Can I borrow your battery charger/balancer/reconditioner?

Albert, This is amazing!

1) Why do you even need to add heat sinks to the chargers? Can’t you just keep them separated by a few inches? I assume they were designed for use without a heat sink. Is that correct?

2) About using the Prius’ fan: why do you need a special wiring harness? Can’t you just tap into the two wires that go to the fan and give it 12 volts? Would there be a problem with the power going upstream of the fan? If so, could you just add a toggle switch to the positive wire upstream of where are you tap in to deactivate it?

3) Is the input voltage 120VAC? I noticed there’s a big range that can be used for those chargers.

4) As you monitor your battery bank voltage, at what point do you turn off the chargers?

GREAT information!! Those chargers are WAY cheaper
than any option I’ve seen so far! They are the perfect amperage also!

Thank you so much for all of this great information!

 

$1000 is a great deal!

 

After a lot of confusion and fact checking I went ahead and ordered those three chargers that you recommended. It seems like a great plan!

Nice photos of your discharging set up! It’s hard to read the multimeters though. I’m assuming one says 205V and the other says 0.9A? Is that showing how far you discharged your battery bank?

 

Thanks! I look forward to finally moving forward on this project.

 

Hi again, i’m at Home Depot right now trying to get lightbulbs, but I don’t know the wattage that I should be looking for. What do you recommend? Thanks

 

I built a battery charger AND discharger similar to Prolong for less than $100 thanks to the information provided by @Albert Barbuto!

By charging and discharging a few times I was able to increase my gas mileage from 33mpg to 37mpg. The battery bank holds a charge wayyyyy longer and the Doctor Prius app shows an improvement from about 50% life expectancy left to over 100%!

My fuel mileage is only 37mpg because when my car originally threw codes about the battery bank going bad I replaced one module which through off the balance of the whole bank… If I would have used a charger like this before replacing anything I probably would have fixed it AND improved my gas mileage from about 43mpg to 47mpg.

At this point it looks like I need to balance each individual module so that they all have the same amp-hours and match them up so they all have the same internal resistances. I calculated my annual driving and I would only save about $150 per year in fuel by fixing it, so I’m going to leave it as is. If I were to fix it it would cost about $200 for an advanced hobby charger that charges and discharges four modules at a time, but I’m not going to bother anymore.

At least now I have my charger which I can use a couple times per year to extend the life of my battery bank.

Here’s what you need:

- BE CAREFUL! Even after you take that orange clip out of the battery bank you need to take a multimeter to the battery output terminals that you will tap into to make sure that they are actually dead. Sometimes they are still live!
-Three of these little chargers wired in SERIES to have a 300V output at a constant 0.350Amps. The inputs should be wired in parallel because they need 120VAC.

-A flat board to mount these little chargers onto. Space them out so they can cool, but it’s really not like they get that hot.
-Some lightbulb outlets for mounting on the board which will be your discharger setup. You really only need two wired in series so that your battery bank doesn’t blow the lightbulbs, but I mounted 4 and wired them up different ways, but it didn’t improve anything. Leviton Plastic Keyless Lamp Holder-R50-08829-CW4 - The Home Depot
- INCANDESCENT bulbs. Two 200W bulbs, two 75W bulbs and two 25W bulbs. Here in California I couldn’t find 75W lightbulbs so I used 40W bulbs instead. You should get one or two extra 200W bulbs because they like to blow since you’ll be using them when your battery bank is fully charged at about 240V.
-A 25ft roll of 14gage wire that’s rated for 600V from Home Depot. It only needs to have two wires running through it. No need to have that center bare grounding wire like I had. If that’s all you can find and go ahead and buy it. Southwire 25 ft. 14/2 Gray Solid CU UF-B W/G Wire-13054221 - The Home Depot
- Three pronged plug for 120VAC outlet which feeds your chargers. Two prongs is probably fine also since you won’t be using the grounding wire. Leviton 15 Amp 125-Volt 3-Wire Plug, Orange-R51-515PV-0OR - The Home Depot
- A bag of wire connectors so you can quickly connect and disconnect wires. From Home Depot. Ideal PowerPlug Orange Ballast Disconnect Discs (5-Pack)-30-1302S - The Home Depot
- 3 amp fuses and in-line fuse holders rated for 600V. This goes between the battery bank and charge wire you install. This is important because the charge wire that you install will permanently be in your car and if it shorts it could electrocute you or catch something on fire.

- Wire connector kit that includes butt connectors and ring terminals. Gardner Bender 100-Piece Terminal Kit-TK-806 - The Home Depot
- Wire crimping tool/stripping tool
- electrical tape
- Multimeter to monitor charge and discharge voltages.

To install and operate your charger and discharger follow the instructions here: Our Product Guides | Hybrid Automotive

To keep your battery bank cool while charging all you need to do is find the two wires that run to your cooling fan which is attached to the duct work on the passenger side and cut those wires, splice into them with a few feet of wire so you can extend it for easy access once your car is put back together (mine can now be accessed from where the 12V battery is located) and use those orange wire connectors to connect and disconnect to the fan. When you are charging all need to do is connect the fan directly to a 12V battery, but not your Prius battery because it will probably die. Ideally you find a 12V power supply, but I don’t know how to guide you on that. Whichever 12V battery you use will need to stay charged for about 24-36 hrs because that’s how long it takes to fully charge your battery and give it extra time to hopefully balance. After doing this, I personally don’t think that it’s possible to balance your battery bank with this kind of charger, but it will definitely add life to it in the form of increased amp hours. To balance modules I think you need to charge them individually and then you are able to collect data and ensure that each module has the same specs before putting them back in the bank.

