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Juan Maderita
Trad climber
"OBcean" San Diego, CA
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Topic Author's Original Post - Jul 17, 2015 - 02:13am PT
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DIY: How to Convert a Bosch "Annihilator" to a LiFePO4 external/remote battery pack. Triple your firepower! (triple the number of holes)
This time around, I converted two more Bosch "Annihilator" 24v model # 11225VSR / 11225VSRH rotary hammer drills (aka: rotohammers). The modification adds an electrical cord to allow for attachment of a powerful external/remote battery pack, while retaining the ability to use the factory NiCad battery. The approx. 5' electrical cord may be plugged into the battery pack worn in a waist pack. Alternately, the pack is suspended on the last/highest protection as the leader ascends with a 35' to 50' extension cord. This method lightens the drill by several pounds for one-handed drilling while on lead.
My 2008 writeup details instructions for converting a Bosch "Bulldog" model # 11213 / 11213R to SLA remote battery pack.
http://www.supertopo.com/climbers-forum/603971/Bosch-Bulldog-Convertiing-to-SLA-batteries-step-by-step
Battery technology has come a long way in the past decade. NiCads gave way to NiMH in the construction tools industry. In more recent years, Li-ion (lithium ion) seems to have dominated the market in tools and consumer electronics. All of these require special charging cycles with "smart" chargers. The hobbyists (RC cars, airplanes, drones) spend more money for LiPo (lithium polymer) batteries, which have superior Energy-Density. The LiPo batteries are lightweight, though regarded as somewhat unstable. They have been known to erupt into fire; that is not the type of battery I want bouncing around in my climbing pack!
After a 25 year history of successful conversions and experimentation with SLA (sealed lead acid, aka: "gel cell") battery packs, I've been interested in trying something more modern. One of my SLA battery packs had grown weak. It was time to replace the tired SLA's. Reading about LiFePO4 (lithium iron phosphate) on a blog for electric bicycle enthusiasts got me excited. With their high amp-hour rating in a smaller and lighter case, the LiFePO4 batteries would be a huge upgrade. More power with only half the weight!
A few hours of on line research and discussions with two engineers/techs working for LiFePO4 manufacturers/distributors led me to choose batteries from Clean Republic, two 12v "Dakota" 10 Ah.
http://dakotalithiumbattery.com/ $99 each, 2 lb. 9 oz. (same size case as a 7 Ah SLA which weighs 5.4 lbs.) There were a few reasons to go with Clean Republic - Dakota: The price was good. More importantly, these are designed to be wired together in parallel or in series. For this application, two 12v batteries are wired in series = 24v output for the Bosch Annihilator or Bulldog. LiFePO4 batteries require special circuit protection and a BMS (battery management system). The Dakotas have a BMS inside of the plastic battery case. Clean Republic sells this battery with their electric bike kits, and enthusiasts report great results. Other manufacturers could not guarantee that their circuitry would allow for connecting multiple batteries in series. Some specifically state that their batteries cannot be wired in series. One company sells a 24v LiFePO4, an easy alternative, but at a cost of $295 http://www.powerstream.com/LLLF-24v-10ah.htm
Clean Republic also sells the 12v chargers. Most sources indicate that an SLA charger will not fully charge a LiFePO4 battery, and that a special smart charger is needed for a proper charging cycle.
The Bosch standard battery for the Annihilator was a 24v, 1.7Ah NiCad model # BAT019 (discontinued?). The larger # BAT021 is 3.0Ah. Replacements with NiMH cells are available for $100.
Using a digital scale, a factory NiCad, 3.0 AH, BAT021 weighed in at 4.35 lbs. That equals 1.45 lbs. per amp hour. I also weighed the complete waist pack with 10Ah LiFePO4 batteries. At a total weight of 7.7 lbs, that equals 0.77 lbs. per amp hour. A waist pack with 7.0 Ah SLA batteries is estimated at 11.5 lbs, which would result in 1.64 lbs. per Ah. Clearly, LiFePO4 is the winner for weight savings.
LiFePO4 batteries have many other advantages:
 LiFePO4 batteries have a very constant discharge voltage. Voltage stays close to 3.2V during discharge until the battery is exhausted. This allows the battery to deliver virtually full power until it is discharged. - LiFePO
4 cells experience a slower rate of capacity loss (aka greater calendar-life) than lithium-ion battery chemistries
One important advantage over other lithium-ion chemistries is thermal and chemical stability, which improves battery safety.
Operating temperature range better than SLA or other lithiums: range -20F to 120F
Longer lifespan: 2,000 charging cycles vs. SLA's 400 charging cycles
I won’t go into the disadvantages of NiCad batteries here. There are numerous shortcomings, serious enough for me to ditch that battery technology 25 years ago. Regarding SLA’s, there are no complaints from me except for the weight factor. SLAs haven’t let me down over 25 years, a few thousand bolts, and a couple hundred new routes.
