Hi all, How does one build a LiFePO battery pack. I have seen the balancing circuits online and i suspect they are required. I have decided to go with LiFe batteries thanks to some good advice and prefer to have my batteries chargeable at the same time so I will need to make up packs. I have seen other homemade ones on the forums so I am looking for some instruction. I would hate to ruin the new batteries I am going to buy. Thanks, J
You really just need to solder on balancing leads to your pack. Get leads that match the connectors on your charger. The leads make connection points across each cell so individual voltage can be monitored. I have pictures of headway cell pack with leads in some of my build threads
Can sort of see in some pictures here, really pretty straightforward compared to other boat wiring https://rcwarshipcombat.com/threads/uss-missouri-build-ircwcc.445059/page-4#post-515568
Okay so I follow the reasoning why, but I can't really make heads or tails of what's physically going on in the MO photos. I see the smaller gauge wires you've attached to each cell, and the little white connector. To charge, are you hooking that little white connector to the balancing circuit, which then hooks to your charger? ie: you're not plugging that XT connector into the charger, and instead are just bypassing it to balance the cells? I'll hit up the videos on such stuff when my internet is un-throttled, but I'm just trying to understand the basic layout *as directly applicable to our hobby in almost the exact configuration I'm planning to use for Idaho* Thanks ahead of time!
The little white connector and the XT hook up to the charger/balancer. Most current is passed through the main line, small leads check each voltage and can perform balancing based on the charger. Balancing isn’t a huge deal if the depth of discharge is relatively low, it only becomes a factor if there is a large difference between the highest voltage cell and lowest voltage cell, the effective capacity would be slightly less (but we typically don’t monitor cell voltage while in the boat). There is of course more to it but that stuff isn’t really relevant to our usage
That was exactly what I needed to understand the wiring. thanks, Kevin. Just out of curiosity, I'm going to run a pair of the new BC pumps in Idaho (off of a power relay, so while the rest of my system is going to be 6V, the pumps are not limited), and seriously considering having separate batteries for them. What kind of amp draw should I be looking at to power these guys? I don't have infinite space, obviously, but I'd like to be able to run both of them full-bore for a whole sortie on a battery.
Just buy 2 cheap chargers for $23 each, and forget the balance is another option. I was the first to ever use these type of batteries, been charging them with el-cheapo chargers, and still have the same batteries from just after the MWC Denver Nats, back in 2009 or 10. Batteries are still going strong. This is the 3 amp version. I run 8 of them, and my batteries are usually all charged in a little over a hour. They also sell a 6 amp, but they can get hot. https://www.batteryspace.com/smart-charger-3-0a-for-3-2v-lifepo4-battery-pack.aspx
[QUOTE=" This is the 3 amp version. I run 8 of them, and my batteries are usually all charged in a little over a hour. They also sell a 6 amp, but they can get hot. /QUOTE] You run 8 chargers? Or 8 batteries? Either way, Thanks. J
Pretty much, but you only need one of the two middle wires since they are electrically equivalent (measuring the same voltage). For 2S you will have 3 balancing wires, one to negative, one in the middle between cells, and one on positive.
These are the packs I run now, 15Ah headway cells, can be swapped between large and medium boats. Connections should be clear
So then if I go 12 V, and I am, just ordered the parts, would I put one POS, one NEG and then one balancing between each of the cells for a total of 5 balancing wires? J