Discharging is very tricky with the lightbulb discharger. You cannot actually calculate when you will reach the termination voltage because it does not discharge linearly, so don’t even try it. You’ll have to keep checking on a regular basis. It discharges fairly linearly for the majority of the time and then all of a sudden the voltage will drop off DRAMATICALLY, so you really need to check it often. You don’t want the voltage to get too low because you can risk damaging individual cells within a module because the current can flow backwards. That happened to me once, but seems to be OK. Also, probably no need to charge/discharge more than three times. More than about three times is not recommended because it’s a little hard on your batteries. Most likely you’ll be good to go after about one or two times.

Try to preserve your connections by not connecting/disconnecting anything under load whether it’s the charger or discharger. Basically you want to avoid sparking so that your nice connections don’t get damaged over time. If any sparking occurs it should be as you screw in your remaining light bulb when activating your discharger.

All supplies that you use should be rated for at least 300VDC. The closest thing you’ll find in the stores are things that are rated at 600V, so don’t let that throw you off. Just make sure everything is rated for 600V as you make your purchases.

That’s about it! Like I said, building this charger is definitely worth it if you want to add more amp-hours and probably overall lifespan to your battery bank, but if you need to balance your batteries then I highly recommend going the hobby charger route, collecting data on each module, matching them up a.k.a. balance them and put them back in your pack. There are other posts on that. This charger however is very convenient for being able to quickly connect it without having to take your car apart in the future so that you can continue to extend the life of your battery bank in the years to come.

Sorry for the crappy photos! I should have taken them when I had everything hooked up.

A7142726-1498-4E69-9396-D130ED805B2F by JamesG123 posted Jul 28, 2020 at 2:27 PM

7CAD9DF9-4A0E-44B4-8874-3C93FC0B2912 by JamesG123 posted Jul 28, 2020 at 2:27 PM

8005DBC5-C933-4C36-8067-FF582405C5C0 by JamesG123 posted Jul 28, 2020 at 2:27 PM

 

Thanks! I think we are actually saying the same thing, but I’m simply outlining a process and providing links to those details on the prolong website.

As you said there are pros and cons to balancing your batteries with one style of charger over the other because when you use the style of charger that I built/prolong then you have less control over the final outcome of your battery bank. If you use the hobby chargers then you can work on each module individually, collect more data and ensure that the entire bank is perfectly balanced.

To those of you who are having problems with your hybrid battery and trying to decide how to go about fixing it in the most efficient way possible then you should consider:

Scenario 1- In this scenario you build or acquire a charger like the one I built/Prolong. This requires you to build/acquire the charger, take apart the interior of your car including the drivers side metal cover of your battery bank so you can install your charger wire which will stay permanently installed, and splice into the fan wiring on the passenger side. You should choose this scenario if:
A. Your car has not thrown codes, but your are starting to notice your battery charge level fluctuate more widely than usual, engine is starting up more often to keep them charged, can’t drive for very long on battery.
B. Your car recently threw codes about your battery bank and you have not changed any modules yet.

Scenario 2- You’re probably better off using the hobby chargers (great thread: Gen II Prius Individual Battery Module Replacement | PriusChat), which requires you to take apart the interior of your car, take your battery bank out, disassemble your battery bank, work on the modules individually and generally spend more time if:
A. You only want to work on your battery bank once and guarantee that you’ll fix it the first time.
B. If you tried the other charger and your car is still not fixed.
B. If you replaced one or more modules, drove it around and it’s still not fixed.
C. If you replaced one or more modules, tried the other charger and it’s still not fixed.
D. If you are considering cleaning/replacing all the copper plates. (That’s probably not going to fix it and it’s a pain in the butt if doing it while in your car, so you might as well take the battery bank out and completely rehab it.)

This is the thought process I would follow if I were to do it all over again. These are by no means ironclad rules, but from my perspective they are the most efficient way to go about fixing a hybrid battery problem. Good luck!

 

I don’t think what you are recommending is a good idea because how can you be sure that the replacement modules that you buy closely match your existing modules? If people go the route you are suggesting it’s more of a gamble because you are suggesting that the style of charger that charges the whole battery bank (the one that I built) will balance the battery pack with the new modules that you just replaced. I would not rely on this style of charger to balance the modules. It did not work for me.

If any modules are to be replaced I think it’s best to use the advanced hobby chargers, collect data on each module and do everything listed in my Scenario 2. Both of these scenarios were laid out so that people can minimize gambling.

If someone is OK with gambling they should follow your Scenario 3, because they could save a lot of time, but I personally think that it’s best to minimize the gambling. In fact, everything you are suggesting is exactly what I just finished doing and that’s what led me to give the advice that I just gave with Scenario 1 and Scenario 2. Another advantage to following my two scenarios is that you don’t even need to use the apps because you already know you have a hybrid battery problem and you either solve it or don’t solve it with Scenario 1 and if the problem is more severe then you follow the instructions in Scenario 2 which means collecting lots of data with the hobby chargers which is more accurate than using the apps. There’s nothing wrong with using the apps, but they are not necessary unless following Scenario 3, but I personally don’t recommend that because I just took that gamble and it didn’t work out.

I won’t be responding on this form for a while. I have a lot of stuff I need to be working on right now. Thanks for the interesting conversation and thanks to everyone who has helped with this project! Good luck to those of you working on your hybrid battery problems!