The Annihilator is easy to modify. Anyone with a few basic tools and the desire to tackle a small project can do it with the help of these photos. The first one took a couple hours. Bringing out the tools and materials ate up some time. Then, nearly an hour was wasted due to a transverse shaft (90 degrees to the other rotating components) sticking to the wrong side of the case upon opening the clamshell-like case. An on-line parts schematic was helpful in determining the proper location for a misplaced flat washer/shim. If I'd immediately recognized the problem for what it was, that the shaft was a slip fit and had lightly stuck, a lot of time and frustration would have been averted. The second Annihilator modification went flawlessly, in about 30 minutes. The transverse shaft remained on the proper side of the case, without any encouragement.
Materials list to convert an Annihilator:
5' of 14/2 (14 gauge, 2 wire) or 12/2 round rubber covered electrical cord
Female 3-prong plug
(all available at Home Depot)
Tools:
#2 (standard) Phillips screwdriver
Diagonal (wire) cutters
Soldering iron & electrical solder (rosin core)
Electrical tape
Fine-tooth hand saw (to trim corner of plastic case)
File or rasp (to notch plastic case for cord)
Round hand file (or drill motor with rotary file or 3/8" drill bit)
Materials list to make a battery pack:
Waist (fanny) pack (13"+ of unobstructed width)
2' of 14/2 (14 gauge, 2 wire) or 12/2 round rubber covered electrical cord
Male 3-prong plug for battery pack
3-prong "cheater" adapter for cover/protector from accidental short
1' of 10 gauge automotive wire, red
2' of 14 or 16 gauge wire, red
2' of 14 or 16 gauge wire, black
(4) 1/4" (.250") female F2 spade (aka: blade) connectors (aka: Faston) for 10 gauge (yellow color coded)
(4) 1/4" male spade connectors, plastic covered type, for 14-16 gauge wire
Automotive blade type fuse holder, ATC fuses 30A (ATC type is enclosed anti-spark)
2’ x 1” x 1/8” aluminum flat bar stock ( 2 pieces @ 11” each for stiffeners)
Duct tape, plastic (non-metallic)
Closed-cell foam (yoga mat material works well)
Optional: 2” webbing holster loop, 3/4” or 1” flat webbing and buckles for zipper back up
Tools:
Electrical terminal crimping tool
Soldering iron
Diagonal (wire) cutters
Phillips screwdriver
Optional: sewing machine
(to add gear loops, reinforce exit hole for electrical cord, add webbing closure to back up a blown zipper, add a hammer holster)
On the left is a typical 7.0 Ah SLA. On the right is a 10Ah LiFePO4 replacement. Same size case. More power and half of the weight.
Wiring, pre-installation. Solder all connections, except perhaps the ends of the charging pairs. The female F2 Faston spade/blade connectors were bare for soldering and are tape wrapped for insulation, hence not visible under the black tape. Don’t be misled by shadows in this photo which may give the appearance of an additional wire(s).
Aluminum stiffeners added. Lots of non-conductive duct tape. Optional to bend and contour to fit the back, as in this photo.
Batteries assembled in “series” for 24V output. Note the gray 3-prong adapter (male prongs removed) to protect from accidental short circuit. There are better (and more expensive) types of plugs available. I’m using the household type grounding (3-wire), so that polarity cannot be accidentally reversed.
Because I have several battery packs, and have built them for friends, our systems are compatible. One disadvantage of these plugs is that someone could unknowingly plug the battery pack into a wall outlet. Not sure what would happen, but I know it wouldn’t be good. Keep your pack labeled and out of reach.
Wrap in closed-cell foam. The output cord has an overhand knot which will be inside of the nylon waist pack. The knot will prevent tension on the connectors within the pack.
Waist/fanny pack with sewn hammer holster and zipper back up webbing & ladder lock buckles. Extra webbing attachment loops sewn on top flap.
Cut end loop off of the lower corner of the handle, using a fine tooth saw. Shape and smooth with a file or power sander. It is easier and neater if done prior to opening the case/housing. In this photo, the case was separated first.
Pull off the rubber end cap from the chuck. Remove 13 Phillips screws (11 long, 2 short at the chuck), using a #2 (standard / medium) screwdriver.
Carefully lift, separating the plastic case/housing. Ensure that the transverse shaft remains in the lower half of the case with the motor and other components. (See subsequent photos). Leave the case on the work surface. The components are loose inside and you don’t want to jostle them out of position. Light movement is not a problem; just don’t rotate the case.
Here’s my mistake. A screwdriver is pictured in the hole where the transverse shaft should have remained. The shaft was lightly stuck to the opposing half of the case.
Here the transverse shaft was put back into position. (Should you make the same mistake, a thin flat washer/shim is on top. Another washer/shim is below the fork, mirroring the top washer/shim).
