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Naomi netDIMM board battery replacement

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big10p View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Topic: Naomi netDIMM board battery replacement
    Posted: 07 Mar 2017 at 8:34pm
From what I've read, the battery fitted to the netDIMM boards only work for a few days before going flat, so by 'replacement', I mean a power supply (preferably UPS) that will keep the game/data loaded on the DIMM, even if the cab isn't used for a couple of weeks.

This would be great for my dedicated Shootout Pool cab, as it would mean the ranking tables don't get wiped every time the cab is turned off. It would also shorten boot up time a fair bit.

I found this thread on KLOV that discusses a solution, but I'm no electronics whizz, so don't fully understand how to build it. Has anyone build something like this, and can give a few pointers on exactly how to make one? Or even better, does anyone make and sell them?

Cheers
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terminator2k2 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2017 at 10:03pm
Just taken this from my Daytona USA 2 thread in the make section, I did this on my chihiro , I can't find the original thread though....

well just a small update.....ive been doing the battery backup mod as done by a few members on here....
pictures not the best.....This will be mounted on the rear of the cab in the empty space....

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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2017 at 10:09pm
It uses a 12 v battery and a ups backup system. This is charged by a 15 volt dc supply.....it then goes to a voltage regulator which steps the voltage down to 7.2v which the original battery was rated at....a diode is fitted on the output to stop any voltage leaking back to the battery mod from the chihiro.....

I use a mains adapter with built in timer , so the 15v adapter only charges the battery for 2 hours a day....and not continuously......
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big10p View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2017 at 11:23pm
That looks like just the setup I'm after. I didn't realize it's a well-known mod, as nothing came up when I was searching for info (except the link I posted).

I still don't quite understand exactly what all the components are, and how they're wired, TBH. If I build something like this, I want to be sure I know what I'm doing, and not make something that's either going to damage my Naomi/netDIMM, or create a fire hazzard! It would be really useful if you could post some links to all the bits I need (think this is the battery you used?), and go in to more detail about how to wire it up.

Cheers!


Edited by big10p - 07 Mar 2017 at 11:33pm
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obcd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote obcd Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 8:43am
Basically, the original lithium 7.4V battery is removed and replaced by a 12V gel PB accu. On the picture, it looks like a 7AH type, but other types can work as well.
 
As the Naomi needs 7.4V, a step down converter is used to change the 12V accu voltage to 7.2V.
This is a module you can buy premade.
 
When the Nedimm (Naomi) is turned on, it sends voltage to the lithium accu to charge it. This behavour is blocked with a diode between the output of the step down converter and the Netdimm accu connection.
 
Third thing that you need is a charger for the 12V gel accu. That's again a premade module. It limits the charging current that goes to the battery. It needs a 15V input voltage. (The input voltage must be higher than the battery voltage)
 
The original netdimm battery has 3 contacts. The black is ground. The red is the output voltage and the blue is a thermistor (or ntc?) to measure the battery temperature. It's function is to stop charging the lithium batteries if they become 2 hot. The wires go to a small pcb that sits on top of the batteries. Normally such pcb should prevent deep discharge of the battery pack as such can damage lithium batteries. It should also stop charging them if the voltage has reached 4.2V (1 cell) Further, it should do some load balancing to ensure both cells are charged equally.
 
It has been described in detail for a chihiro 3 "outrun 2 sp" setup. When the netdimm batteries on that run flat, it loses it's high scores and network setup. (and the game code itself obviously)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 9:49am
Heres a thread :


theres links on that thread to get the stuff needed on ebay.....

Is the battery in the Naomi the same as the chihiro? ive never messed with a naomi net dimm so wouldnt know...


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Post Options Post Options   Thanks (0) Thanks(0)   Quote seanr28 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 10:40am
Originally posted by terminator2k2 terminator2k2 wrote:

Heres a thread :


theres links on that thread to get the stuff needed on ebay.....

Is the battery in the Naomi the same as the chihiro? ive never messed with a naomi net dimm so wouldnt know...



yes they are the same batteries used.
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big10p View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 11:39am
Cheers for the info, fellas. Somehow I missed the schematic in the link I posted, when I scanned through the posts.

