whites spectrum use lithium batterys ??

[angleiron]

hi i have a old spectrum but the Nickel cadmium batteries are duff the battery voltage should be 4.8v is there anybody could advise me if i used 2 lithium ion salvaged from old laptop 7.4v would it blow my detector, if so anyone got a circuit for a voltage regulator that would do the job or any better idea for the problem other than repack with new nicads or Nimh thanks for your interest .

[Carl-NC]

The Spectrum takes the battery voltage and boosts it to 8.8V, so as long as you stay below 8V you should be OK. There are a couple of electrolytic caps on the battery but they should be derated enough to handle 7.4V.

[Skippy]

A standard charge on Li-Ion's would be to 4.2V per cell, that is 8.4V for a two-cell battery. Perhaps it would be prudent to limit the charge voltage to 4.0V per cell. As a bonus, they apparently have a longer life if you don't push the charge voltage so high.

[angleiron]

many thanks for the replies, so now i can get the old girl back in the field and it will probably run a little longer than on them crapy nicads its a little heavy but still a good detector.

[Skippy]

Even if you re-built the pack with 2400 mAh NiMH's, you would be looking at double the run-time of the old NiCads.
And, now knowing the first stage is a switching regulator, you could actually make a 5-cell NiMH pack up. The current draw will be less if you have a higher voltage battery, hence giving longer run-time.

[angleiron]

hi skippy, yes tagged aa cells instead of c cells, that is in it, would give me more room in the pack for 5 nimhs they are very affordable on ebay might try both, 4 18650 Li-lon two sets in parallel, and another with Nimh. many thanks for your input .

[nickel_n]

the spectrum was my favourite detector
I solve the battery problem by using 3 sets of 4 AA 2200 mAh rechargeable batteries in parallel.

I hot glue together an 8 and a 6 cell aa battery holders and rewire it.

it fits perfectly in the spectrum's battery spot.

look at the photos.
you get hours of power with this set up

[angleiron]

good idea nickel n good job looks like i have a few options, got a few rechargables kicking about i have had the spectrum (rainbow coil) over 15 years had ace 250 but still prefer the spectrum, thanks very much for sharing your fix.

[TH'r]

hi i have a old spectrum but the Nickel cadmium batteries are duff the battery voltage should be 4.8v is there anybody could advise me if i used 2 lithium ion salvaged from old laptop 7.4v would it blow my detector, if so anyone got a circuit for a voltage regulator that would do the job or any better idea for the problem other than repack with new nicads or Nimh thanks for your interest .

Attached is a photo of the battery pack mod I did to keep my Eagle Spectrum going. I removed all four contact springs cemented the access cover on. Then, cut a hole in it’s top and nested in a battery holder from Mouser secured with VHB tape (the leads of which are soldered to the original terminals of the pack).

[angleiron]

Attached is a photo of the battery pack mod I did to keep my Eagle Spectrum going. I removed all four contact springs cemented the access cover on. Then, cut a hole in it’s top and nested in a battery holder from Mouser secured with VHB tape (the leads of which are soldered to the original terminals of the pack).
[ATTACH]50178[/ATTACH]

hi TH'r excellent job, spoiled for choice at the moment im grafting 2 1850 li-lon tried 4 but just to tight will post when done, yours uses 5 batteries or 10 at 6v sorry dont know what a mouser is, many thanks for your post.

[TH'r]

hi TH'r excellent job, spoiled for choice at the moment im grafting 2 1850 li-lon tried 4 but just to tight will post when done, yours uses 5 batteries or 10 at 6v sorry dont know what a mouser is, many thanks for your post.

I bought the battery holder from Mouser Electronics(USA), part # 12BH364-GR. Just checked and found that part # now to be obsolete. They suggest part # 12BH364A-GR.

[Skippy]

As it's clearly possible to fit ten AA cells inside the battery box, yet another option is to make a 5-cell pack with cells paired up. That is : make five pairs of cells, then join those pairs in series to make a '6 Volt' pack of double the capacity. You would really be needing tagged cells, properly soldered together, to do this, as battery holders are not suitable for this kind of modification. I wouldn't wire them up as two 5-cell packs in parallel. It's also good practice to fit a regular pn silicon diode, like a 1N4001, across each cell ( or cell-pair) to limit the reverse charge voltage when a pack is heavily discharged.

[angleiron]

As it's clearly possible to fit ten AA cells inside the battery box, yet another option is to make a 5-cell pack with cells paired up. That is : make five pairs of cells, then join those pairs in series to make a '6 Volt' pack of double the capacity. You would really be needing tagged cells, properly soldered together, to do this, as battery holders are not suitable for this kind of modification. I wouldn't wire them up as two 5-cell packs in parallel. It's also good practice to fit a regular pn silicon diode, like a 1N4001, across each cell ( or cell-pair) to limit the reverse charge voltage when a pack is heavily discharged.

hi skippy, do you mean link the batteries with the 1n4001 dose that apply to li-lon batteries to, i have just linked mine, 7.4v but in reality it ended up at 8.2v for some reason tried the pack it works well dont know how long it will last not tried it in the field yet should be better than crappy nicads.

[angleiron]

dont know what happened to the pics i will try again

[Skippy]

"Do you mean link the batteries with the 1N4001 diode?"
No, the diode goes from + to - on each cell in the pack.

"Does that apply to Li-lon batteries too?"
No, if you've reverse charged a Li cell, you've clearly done something wrong. This is what battery protection circuits are for.

"I have just linked mine, 7.4v, but in reality it ended up at 8.2v for some reason"
3.6 Volts or 3.7 Volts is the typical cell voltage when you are discharging it. When you charge it, most standard chargers charge up to 4.2 Volt per cell, making the two-cell pack have 8.4 V direct from the charger. I suggested ( in an earlier post ) deliberately under-charging the Lithium battery to 4.0 Volt per cell. But if you are using a standard commercial charger, you cannot normally do that.

"I tried the pack, it works well"
Good.