A rotary file neatly carves a slot for the new power cord. A drill bit, approx. 3/8”, would do the job too. Or file by hand with a round file.
Carve a slot on the opposing half of the case.
Gently nibble the plastic insulation from the positive (red) and negative (blue) wires, using diagonal cutters. Clear approx. 1/2" of insulation. Separate the strands by inserting a nail to create a “hole.” Strip 1/2” to 3/4" of insulation from the ends of the new power cord. Insert each wire from the power cord into the hole (black to blue for the negative) and twist tightly. Solder. Tape thoroughly.
Note at the bottom of the photo, there is a knot tied in the synthetic fiber cords. Those fiber cords are packing/filler material to make the rubber covered cord round. Tying a bulky knot and placing the knot inside the plastic housing will prevent the power cord from ripping out of the rotohammer if tensioned. Such as might happen when the rotohammer is dropped and caught by the cord.
Check the motor armature and carbon brushes for excessive wear. This photo shows no visible wear or groove in the armature. If suspect, the carbon brushes can be replaced. Clean dust and carbon residue to prevent arcing. Gather some clean grease from splash inside the case, and add a little to the gears.
Reassemble. The case should go back together smoothly. The exception may be at the trigger and red plastic forward/reverse selector “button”. Align the button straight up and down, maybe a bit of a jiggle should fix the hang-up. If the case hangs up and doesn’t go together smoothly, start over. Ensure that the major components are correctly seated by pushing down on each of them. They are only held into their respective recesses by gravity.
The Annihilator can now be used with either source of power, the factory battery pack, or the remote waist pack.
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Ghoulwe
Trad climber
Spokane, WA
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Jul 17, 2015 - 06:00am PT
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Nice job on that Juan and a great write-up. Now I may have to re-consider upgrading from my old converted Bulldog to an Annihlator...
Eric Barrett
Spokane WA
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MisterE
Gym climber
Being In Sierra Happy Of Place
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Jul 17, 2015 - 04:39pm PT
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Cool - I remember your last thread. Nice upgrade, Juan!
What's involved in the charging set-up? I scanned the other thread, but didn't see any info on that. Inverter?
Thanks again for the instructionals.
Erik
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Juan Maderita
Trad climber
"OBcean" San Diego, CA
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Topic Author's Reply - Jul 17, 2015 - 05:32pm PT
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Hey Erik,
Charging is with a 12v "smart" lithium battery charger which puts out a special charging cycle. Clean Republic also sells the charger. An SLA charger will not give a full charge to the LiFePO4 batteries.
Will be in Baja for the weekend, trying out the new system.
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Climberdude
Trad climber
Clovis, CA
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Jul 17, 2015 - 06:28pm PT
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Very nice write up. I have one of those drills with the old (and horrible) NiCd batteries that are cooked. I may give this a try. However, I would put the male plug on the drill rather than the battery pack for safety reasons (not someone plugging it into the wall, but rather accidental short circuiting of the two prongs directly connected to the battery despite the fuse).
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Juan Maderita
Trad climber
"OBcean" San Diego, CA
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Topic Author's Reply - Sep 11, 2015 - 04:00pm PT
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Werner, Thanks for that on the Shorai's. Unfortunately, too good to be true.
The Shorai battery is a starting battery (primarily for shaving weight on motorcycles). It is only 2.3Ah, not a true 7.0Ah. Shorai uses a scheme of "equivalent" to 7.0Ah, with the rationale that LiFePo4 batteries can be more deeply discharged than lead-acid batteries. Shorai calls their rating scheme: "The Shorai PbEq AH (lead-acid equivalent) rating system". with the justification that it "allows users to compare a very different technology from lead-acid, but to still compare “apples to apples”.
So multiply the weight of the Shorai x3 to arrive at 6.9Ah = 3.03 lbs. and it adds up to heavier than a single Dakota 10Ah (2 lb. 9 oz.)
http://www.batterystuff.com/kb/frequently-asked-questions/powersports-batteries-faq/lithium-iron-faq.html
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B.Warne
Trad climber
The flip side
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Great looking system! Its been awhile now, just curious how you found performance? How many holes can you get with the new setup?
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Juan Maderita
Trad climber
"OBcean" San Diego, CA
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Topic Author's Reply - Apr 7, 2017 - 07:26pm PT
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B.Warne,
The performance is great. I've been drilling numerous 1/2" x 4" holes in granite for bolt replacement and anchors. The batteries haven't run low, so I have no actual data on number of holes.
The Bosch OEM "big" battery is 3.0 Ah, so it is at least 3x the number of holes that you can get out of the OEM battery. Perhaps far more than that, since lithium iron batteries hold their voltage until nearly depleted.
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zBrown
Ice climber
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Are any permits required?
I remember when Don Genaro and Don Juan used to do this sort thing as if by magic!
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