Chris: from your pics, looks like you haven't fitted any fuses? I also can't see where you've fitted the diode?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 12:52pm
Originally posted by big10p big10p wrote:

Cheers for the info, fellas. Somehow I missed the schematic in the link I posted, when I scanned through the posts.

Chris: from your pics, looks like you haven't fitted any fuses? I also can't see where you've fitted the diode?

The diode is on the output of the regulator and soldered to the wire , then insulated with a bit of heat shrink..possibly why you cant see it...

Fuses.....yes i missed them out , but im going to fit 1 between the battery and the micro ups....

generally speaking the power supply (charger) should have it own internal  fuse, and the fuse on the output will only protect against short circuits in the cable run , or from the naomi/chihiro (which should be very rare  unless you put too much voltage through it imo)

Fit them for peace of mind......

you will get a 0.6v drop across the diode this is normal......so my regulator is set to 7.8v - 0.6v = 7.2v

ive also seen mo's post about the voltage being over 9v once connected to the chihiro and the chihiro powered on .....i think this would be normal as the chihiro would be trying to charge the original battery.....The only way to really find out would be to check the voltage on a good battery in a chihiro , with the chihiro running.....i would say it would roughly the same......


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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 1:58pm
I see - thanks. I think I will just do the same as you. What type/rating of fuse is needed, between the battery and micro UPS?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 5:15pm
This is what i got:


you could possibly source the battery closer to home unless you trust batteries in the post.....the seller on ebay was only 10 minutes away from me....

for the fuse , i would go with a 5amp fuse....shouldnt need anything higher.....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote richmal Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 6:41pm
If you do this modification to the dimm board battery do the games load any faster?
Just wondering
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 7:09pm
Originally posted by terminator2k2 terminator2k2 wrote:

This is what i got:


you could possibly source the battery closer to home unless you trust batteries in the post.....the seller on ebay was only 10 minutes away from me....

for the fuse , i would go with a 5amp fuse....shouldnt need anything higher.....
Thanks for that. One last question. Big smile Do you know what size the crimp connectors (yellow ones, in your pics) are? They look like they're bigger than ones I have in stock, so will have to order some.

Originally posted by richmal richmal wrote:

If you do this modification to the dimm board battery do the games load any faster?
Just wondering  
Should load plenty faster, as the game is held on the netDIMM. It then just gets loaded onto the Naomi when it's switched on. Should basically be like having a cart of the game. Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 7:15pm
Originally posted by richmal richmal wrote:

If you do this modification to the dimm board battery do the games load any faster?
Just wondering

it keeps the last game in the dimm memory , so no need to keep loading the game on bootup.....

if you change the game, you still have to load it into memory.....so no it doesnt make loading up any faster,  it just saves your last game.....

it helps folks like me that run 1 game permantley in a cab...or if you dont change that often...


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Post Options Post Options   Thanks (0) Thanks(0)   Quote terminator2k2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 7:20pm

Quote
Thanks for that. One last question. Big smile Do you know what size the crimp connectors (yellow ones, in your pics) are? They look like they're bigger than ones I have in stock, so will have to order some.

i dont sorry.....i found them in my box of bits and bobs LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2017 at 7:26pm
Originally posted by terminator2k2 terminator2k2 wrote:


Quote
Thanks for that. One last question. Big smile Do you know what size the crimp connectors (yellow ones, in your pics) are? They look like they're bigger than ones I have in stock, so will have to order some.

i dont sorry.....i found them in my box of bits and bobs LOL
Gotta love boxes of bits and bobs. Big smile No worries, I might just order a set of assorted ones.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2017 at 12:07pm
I've almost finished building and fitting this, but the diodes I ordered must have got lost in the post, or something. Confused Now I'm having trouble finding somewhere else that sells the diode - even RS don't seem to have them. Do I have to use a 1N4008 diode, or will something else do?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2017 at 2:06pm
Looks like I have a few 1N4007 diodes on an old chassis. Will they do?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote obcd Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2017 at 4:36pm
1N4007 is fine. The last number is just the reverse breakdown voltage. In your case, it should withstand 7 - 8V. The 1N4007 can handle up to 700V if I remember well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2017 at 4:38pm
Originally posted by obcd obcd wrote:

1N4007 is fine. The last number is just the reverse breakdown voltage. In your case, it should withstand 7 - 8V. The 1N4007 can handle up to 700V if I remember well.
Cheers!
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