 5. Continue until all your packs are connected, and start the charge as the video recommends. If you want to be extra careful, check your packs are all balanced after charging too, it only takes seconds if you have a Lipo battery checker like the CellLog 8S that shows cell voltages on the first screen. I routinely charge 12-24 batteries in about 30 minutes flat, parallel charging is very reliable once you understand it.

[@bpierce4884]

Great explanation, Thank you. I have a question. I've watched some videos' explaining that your batteries need to be within 0.03v of each other or more ideal, 0.01. Now I just got back in from the field & I'm storage charging (2) 2200 11.1 S3 batteries. The first one finished with storage charge of 11.46v and the second finished with storage charge of 11.52. Question: How do I get those 2 batteries or for that matter, all of the batteries I want to Parallel charge to be within 0.01 or 0.03 of each other before hooking them all in parallel charge? Is it really critical to have them all that close? Thank you in advance.

[@og_myxiplx]

@@bpierce4884 That recommended difference is per cell. I always use a battery checked with cell voltages as you need to monitor these yourself if you parallel charge. Your packs there are at 3.84 and 3.82, they're more than close enough. If you check online there's a video showing even a full and empty pack connected together only exceeds the recommended charge current for a brief second. Even a 0.1V gap in cell voltage between the packs is unlikely to harm your packs. But do get a lipo checker like the CellLog 8S that can display per-cell voltage by default. That's the single most important thing you need to parallel charge safely.

[@bpierce4884]

@@og_myxiplx Yes, I have a lipo checker that reads and displays each individual cell voltage as well as combined total pack voltage, can't live without one of those in the hobby. I'm constantly using it so I've got that covered. I'm just concerned about the difference between the two batteries I mentioned. So, what you're saying is that it's the Individual Cell # I should be concerned with and Not the combined voltage? That's what I'm a little confused about. I am looking to purchase a parallel board but want to be comfortable before I do so I don't burn the house down.

[@og_myxiplx]

@@bpierce4884 Follow the steps in my post and you'll be golden. In a pinch I've happily connected a pack with cells at 3.75 and 3.85V together, any more than that and I tend to charge them separately, or for a group of batteries split them up into groups that are close together. Ultimately so long as all the cells within a pack are a similar voltage, and you're parallel charging packs of similar quality it's very reliable. I just wouldn't parallel charge a beaten up, swollen pack with 300 cycles in parallel with one that's brand new from the factory.

[@Michelsen3K]

Super helpful. Thanks!

[@k.o.0]

James a great topic. Only recommend 2 modifications to this video - please tell them 1) only identical batteries (cells and mah) 2) all batteries must be at nearly the same charge. I know this is common knowledge to us veterans but but for noobs this may not be apparent. Parallel charging is a huge time saver, but, if you fail to follow those 2 points above, it could equal disaster. Thanks again James and RCM!

[@mikekennedy9174]

I was just about to make the same comment

[@M0rdH0rst]

The capacity may differ by some amount. I'm charging 1600 mAh and 2200 mAh parallel as long as they are at storage level. A problem may occur, if you have a big, almost fully charged battery in parallel with an almost empty smaller battery. Different cell count is easily detectable by the smoke coming from the board 😁 This happened to me, when I didn't notice, that one wire on the balance adapter of the battery was broken. It turned the 4s into a 3s battery and destroyed the multi charger board.

[@og_myxiplx]

Point 2 is spot on, but you're wrong with point 1, the batteries don't need to be the same mAh. So long as they're the same number of cells they'll connect in parallel just fine. For example last week I had 3x 850mAh 3S packs, and 3x 2150mAh 3S packs to charge. Once connected together via a parallel board they're effectively a single 9,000mAh pack, and charging at 18A is a 2C charge rate for all of them.

[@k.o.0]

@@M0rdH0rst Although it is possible to charge batteries with different mAh, it is not recommended since you could have the smoking situation you described. Also, if using the balance charging setting it can knock in many more discharges along the way, thus shortening your batteries life which is why it’s best to keep it all the same.

[@M0rdH0rst]

@@k.o.0 Isn't that more an issue of old batteries with new batteries? Do the differences in the internal resistance have less effect than different capacities?

[@JeffsCustomRC]

Love the quick tips!! Parallel charging is awesome when done properly, thanks for sharing James 👊🏼👊🏼

[@txkflier]

The first thing I do is check all of the cell voltages in the packs I'm about to connect to the parallel charging board. If you connect battery packs in parallel that aren't at about the same voltage, a lot of current could flow between them. My personal limit is a maximum difference of 0.1 volts between the lowest cell and the highest cell. I use a Hitec RCD 44173 battery checker because it will show me all 6 cells without having to press any buttons. Also, the packs you connect in parallel MUST have the same number of cells and SHOULD be the same capacity. You can charge a 3300mAH-6S pack in parallel with a 5000mAH-6S pack, but you should calculate the charge rate based on the smaller battery. Batteries charging in parallel divide the total current equally regardless of their capacity..

[@rusack7174]

To that end one can charge different capacity packs but not limited to the smallest pack's 1C charge rate. For example, parallel charging a 1500mAh pack with a 1300mAh one can add up the total capacity of both, in this case 2800mAh, or 2.8A charge rate. Charge is divided by all packs. And always, keep close attention to wire connections as lithium batteries can pack a wallop!

[@jeffjackson6358]

Great info as always. Some other comments have covered a few more important tips that everyone should follow when parallel charging.

[@victorrcjets7660]

I was doing a lot of parallel changing before. I let them almost get done then balance change them to complete them.

[@jonoedwards4195]

Crikey, best tip EVER! Beauty Motion, My knuckleheads spinning right about now.

[@JohnVHRC]

Great explanation James! I've been doing this for years!

[@jonoedwards4195]

Ahahahha, Ive had My Smart Charger covered in dust for years. Had to wipe the LED display clean the dust was so thick! Charging two 2200s right now, this Tip is perfect, Beauty Johnny.

[@michaelholder2649]

Never used a parallel board. Great tip to know. Might have to get one.

[@stevejohnson1871]

Great explanation,James

[@rusack7174]

... and you can daisy-chain those parallel boards to increase the number of packs charged/discharged at the same time, following the same rules. Remember, all packs parallel charged must be of the same cell count and best if close to the same level of voltage when beginning. Parallel boards are a massive time saver when having a number of packs to charge. I also keep an eye out for packs whose internal resistance has crept up. I test all packs coming off the charger.

[@medscott2]

Love the quick tips.

[@Cuisinenomade1]

Not checking the voltage before? Isn't that exact detail, if left unchecked, that can kill a battery or worse?? I am confused.

[@guisblacio]

Great 👍 info. Thanks for sharing.

[@ignaciovera8107]

BTW, since we already have working shooting in tanks and working swaping wings in the tomcat, when working gun for A10? JK

[@DadsRCHangar]

Never used parallel charging before, my charger has 4 outlets. But an interesting tip 👍🏻

[@twincitymoo7141]

Great tip James. What is the export at the end of the charge board?

[@rusack7174]

To daisy chain additional boards if wanted so if/when charging more than one board's total pack capacity.

[@2erc22]

Awesome 👍

[@winecountryrc2143]

Great